Lithium batteries don't need a balancer either. I've been running a 3.6kWh pack of 12 cells for almost 5 years with no BMS or balancer.
I bottom balanced all the cells before building the pack and setup my chargers to only go to about 98%. This leaves more than enough leeway to avoid problems if one or more cells drift.
I've rebalanced a couple of cells once because they were off by a few hundreds of a volt. They're probably about due for another minor rebalance.
That said, this is in controlled conditions with regular use and monitoring. The cells are LiFePO4. I wouldn't run other chemistries without a BMS. Next pack I build will be much larger and have BMSes for safety and so I don't have to think about it.
Hmm ok. My experience with Lithium batteries is with EVs. Do you have a low discharge rate on your pack? Because the EV battery pack needed balancing like every charge. Otherwise it has to be a quality difference.
Most EVs don't use LiFePO4 although some are moving to it. There are also hundreds or thousands of small cells in most EV packs. With that volume you'll get more variation between the best and worst cells. You also need it to be foolproof and require no maintenance.
My average discharge rate is much lower than 1C which does help. The max is around 0.9C but that is pretty uncommon.
I bottom balanced all the cells before building the pack and setup my chargers to only go to about 98%. This leaves more than enough leeway to avoid problems if one or more cells drift.
I've rebalanced a couple of cells once because they were off by a few hundreds of a volt. They're probably about due for another minor rebalance.
That said, this is in controlled conditions with regular use and monitoring. The cells are LiFePO4. I wouldn't run other chemistries without a BMS. Next pack I build will be much larger and have BMSes for safety and so I don't have to think about it.