I decided to try and fit two of my three battery modules in the engine bay (The smaller two modules.. 30s3p and 18s3p modules) This was immediately impossible because of my motor mount. I modified the mount so it would take up less space and now I’m back at trying to get everything into the engine bay. I successfully bolted the batteries to the modified (cut up) battery tray (the huge T shaped ones that the chevy volt is famous for). I cut that up into three parts so my three modules will all be bolted separately.
I think I’ve figured out how the batteries will fit in the engine bay. Now I’m concerned about air-flow around the heat sink on my controller. This is an old Kelly controller (apparently they are infamous for over-heating issues). I’m not worried about the batteries over-heating because I will have them wired 24s 12p which means that each cell is supplying less than 8.33% of the maximum 500 amps the controller is rated at. Doing the math shows that each cell will be asked for no more than 41.67 amps at peak draw. For some reference the 2011 Chevy volt is rated at 149 horse power, which is equivalent to 111.1kW. The Chevy volt battery pack is rated at 360 nominal volts and actually operates between 300 and 400 volts depending on the state of charge and engine load. Let’s do the math with 360 volts because that’s nominal voltage.
power (watts) = volts * amps. So 111.1kW=111,100 W = 360 V * amps
That gives us about 310 amps peak draw on a 96s3p battery pack so each cell can provide just over 100 amps with proper cooling. I don’t have proper cooling yet, but I plan to. But as long as I keep the load on the batteries to half of the original I’m probably fine. Right? Any smart people who know better, please tell me before I blow up.
Here’s the batteries resting in the engine bay above the motor and transmission.
I can fit the bonnet over the batteries but there is not quite enough room for the heat sink on top of the controller. The controller will either melt or self limit at really low power without a heat sink. What if I put the heat sink through the hood? Is that blasphemy?
Should I cut a hole in the hood for the heat sink or just leave it off until I figure out a liquid cooling option?