amp draw for on-board boat battery charger?

[jstorm42]

I'm trying to figure out what the wattage is used on my 3 bank 5 amp boat battery charger. I'm need to know for a portable generator. If I used the formula for wattage 120 volts x 15 amps = 1800 watts I would need a 2000 watt generator. Is this correct or do chargers draw less? I can't find anything on the manufacturers HSOforum.

TNX

[BobT]

You're probably pretty close but to be sure, check the nameplate on the charger. It should provide the FLA rating for you.

[eyebjim]

It is likely much lower than you estimated. The 5 amps is at 14 vdc not 120vac per bank. That equals 70 watts per bank output or 210 watts total output. There will be losses in converting from 120 vac to 12 vdc so I would say 400 watts input to be safe.

[Whoaru99]

It is likely much lower than you estimated. The 5 amps is at 14 vdc not 120vac per bank. That equals 70 watts per bank output or 210 watts total output. There will be losses in converting from 120 vac to 12 vdc so I would say 400 watts input to be safe.

I concur, FWIW.

[Lip_Ripper Guy]

I would agree with the guys above me. I have a 3 bank, 30 amp charger, and it won't even kick my 2000 watt inverter generator off idle.

[BobT]

I have to concur. My brain wasn't in gear this morning. Forgot that we're converting 120vac to 12vdc.

[jstorm42]

TNX everyone for the input. Looks like I should be able to get away with a 1000 watt Honda.