Engine electronics current draw

RaveOn · **Posted:** Fri Jan 02, 2015 12:57 pm

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

ric · **Posted:** Fri Jan 02, 2015 2:07 pm

RaveOn wrote:

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

The main harness which sits behind the fuel pump, ECU, etc is protected by a 50 amp fuse, so the engine is going to draw up to a maximum of around 49 amps.

Adding a second battery, or even a third, will not harm it. 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. That way the charging system will charge the 2nd battery, but if you run the system dead it will not steal power from the 1st starting battery and you'll make it home.

Oh, and Class D amps are a must.

babbot1 · **Joined:** Tue Mar 12, 2013 3:46 pm **Posts:** 570

Just a few things to note.
Your alternator may put out 75 amps if that's what the manual says but that's at max rpm. At cruise it may only put out 40-50 amps or so. If you are using all those amps for your stereo and all the boats electronics the battery will never charge. Definitely put in another battery that is isolated from the starting battery and if you hook it into your charging system from the engine you are now cutting that 75 amps in half for each battery. Keep both batteries on a maintainer when not in use for piece of mind.

Paul I. · **Posted:** Tue Jan 06, 2015 10:28 am

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. :wink:

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

ric · **Posted:** Tue Jan 06, 2015 10:44 am

Paul I. wrote:

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. :wink:

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.

Paul I. · **Posted:** Tue Jan 06, 2015 11:20 am

ric wrote:

Paul I. wrote:

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. :wink:

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.

Geneally speaking, a breaker is rated about 10 to 15% higher than its normal load. The same would hold true for the wiring, if its done right. So Ric is saying, that the beaker is 1 amp more than the load. What about surges?

Case in point: Bilge pumps if you look at the chart of fuse ratings. http://store.waterpumpsupply.com/ru12vodcnobi.html

Graham R · **Posted:** Tue Jan 06, 2015 11:46 am

ric wrote:

RaveOn wrote:

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

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. .

Someone should have told the factory that; the 70A breaker and power wire to the factory fitted amplifier on my 2009 boat was connected to the starter battery, admittedly on the switched side of the starter on/ off breaker switch. (Or rather, it was connected to the starter battery; it isn't anymore ), .They did that as the standard "systems" on/ off switch and breaker has a lower rating and would trip if the amp was on.

RaveOn · **Posted:** Tue Jan 06, 2015 8:50 pm

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.

RaveOn · **Posted:** Tue Jan 06, 2015 9:01 pm

ric wrote:

Paul I. wrote:

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. :wink:

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.

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.

ric · **Posted:** Tue Jan 06, 2015 10:39 pm

RaveOn wrote:

ric wrote:

Paul I. wrote:

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. :wink:

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.

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.

What you're saying is true, cause the 50 amp breaker is on both carb'd and FI models. The FI models using substantially more amps than carb. I'm pretty sure with enough time and google I could get the specs of the whole boat and tell you exactly how many amps but it's safe to say a late model FI boat takes at least 50 amps total draw running with all accessories on. 50 amps of 12v is not a lot of power we're talking about running 6 100w 120v lightbulbs.

RaveOn · **Posted:** Wed Jan 07, 2015 6:27 am

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

ric · **Posted:** Wed Jan 07, 2015 7:16 am

RaveOn wrote:

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

At first I thought I was doing drunk midnight math, but I was just converting 12v dc to 120v ac so people can get the idea of something they're familiar with.

Paul I. · **Posted:** Wed Jan 07, 2015 8:39 am

RaveOn wrote:

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.

RaveOn · **Posted:** Wed Jan 07, 2015 9:32 am

Paul I. wrote:

RaveOn wrote:

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.

ric · **Posted:** Wed Jan 07, 2015 9:49 am

RaveOn wrote:

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.

Well, you bought the wrong brand boat if you're a wiring hobbyist. Or the right one maybe. Four Winns wiring is designed by middle schoolers on a budget with no training. Maybe they fixed that in your year vessel.

I've said it before and I'll say it again. The best boat made would be Four Winns styling with Chaparral wiring.

www.iFourWinns.com

Engine electronics current draw

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