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diy solar

Did I buy the wrong BMS?

lockep

New Member
Joined
Aug 11, 2021
Messages
6
@lockep, I think you posted an aliexpress link to your personal order instead of the product page. No one but you will be able to view it.
 
OK thank you. I have already ordered a new BMS from overkill solar after reading about issues with Daly I will hold off on doing anything else with the pack till I get the new BMS
 
I was going to suggest using a different BMS - good you found it. By the way, the advertising on that Amazon Daly is confusing, so no wonder you got mixed up. The link you posted has LiFePO4 in it, but once you get to the product page and look at the tech details it's obvious it's not for LiFePO4. Refund!
 
I got the overkill BMS installed and have it all hooked up. I also installed this (https://www.amazon.com/dp/B08CKPZ7PH?psc=1&ref=ppx_yo2_dt_b_product_details) active balancer. When charging my voltage difference between cells slowly goes from .005 up to about .155 One of the cells seems to charge much slower. But once one cell hit the high voltage level the amps from the charger drops to between .1-.5 and after a few hours the cells balance out to within .005 of a volt again. Is this OK? Is this because these "New" cells I got from AliExpress are not REALLY new?

Thanks in advance.
 
Did you top balance your cells in parallel, or immediately put them into series and charged them up? Safer to assume that EVERY cell you encounter needs top balancing, mainly because of the very flat discharge rates of LifePo4.
 
I did not do a top balance because I did not have a variable voltage power supply.
 
I got the overkill BMS installed and have it all hooked up. I also installed this (https://www.amazon.com/dp/B08CKPZ7PH?psc=1&ref=ppx_yo2_dt_b_product_details) active balancer. When charging my voltage difference between cells slowly goes from .005 up to about .155 One of the cells seems to charge much slower. But once one cell hit the high voltage level the amps from the charger drops to between .1-.5 and after a few hours the cells balance out to within .005 of a volt again. Is this OK? Is this because these "New" cells I got from AliExpress are not REALLY new?

Thanks in advance.
New or not they just arrived slightly different state of charge. Or they are less than grade A with not so matching specs. Very normal and common.

As long as the BMS does not cut for cell overvolt, the active balancer should bring the cells in balance. This could take some time like a month or more due to the limited time spent at the higher charging voltage. Once the charger goes to float, the cells drop back in line and the active balancer stops balancing while in use.

If the BMS does cut for cell overvolt you could reduce the charging voltage or manually bleed off some power from that high cell.
 
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