A straight-stack layout like this is inherently weaker than a stagger-stack, because the cells have, at most, 4 points of contact with their neighbors vs. 6 points in a staggered layout. There is also a lot more air space in a straight layout, so your glue has less contact with the cells around it. In a staggered layout a very small amount of glue can squish into all the spaces and makes the brick very rigid.
All that said, you can still definitely make a straight layout work, and it will almost certainly be strong enough. You just might need more glue.
Cell holders pretty much negate everything I said here.
I want to be able to switch the power source from the main internal pack to a temporary backup box pack on top. What are my idiot-resistant switching options without having to open the enclosure every time I want to swap in the backup battery?
Edit: most relevant thing Iâve found is 300a solenoid relay used in golf carts, which is wildly unpractical for this application.
Are your ESCs in the same enclosure as your main battery?
If theyâre not (as in a split enclosure for example), you could just have a connector on the cable from the battery to the ESC, and then disconnect that and connect it to the other battery.
If itâs all in one, the best bet would probably be to have two loop key ports, arranged so that you have to pull the loop key out of one (disconnecting the main battery), before installing it into the other one (connecting the spare).
Some clever sliding/pivoting/moving cover over the loop key ports that makes it physically impossible to have two keys plugged in at once would also be a good idea.
Or you could use a handful of fets and a switch, and do like this circuit, but itâs quite a bit more involved:
Question - are the BMS lines on the left side of the image soldered to the negative connection of the braided wire? Iâve used braided wire as well but am unsure where to make the BMS solder connections? I thought all BMS (except the negative main) are soldered to the positive battery terminal.? Maybe Iâm getting my + and - confused in the image?
It doesnât really matter, itâs between the cells so the positive of one is the negative of the other. Typically youâd do the negative side for safety (no voltage potential)
OK, I think I understand. You basically have 13 braided strands and 13 BMS wires - the location for the soldering of the BMS on each strand doesnât really matterâŠ
I just used lots of adhesive and fiber tape to wrap everything up, then packed the enclosure (in my case a pelican) with the provided foam so that the battery doesnât move around at all. Others may do it differently though.
