Hi, I have a question for you. I have a Bafang BBS02 middle motor, where I changed the battery for 52V, (fully charged is 58,8V) originally it was 48V (fully charged is 54,4V) I successfully flashed the controller according to the instructions to accept a 52 V battery The motor has a controller designed for maximum 60V. With the new battery I have a problem with high gears and heavy gearing (I understand that this is not driving but sometimes I don't have time to change gears) that when the engine is assisted at low rpm, when the engine is giving the most power, there is a momentary noticeable vibration in the pedal, the engine seems to split before it gets up to speed. Do you know what this could be? When driving I measured if there is a bad contact on the leads, connector etc, see the picture with the eggrider display which monitors the operating values, but the battery is too hard. So the battery or its bms is not the problem. The controller has a 25A voltage limit of 58,8V when the battery is fully charged, so the peak power is around 1400W. Otherwise, the motor has an effective speed of 130-150 rpm and I suppose the change in voltage has raised it a bit, so I don't know if it's related? Otherwise the controller has 9 IRFB3077 mosfets, three on each phase. Thank you for your feedback.
Bafang BBS02 vibrations under load
- Thread starter JerryT
- Start date
This may not have anything to do with your problem, but it's all I can think of.
My hybrid bike uses a Bafang 350w 80Nm MaxDrive (M400). The bike came with a mediocre Samsung celled battery with limited current capability. When drawing very high current in too small a gear, there can be a very rapid stutter (vibration as you describe it). I haven't modified the controller settings/parameters in any way: It's still as the maker set it.
What that definitely is in my case is the motor attempting to draw more current than the battery can deliver, and the controller rapidly oscillating on/off (the controller has an LVC of 32v, the battery LVC is 28v, so it's the controller intervening not the BMS). It's an odd sensation felt at the pedal. Reducing the assist level or using a more appropriate gear (i.e. reducing maximum demand on the battery) stops the problem altogether.
My suggestion would be to try reducing current demand or using a more capable (higher current) battery.
I've been thinking about it, too. But my battery is composed of a LG MH1 3200mAh cell with a maximum discharge current of 10A per cell. I have a 14s5p composition so total 50A .Bms of the battery is 40A,the controller has a maximum draw of 25A What I looked at the voltage graph, the battery is very hard, the voltage drops very little, under load. What exactly does LVC mean? I could not find this parameter anywhere. Thank you
LVC is labelled Low Battery Protection in both PC & Android apps. The on/off oscillation happens with the rapidity of a machine gun. Would measurement even pick that up?
Other forum members here bought the same bike as me at the same time: Some lowered the controller LVC (32v on a 36v system is perhaps a little high), others bought higher current/larger capacity batteries to milk the performance capabilities of the M400 motor.
Other forum members here bought the same bike as me at the same time: Some lowered the controller LVC (32v on a 36v system is perhaps a little high), others bought higher current/larger capacity batteries to milk the performance capabilities of the M400 motor.
I understand now. According to the manufacturer, my battery has LVC set to 39.2V in the BMS. The original 48V battery was set at 41V. The 52V setting was not intended for it, but according to discussions people are setting 42-43v for this battery. So I can set the 42V, which is exactly 3V per cell. But I don't think this will be the problem in my case. But I don't know 100%.
Tbh 3v per cell is a bit too deep for my liking for cell dischage using a bms , a bms may or may not like the low voltage. One is best imho in using 3.2v as min discharge figure but that is my view and what I use.
It is a different story if one is using manual balancing or a balance charger sans bms.
For 14s 45v or 46v would be a better lvc, but each to their own.
It is a different story if one is using manual balancing or a balance charger sans bms.
For 14s 45v or 46v would be a better lvc, but each to their own.
This graph shows the curve drop off dependant on the current draw of the cells. At low current draw one can see there is little point going below 3.3v as there is hardly anything left regarding mah.
If using the full 25a BBS02 draw then going down to 3v - 3.1v per cell for lvc will hasten it's ageing and affect capacity over 18 - 24 months. The higher one can keep the lvc the longer the battery will last.
If using the full 25a BBS02 draw then going down to 3v - 3.1v per cell for lvc will hasten it's ageing and affect capacity over 18 - 24 months. The higher one can keep the lvc the longer the battery will last.
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OK, very interesting, thank you very much. I'd just like to point out that I drive gently. This was a situation where the problem occurred and then I tried to replicate it. Otherwise, I try to shift gears ahead of time. I only use the maximum assist when driving on the flat and at high rpm and cadence.