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DIY Battery Discharger Idea

cwozny

Junior Member
#1
Hey everyone,

I've got an idea for a DIY Battery Discharger since my HobbyKing ECO6 50w 5A charger can only discharge at 1A and I'd like to charge and discharge in bulk per YCopter's parallel charging/discharging tutorial. I just want to make sure my logic is sound before I post an article about it. So here it goes:

I purchased two 3 ohm 50W resistors and two 1 ohm 50W resistors. In order to discharge a single 3S 2.2Ah LiPo at about a 1C rate, that means I could use two 3 ohm resistors in series resulting in 6 ohms. This would discharge at 2.083A (12.5V/6 ohms) which is just under 1C. The resulting wattage output would be 26 watts which is about half the tolerance of the heavy duty resistors so I don't have to worry about them burning out. For the discharge of four 3S LiPos at a 1C rating (approximately 8.8Ah) I could use a 3 ohm resistor and 1 ohm resistor in series and then put that in parallel with another pair for a net resistance of 2 ohms. This would discharge at 6.25A and the resulting wattage would be 78.125 watts. That means that each pair would see 39 watts. Therefore all of the tolerances are not exceeded.

Finally, these would have to be watched to so they don't discharge beyond a safe point so I'd just keep a multimeter on the battery and unplug just above 11.4V.

Has anyone done anything like this or thought about this? I look forward to seeing everyone's replies.

Best,
Chris
 

Tritium

Amateur Extra Class K5TWM
#2
If you want to burn off charge as heat. Personally I use several 12V strings of leds from xheli.com in the evening to burn off charge for storage of my lipo's and get a nice lighting effect as well. Still have to monitor charge state with this method as well. No waste for me either way though since my batteries are all solar charged. ;)

Thurmond