My first DIY battery will be a small one, 12.8v (4S) of CATL prismatic 120Ah cells. I bought the cells from Basen. On the forum, I read that I should probably compress these cells to about 6 PSI. Can some of you please review this scheme, and advise if I'll be making a 'misteek' by proceeding with this plan?
In the listing, Basen gives cell dimensions as 48mm x 174mm x 168mm. The width x height area is 45.3 square inches, calling for compression of about 270 lbs. I bought a couple of cheap 8x8 inch baseplates, in thickness 3/16". They're larger than I need, but I don't have good cutting equipment for heavy steel. Some of the excess area between the plates will be taken up by a thermostat-controlled heater pad (which is enabled by both the thermostat and a separate 'enable' switch). The rest will be taken up by foam insulation, protecting the battery cells from RV Trailer vibration during travel. (The inner floor and sides of the outer battery box will also have anti-vibration foam, except for an area where the BMS can release heat.) BMS will be mounted on one of the end plates. With another el-cheapo thermostat unit, I could cover that BMS heatsink with a small computer fan to assist in pulling heat out when the battery gets warm, but I'm not sure that I want to bother with that. Each added thermostat creates a phantom load of about 0.3 Watts.
The 3/16 steel baseplates should be quite inflexible. If ordered pre-drilled, they would have been pre-drilled with 9/16 holes supporting 1/2" threaded rod. But I don't want to use rods that large, unless the inner diameter of suitable compression springs require that I go there. Being soft steel, I can drill my own holes (for either 1/4" or 3/16" rod). In the case of the small ones, each 1/4" rod can support about 200 lbs of tension before stripping its nut or stretching too far. I will require only 270/4 lbs of tension on each one (just under 70 lbs), so even 1/4" looks OK to me -- if that's not too tight radius for the controlling springs.
I have no idea what springs to buy, and will be reading whatever messages Threads I can find on that topic shortly. Thank you all for reading!
In the listing, Basen gives cell dimensions as 48mm x 174mm x 168mm. The width x height area is 45.3 square inches, calling for compression of about 270 lbs. I bought a couple of cheap 8x8 inch baseplates, in thickness 3/16". They're larger than I need, but I don't have good cutting equipment for heavy steel. Some of the excess area between the plates will be taken up by a thermostat-controlled heater pad (which is enabled by both the thermostat and a separate 'enable' switch). The rest will be taken up by foam insulation, protecting the battery cells from RV Trailer vibration during travel. (The inner floor and sides of the outer battery box will also have anti-vibration foam, except for an area where the BMS can release heat.) BMS will be mounted on one of the end plates. With another el-cheapo thermostat unit, I could cover that BMS heatsink with a small computer fan to assist in pulling heat out when the battery gets warm, but I'm not sure that I want to bother with that. Each added thermostat creates a phantom load of about 0.3 Watts.
The 3/16 steel baseplates should be quite inflexible. If ordered pre-drilled, they would have been pre-drilled with 9/16 holes supporting 1/2" threaded rod. But I don't want to use rods that large, unless the inner diameter of suitable compression springs require that I go there. Being soft steel, I can drill my own holes (for either 1/4" or 3/16" rod). In the case of the small ones, each 1/4" rod can support about 200 lbs of tension before stripping its nut or stretching too far. I will require only 270/4 lbs of tension on each one (just under 70 lbs), so even 1/4" looks OK to me -- if that's not too tight radius for the controlling springs.
I have no idea what springs to buy, and will be reading whatever messages Threads I can find on that topic shortly. Thank you all for reading!