electric bike repair guide checking hall sensors motor speed controller and battery charger

8/18/2019 Electric Bike Repair Guide Checking Hall Sensors Motor Speed Controller and Battery Charger

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Check Hall Sensors

If the phase wires seem to be intact, then the next thing to check is the Hall sensors if the

motor is brushless. The Hall sensors should switch between high (6 ! and low (" ! as the

motor is spun. The Hall sensors need to be supplied with power from the controller in order to

do this, so #ou ha$e to plug the controller into the batter# and to the Hall sensor cable andswitch it on. %ou don&t need to plug the motor phase wires in. 'se the multimeter on $oltage

setting to measure between each of the blue, green, and #ellow Hall sensor wires and the red

Hall sensor wire while spinning the motor b# hand. oltage should switch between high (6 !

and low (" ! as the motor is spun. If an# Hall sensor wire $oltage does not switch, if it is stuck

on 6 or " , then that Hall sensor ma# be damaged and need replacing. Check that the

controller is suppl#ing the $oltage to the Hall sensors b# measuring the $oltage between the

black and red Hall sensor wires. It should be around to )* + if it is " , then there is a

problem with the controller.

In a brushed motor, it&s more difficult to check the brushes. The motor has to be disassembled

and examined. If there is a problem with #our brushed motorfor example, it has lost power

and is running hottest the windings as indicated earlier, and then follow the disassembl#

procedure mentioned in Section -..6. ook for burn marks caused b# sparks arcing or buildup

of carbon dust from the brushes on the contactor plate. /isassemble the brushes, and check

for damage. 0ake sure that the# slide smoothl# inside their housings.

Check Hall Sensor Se1uence and Timing

To check the se1uence and orientation of the Hall sensors, there is another test #ou can

perform. This one re1uires building a small 2/ board (3igure -.)-!. The idea is to $isuali4e theopen5close of the Hall sensors with 2/s. If there is a time when all 2/s are either on all at

once or off all at once, then the motor has 6"degree Halls. If the se1uence shows onl# two

2/s on at an# one time, then the motor has )*"degree Halls. %ou can use this to set the

7umper settings in the controller for what t#pe of motor #ou ha$e. The 2/s should light up in a

se1uence one after the other when the# are in the correct orientation. %ou can use this to find

the correct orientation, and this will narrow down the 86 possibilities when tr#ing to match a

motor and controller wiring.



3I9':2 -.)- Circuit diagram of the Hall sensor checker and the finished item on a copper strip

board.

). 9et a piece of bread board or copper strip board, three different colored 2/s, three )k ;

resistors, and a < batter# or power adapter.

*. =ext, connect the circuit as shown in 3igure -.)-.

8. Cut two lines through the copper strips.

. >osition the resistors across one of the cut traces and the 2/s across the other cut trace in

series with the resistors.

-. ?t the positi$e end of the 2/s, the side without the flat part, tie all the strips together.

6. ?t the negati$e side of the 2/s, after the resistors, add wires that lead to the Hall sensor

wires. ?dd crocodile clips, or whate$er, to attach to the Hall sensor wires.

@. Tie the positi$e end of the power suppl#, through two parallel )k; resistors, to the 2/s.

A. ?ttach crocodile clips to the negati$e of the power suppl# so that #ou can hook it to the

black Hall sensor power lead.

<. ?ttach a lead with a crocodile clip to the positi$e end where all the 7unctions meet. This will

hook onto the positi$e Hall sensor lead.

-.*. How to Check the Throttle

There are two t#pes of throttles used on electric bic#cles, a potentiometer or a Hall throttle.

3ollow this procedure to test an unknown throttle t#pe or to check for a damaged throttleB



). 3irst, use a multimeter to test the throttle. Check the resistance across all the pins (three

combinations!. Check the resistance while #ou twist the throttle and look for changes.

*. If there is a change in resistance when #ou twist the throttle, then this is a potentiometer

based throttle. If not, then this is either a Hall throttle (likel#! or a broken throttle.

8. =ext, find an old mobile phone charger or batteries, around , and wire this up to the

throttle, red throttle wire to positi$e and black throttle wire to negati$e. >ut a )""; resistor in

the circuit on one of the power suppl# leads. If #ou don&t know the polarit# of the phone

charger, then use a multimeter to polarit# check it (see Section -.).)!.

. Set #our multimeter to the *" setting, and measure between the green sense wire and the

black negati$e wire or red positi$e wire and twist the throttle while #ou do this.

-. If there is a $oltage change, then this is a working Hall throttle. If #ou don&t see an# changes

on either of these tests, then the throttle is dead.

-.*.- How to Check the Controller

The two main faults that can happen with the controller are that the fieldeffect transistors

(32Ts! can short circuit or the capacitors can blow. To check that the capacitors in the controller

are not short circuited, connect a multimeter in resistance mode across the controller&s

positi$e and negati$e batter# connections. The resistance should be infinite or $er# high. To

check that the capacitors ha$e not been blown open circuit, connect the controller to the

batter# while a $oltage meter is connected across the same controller batter# power leads.

There should be a small spark as the capacitors charge up, and the $oltage should rise 1uickl#

to the batter# $oltage. Then disconnect the batter#, and the $oltage should drop slowl# to " .If the $oltage drops instantl# to " , then it&s likel# the capacitors are blown and need replacing.

=ext, test that the 32Ts in the controller ha$e not been shorted. %ou need to test resistance

between each phase wire (motor side! and each power wire (batter# side!. There are six

combinations. The resistance should be high or infinite on all the combinations (3igure -.)6!. If

an# show a resistance lower than ),""" ;, then there is a short circuit, and the controller will

need some work to fix it.

-.8 0aintaining 2lectric ic#cle Components

-.8.) 0aintenance of a atter# Charger

Dhen plugging in an electric bic#cle batter# charger, there is usuall# a recommended se1uence

of doing things depending on the t#pe of batter# and charger, so read the manual if #ou ha$e

one. The opencircuit $oltage of some batter# chargers will EfloatF up much higher than the

batter# $oltage if it is plugged into the main circuit first with no load before plugging it into the

batter#. This is true with man# of the older car batter# chargers. Then, when the batter# is

plugged into the charger, the $oltage difference and low resistance cause a spark to 7ump

across the connectors and partiall# melt them. The spark also can damage capacitors in the

charger. It therefore used to be ad$ised to plug into the batter# first before plugging into the

main circuit. Howe$er, most modern chargers will onl# float up to the end of charge $oltage



when plugged into the main circuit if not connected to a batter#. 2 packs are much higher

$oltage than car batteries, and when the# are plugged into the batter# first, the capacitors in

the charger fill up so 1uickl# that the# cause a spark. It therefore would be a better option to

plug an electric bic#cle charger into the main circuit first before plugging it into the batter#. %ou

usuall# can hear the spark when the wrong connection is made first, so it&s best to connect

whate$er end first that doesn&t cause a sparking noise. It also might sa# in the manual which

end to connect first.

3I9':2 -.)6 Checking the 32Ts. In this figure, the blue phase shows no sign of short circuit to

the positi$e suppl# with )" 0; of resistance.

?$oid taking the charger with #ou on #our electric bic#cle because it ma# get damaged. If #our

charger is being bashed around inside a shoulder bag, components ma# come loose inside the

case. It&s best to ha$e two chargers, one at the destination and one at home.

-.8.* Hub 0otor 0aintenance Checklist

er# few things are needed to maintain a hub motor because the# are $er# reliable.

Tire >ressure

Check the tire pressure regularl#. Take action if it is dropping, before #ou get caught out b# a

flat.

Spokes



Check the spokes regularl#+ look out for snapped spokes or loose spoke nipples. Tighten and

replace the spokes as needed. Spokes usuall# snap at the hub. It is sometimes possible to

change a broken spoke without ha$ing to take off the wheel. Gust unscrew the old one, lea$ing

the nipple held in place b# the inflated inner tube. Then thread the new spoke through the

hub, and turn the nipple around and up onto the spoke. The spoke ma# need to be bent slightl#

to get it into position.

earings

If #ou feel the wheel bearings break, then stop riding immediatel#+ otherwise, #ou might cause

damage to the Hall sensors or magnets. Change the bearings when the# wear out (e$er# ) to *

#ears! or whene$er the hub motor is open for other maintenance. See Section -.. for how to

open up a hub motor and Section -..< for how to change the bearings on a hub motor.

:ims

Check the rims for damage, buckling, and weld damage or corrosion. If #ou are using rim

brakes, then clean the rubber residue off the rims e$er# few weeks.

Connectors

Check for contact corrosion caused b# sparking and melting caused b# high current flow.

-.8.8 atter# 0aintenance Checklist

atteries are a consumable item and will #ield a ser$ice life based on how well the# are

treated.

?lwa#s keep the batter# topped up.

It is generall# good for batteries to be full# charged, especiall# leadacid batteries. Topping up

lithium batteries also enables the 0S to balance the cells.

Check that the charger is putting out the correct $oltage.

Sometimes charger $oltage can be too low, and this won&t acti$ate the 0S balancing function

at the end of batter# charging. 3or example, a A i3e> batter# charger should put out

6).- .

/on&t lea$e the batter# unused for more than a month.

ithium cells don&t ha$e a $er# fast selfdischarge, usuall# around ) percent a #ear. Howe$er,

the 0S will drain the batter# at a faster rate than this. ? number of people ha$e left their

batteries o$er winter while not using their bic#cles, onl# to come back to a nonfunctional pack

in spring because the 0S drained the pack down to " . To pre$ent this, it&s best to either

unplug the 0S or put the pack on its charger using a @da# timer plug to keep it topped up for

a short period once e$er# week.

/on&t o$erdischarge, short circuit, o$erheat, or drop #our batter#.

/on&t seriesconnect with different capacit# or stateofcharge batteries.



/on&t parallelconnect with different $oltage packs.

/on&t put things such as bic#cle locks in the same container as the batter#.

Thermal 0anagement

The batteries shouldn&t heat up much during operation+ otherwise, there is something wrong.

Sometimes it can be difficult to monitor temperature b# touch if the batter# is in a strong box.

0onitor batter# temperature on a new batter# or new controller or when an# component

changes on the electric bic#cle. /on&t exceed "JC in e$er#da# use.

Current /raw

0ake sure that #ou do not exceed the peak or continuous current rating of the batteries.

0onitor this at least on a new build or when an# component changes on the bic#cle, if not allthe time.

oltage /rop (min!

It&s easier to measure batter# $oltage than current. The $oltage should not drop far below the

nominal working $oltage of the batter#. 0onitor this at least on a new build or when an#thing

changes on the bic#cle, if not all the time.

Capacit#

To test the batter#, #ou might want to do a long ride to drain the batter# and measure capacit#and range of the bic#cle. It&s not good to )"" percent discharge the batter# on a regular basis.

It&s good to do this when #ou first get the batter# and then once e$er# #ear to check that #ou

still ha$e the full capacit#.

Insulation and >adding

Check that the batter# insulation and padding is not damaged. It can become damaged b#

attrition if the batter# bounces around a lot. :epair the damage, and use a more secure batter#

mounting to pre$ent it from happening again.

Corrosion on Cells

Check for corrosion. Corrosion or a deposit around the cells usuall# means that either the cells

are leaking electrol#te, ha$e $ented electrol#te at some point, or are being exposed to water.

-.8. Controller 0aintenance Checklist

/on&t use lots of power when mo$ing slowl# or when stationar#+ this will blow the capacitors.

/on&t ride in sand or thick mud for long periods+ this will o$erheat the controller.

0ake sure that the controller is not getting hot.



0ake sure that the throttle cable is protected from rain. /on&t allow insulation tape to collect

water around the throttle cables. 'suall# the# are splashproof to some extent.

0ake sure that none of the wires gets worn or trapped within the bic#cle frame, suspension,

or batter# mounts.

-.8.- ic#cle 0aintenance

Check brake pads once e$er# 8 months for disc brakes and e$er# month for rim brakes.

Check brake ad7ustment once e$er# 8 months for disc brakes and e$er# * weeks for rim

brakes.

Check batter# mounts for signs of bending or mo$ement under the weight of the batteries

once e$er# 8 months.

Check headset bearings for signs of excessi$e pla#.

Check lights e$er# month for damage or mo$ement.

-. :epairing 2lectric ic#cle Components

-..) How to :epair a Controller with roken 32Ts

roken 32Ts result in a fault that usuall# occurs in a controller operating near its $oltage limit.

This problem can be fixed, the replacement parts are not expensi$e, and it sa$es #ou the cost

of bu#ing a new controller. %ou don&t alwa#s need to replace all the 32Ts, onl# the ones that are

shorted out. The controller usuall# has groups of 32Ts ganged in parallel to increase thecurrentcarr#ing capabilit# (3igures -.)@ and -.)A!. This means that the 32Ts short circuit in

groups. 'suall#, a controller will ha$e multiples of three 32Ts for the phases. 2ach phase usuall#

will ha$e two 32Ts for switching positi$e and two for switching negati$e. ? controller will either

contain 6, )*, or )A 32Ts depending on how powerful it is. If onl# one short circuit is detected

between phase wires, then #ou can open the controller and trace the broken group of 32Ts

causing the short circuit b# continuit# tracing the wires back from the phase wire to the group

of 32Ts.



3I9':2 -.)@ 'nderneath the circuit board, where the legs of the 32Ts come through. The big

masses of solder are the main power rails and the motor phase rail.

3I9':2 -.)A The 32Ts. There are four 32Ts for each phase, two parallel to switch positi$e and

two parallel to switch negati$e.

There are lots of different 32Ts a$ailable with different current and $oltage specifications.

Therefore, when #ou bu# the replacement, #ou ma# want to go for an upgrade at the same

time because this will allow #our controller to deli$er more current and be more powerful. So

#ou ma# need to decide that #ou 7ust want to replace the broken 32Ts or upgrade all the 32Ts.The best1ualit# 32Ts are I:))"&s. These can deli$er )"" ? and work at )"" . Table -.8 shows



the other choice of 32Ts a$ailable and their currentcarr#ing capabilit#. Dhen #our replacement

32Ts arri$e, it&s a simple matter of desoldering the old 32Ts and soldering in the new ones.

Howe$er, it is a complex soldering operation and re1uires a little skill and coordination with a

solder sucker and a powerful K"D soldering iron. :eplacing 32Ts on a controller will be the

same as replacing 32Ts on a 0S. Similar instructions will appl#. Thanks to :ichard 3echter in

San 3rancisco for working out this repair procedure.

T?2 -.8 32T Selection 9uide

). pen the controller.

*. Continuit# trace the shorted phase back to the circuit board, and track down which 32Ts

ha$e short circuited. It ma# be all of them or 7ust one phase group.

8. /ecide to upgrade all the 32Ts or 7ust replace the broken ones.

. rder the 32Ts #ou need.

-. 'nscrew the 32Ts from the heat sink.



6. :emo$e the plastic insulating slee$es and washers that insulate the 32Ts from the screws.

Leep the screws and insulators safe.

@. Snip off the dead 32Ts at the legs, lea$ing behind as much leg as possible so that #ou can

remo$e them later with pliers.

A. =ow #ou need to remo$e the leg left behind and clear the holes of solder to insert the new

32Ts.

/ebulk the mass of solder to make it easier to remo$e the 32T legs (3igure -.)<!. 'sing the

soldering iron, heat up the mass of solder around the stumps left from the legs of the dead

32Ts. /on&t lea$e the iron on the board for more than A seconds or #ou might lift a track from

the surface of the board, which is difficult to replace. Suck up the solder using the solder sucker

and iron.

3I9':2 -.)< This shows the gap where the dead 32Ts ha$e been remo$ed. /ebulk the mass of

solder so that #ou can remo$e the dead 32T legs.

:emo$e the legs left from the dead 32Ts using twee4ers and the soldering iron or the solder

sucker. 9entl# pull on the stump while melting the solder around it. /on&t use force, or it will

lift a track on the board. It should come out easil# when the solder is melted all the wa#

through. Sometimes #ou can poke the leg out+ sometimes #ou can solder suck it out. 'se

whate$er it takes to remo$e the leg stumps, but don&t lift a track. e especiall# careful on the

third leg, the one that is not attached to a great lump of solder. The traces here are eas# to pull

out. 'se a lower temperature setting if #ou ha$e a temperaturecontrolled soldering iron.

Clear the holes left b# the dead 32Ts using the solder sucker. Suck from one side of the board

while heating from the other. >oking through with a wire while heating sometimes helps, too.



<. end the legs on the new 32Ts o$er in the same wa# as the other 32Ts.

)". >osition the new 32Ts in the holes in the circuit board.

)). Screw all the 32Ts back onto the heat sink. It&s best to screw the 32Ts into the heat sink first,

as a guide for soldering, because if #ou do it the other wa# around, the# might not line up withthe heat sink properl#.

)*. Solder the new 32Ts into position. If #ou find it difficult soldering with the heat sink in the

wa#, then 7ust do one leg on each new 32T to hold it in place, and then remo$e the heat sink

and solder all the other legs properl#. e careful not to accidentall# connect neighboring traces

or legs with solder.

)8. ?dd loads of extra solder back to the main busbars to beef up the currentcarr#ing

capabilit#.

). ?dd extra thermal paste to the 32Ts, and then fix them onto the heat sink for the last time.:emember to use the insulating slee$es and washers on the screws.

)-. If #ou remo$ed a trace during this process, follow where it went, and solder a 7umper lead

to repair it. If it was on the third leg, then it will lead to the gate resistor. %ou can solder a

7umper lead from the 7umper resistor.

)6. 0easure the resistance again between all the phases and each power wire. 0ake sure that

there is no short circuit.

)@. Check that the gate resistors are working properl# (3igure -.*"!. Dhen a 32T blows, it

sometimes takes out its gate resistor. 'se a multimeter to resistance test between the third

pins on each set of 32Ts. This should read *" ;. 2ach gate resistor is )" ;. The resistors blow

open circuit, so if there is a problem, the resistance will be much higher than )" ;. The gate

resistors are shown in 3igure -.*" and are usuall# located close to the 32Ts that blew. %ou can

continuit# check to make sure because it will be connected to the third leg of the 32T. If the

gate resistor blew, then chances are that the gate dri$e transistor also blew, and these are

difficult to test.



3I9':2 -.*" Here, the gate resistors are $isible. These ma# need to be replaced as well. The

gate resistors are connected to the third leg of the 32Ts.

)A. :eplace an# blown resistors with new ones.

)<. Check the board for stra# pieces of solder that could cause short circuits.

*". If there are big deposits of solder flux around the traces, then carefull# scratch them awa#

with a small screwdri$er. Solder flux can be slightl# conducti$e and could cause problems.

*). Dhen finished (3igure -.*)!, put the controller back into its )) enclosure, and test it on the

bic#cle. 3or testing, it is best to use a currentlimited suppl#. %ou can do this b# putting a light

bulb in series with the batter# (e.g., slot an 0:)6 )"D bulb into the fuse holder!. If it still

doesn&t work and #ou are sure that #ou did e$er#thing right, then probabl# the gate dri$er chip

has blown too.

**. If the test is successful, then put the controller back on the bic#cle and clean up. If the test

was not successful, then replace the gate dri$er transistor as in the next section.

-..* :epairing a Controller with roken 9ate /ri$e Transistor

Dhen #ou replace the 32Ts on a controller #ou sometimes ha$e to replace the gate dri$er

transistor as well. If a gate resistor blew, then chances are that this is the case. :eplacing the

gate dri$e transistor is a $er# difficult soldering 7ob because it is surfacemount technolog#. This

repair will re1uire two soldering irons, a finetipped iron and a temperaturecontrolled iron.



3I9':2 -.*) This side $iew shows the capacitors and all the 32Ts.

). ocate the gate dri$er chip. The boards are usuall# split into thirds for each of the three

phases, so it will be near the 32Ts that blew. The most common gate dri$er chip is the I:*)").

This is what is used on the Cr#stal#te ) and * controllers.

*. u# a replacement I:*)"). The# come in both surfacemount and chip forms. The surfacemount form is easiest to use.

8. :emo$e the dead chip. 'se two soldering irons at medium heat, not tinned, and position

them on the legs on either side of the surfacemount chip. Dait until the solder melts, holding

it to the board, and then mo$e it awa# from the solder pads with the irons. 0o$e it to an

uncluttered area of the board, and then retract the soldering irons. Hopefull#, the chip won&t

stick to something else on the board as the solder sets. :emo$e it when it is free.

. 0ake sure that none of the solder pads are shorted. Clean up the solder pads b# gentl#

melting the solder and sweeping it with the iron.

-. Solder the new chip in place.

If #ou ha$e a surfacemount chip, then position it on the solder pads, and heat the legs

indi$iduall# with the iron. ? piece of wire wrapped round the soldering iron called a stinger can

help with soldering the little legs of the surfacemount chip. e careful not to short circuit the

legs+ this is delicate work. 'se a magnif#ing glass if needed.

If #ou ha$e a throughhole chip, then #ou will ha$e to fashion something like the spider

shown in 3igure -.**. Solder wires to the solder pads first and then to the chip legs.

6. Continuit# check between neighboring legs to check for short circuits.



3I9':2 -.*8 Capacitors are 7ust connected across the main negati$e and positi$e suppl# rails,

as shown from underneath.

3I9':2 -.* :eplacement of one capacitorsame capacit#, same or higher $oltage.



3I9':2 -.*- =ote the burnedout trace repaired b# careful placement of a blob of solder to

7oin the broken ends.

3I9':2 -.*6 :eplacement of the other capacitor. Datch out, the# can still fit back in the case.

). Snip off the dead capacitor, and pick off an# debris from the circuit board.

*. ook to see if there are an# melted traces on the board that need repairing (see 3igure -.*-!.

8. If there are melted traces, then #ou will need to solder in a makeshift 7umper wire to replace

the broken trace. The 7umper(s! wire should connect the places that are no longer connected



b# the broken trace. This ma# re1uire some skillful soldering, but if much of the board is

destro#ed, the damage ma# be irreparable.

. =ext, snip off the dead capacitors, lea$ing as much leg behind as possible.

-. 'sing the soldering iron, heat up the mass of solder around the stumps left from the legs ofthe dead capacitors. /on&t lea$e the iron on the board for more than A seconds, or #ou might

lift a track from the surface of the board, which is difficult to replace.

6. Suck up the solder using the solder sucker and iron.

@. :emo$e the legs left from the dead capacitors using twee4ers and the soldering iron. 9entl#

pull on the stump while melting the solder around it. /on&t use force, or it will lift a track. It

should come out easil# when the solder is melted all the wa# through.

A. Clear the holes left b# the dead capacitors using the solder sucker. Suck from one side of the

board while heating from the other.

<. 3ind the best location for the capacitors in the board. 0ake sure that the capacitors don&t

pre$ent the case from sliding back on to the board (see 3igure -.*6!. 0ake sure that no traces

touch the case. The capacitors can go an#where in the case where there is space to fit them,

but it&s best to keep the wires short.

)". >ut the capacitor legs through the holes, and solder them in position

)). ?dd loads of extra solder back to the main busbars to beef up the currentcarr#ing

capabilit#.

)*. 9lue down the capacitors to stop them from $ibrating.

)8. Close the case and finish.

-.. pening 'p a rushless, =ongeared Hub 0otor

The brushless gearless motor is the simplest and easiest to disassemble. It has onl# four main

parts. The stator is the big wirewound centerpiece in 3igure -.*<. This is fixed to the axle and

is stationar#. The wheel housing hub with the magnets is around the outside of this part, and

the co$er plates all rotate. See 3igures -.*@ through -.*<.

). :emo$e both side co$ers from the motor. It ma# be slightl# easier to remo$e the gear

cassette from the right side co$er before remo$ing the co$er. %ou need a gear puller to remo$e

the gear cassette.

3it the gear puller, and use a wrench on it to unscrew the gear cassette.

9entl# unscrew all the bolts holding the side co$ers in place. e careful not to shear off the

bolts.



3I9':2 -.*@ Inside, the nongeared brushless hub motor is $er# simple. Here is where the wires

enter the hub. The inside (stationar# part! is the stator+ the outside (rotating! part is the

magnet ring.



3I9':2 -.*A The other side looks the same, but #ou can&t see the wires entering the hub.

3I9':2 -.*< Here is the stator remo$ed from the magnet ring.

Carefull# pr# open the side co$ers e$enl# all along the seam with a knife or screwdri$er.

The co$ers should pop out of the wheel housing as the magnet ring comes off the ring in the

side co$er.

Then there should be enough space to get #our fingers behind the co$er and pull it off. >ull

the co$er and bearing off the axle until the side co$er is free. /o this to both side co$ers.

*. =ext, get the stator out of the hub magnets. The stator is the middle part attached to the

axle. The magnets are $er# strong, so #ou need a lot of force to achie$e this. e careful not to

trap #our fingers because the magnets can pull on the stator $er# 1uickl#. ?lso be careful not to

fall o$er while #ou do this.

>ut the co$erless hub motor on hard ground with the axle and rim touching. If #ou remo$e

onl# one side co$er, then the open side of the motor must face up.

Step on one side of the wheel rim while the axle contacts the ground.

The opposite edge of the wheel will be sticking in the air. To get the stator out, step on the

other side of the wheel and use #our weight to push down on both sides of the wheel while

the ground holds the stator. It should pop out as soon as #ou get awa# from the action of themagnets.



Take the stator awa# from the magnets.

-..- :eassembl# of the rushless, =ongeared Hub 0otor

). >ut the stator back into the hub. e careful that #ou don&t get #our fingers damaged while

#ou do this because the magnets are extremel# strong. >utting the stator back in is basicall#the re$erse of step * abo$e, taking it out.

>ut the co$erless hub wheel on the ground, and stand on opposite sides of the rim.

Hold the stator in the middle with the axle touching the ground.

Slowl# lift the rim into the stator while using #our weight to pre$ent $iolent mo$ement b# the

magnets that ma# cause damage. The stator will pop back into position between the magnets.

*. >ut the side co$ers back on.

Slide the side co$er bearing back onto the axle.

The stator will be off center, attracted b# the magnets. Center the axle b# slotting the magnet

ring o$er the ring in the side co$ers.

8. >ut the bolts back into the side co$ers. It ma# be difficult to tighten the bolts because

tension in the spokes can stretch the magnet ring out of alignment with the co$er plate bolt

holes. %ou ma# ha$e to loosen all the spokes in order to match up the holes in the co$er plate

with the holes in the magnet ring. %ou need a spoke wrench to loosen the spokes.

. 3asten the bolts. e careful not to shear off the bolts when tightening them.

-. Then retension the spokes.

-..6 pening 'p a rushed Hub 0otor

The brushed hub motor is a little more complicated to disassemble because the brushes are

springloaded. It consists of four main partsB the hubmounted stator that rotates, the side

co$ers that rotate, and the magnet ring mounted on the axle with the brushes, which is

stationar#. In this respect, it is opposite to the brushless motor in that the positions of the

stator and magnets are different.

:emo$e both side co$ers from the motor. It ma# be slightl# easier to remo$e the gear cassette

from the right side co$er before remo$ing the co$er. %ou need a gear puller to remo$e the gear

cassette.

). 3it the gear puller, and use a wrench on it to unscrew the gear cassette.

*. 9entl# unscrew all the bolts holding the side co$ers in place. e careful not to shear off the

bolts.

8. Carefull# pr# open the side co$ers (3igure -.8"! e$enl# all along the seam with a knife or

screwdri$er. e careful not to slip and damage the windings. Sometimes the windings areprotected b# a plastic shield for this reason.



. The co$ers should pop out of the wheel housing as the magnet ring comes off the ring in the

side co$er.

-. Then there should be enough space to get #our fingers behind the co$er and pull it off. >ull


Sometimes the# are stiff and re1uire extra force or le$erage. Dhen the co$ers are off, it shouldlook something like 3igures -.8) through -.88. ?t this point, #ou can access the bearings.

3I9':2 -.8" e$er the side co$ers off. e $er# careful not to slip and damage the windings.

). n the brushed motor, it is not ad$isable to remo$e the stator from the magnets because

the brushes are springloaded and are $er# trick# to get back in during reassembl#. It is also

difficult to find replacement brushes. n the brushed motor, the magnets are in the center, as

shown in 3igure -.8*. The magnet ring can onl# be taken out of the hub on one side.

*. To remo$e the magnet ring, use the Estep onF techni1ue described earlier. 0ake sure that

#ou ha$e the #ellow brushholding plate side in 3igure -.8) facing the ground and the magnet

side facing up. Step on one side of the wheel rim with the axle touching the ground. Then step

on the other side to push the inner magnet ring and axle assembl# out of the hub.

8. :eassembl# is difficult and ma# re1uire #ou to tape the brushes into the holders while #ou

put the magnet ring back into the stator.



3I9':2 -.8) This side shows the windings and the rear of the contractors. The bearing is $isible

in the center of the co$er plate. Holes ha$e been drilled in this plate for heat dissipation.

3I9':2 -.8* This side shows the magnets attached to the axle and the connections to the

brushes. The bearing is $isible in the co$er plate.



3I9':2 -.88 This $iew shows the inner workings. ne of the two brushes is $isible. The brush

skims o$er a disk of flat copper contacts on the other side of the #ellow board. This is what

does the commutation in the brushed motor.

. 'se the Estep offF method $er# carefull# to ensure that the magnet ring doesn&t hit the

contactor plate with force because this might cause damage.

-. Take the tape off the brushes using twee4ers from the other side.

6. >ut the co$er plates back on.

@. Screw the bolts back into the co$er plates to secure them.

-..@ pening 'p a rushless, 9eared Hub 0otor

The geared brushless motor has onl# one side co$er, and the motor windings are hidden inside

an inner motor compartment. This motor has man# gears and mo$ing parts and is more

complicated than the nongeared t#pes. 9eared motors are not suppose). 'nscrew the hub

bolts.

*. Take off the side co$er (3igure -.8!.

8. 3rom the other side, hit the axle with something to push the motor unit out of the hub

(3igure -.8-!.

. =ow, both bearings are accessible (3igure -.86!.



3I9':2 -.8 'ndo the bolts and le$er the side co$er off.

3I9':2 -.8- Hit the axle from the other side with something, and the inner motor will pop out

of the hub.

-. To access the windings and Hall sensors, open the back of the motor unit. 'ndo the bolts,

and it should pop open (3igure -.8@!.



6. :eassembl# is 7ust the re$erse of this disassembl#.

3I9':2 -.86 Here #ou can see the hub bearing and the planetar# gears on the motor+ the other

bearing is in the side co$er.

3I9':2 -.8@ Dhen #ou open the other end of the inner motor, #ou access the Hall sensors,

windings, and magnets.

-..A :eplacing Hall Sensors in a rushless, =ongeared Hub 0otor

The Hall sensors usuall# need replacing if #ou spin the motor without securing it properl# and

wrap the wires around the axle. Sometimes corrosion can cause broken Halls, but usuall# the#

are coated in silicone, so this is rare. 'suall# it is the wire that breaks, and #ou should eliminate



this possibilit# first before #ou open up the hub motor. The Hall sensors #ou need are the

bipolar latching t#pe with an open collector output, something such as SS"?, SS), or SS66?.

). pen up the motor as described in the preceding section.

*. 2xamine the Hall sensors for damage. ook for broken wires or corrosion. 3ind the sensor(s!that need replacing.

8. The Hall switching test in Section -.*.8 can be used to decide which Hall sensors are broken.

%ou don&t ha$e to replace all the Hall sensors if onl# one is broken. 3ollow the wiring color of

the broken, nonswitching sense wires back to the motor to find the broken Hall sensors.

. :emo$e the broken Hall sensors an# wa# that is possible (3igure -.8A!. It is sometimes

possible to melt the hot glue holding a sensor in position and pick it out. ther times #ou ma#

ha$e to destro# it to get it out. Clean an# debris from the notch in the stator.

3I9':2 -.8A The stator of a brushless motor showing the position of the Hall sensors.

-. Connect the new Hall sensor. This is a delicate 7ob, and it&s easier to solder wires onto the

sensor first and then solder those wires onto the motor leads. 2ach Hall sensor should ha$e a

positi$e suppl# (red!, negati$e suppl# (black!, and a sense wire.

6. =ow glue the Hall sensors into the notches where the old sensors were. /on&t get the

positions of the sensors and their colors mixed up.

@. 0ake sure that all the wires are shielded from the inside walls of the rotating hub. Hot glue

them in place, if necessar#.

A. :eassemble the hub as described in the preceding section.



-..< :eplacing the earings in a Hub 0otor

The bearings wear out in about a #ear of use on some of the big hub motors. It is important to

know how to change them because #our local bic#cle shop won&t know. The replacement

bearings ma# be of different si4es for each side of the hub. n the M- motor, the bearings are

6""- on the left and 6"" on the right. If #ou don&t know what si4e bearings to use, there arethree measurements #ou ha$e to take before #ou can order a replacementsB the inside

diameter, the outside diameter, and the thickness. 0ake these measurements with a $ernier

caliper on the shaft, co$er plate hole diameter, and thickness. The bearings usuall# ha$e the

part number on them, but the# are sometimes destro#ed too badl# to read.

). :emo$e the gear cassette from the hub. %ou need a gear puller to remo$e the gear cassette.

3it the gear puller, and use a wrench on it to unscrew the gear cassette.

*. :emo$e both side co$ers from the motor.

'nscrew all the bolts holding the side co$ers in place. e careful not to shear off the bolts.

Carefull# pr# open the side co$ers e$enl# all along the seam with a knife or screwdri$er.

The co$ers should pop out of the wheel housing as the magnets pull the axle off center.

Then there should be enough space to get #our fingers behind the co$er and pull it off. >ull


8. The best wa# to get the bearings out is to press them out. If #ou ha$e access to a hand press,

use it. If #ou don&t, then it is possible to tap the bearings out. If the bearing is badl# damaged

or disintegrated, then #ou ma# need to le$er and dig it out piece b# piece.

. Hand press methodB

>osition the side plate on the hand press with the bearing side facing down.

>ut something flat and diskshaped (such as a coin! inside the axle hole resting on the rim of

the bearing.

>ress the bearing out using the hand press.

-. Tapping methodB

>osition the side plate on some blocks with the bearing side facing down.

>ut something flat and diskshaped inside the axle hole resting on the rim of the bearing.

'se a pipe like a chisel to tap on the disk to push the bearing out.

Tap gentl# and e$enl# around the disk, and keep it parallel with the side co$er.

6. To fit the new bearing, 7ust re$erse the procedure, tapping or pressing from the other side.

'se grease to help ease the bearing into position.-..)" :epairing a atter# with /ead Cells

=ickel atter# Dithout a 0S



=ickel batteries tend not to ha$e $er# sophisticated 0Ss. The# don&t need them for normal

operation. This allows a simple maintenance trick. If a single cell in an =i0h batter# breaks

open circuit, then there is a $er# eas# solution. The cell can be short circuited, and the batter#

will go on working. The charger will see a reduced $oltage, but t#picall# =i0h chargers workbased on constant current and a temperature cutoff limit that will be unaffected. 0ake sure

that the cell is dead before #ou short circuit it+ otherwise, there could be smoke. If it shows "

at the terminals and there is no conducti$it# through it, then it is broken open circuit, and it is

oka# to fit a b#pass wire. The b#pass wire should be thick enough to carr# main power current.

:eplacing a /ead Cell that Has a 0S or Constantoltage Charger

'suall#, for one of man# reasons, it is necessar# to replace a dead cell. If the batter# has a 0S,

if the pack is to be paralleled with another pack, or if the batter# charger is of the constant

$oltage t#pe, then it is necessar# to replace a dead cell. To replace a cell in a batter#, #ou ha$eto locate the dead cell, remo$e it, and then fix in a replacement. The wa# #ou do this will

depend on the configuration, how eas# it is to get at the cell, and how the cells are 7oined. If

the cell is $er# difficult to get at, then it ma# be best to solder a short across the dead cell and

then fix a new cell into the end of the pack, where it is easier to do. This would re1uire a

rearrangement of the balance wires if the pack has a 0S (see Section -..))!. :eplacing a

dead cell in a pack ma# re1uire complete disassembl# and reassembl# of the pack. If this is the

case, then read Section 6.).). Dhen working on batteries, a$oid using metal tools whene$er

possible+ work on a clean, empt#, nonconducti$e surface+ and don&t wear 7ewelr#. :emember

there is no off switch on a batter# #ou ha$e to work on them li$e.

:eplacing a /ead Cell in a >ack

). /isassemble the pack co$ering. Cut open the heatshrink or ducttape shell. e careful not to

stab or cut an# of the cells+ the# ma# onl# be a few millimeters under the surface of the

packaging.

*. 0easure the cell $oltages to locate the dead cell.

8. Cut the dead cell out at the contact tabs. 'se side cutters to cut the metal tabs 7oining the

dead cell to its neighbors.

. :emo$e the cell. reak off an# hot glue used to secure the cell, and push it out.

-. >osition a new cell with contact tabs.

6. Solder the contact tabs to the correct cells (see ESoldering to atteriesF in Section 6.).)!.

@. :efit the cell insulation.

A. :eco$er the batter# pack (heat shrink or duct tape!.

A. Check that the pack still charges.

-..)) 3ixing roken alance Dires in a >ack That Has a 0S



If a batter# pack with a 0S is knocked around a lot or there was insufficient strain relief on

the balance wires, then this can result in a broken balance wire. ? broken balance wire will

cause the 0S to trip and stop #ou dead in #our tracks. To replace the balance wire, #ou ha$e

to open up the pack to find the broken wire and then fix it back in place. Dhen working onbatteries, a$oid using metal tools whene$er possible+ work on a clean, empt#, nonconducti$e

surface+ and don&t wear 7ewelr#.

). /isassemble the pack co$ering. Cut open the heatshrink or ducttape shell. If the cells are

pouch cells, be ultracareful not to stab or cut an# of the soft cells+ the# ma# be a onl# few

millimeters under the surface of the packaging.

*. Check all the cell $oltages at the cell terminals.

8. ook for the broken 0S wire (3igure -.8<!.

. If se$eral balance wires are disconnected, don&t guess where to connect them. 3ind out

where each wire was supposed to be connected b# tracing the continuit# of the wire back to

the position on the 0S. The se1uence of the balance wires in the 0S will tell #ou which wire

needs to go to which cell terminal. The# will be ordered from positi$e to negati$e.

-. Solder the wire back in place.

3I9':2 -.8< alance wires connecting the 0S to cell terminals.

6. If an# of the balance wires look too short or under tension, as in 3igure -.8<, then extend

them with extra wire of similar t#pe.



@. Dhile #our pack is open, inspect the cell insulation and padding. Check that it is sufficient for

the wear and tear that #ou are putting on it.

A. Close up the pack, and reappl# the heat shrink or duct tape.

-..)* :epairing a atter# Charger

The usual causes of batter# charger failure are o$erheating, $oltage spikes, and rough handling

b# the user. It is rarel# possible to repair a broken bic#cle charger. If there is an ob$ious blown

component to swap that #ou can identif# and replace, then replacing this component might fix

the charger. Capacitors are one of the most likel# components to blow through $oltage spikes.

I&$e had se$eral bic#cle chargers blow and not been able to fix them (3igure -."! despite

changing capacitors, resistors, and transistors. >re$ention is better than a cure, so follow the

mods in the maintenance section if #ou think the charger runs hot, etc. If #our charger does

fail, the best thing to do is to bu# a different brand of the same $oltage. 0ake sure that #oufollow the wiring guide for a new batter# pack or charger in Section -..)8 so that #ou get the

connections correct. The# might not be the same as the old charger. 0ake sure that the

charger is disconnected from the main circuit before #ou work on it.

3I9':2 -." ? cheap =i0h batter# charger (prone to breaking after 6 months!.

-..)8 Diring 'p a =ew atter# >ack or Charger

Dhen #ou bu# an electric bic#cle package, e$er#thing is set up for #ou, but when #ou bu# a

new batter# or charger to work with an existing kit, then there ma# be some minor but

important wiring 7obs for #ou to do. It is important not to rush these and to know what #ou are

doing because it is possible to wreck these lo$el# new to#s with a single illthought connection.

=i0h >ack and Charger Connections



0ost =i0h packs will come with a thermistor alread# attached. Some batter# chargers are

different, though, and use different $alue thermistors, so it is important to check that the new

pack will work with the charger #ou ha$e. ikewise, it is important to check that a new charger

operates using the same thermistor resistance as #our old one. If #ou don&t check the

thermistor $alue, then the pack might not charge, or worse, it might not recogni4e when the

charge has finished and o$ercharge #our new batter#. The thermistor is usuall# connected in

the batter# across the negati$e and third terminal of the plug, as shown in the circuit diagram

in 3igure -.). 'sing the multimeter on $oltage setting, check all the pins, and find which are

positi$e and negati$e. The thermistor is connected to negati$e, so it also will ha$e a $oltage.

It will appear as if there are two negati$e pins. The one with the lowest $oltage with respect to

positi$e will be the true negati$e+ the other one is connected to the thermistor. 'sing

resistance measurement, check the resistance between the negati$e and sensor pins. It should

be between ) and *" k;. =ow do the same checks and measurements on the batter# pack that

came with the charger. 0ake sure that both packs are the same temperature, or the readings

will be different. %ou want to make the resistor $alues the same. If the# are not, then #ou will

ha$e to open up and change the thermistor in the new pack to match the $alue the charger

expects. Thermistors are rated b# their highest resistance, so when #ou are bu#ing a

replacement thermistor based on the resistance reading, round up the $alue from when the

pack was coldest, and bu# a thermistor close to that resistance, or check the resistance with a

meter before #ou bu#.

3I9':2 -.) How to connect an =i0h pack showing the thermistor and the charger plug.

ithium >ack with 0S Connections



ithium packs usuall# need to ha$e a 0S to balance them and ensure that no cell drops below

a minimum $oltage limit. The 0S is connected to the main negati$e on the pack and then

offers to the user separate controlled negati$e connections for charging and discharging (3igure

-.*!. The 0S can electricall# switch off the connection to these negati$es if it detects that

something is wrong with a cell. The 0S also has a connection to the batter# positi$e, from

which it draws operating power, and connection taps between each cell. 'suall# there is no

direct connection to batter# negati$e for the user, but it can be useful to ha$e one for fault

finding or emergenc# purposes. The main 0S connections should be clearl# marked on the

circuit board b# N and O s#mbols. The 0S wires should be clearl# marked with EdischargingF

and EchargingF labels. The negati$e connections also should be indicated on the board if the

0S comes without negati$e wires attached. If #ou bu# a large batter# and need to separate it

into smaller sections to fit on #our electric bic#cle, then #ou ha$e to be mindful of 0S

connections. Some packs ha$e series and parallel cells, so it&s possible to separate them in two

wa#s. %ou should separate the pack the easiest wa# possible. If #ou separate a series string of

cells, then the connecting main current wire between the two hal$es needs to be $er# thick.This is because an# $oltage drop in this wire will be assumed b# the 0S to be a result of a bad

cell. ?n# ?nderson connectors or fuses here could cause 0S cutoffs. ?lwa#s remember to

reconnect the balance wires. If #ou separate the batter# into two parallel hal$es, then #ou can

use 3igure 6.) as a template.

3I9':2 -.* How to connect a lithium pack with a 0S including charger port and balance

wires.

Connecting the atter# >lug and Charger

Sometimes when #ou bu# a new batter#, it will come with the charger plug remo$ed, for #ou to

connect #ourself. This is done so that #ou can panelmount the plug on #our batter# box and

thread the wires through. Sometimes the wires will be clearl# marked so that the# can be



connected easil#. If the# are not marked, then use #our multimeter on $oltage setting to check

the polarit# of the wires and compare that with the polarit# of the charger when plugged in.

The batter# should be connected to the charger positi$e to positi$e and negati$e to negati$e.

>olarit# detection is explained in the tips in Section -.).). If the 0S has separate

negati$ewires for discharge and charge, then the smallerthickness blue wire is usuall# the

charge wire. The charge plug will ha$e the negati$e 0S charge wire and a connection to

positi$e. The discharge power wires that connect to the controller will be the thick positi$e

wire and the thick black negati$e discharge wire.

electric bike repair guide checking hall sensors motor speed controller and battery charger

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