Can you fully charge 4, 25v 5500 MFD capacitors using a 12v lead acid battery charger?

Question

without using any inverters or transformers?

Answer 1

Yes, eventually, provided you can isolate the charger.

Answer 2

If you apply steady 12vdc to the caps,  then in five time constants(TC) the caps will be fully charged to 12vdc...

1TC in seconds = capacitance in farads x resistance in Ohms.

The 25vdc on the cap is a working voltage rating which merely indicates how much voltage can be applied to the cap without causing the dielectric (the insulation ) between the plates to break down.

Answer 3

is that really MF or mF or is it µF? I'll assume µF because otherwise you would have 20 Farads of cap, a huge value.

I doubt it is MF, which is MegaFarad, million farads.

For some reason, capacitor manufacturers have always gotten mF, MF, and µF confused.

Depending on the size of the charger, you may be able to charge them all in parallel, just connect them to the charger, + to +, - to -. I'd use a 10 ohm power resistor (20w) in series to slow things down and minimize the sparks.

What I'm worried about is that the output of the charger is usually a full wave rectified AC waveform, and the peak voltage may be higher than the 25 volt rating on the caps, and cause them to blow up. Chargers depend to some extent on the battery being present to limit voltage and smooth the current.

I don't know how to check this, other than with an oscilloscope. If you do try this, connect a voltmeter across the caps, and keep some sort of shield between the caps and you.

Personally, I'd get a 25 volt supply and use that. I'd stay away from the charger for the reasons I note.

Some of the other answers are incorrect, be careful.

Answer 4

Ok so to fully charge a Cap you bring its Voltage to the Max before it fails,so if you consider the maximum Voltage as 25V and the 12V battery is at 12.5 V you would charge one Cap to 12.5V then charge the next Cap to 12.5V then charge the second Cap with the Battery in series with the first Cap,now if you repeat this several times with all the Caps they will all be fully Charged;Or is that an Inverter?