batteies

otrfun wrote:

StirCrazy wrote:

Tom_M wrote:
When I'm plugged in my battery will not charge fully but that is not a problem with lithium.

be careful saying that. yes, I agree it doesn't have to be charged fully on a regular basis, but you still have to charge it full once and a while to ensure the cells stay balanced.

You can get away with this because you let your solar charge it with proper profiles and hopefully you take it up to 100% with that once and a while and let it fully balance. My BMS has a passive balancer that would take forever to balance so I added an active balancer to mine, so it only needs 2 hours or less to balance my 300AH battery. When I am camping, I do this once a week, the rest of the time I cut off at 90% but that's the BMS controlling that.

Tom_M didn't mention what voltage his converter or solar charger is using to bulk charge with. Without this information there's no way to know definitively what's going on with his system.

Also, in a number of your posts you seem to allude that you must have 14.6v to properly balance a 12v lifepo4 battery. This is not true . . . unless the BMS's threshold voltage for balancing is set too high. A 12v lifepo4 battery bulk charging at 14.4v (equivalent to a 3.600v parallel top-balance) should be more than enough voltage delta to allow a BMS to balance in a timely manner. If it's not, then you probably have bigger problems (see next paragraph). For what it's worth, Battleborn lifepo4 batteries are capable of supporting all BMS balancing functions when bulk charged at 14.2v - 14.4v (14.4v recommended). As you know, BB does not recommend long-term bulk charging at 14.6v.

Yes, an active balancer, especially a 5-10a version, will balance rather quickly. However, if you have properly top-balanced, "matched" cells, the 100-150ma passive balancer found on most BMS's should balance in a reasonable amount of time. If the 100-150ma passive balancer is not capable of doing so, then an active balancer may be compensating for, or putting a band-aid on, the true problem: moderately to badly mis-matched cells. No amount of top-balancing, passive balancing via BMS, or use of an active balancer can correct this problem. The result, permanently reduced ah output from the battery---especially during high c discharges.

No, not necessarily do you need 14.6v, for instance my BMS will start balancing at higher than 13.6V but for me the cell manufacture recommends charging at a constant 14.6 and then cutting the voltage when the state of charge is reached. Considering they are one of the biggest prismatic cell manufactures, I would assume they know what they're talking about and that is how I set up my system. I do play with it to see how it behaves in different situations though.

I only used my active to do the initial setup. it's still attached, and I can use a switch to turn it on.. that was because someone on here recommended that for the 20 bucks I get one. That was couple years ago when I was looking into the stuff, I needed to build mine.