Homebrewed Electricity > Other
Using BadBoy charger for 30S battery
MagnetJuice:
Here are the results of testing the Variac with different loads.
As you can see, the highest voltage that I can get out of the Variac with the dial set all the way into the 130 Volts setting was 116 Vdc with a load of 10.3 ohms. That is the resistance of the full heating element. The last three tests on the table were done with the dial all the way into the 130 volts setting.
I suspect that the low voltage output is because of the thin wire that they use to wind the transformer. Too much resistance in the wire.
For an output of 2 Kw, the maximum voltage was only 103.7.
I expect that if a Variac like this is going to be used to charge a battery to 126 volts, some type of voltage doubler has to be added to the circuit.
I don't have any high capacitance, high voltage electrolytic capacitors that I can try. The biggest I have is 160 uF at 200 V, and 220 uF at 385 volts. Not sure if that would increase the voltage that much.
I have a few microwave oven capacitors rated at 2 Kv, but the capacitance is only .92 uF. Could those be used on the AC side before the bridge rectifier?
Ed
Harold in CR:
Wow. 103.7V is kinda pitiful coming out of a 130V 2KW rated transformer. How warm/hot did the variac get.
Fishing for info here; can I assume that "run" caps on an electric motor act similarly to a governor on a combustion engine to keep rpm's up in a heavy load situation ?
If I were to buy one of these variacs, I think it would be the 20A max listed one, to keep from running maximum output to help with resistance at around 15A output or so. Price difference is $12.00- $15.00with free shipping.
Thanks for doing all the testing and reporting the results here. Really appreciated.
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