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Old Sep 11, 2004, 05:02 AM
lazy-b is offline
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Manila, Philippines
Joined Jul 2004
1,239 Posts
DC to DC converter Module/no need for balancing circuit to charge Multi-Lipoly.

Have you tried a DC to DC Converter module, to created an Isolated DC power supply connected to the INPUT of a LIPO battery charger, with this setup you can make 3 identical single cell LIPO charger to charge an individual cell of a LIPO battery that connected in series, with this configuration all individual charger will charge a single cell, and no need for a balancing circuit.

3 units Converter 3 units Charger 3pcs Lipo
connected in series
12V---Dc to DC converter-----Lipo Charger------Lipo cell
12V---Dc to DC converter-----Lipo Charger------Lipo cell
12V---Dc to DC converter-----Lipo Charger------Lipo cell

all 12V input is connected in parallel

DC to DC converter is 12Volts in and 12Volts out 50 watts converter.

the Lipo charger is just a LM317 (constant current) and another LM317 (constant voltage)...or any single charger you prefer.

Lipo cell battery can be of different capacity. you can mixed 1000, 1500 or 1200....just assume its the lowest capacity available for the whole pack.

some of you might say that brand new DC-DC is expensive, but you can check at surplus store, its really cheap about 5 doller only.

I am sure it will work cause the output of the DC-DC converter is totally isolated, just imagine its a separate 12 volts battery on the output of DC-DC converter, in fact you can create a 24 volts power supply by connecting the negative of the output to the positive of the input.

if you can get lucky, you might find a Li-ion battery sell for less than 1 doller.....the Lithium-Ion has a low discharge rate, so I use 2S6P thats equivalent to 8400MAH 7.2 volts, I use it on my electric Speed boat, can run it for more an hour.
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