Hi. Does anyone know the approximate value of current the efi and electronics draw on a 2013 4.3 volvo by chance? (I'm guessing around 30amps?) Just trying to get an idea of the load on my starter battery. My alternator puts out 75 amps and I'm adding another battery for stereo upgrade. Thx

I am willing to bet your right, ReveOn. Closer to 30 to 35 amps. Not the 49 as someone suggested. Thats just to close the the breaker's rating.

Generally with a 75 amp Alt. you don't want to go over 4 times the amp hours on your batteries.

Personally, I like battery combiners. There is no votage drop across them and some have a control wire. Them that battery can also help start your engine.

Installing a good on board 3 stage charger, would not hurt at all.

You wouldn't put a 50 amp breaker on a 35 amp load unless you wanted your boat to burn down in a raging fire during a fault.

The question is what about your stereo? If you're planning on adding a subwoofer, big amp(s), etc? The route to go will be adding the 2nd battery behind an isolator and run the stereo electronics on the 2nd battery. .

You wouldn't put a 50 amp breaker on a 35 amp load unless you wanted your boat to burn down in a raging fire during a fault.

Hi Rick

Always remember that the fuse or breaker is sized based on wire size and not device loads. As long as the breaker is sized to the wire size the wire should never melt or catch fire. Branch circuits are sized to the branch loads and main feeds are based on the cumulative branch loads if feeding a fuse panel for example. Always size the wire to the load or loads (derate accordingly) then fuse accordingly to wire size of the branch or main feeds.

I think you mean 60-100w incandescent bulbs. 6000w/120v=50 amps.

In terms of fusing always remember that the fuse or breaker is meant to protect the wire and not the device. Always derate for voltage drop (no more 3 %) based on length of cable run. Size the cable of either the main circuit or the branch circuit based on the device loads accordingly. Then fuse based on wire size. Also load the circuit no more than 80 percent capacity of the current rating of the awg of the wire. Just because a main fuse in a harness is set at 50 amps doesn't mean that the continuous load is 50 amps and the continuous load shouldn't be close to the fuse rating.

Could not have said it better!

I will say that in house wiring it's more based on wiring for the fuse rating. The loads can be different, T.V., lamp, cell phone charger, A/C unit. In a boat, generally they/you know what the load will be and plan accordingly. So now you can protect the device and the wiring.

Yup. Definitely. If in doubt upsize the wire by a size. U can always install a smaller fuse just never overfuse. I hate voltage drop and I size accordingly Lol.