Battery Voltage

[SirWilliam]

Can someone help me re my new 52Volt battery (14S/6P)
Although my new charger is marked 58.8 V, 3 Amp on a full charge from empty it only reached 58.1V and cut out.
During the charge I was also taking voltage readings across each of the 14 banks of cells and it is clear at the end there was no cell balancing taking place.
As 58.1V equates to 4.15V which is the point that my Daly BMS would should initiate Balancing.
Is my charger defective with being slightly under voltage and given voltage sag what open circuit voltage should be available to achieve balancing at 4.2V. By open circuit voltage I mean the no load voltage at the charger output.
Any help will be appreciated
Regards
Bill

 

[Voltron]

I have several that cut out a little early like yours, but wouldn't call it defective, just poorly calibrated, and yes, by not going high enough, it might not be triggering balancing.
Some you can open the case, and there are trim pots one can adjust for terminal voltage, and low current cutoff, but others maybe not.
(Blows the warranty usually too getting in there)
Have you measured the direct charger output voltage (some chargers are hard to measure at the bare plug without shorting it)?
I've had a few times the charger was fine, and it was the BMS.
On those, it seemed like if the BMS decided it couldn't keep up with discharging the high groups fast enough, say one or two groups staying at 4.18 where it would keep trying, but if one pushed thru to 4.21, it would shut down all the charge current, which would make the charger green out like it was full. Some would reset after a while, and make a charger start going green/red, but others would need full disconnect from the charger cord and waiting for a little natural voltage sag, but go right back to shutting down.

 

[pwd]

The charger output should measure 58.8V for 4.2V per cell on a 14S pack. Some charges (most of the generic ones) can be adjust via a trim potentiometer inside. For good lithium ion cell treatment though, 4.1V max per cell is recommended.

 

[docware]

Assuming the voltage is reading from Daly app. I am not sure if you have chance to recognize possible balancing from voltage reading on the cells, probably not.
Even if your charger has really 58,8 V at the output, 58,1 V reading on battery at the end of charging is normal because there are always voltage drops on the connectors and wires. It is very similar to my measurement on Sanyo GA cell where I simulated connectors and wire voltage drops. You can see that charging was finished slightly before the cell voltage achieved 4,2 V.



However, if your peak load is mild, suppose max 3 A/cell, don´t worry about balancing.
My 10s5p Sanyo GA battery is working more than 2 years without balancing and the voltage of all paralell groups is still within 3 – 5 mV and concurrence is very stable, see the pictures bellow.