January 24, 20179 yr Have a self build running a 500w Bafang BB02 mid (crank) motor with 48v battery. System has developed a fault whereby all runs fine when back wheel raised and throttle applied. However, as soon as load of a rider is applied, motor cuts out and system shuts off i.e. VDU turns off. Removal and reinstatement of battery gets system back on until again load is applied. Have checked all battery/power connections - all good Can you assist by way of either diagnosis or, better still, solution
January 24, 20179 yr Have a self build running a 500w Bafang BB02 mid (crank) motor with 48v battery. System has developed a fault whereby all runs fine when back wheel raised and throttle applied. However, as soon as load of a rider is applied, motor cuts out and system shuts off i.e. VDU turns off. Removal and reinstatement of battery gets system back on until again load is applied. Have checked all battery/power connections - all good Can you assist by way of either diagnosis or, better still, solution What battery are you using? A link to vendor would be useful.
January 24, 20179 yr Author Hi Fordulike In short, not sure of the name of the battery manufacturer (if that is what you mean) and acquired it from the same Chinese company that sold me the Bafang 500w motor. Its a 48v 10.6 A/h
January 24, 20179 yr Hi Fordulike In short, not sure of the name of the battery manufacturer (if that is what you mean) and acquired it from the same Chinese company that sold me the Bafang 500w motor. Its a 48v 10.6 A/h Depending on how the Bafang is programmed, it can draw a lot of current from the battery under load. It may be that the battery is sagging badly under load and tripping out the BMS' low voltage cut-off. It's not the Bafang's low voltage cut-off, as this produces a stuttering sensation in the motor unit, plus the LCD display stays on.
January 24, 20179 yr Author Battery is old, but can confirm that a new BMS was fitted recently, and fault started almost immediately after that.
January 24, 20179 yr Battery is old, but can confirm that a new BMS was fitted recently, and fault started almost immediately after that. Oh right, I assumed the battery was new. Most likely the battery can't provide enough amps for the Bafang then.
January 24, 20179 yr Author Whilst I must bow to your knowledge of these things, can I check - when the bike is tilted onto its side, and I run the system on throttle only, it works absolutely fine. Would this still fit with your theory?
January 24, 20179 yr Author to clarify last comment, i.e back wheel is off the ground and able to free wheel under throttle power
January 24, 20179 yr Author Hi Brightonebikes - Battery insides slid out of their aluminium sleeve. On trying to re-insert, there was a small "pop", fizzying and smoke. Took it to a battery builder here in N London (UK), who spotted another burnt bit on the old BMS so replaced it.
January 24, 20179 yr Whilst I must bow to your knowledge of these things, can I check - when the bike is tilted onto its side, and I run the system on throttle only, it works absolutely fine. Would this still fit with your theory? With rear wheel off ground, the Bafang will only draw a few amps maximum to spin the wheel. With the wheel on the ground, a person on the saddle and starting from standstill, it could require 20 amps+. This condition can cause an old worn battery to sag to BMS low voltage cut-off point.
January 24, 20179 yr Hi Brightonebikes - Battery insides slid out of their aluminium sleeve. On trying to re-insert, there was a small "pop", fizzying and smoke. Took it to a battery builder here in N London (UK), who spotted another burnt bit on the old BMS so replaced it. I see. Do you know if they checked any of the strings or individual cells within the battery at the same time? Kind of false economy to replace BMS if the cells are near to the end of their usable life.
January 24, 20179 yr Author Afraid do not know, Brightonebikes. Battery was old, but hadn't been used that much.
January 24, 20179 yr Author Seems like a battery problem from what I can ascertain from you guys, and others on other forums. Will have to find another 48v to see if that resolves it
January 24, 20179 yr If you have access to another 48V battery, try process of elimination starting with the battery. From what you say and coupled with Fordulike's input it does sound like battery issue rather then the BBS02.
January 24, 20179 yr One of my bug bears on here peeps wanting advice but won't tell us where they live. Sounds like the battery is sagging and can't cope however the LVC on the BMS could also be to high or is asking for to many amps to be supplied. What is the full charge voltage hot off the charger and do you have a programming lead ?
January 24, 20179 yr Seems like a battery problem from what I can ascertain from you guys, and others on other forums. Will have to find another 48v to see if that resolves it Although pricey, I can vouch that the dolphin style frame batteries from Eclipse Bikes, work perfectly with BBS02's. http://www.eclipsebikes.com/116ah-lithium-frame-battery-samsung-cells-p-1105.html
January 24, 20179 yr Author Hey Nealh - I've no problem telling people where I live - SW London, United Kingdom.
January 24, 20179 yr Author Ah - nice suggestion Fordulike, but there is a very good reason why it has to be an old-style cylindrical battery - I had the frame modified to have a 100mm diameter seat post which houses the battery
January 24, 20179 yr Ah - nice suggestion Fordulike, but there is a very good reason why it has to be an old-style cylindrical battery - I had the frame modified to have a 100mm diameter seat post which houses the battery No probs, just be sure that any battery you do buy is rated for a continuous 20+ amps. Edited January 24, 20179 yr by Fordulike
January 24, 20179 yr Ah - nice suggestion Fordulike, but there is a very good reason why it has to be an old-style cylindrical battery - I had the frame modified to have a 100mm diameter seat post which houses the battery Huh? Love to see a photo of this! Have you posed these questions to the outfit that recently fixed(?) the battery for you?
January 25, 20179 yr Author Hi Brightonebikes - here is an image of the bike - you can see the extra wide seatpost housing a battery which slides out by pulling up the saddle
January 25, 20179 yr Author Many thanks, Tommie. Was one helluva job getting it done. Hard enough getting an engineering firm here in UK to do such a one-off job. Then had joy of modifying battery casing so that a female connector located on the base-cap would sit onto a male inside the seat-post. Got to thank a brilliant electronics engineer pal of mine who did the battery. Alas, has now moved to Margate (DOH!!) so have no-one locally to fix the sort of issues discussed above. MESSAGE TO ALL - anyone know a London based electronics whizzkid (all ages considered!) wanting to join up with an extremely fledgling E-bike company. Please email warren@smugcycles.co.uk for a chat
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