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BMS SOC always show 0 percent

Aperture76

New Member
Joined
Sep 17, 2021
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Hi I am new to lifepo4 battery. Currently I bought 4 - 3.2 Battery from china with 150A daly BMS. I have it setup correct and my reading between each cell is reading correct. My problem is how come my SOC guage on BMS doesn't show anything always stay at 0 percent. All the other reading show each individual cell with in .01V different. is there I miss before hand. The BMS is awake and bluetooth is working temp cut off is working. can't figure what ready went wrong. would it be bad BMS?
Any help will be greatly appreciated.
 
just to clarify,
You have four 3.2 cell connected in series to make a 12v battery?
A Daly BMS is connected and you are able to charge and discharge the battery?
The app is reading voltage of the battery and cells, and also current in/out to the battery?
The app display of SOC is not changing from zero?

There are known issues in Daly BMS with recording low value currents less than a few amps and errors in displaying the SOC.

If readings of current and SOC are important, alternative BMS from JBD/Overkill will offer this.

Mike
 
Here are some of the photo on the BMS app.
 

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I see two things.
You have no cycles on the battery bank. So it has no way of knowing how much charge is in the cells. And the SOC set value is sitting at 0%. Your current voltage of 13.2 volts is 3.3 volts per cell, that is certainly in the very flat charge/discharge area for LFP cells.

What you need to do is charge the pack up to your desired full state. Then enter 100% (or maybe 90-05% if you don't fully absorb the cells) in the SOC set value and that should pre-set the SOC counter to your now full charge state. As you pull current through the BMS, it will count the amp hours going out and subtract that from the stated capacity. In your case, 280 AH. So if you set it to 100% and pull out 28 AH, it should then count down ad show 280 - 28 = 252... 252 / 280 = 0.9 or 90% SOC.

The cell over and under voltage values are a bit wide, but that is actually ok as long as the charging source and loads are set to shut down below 3.65 volts and above 2.5 volts (2.7 is better). If a cell does go out of range, it will run quick and hit the 3.75 or 2.2 limits in short order. I am being a bit more conservative, but I am also using flammable NMC cells, so I don't push them close to the edges. LFP is quite safe, so as long as your balance is good, you should just never hit those wide limits. I se you also have balance turned off, is there a reason? Or does it turn off balance since the cells are in range? My JK-BMS shows balance on even though it has not triggered any balance current in months.
 
Did u know how to fixed it? I got a same problem with u.
Yes...I have solve the problem. I have completely discharge the battery and recharge again. Then the SOC start to register but I could not get it to 100 percent but most is 95 percent. Hope it doesn't damage my battery.
 
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