Dumb, Ignorant Beginner Balancing/BMS Question

[Rabbit]

I'm about to build a 12-volt 280ah battery with cells from one of Mr. Prowse's current favored Ali Express sources, using a 250 ah Daly BMS. I don't have a hobby-charger or any of the relatively specialized bench-gear I see others using to top or bottom balance, and don't want to buy any given that I'll probably only ever use it once. I don't need anything even remotely resembling 100% performance from the battery from Day One, so can I wire it up without cell-balancing (assuming the individual cell voltages are very close) and count on the BMS to slowly balance it? If so, should I leave it connected to a (proper, good-quality LiFePO4) charging source? I have one of these, since I already own several "drop-in" LiFePO4 batteries. Thanks!

 

[snoobler]

Consider the cost of the power supply as a small portion of the substantial money you're saving doing DIY.

If you really don't care:

Measure voltage. Confirm no outliers
Charge to 14.6V absorption.
If BMS trips, lower absorption voltage until BMS does not trip.
Use and cycle them, monitor cells for outlier behavior.
Raise absorption voltage 0.1V/week (as you're able) until target absorption is reached.

The BMS needs to be configured to balance during charge only and only above 3.4V. If it balances all the time, it will slow the top balancing process.

 

[OnTheRoadAgain]

A 10A power supply is about $70
A 5A power supply is about $40

Trust me, once you get one you'll find 1000 uses for it.

 

[time2roll]

I went with a $12 active balancer found on eBay that moves 1.2 amps as needed at all stages. I plan to just strap it on with the BMS and let it go. Probably not the best but seems adequate. BMS balancing alone could be very slow if the cells are significantly out of balance.

https://www.ebay.com/itm/254285645186?mkevt=1&mkpid=0&emsid=e11050.m43.l1123&mkcid=7&ch=osgood&euid=e525af18991a4dfa8481d05998be111b&bu=45260051349&osub=-1~1&crd=20210322033105&segname=11050&sojTags=ch=ch,bu=bu,osub=osub,crd=crd,segname=segname,chnl=mkcid

You want the 4s model.
I even have a digital power supply although it is just 3 amps.

 

[Rabbit]

Thank you all. I've decided I'll go ahead and do something for balance, though it'll probably be the 4s active balancer and let the completed battery sit on a charger for a couple days before I do anything else with it. Much, much appreciated! This forum is wonderful for people like me. Bit by bit, I constantly learn a little more.