DIY 200Ah LiFePO4 battery <$1400

Yes I had seen 2.2 as a low cut off but more are listed as 2.5 and I see most of the energy is gone by 12.0 volts anyway. Great information.
Looks like most inverters will take these right to the bottom and still it is far better to stop much earlier.

I am looking at two different uses including an emergency back up for a sump pump that I would allow to run to the BMS cut off vs RV use where longevity for general use is far more important and the lowest voltages would be avoided.

time2roll wrote:
Minimum voltage looks like 2.2 per cell or 8.8 volts to get full rating. Inverter shuts down at about 10.5 volts.

How much of the power have you got at 10.5 volts? More than 90%?

not sure what you talking about they stay above 12.5 untill there 86% discharged. here is a chart for you. I guess the 8.8 could be absolutly stone cold dead but we dont use that part of the range when we talk about there capacity , thats the " 10 or 20% that we stay out of to increase life. I think 5% wold be the lowest you could use them and stay above the inverter shutdown but I would only go down to roughtly 14% personaly.

LiFePo4 discharge vs. voltage

Steve

Minimum voltage looks like 2.2 per cell or 8.8 volts to get full rating. Inverter shuts down at about 10.5 volts.

How much of the power have you got at 10.5 volts? More than 90%?

I ordered 8 280AH cells from China for 900$ delivered. BUT it will take 6-12 weeks for delivery.

Here is a good write up on what you need.


https://coconup.medium.com/lithium-on-the-cheap-build-a-12v-280ah-3-4kwh-lifepo4-battery-for-less-than-600-ecce00dd1bbd.

I ordered 2 boxes 2 BMSs and 8 cells to make 2 12v batteries.


Forum with all the information you could possibly want.
https://diysolarforum.com/categories/energy-storage.19/

StirCrazy wrote:
here is a listing for 280 ah cells and free shipping seams to have pretty good reviews 280ah cells

This cost per AH is getting close to GC2 and much better performance. I think we have hit the inflection point.

The title to the thread seems a bit off. This is 280 Ah for about $600.

Ivylog wrote:
Overkill ^^^^ wants $155 for one 100AH cell...I paid that for 4 100AH cells delivered.

Still available? Source link?

here is a listing for 280 ah cells and free shipping seams to have pretty good reviews

280ah cells

Steve

Overkill ^^^^ wants $155 for one 100AH cell...I paid that for 4 100AH cells delivered.

He sure makes it look easy. With something like that even I could roll my own.

https://overkillsolar.com/shop/

Looks like the build is about 1/2 the price compared to a packaged Relion battery.

I like this guy and all the videos he does. It really is that easy to build a LiFePo4 battery. Not sure where you came up with 12V/200AH for <$1400. I recently bought 600 AH at 12V (24X100AH 3.2V cells) for $900 delivered. Add $300 for 6 BMS so $1200 for six 100AH 12V batteries... $200 for a 100AH battery, not $700.

I thought about going Lithium 3 years ago but figured the price would come down. Yes, the DIY price has come down to what a good 100AH AGM battery will cost BUT the AGM only has <1000 cycles if you only use 50AH. I’m replacing 880AH of AGM batteries, 440 AH usable. Using 80% of the Lithium will give me 480 AH usable at 1/3rd the weight and hopefully 3000 cycles.