Many years ago I purchased a "bag battery" that hung on a leg to use with a GPS semi permanent base station for a long project that required us to be on call, on site and up and running in minutes for up to 10 hours a day.?ÿ It cost about $300 and it would charge overnight and be good the next day for that length of time (or close to it).?ÿ I like that so much that about 5 years ago I bought another from the same vendor for $400 that was about the same thing.?ÿ We do a lot of rural boundary surveying where returning to the base to switch out batteries is extremely inefficient.?ÿ The original bag battery has finally seen better (and longer staying charged) days, so I called my friendly supplier and now that battery is over $500.?ÿ A little disassembly and internet searching revealed a solution.?ÿ The big plus is I found a use for an old and stained SDR33 case!?ÿ Total cost, other than a little of my time? $70.?ÿ The key is the LiFePO4 battery.?ÿ They have internal overcharging/discharge protection and are very light. That is type of battery that is already in the others except that they are a little smaller and are more a round block.?ÿ
The first pic is of the 5 year old $400 unit I bought and it still works good.?ÿ The second is the unit I made and placed in the long retired SDR33 case and the last is a shot of the battery with specs.?ÿ The cables have quick disconnects (blade type) to the battery and work great with the pigtail power cable on our HiPer V's.?ÿ I overdid it on the cables. The don't need to be automotive/motorcycle size 10 awg wires.
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Nice work!
