I have 4 of the 300ah batteries that were actually 280ah. Every time I charge them they rest at 13.3v. Shouldn't resting voltage be 13.6v? I've tried unhooking them and charging them all to 14.6v and they still go back to 13.3v.
I have 4 of the 300ah batteries that were actually 280ah. Every time I charge them they rest at 13.3v. Shouldn't resting voltage be 13.6v? I've tried unhooking them and charging them all to 14.6v and they still go back to 13.3v.
I just came across your post. I have similar problem. Until 23 Dec, my 300ah (280ah) would charge to 14.4v. Starting 24 Dec it only charges to 13.6v. Is this a failure of the BMS?
That's a great looking setup by the way.
Wattcycle admitted that a large batch of their "300Ah" Mini batteries were mislabeled and actually contained 280Ah cells (often EVE LF280K cells) but, I don't think that's your "issue". If your getting 280Ah out of them, the cells are healthy.
Your probably seeing "Float Voltage" (probably set to 13.5V or 13.6V) and assuming the battery should hold that naturally. It won't (at least without a charger actively pushing a "float" current). Any 12v 280ah LiFePO4 battery will naturally settle to about 13.3V) after charging. That's normal. The battery is "coming to rest".
There is really no usable energy difference between 13.6V and 13.3V anyway. Both represent 99–100% SoC.
Robert, as to the specific Dec 24th date the lower voltage (13.6V), my guess is that it's either a cell imbalance or CTP ("Cold Temperature Protection"). Are you in a northern environment?
With these batteries, sometimes cel's get out of sync. If one cell is slightly more charged than the others (i.e., "runner"), it will hit 3.65V very quickly while the other three are still sitting at 3.3V. The BMS sees that one cell hit the "danger zone" (3.65V) and cuts off charging ("High Voltage Cutoff").
Assuming the batteries are cold, you can try warming them up. Whether or not they're "cold", if you have a variable charger, set it to a very low amperage (5 Amps or less) and charge it slowly so that high amps don't spike the voltage of the "runner" cell. If the charger allows, set the voltage to 13.6V or 13.8V and let it sit there for 24–48 hours. This gives the BMS time to balance the cells. Afterwards, try charging it at 14.4v and it should work.
Question for you guys... has Wattcycle responded to you at all? Not sure if I'm doing something wrong trying to communicate with service. I can't even get a response to requests for an RMA (within the 30 day return window).
It's too bad, I really like the batteries, the support is awful though.
Paul
