I have been building an 18650 based battery pack for our new motor home and have run into a few snags that I cannot find answers for. Some issues have been addressed on this site but I am going to list them aswell for good merit.
Pack Specifications 18650 cells that are used but tested for mAh (2200+) and internal resistance (200mOhm or less) 20 - 18650 cells per module 6 - modules in parallel per battery 2-12 batteries total So each battery pack is 20p6s
Each battery has BMS Each cell is fused All modules in all batteries have very similar cells as to not become unbalanced.
Two batteries are currently connected to a charger/inverter and have stayed remarkably balanced. Teating each module regularly has shown difference of no more than ~.1 volts
Questions 1. I recently acquired a few hundred 18650 cells of different chemistry. Can I use them all in the same modules?
Specifically I have used all low amp >5 laptop cells (lithium cobalt) and this new batch is high amp <10 vape cells (lithium magnesium) I have found no information on this subject and would love to get some in site
- I am soon adding two more batteries (with individual BMS) identical to the current two. Is there a limit to how many batteries I can use in parallel like this?
If anyone is interested i will also soon be releasing a DIY guide on how to build this style pack. It's all modular so testing for low voltage or failed cells is easy and replacing them is just as easy.