LiFePO4 battery build

pianotuna wrote:
Once every 30 cycles do a full recharge. The rest of the time charge to 85%. Try not to go below 20%. (40% would be even better for cycle life).

The best way is to have a bms. Sure, it costs more--but no battery is cheap. So why not do it the best possible way?

900 amp-hours is a respectable bank. I got to 875 in 2012.

Where are you getting every 30 cycles from and do you even know why you charge to 100%, or for that matter do you even halve to? yes, lowering the actual amount of discharge you use will increase life but there are other ways to do it without losing capacity also. for example, uncompressed my cells have a cycle life of 4000 cycles at 100% discharge. do if I do that twice every weekend so 104 cycles per year, which will last me 38 years. by compressing them properly that will add another 1800 cycles to that 4000. but having said that the compression has the biggest effect in the first few cycles where it acts to squeeze out any air bubbles that are trapped in the cell during manufacturing, so I'll probably just compress them while I do my capacity testing and do 4 or 5 cycles of the battery.

I already stated that I did have a BMS which makes me wonder do you even read the posts or just start spouting out after reading the first two lines?

There is also a difference between your 875 of AGM which gets you about 437 of usable AH if you want them to last, probably less than that as you said they were used telecom jars which means they probably have already lost capacity. I will have 900AH which I can use 100% of if I like and they will outlast me.

I will not be discharging 100%, I build my batteries to have between 5 and 10 days capacity if the solar breaks so normally I'll only discharge 10 to 20% and yes, I will be setting 90% as the top of this battery in the camper, but I won't be charging it to 100% ever, aside from the first few cycle tests. After that I will be adjusting the parameters to make 90% act as 100% so it will balance every time it gets to 90%.


Admin's Edit: Removed some of the vitriol towards Pianotuna.