In article ,
"Dennis Pogson" wrote:

Wet-n-Wild Bill wrote:
Planning to install a 3000watt inverter (not inverter/charger) on a
boat with twin outboards. The House batteries are maxed out with the
electronics. I thinking of installing a dedicated battery bank for
the inverter or utilize one of the starting batteries on the
outboard. What do you think

Bill

I would have divided the 3000watts (AC) by 120 Volts (AC), not 12 volts.

That size of inverter at 12 volts will need a nominal 25amps when drawing
max power. Add on say 15% for loss on conversion and you would be looking at
near enough 30amps.

Personally, for that sort of current draw I would be looking for about
500A/H batteries and massive section cabling dependant on how close to the
inverter you can locate the batteries.

You need to properly work out the likely maximum draw before working the
figures for required battery power.

Deep-cycle truck batteries are worth a look. Don't buy starter batteries for
this type of application.


Dennis.



Dennis, you need to go back and check your MATH....3Kw from 12Vdc
requires 250 AMPs, that is not including any efficency factors....
250 Amps is Welding Cable REQUIRED for battery to Inverter connections.
3Kw means you need BIG batteries with lots of AMP/Hour capacity
if your going to run much.......

Bruce in alaska
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add a 2 before @