- Nov 17, 2011
You state low temperature charging - There aren't battery temperature controllers available?Batteryhookup discloses the source of the cells they sell. For a while, they had 18650 cells from Ring cameras that were brand new cells just in a plastic housing you had to crack open. The green cells in my latest pack were surplus from a manufacturing run. They are grade A cells that met specs, just not enough of them for anyone to use them in a new product (at least that's my guess).
The 32650 cells in my other pack were manufactured for batteryhookup and so far I have had zero issues with them. Time will tell on how long they last. A lot of DIYers are using them and have not reported any issues. Even if a cell goes bad it should be pretty easy to fix. Word of advice on these: I'm fairly sure the 5AH and 6AH cells are identical! The only difference is grading...the 6AH cells tested above 6AH and are being sold for more. Personally, I bought the 5AH versions which test out at well over 5AH and are IMO a better deal.
Historically, I've used golf cart batteries in my systems. Those are about $225 for 200 amp hours. These are crappy consumer batteries that work ok for a while but degrade quickly. Some of that is probably my lack of maintenance and the rest is that they are just shit. My gut feeling is that a 100AH LiFeP04 pack will perform as good or better than a pair of golf cart batteries over time. If your application is large drain over a long time then of course the lack of capacity hurts you. Off grid power is seldom that kind of load. It's running the microwave for 3 minutes, full sunlight for 4 hours, some lights for a few hours, more full sunlight, etc etc. In the typical off grid power profile shit grade golf cart batteries become unusable after 24 months. My feeling is that LiFerP04 packs will easily last 24 months and probably longer. The only issue is charging in low temperatures...they need to stay warm to accept a charge (my BMS has low temp cuttoff). An unheated cabin up in northern NH will need some lead acid cells to give you power while the place warms up.
Quite easy to use the energy that you would throw away to heat the enclosure up to a safe charging temperature.