The finished pack on my bench.
Taking up much less space and weight on my mower!
I finished the top and bottom for my battery pack and I am quite happy how it came out.
When I had first tested my pack, I found the middle cells got a bit hot and the BMS got very hot, so I wanted to add some better cooling. I also wanted to add some convenience items like a capacity meter, voltmeter, and a charge port. Then while I was at it, I figured a fuse would be a smart idea too.
The heat sink cools the BMS and the fan cools the pack.
I added a 30 amp fuse, and charge port that is wired to the BMS.
Notice the oval vents on the bottom, that is where the air is drawn in or the center cells.
Although I have a number of fans laying around, I ordered a new one. I wanted to get one that had a high static air pressure value, vs high volume, so that it would suck the air through better. I smoke tested the air ventilation and was shocked how well it worked. It was drawn into the lower vents and blown right out the top.
Nice big power switch! It is a SPDT so the fan can have it’s own lower voltage circuit.
Originally I was going to use threaded rods to hold it all together, but I did not have enough laying around. When I was test fitting, I found tie straps worked better than expected, so I just kept using them.
Notice the little button below the display. It changes between voltage and % capacity.
The pack came out great and works even better then I had calculated now that it stays cooler. I was about to mow my very tall grass in the backyard and it only took about 60% of the battery!
I have uploaded all the files to Thingiverse and you can read all the details about the rest of my pack here.