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tushingham2

Pedelecer
May 9, 2020
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Hi We have an A2B Obree ebike brought in to my workshop, The bike has fallen over off its stand no sign of any damage or any marks to where it’s hit ground and nothing
broken. Could you help where to find a fault, display is not showing any life. Connections seem all good with plenty of battery power.

Or if you could point us in the direction who could assist

Thanks Tushingham2
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
Have you tested the battery discharge voltage with a meter to stat with ?
 

tushingham2

Pedelecer
May 9, 2020
89
2
Have you tested the battery discharge voltage with a meter to stat with ?
Thanks good you asked me that, at the out put connection only 8v but from
inside the casing 41v but have tried a direct connection another battery 36v but still no life in the display
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
14,661
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West Sx RH
Forgot A2B bikes won't work with any old battery as they use CANbus hand shaking protocols between components (a locked in system like Bosch and others use),
these type of batteries with the CANbus system afaik don't allow discharge voltage to be measured at the pin outs.
These bikes don't come cheap and are a quite a high priced German brand.
Probably needs a dealer and diagnostics.

Is there a fuse inside the battery ?
 

tushingham2

Pedelecer
May 9, 2020
89
2
Forgot A2B bikes won't work with any old battery as they use CANbus hand shaking protocols between components (a locked in system like Bosch and others use),
these type of batteries with the CANbus system afaik don't allow discharge voltage to be measured at the pin outs.
These bikes don't come cheap and are a quite a high priced German brand.
Probably needs a dealer and diagnostics.

Is there a fuse inside the battery ?
Hi thanks yes this did go through my train of thought there is 41v from main power circuit
 

cyclebuddy

Esteemed Pedelecer
Nov 2, 2016
776
397
Beds & Norfolk
...at the out put connection only 8v but from inside the casing 41v...
Left field suggestion...

That sounds to me as if the BMS has gone to sleep. Try holding down the battery power button for several seconds to see if it wakes up? Or else there may be a break/defect in the handle bar control on/off or connection wire which isn't sending the signal to wake the BMS up.

My own battery (again a can-bus system) measures <16v at the output until the BMS wakes up, then full voltage appears.
 
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Reactions: Nealh

tushingham2

Pedelecer
May 9, 2020
89
2
Left field suggestion...

That sounds to me as if the BMS has gone to sleep. Try holding down the battery power button for several seconds to see if it wakes up? Or else there may be a break/defect in the handle bar control on/off or connection wire which isn't sending the signal to wake the BMS up.

My own battery (again a can-bus system) measures <16v at the output until the BMS wakes up, then full voltage appears.
Thanks Where will i find a power button it’s only showing 8v at out put
 

cyclebuddy

Esteemed Pedelecer
Nov 2, 2016
776
397
Beds & Norfolk
The button on the battery you press to show the state of charge: Hold it down for several seconds... it may wake the battery BMS up (it does on my TranzX CAN-bus system - I don't know your A2B so it may or may not).

Most smart BMS battery boards go into low power (sleep) mode when not used for a set period of time to reduce consumption... the 8v you measured at the output suggests that. Once the BMS in the battery wakes (if you can force it to), it should give you the full 41v you measured inside but at the output too.

If that doesn't work, I would be checking cable continuity between the display and the battery; if the bike fell with no visible signs of damage, but the display doesn't work at all, the owner may have grabbed/pulled on the cable(s) to save the fall. My logic here is that pressing the on switch on the handlebar should send a pulse to the battery to awake the battery, yet you say the display is dead.

EDIT: I just googled and found your A2B model has a removable display; contacts on removable displays are always dodgy - give them a good clean. One other final thought: Bosch CAN-bus systems have a battery in the display for memory/function which causes problems when old/flat; possible A2B do too. The bike is an old model; that battery may need replacing. Otherwise, I'm out of ideas and would try contacting A2B to see who has one of their plug-in diagnostics systems.

 
Last edited:

tushingham2

Pedelecer
May 9, 2020
89
2
The button on the battery you press to show the state of charge: Hold it down for several seconds... it may wake the battery BMS up (it does on my TranzX CAN-bus system - I don't know your A2B so it may or may not).

Most smart BMS battery boards go into low power (sleep) mode when not used for a set period of time to reduce consumption... the 8v you measured at the output suggests that. Once the BMS in the battery wakes (if you can force it to), it should give you the full 41v you measured inside but at the output too.

If that doesn't work, I would be checking cable continuity between the display and the battery; if the bike fell with no visible signs of damage, but the display doesn't work at all, the owner may have grabbed/pulled on the cable(s) to save the fall. My logic here is that pressing the on switch of the display should send a pulse to the battery to awake the battery, yet you say the display is dead.
Hi Many thanks, I keep checking different areas all.over again cables all check out fine they are quite well protected on these German bikes, It’s great
when a bike comes in with compatible components that we can use to eliminate saves a lot time fault finding. There is a coin battery in main battery
casing, reading low voltage
 

tushingham2

Pedelecer
May 9, 2020
89
2
Hi Many thanks, I keep checking different areas all.over again cables all check out fine they are quite well protected on these German bikes, It’s great
when a bike comes in with compatible components that we can use to eliminate saves a lot time fault finding. There is a coin battery in main battery
casing, reading low voltage
I do feel it’s the battery area where the problem lies and possibly the bms.
 

tushingham2

Pedelecer
May 9, 2020
89
2
I have fitted a new rear hub 350 watts 9 pin 36v new controller new display its runs okay no speed reading on the display. after half mile shuts down and no power battery is okay.
I disconnect the display plug fit in an isolator plug and it runs fine.
Connect it all to a front hub and all working fine with a speed reading
 

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