I decided to build a battery bank for solar power use. This is the first prototype using 18650 LiIon cells. The production units will use plastic instead of copper, to save cost, and for increased safety. I intend to current limit this stick to 2.5 amps, for battery life. These sticks will be placed in 5 gallon buckets, through holes drilled in the lid. The buckets will be filled with water, to sink any heat that builds up. Placing MTP3055e TMOS power Fet under the cathode (negative end) of the battery, will allow me to electrically disconnect individual batteries, should the need arise.
Looking inside we see the cell stack with about 4 volts per cell. These are 24 volt, and 12 volt batteries, each at 2.5 amps.
The 24 volt unit is a 60 watt assembly. I intend to use 350 of these in parallel, to form a 21,000 watt battery bank, for primary house power. These 18650 LiIon cells can be salvaged from dead laptop battery packs. I buy them for recycle costs, and find the good batteries cost me fron a dime to 20 cents. Here is the last batch that cost me seven dollars:
Some of the other salvaged and tested batteries. This is a good way to accumulate low cost (sweat equity ) batteries for DC power storage.