BMS not working...Do I need it?

GoldenMotor.com

beach cruiser

Member
Mar 13, 2012
126
1
18
Puget Sound Convergence Zone
My Battery Management System (BMS) doesn't light up anymore when charged,
but my battery charger and my Cycle Analyst says that my battery is fully charged. Should I be concerned? I've had the battery a little over 3 years. It's a Ping 48 volt 15 amp hour. Do I need to replace the BMS? Will the battery explode if I continue to charge it with non functioning BMS lights, or can I safely rely on my Cycle Analyst and battery charger? Attached is a pic of the battery with the BMS. Click on the attachment a couple of times and the picture will right itself.
 

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snellemin

New Member
Feb 4, 2014
220
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0
Spring TX
The BMS is there for safety. The BMS balances and limits the output of the battery. If you don't mind checking the cells charge status yourself, I would say take out the bms. If you are not comfortable with that, then replace the bms.
 

beach cruiser

Member
Mar 13, 2012
126
1
18
Puget Sound Convergence Zone
Thanks Snell...so does that mean that when I charge the battery now it's most likely an "unbalanced Charge"? If I'm not mistaken, one of the many functions that you can program the Cycle Analyst to do is limiting the output of the battery. zptzpt
 

snellemin

New Member
Feb 4, 2014
220
1
0
Spring TX
The cycle analyst is a pretty nice device, especially the V3 version. But it will not measure individual cells, but rather total pack voltage. It can also limit current for you among one of its many features.

I don't know what type of BMS you have. Some bms's use a little bit of power from one cell, so it will get unbalanced over due time.

I use lipo and no bms. I don't really balance my batteries at every charge as the cell voltages matches each other pretty tight. I mostly ride with capacity in mind. So I depleted my batteries and charged to full with balancing involved. I make sure never to go below 10% capacity(usually 20%). This way the batts in my setup stay pretty balanced. I also only charge to 4.15V instead of 4.25V. I get more battery cycle life out of them. This also gives me some headroom if one cell goes above the other cell voltages.