Lithium Iron Phosphate (LiFePO4) cells are very common in today’s solar systems and the chemistry makes them the safest option on the market. If you want to DIY a battery you will need to source LiFePO4 prismatic battery cells. These can be shipped directly from China or purchased here in the USA.
A LiFePO4 cell has a voltage range between 2.50V and 3.65V and has a “nominal” or normalized voltage of 3.2 Volts. Cells are combined in series packs to make up a battery.
| Bat. Nominal | # of Cells | Operating Range |
| 12V | 4 | 10V - 14.6V |
| 24V | 8 | 20V - 29.2V |
| 48V | 16 | 40V - 58.4V |
A 12-Volt battery made up of 4x 280Ah cells can store around 3.5Kwh! Thats enough power to charge a cell phone 175 times or run a 1500-Watt space heater for about 2 hours.
Cells are rated in Amp Hours (Ah) and will have ratings like C-rate and Cycles. The C-rate or cycle rate is how much current the cell can be charged or discharged with.
Cycles are the rated number of times a cell can be fully charged and discharged (one cycle). A good Cycle rating to look for is between 6000 and 8000. A good C-Rate is 1.0 discharge and 0.5 charge. Using these values, a 200Ah cell could be discharged at a rate of up to 200A (1C/100%) and charged at 100A (.5C/50%) in relation to its capacity.
If cells are pushed beyond their C-rate, this will reduce the lifespan (Cycles) of the battery. If you cycled your battery fully every day, a 4000 Cycle battery would last over 10 years! At this time, the battery will still retain 80% of its original capacity.
Where to Buy Cells
USA: BatteryHookup.com
COUPON CODE: NATESDIY
Batteryhookup.com has crazy good deals. They have all kinds of batteries from small to huge. Its like the eBay of batteries!
China:
If you are willing to wait, you can save a lot by ordering directly from China. Typical shipping time is 6 to 8 weeks. Here are the companies I deal with regularly and recommend.
Click on Chat Now to speak to a representative. You can order cells with in either single welded threaded stud or EVE style double hole welded stud.
| Company | Cell Model | Product Page |
| Docan | CATL 280AH | Alibaba |
| Yixiang | CATL 280AH | Alibaba |
| Yixiang | EVE MB31 | Alibaba |
| Yixiang | EVE MB56 | Alibaba |
| XIHO | EVE MB31 | Alibaba |
| XIHO | EVE MB56 | TBD |
Quality LiFePO4 Batteries: LiTime.com
COUPON CODE: NATESDIY
DIY Battery Enclosures (12V): SunFunKits.com
COUPON CODE: NATESDIY
UPDATE 2024: Cells have dropped precipitously by some 40 – 50%! Get them before Tariffs go into place. A good price to pay now for 280Ah cells is between $45 and $50 USD per cell shipped! Depending brand of cells you buy.
Cell Buying Tips:
- Always buy cells with welded studs.
- Cells should have at least a 1C discharge rate and a .5 charge rate.
- Look for proper QR code stickers that can be verified.
- Do not use cells of differing capacity and or manufacturer in the same pack.
- Internal resistance should be the same for all cells less than 0.21m Ohm