[9852]

hello all, i thought that I would share my version of the bad boy capasative charger. it is a true bad boy charger in that it gets its voltage directly from the mains power. I use 120v ac, a 300uf run capacitor and a bridge rectifier to get my dc voltage and current. the 300uf capacitor allows me to charge at around 15 amps constantly, with no voltage tapering off. now when you charge like this one would usually use a timer plugged in to the circuit to turn it off, but Im turnig it off another way. I have built a battery monitoring circuit to monitor the voltage of a 12 volt battery, with my circuit you can switch off power when the battery reaches a preset voltage. in my case that disconnect voltage is 13.8v, the circuit will automatically reconnect at 11.5 volts but those voltages can be adjusted with the 100k pot that is installed in the circuit. hope every one likes it it cost me 60 bucks to build and can charge from 48v to 120v.

just incase you are wondering, the case is from an old ship n shore charger that i bought from e bay and never worked, so i took what i wanted and tossed the rest.

 

[ngrimm]

Good job! Does the rectifier or capacitors generate much heat? Have you thought of any inexpensive ways to isolate the charger for the sake of safety? For instance some of the old timers would use a light bulb if they had no isolation transformer when working on a crt display. Of course by the time you used a high enough wattage bulb for say 10 amps it wouldn't give much protection. Can you share the details of your battery monitor/switching circuit?

 

[9852]

Good job! Does the rectifier or capacitors generate much heat? Have you thought of any inexpensive ways to isolate the charger for the sake of safety? For instance some of the old timers would use a light bulb if they had no isolation transformer when working on a crt display. Of course by the time you used a high enough wattage bulb for say 10 amps it wouldn't give much protection. Can you share the details of your battery monitor/switching circuit?

the rectifier does get hot, I added a fan to the otherside of the charger to keep it cool, I never thought of isolating it because my battery pack is already isolated from the rest of the car. That is that the b- cable is not bloted to the chassie of the car, it runs straight to the controller, wich is also isolated with plastic bushing so bolted in place it doesnt come in contact with the car. the battery monitor is just a normal relay switcher but i added hystersis to make it disconnect at a certain voltage, right now the hystersis is set with a 220 ohm resistor, but you can change that with a different value resistor. it is a very simple circuit that any one can make, I will upload the circuit to my computer and post it here later. it switches a 12v 3amp relay which switches the coil of the 20amp 120v relay, coil voltage is 12v, hystersis makes it discommect at around 13.8 voltsbut can be set more by using a bigger value resistor or less by turning the 100k ohm pot