Power loss

[AlanL]

Bike: Ancheer folding 20” 36v 8 Ah with 3 level power assist plus pure electric. Folding the bike automatically breaks batter connection to controller.
Problem: frequently (about every other use) ebike electrics wont power up or electric power shuts off while operating. There does not seem to be any pattern to the behavior and battery charge state makes no difference ( problem occurs fully charged or partially depleted (verified with voltmeter in battery pack contacts. Buttonpad / display goes all dark and will not restart. I have found the only way to restart the system is to fold bike (which disconnects both pos&neg battery leads, wait several seconds and then unfold bike (reconnect battery). this revives system 95% of time otherwise I wait hours and repeat fold/unfold battery disconnect.
i have installed new Ancheer controller—no improvement.
Hardwired battery using bullet connectors to controller to eliminate possible dodgy “folding hinge battery spade connection”—- no improvement.
I now suspect the BMS of the battery pack is faulty or unhappy with controller. Before I replace battery pack on 6 month old ebike $$$.... any suggestions?

 

[indianajo]

I load tested my battery on the back patio to determine if my road failures were the battery or the controller/motor/throttle. Turned out to be the battery, two different ones. there is a picture of the rig on here somewhere. couple of spare bullet connectors, some wire, clip leads, 10 ohm 450 watt resistor for a 5 amp load. For a 36 volt battery 5 amp load you'd need more like 7 or 8 ohm 400 watt resistor. I had the resistor for load testing of PA amplifiers, which also work great on tiny loads and not at the concert. If the voltage collapses from 42 full charge to 7 under load, your battery has bad internal connections.
OTOH, a patented connector on an integrated battery may make it impossible to test. Mine had insulated spade lug connectors. I cut the wrap off the top of one of mine, it had 14 stacks and only two were making voltage at the BMS. One would drop out with a load.
BTW I bought generic batteries with standard connections. Limited my loss to $320, not the $1000-5000 of an unrideable ebike with patented battery shape and connectors.
If you live in California, Colorado, or Ohio, you can drive your battery to a shop for repair. You can't ship it without hazmat certification, which you can't afford.

 

[harryS]

Since you're losing power occasionally when riding, that does indict the battery especially if it happens with full charge.

Still ...maybe you got a bad cable to whatever button is used to start the bike, and unfolding the bike unkinks it?

I don't think Ancheer is much different from the controllers used on my DIY ebikes. They all send battery voltage to the the handlebar unit on one wire. Starting the bike from the unit sends battery voltage back on second wire to the controller where it turns on the controller. If you find those two wires on your controller connector, then jumper them so the unit is always on. Then see if your problem persists. Or do a continuity test on those wires while folding the bike. The continuity test is probably the safe option, if you haven't wired up a dozen controllers. I've done at least six.

 

[AlanL]

I will add some comments and observations to focus the forum’s collective mind on my reported problem:

In this Ancheer eBike All Battery power goes to the controller first. Even the DC power for the headlamp and horn buzzer passes thru the controller but (fortunately) this headlamp & horn power is not controlled by the handlebar keypad/display for the electric motor. With drive motor completely off and inactive, display dark, the headlamp & horn will NORMALLY work.

When my complaint occurs ( failure to initialize / activate thru keypad display OR power failure while riding with motor assist) I can usually reactivate by disconnecting battery from controller and then reconnecting and reinitializing system . I have noticed that for recovery to be successful that with battery disconnected I MUST discharge any residual capacitance in the controller by switching on the horn or headlamp. After the horn gives a brief chirp i can reconnect the battery which generates a significant spark at the bullet connector. The whole system will now work for a while,

If I DO NOT discharge the residual capacitance of the controller thru a horn chirp then reconnecting the battery usually will NOT be successful in restoring the system to normal function. ( Note: if I wait a long time it will be successful)

I suspect the battery’s BMS has erroneously decided to shut Off the battery output (presumably it thinks it is protecting the battery) and only when the controller internal capacitance is discharged will the BMS decide to turn on the battery output again (hence the spark upon reconnection). This is the best theory I have based on the observations. Replacing controller did not fix the problem so I am leaning toward blaming the BMS/Battery. (but I am not sure of the BMS protective circuitry features)

 

[indianajo]

If you bought a bike with a computer in the battery, you're on your own, dude.
My bms has various linear integrated circuits that read voltage of the stack, then turn a fet on or off to connect/disconnect the stack during charging. No computer to turn current on or off.
You still don't know if the battery is providing voltage when your bike won't run, or not.
I wouldn't spend money to repair a battery with a computer in it. Get something generic, like my lunabikes one. Your controller might be specific to that battery, too. The 3 phase wires on the motor and the 3 hall effect pickups are pretty common. The connectors are hard to match; they are sold on ali in minimum quantities of 10000.