[Nebster]

I highly recommend building a big mobile power system so that you have an excuse to buy a FLIR thermal imager. These things are so fun, and they're useful for tons of stuff, too. You can see how your roof airs vent into the cabin. You can figure out if your slide seal is actually, you know, sealing. You can literally look at the heat patterns on your wheels after a hard drive to see if you are getting even wear.



But, for large lithium packs, the real motivation is to be able to look at a large number of cells or interconnects and very quickly determine if there are any issues. One poor connection could lead to big problems, and an imager is a good part of a defense-in-depth against a mistake. (Especially if you are a novice, like I am.)

Above, you can see the battery bank under a medium-sized load. The hottest point there is where all the energy is bussed up onto the single main pole of the big power contactor -- as it should be. More importantly (and not so obviously from that picture, sorry), each of the string wiring paths is heating up about the same as all of the others.

I'll be repeating this kind of testing over the first few weeks and months, as system gets used more and as the road jostling puts stresses on all the interconnects. I've already identified one bad crimp this way and rebuilt that wire. Needless to say, I am carrying a bunch of hardware and tools to be able to fix stuff during the early going!