How much fusing do I need? (pics)

[RedFred]

I'm about to finish up my system build, and just need to put in some fuses.

I've got an AGM G78 under the hood, AGM G31 in the rear, 270A alt, and it'll be powering 2 SQ2200 and a SQ Q4-90.

So far all I have is two 250A fuses right after the front battery.

That's how I currently have it (not hooked up, but just showing the only 2 fuses I have).

I'm running all 2/0 wire, and have an adapter for 2/0 to 4ga inputs for the 4 channel.

This is what I'm thinking of doing for fusing:

Does that look alright? Am I over-fused, under-fused, properly fused?

I read many threads on this forum about it, but couldn't come to a consensus. Some say fuses between the rear battery and amps are unnecessary, others say they're needed.

[MrSkippyJ]

that is exactly the way I would do it. I would never leave a pos (+) wire connected to a battery without a fuse as close to the battery as possible. No matter where or what the wire is going to.

[RedFred]

that is exactly the way I would do it. I would never leave a pos (+) wire connected to a battery without a fuse as close to the battery as possible. No matter where or what the wire is going to.

Awesome thanks

I figured it's always better safe than sorry, especially when a fuse holder is only $8 or whatever

[WalledSonic]

I think your setup is great. Although, you may not need a second set of fuses on the front-to-back wire run.

For instance, you have an alt up front with one batt. All your power consumers (amps) are in the back of the car. Amperage shouldnt flow towards the front of the car like it will towards the back. This justifies keeping the fuse set near the front battery.

As for the starter (your largest amp draw under the hood), it should be fused/linked from stock, so that power consumer is not a concern.

IMO, since the starter is already fused, and since the power consumers are all at the rear bank, you may only need to fuse your front-to-back run under the hood since that is the primary direction current will be flowing. Although, there is nothing wrong with fusing that run twice

EDIT: This thread is making me consider adding a second set of fuses on my long run, so I'm interested to see the responses.

EDIT 2: Thanks for correcting me Skippy. My opinion is not safe advice. 

[MrSkippyJ]

What if a short happens after the fuse under the hood in that case?

[WalledSonic]

What if a short happens after the fuse under the hood in that case?

I suppose the threat of damaging any part of your run that may not be accessible is indeed more time and money spent than just having a second fuse block. Didnt really consider a problem in the middle of the run, but a chafe/rub could def burn some wire and drain the batts.

[MrSkippyJ]

drain the batts or burn the vehicle down.

[SkarredSierra]

Ive seen wire smolder in a car before due to a faulty circuit breaker. Definately dont want that. Buddy had to replace most of the interior carpet and the rear seat. Hes lucky it didnt burn up.

[06RTCharger]

Ive just recently heard of some people recommending a fuse between the alternator and front battery also. Just throwing that out there, if thats another precaution you'd like to take care of.

[06RTCharger]

What if a short happens after the fuse under the hood in that case?

Because the short is happening after the fuse, that means it wouldnt be able to blow that early placed fuse?? Shit i better add more to my build when it gets going. I assumed a fuse would blow if any short happens anywhere along that wire. But i guess it makes sense if u think about the currents flow direction.