ripple4
Well-known member
On the laptop battery suggestion I found that new laptop batteries packaged for dell laptops cost less $/kwh ($.17/wh) than the china pouch cells i'm currently testing ($.27/wh). the question is do these inexpensive laptop batteries really have the 54wh or whatever capacity that is printed on the battery case. and how much time is required to libertate 4000 cells from plastic cases with 8-cells each in them. also I found there are people who take apart laptop batteries and sell the individual cells in places like Lithuania, and these are as little as $.10/wh, but the capacities range from 1ah to 1.5ah, so they would be mixed and I would need a lot of them. a different angle on it would be the 26650 format battery which also has a strong market pretense and higher per cell ah rating, but these round cells may not pack into the leaf battery case at 40kwh volume due to the interstitial space between the cells. maybe that's a big deal maybe it is not. if most of the battery was in the case and then more of it outside the case, in a second place, then the BMS wires would need to run out of the battery case to balance charge the remainder of the pack, not elegant. thoughts?
if I had a leaf battery shell I could do fitment trials, anyone know where I can get one inexpensively? I'm near Toledo ohio.
I also made the discovery that the 2s3p probably is not going to work with the cells I bought, the reason is that the Nissan metal case modules nest inside each other a little and the difference in the overall height and the nested height is going to prevent 6 cells being stacked. The 37ah cells are not near as wide or long as they could be, but they are more than 1/2 the format of the Nissan cell, so two are larger than the Nissan cell when laid next each other on one layer. they do make 50ah cells with the right size which would net a 100ah capacity in a 4 thick arrangement, but I cannot find 60ah pouches that will work, ie both tabs on one side and <9mm thick. as it stand just using the 37ah cells in the stock 2p2s arrangement will net 26kwh with TMS, more than stock and able to DCQC better than stock, but not the 150 mile range I was targeting.
So far the liquid cooling trails showed me that when the 2s/1p pouch cell pack is insulated on the top and bottom, but not the sides, I can charge/discharge without any cooling at the 30amp rate and the cells stay below the manufacturer 113F limit. I found that they get hotter on charging than discharging at the same current flow. and the copper plate with cooling blocks glued on the edge and the particular of the cooling system I have (small 110v aquarium pump and 3x120mm CPU cooling radiator) cool the cells so that the peak temperature is 8 degrees less at a 30amp charge (92f vs 100F with 80f air), and also the cell bulk temperature returns to albeit temperature more than 90 minutes sooner, that's the big difference there. so the next step is to increase the flow of the coolant and try to hold the water temperature at 5 degrees less than air temp by dropping ice cubes into the water reservoir periodically to simulate the chiller cooling the heat transfer fluid below ambient temp just a little. any other suggestions? maybe I could get a second 30 amp charger and power supply and run them in parallel and get the actual charging rate of a DCQC.
if I had a leaf battery shell I could do fitment trials, anyone know where I can get one inexpensively? I'm near Toledo ohio.
I also made the discovery that the 2s3p probably is not going to work with the cells I bought, the reason is that the Nissan metal case modules nest inside each other a little and the difference in the overall height and the nested height is going to prevent 6 cells being stacked. The 37ah cells are not near as wide or long as they could be, but they are more than 1/2 the format of the Nissan cell, so two are larger than the Nissan cell when laid next each other on one layer. they do make 50ah cells with the right size which would net a 100ah capacity in a 4 thick arrangement, but I cannot find 60ah pouches that will work, ie both tabs on one side and <9mm thick. as it stand just using the 37ah cells in the stock 2p2s arrangement will net 26kwh with TMS, more than stock and able to DCQC better than stock, but not the 150 mile range I was targeting.
So far the liquid cooling trails showed me that when the 2s/1p pouch cell pack is insulated on the top and bottom, but not the sides, I can charge/discharge without any cooling at the 30amp rate and the cells stay below the manufacturer 113F limit. I found that they get hotter on charging than discharging at the same current flow. and the copper plate with cooling blocks glued on the edge and the particular of the cooling system I have (small 110v aquarium pump and 3x120mm CPU cooling radiator) cool the cells so that the peak temperature is 8 degrees less at a 30amp charge (92f vs 100F with 80f air), and also the cell bulk temperature returns to albeit temperature more than 90 minutes sooner, that's the big difference there. so the next step is to increase the flow of the coolant and try to hold the water temperature at 5 degrees less than air temp by dropping ice cubes into the water reservoir periodically to simulate the chiller cooling the heat transfer fluid below ambient temp just a little. any other suggestions? maybe I could get a second 30 amp charger and power supply and run them in parallel and get the actual charging rate of a DCQC.