Fuse size & locations for battery relocation - with diagram

[calum001]

I'm going to be relocating my battery to either the spare wheel well or under the passenger seat and i'm just trying to get my head round the correct wiring layout so i can get all the bits ordered

i'll also be fitting a cut off/kill switch for the battery on the dash but hopefully that won't be too much hassle if i get the right one

i'm wanting to put in a fuse or 2 for piece of mind and to make sure it's all protected but i'm lost at what to do at the engine bay end, i'll be putting an in-line fuse near to the battery but the biggest problem i have is with the fuse size as the Odyssey battery that i have has a cranking amp rating of 680A which i believe is quite a bit higher than a standard battery

can anyone help with the size of fuses i'll need ?

also i'm not sure where to put a fuse towards the left of the diagram shown below (not sure if theres anything i've missed that comes from the fuse box etc..) i was thinking about a fused junction box instead of a normal junction box ? would that work or does the fuse need to located elsewhere ?

 

[calum001]

anyone ?

 

[mat-nos]

just cut the possative wire after the in-line fuse then run an extension of the same guage wire to your new battery loacation and find a nice solid place with bare metal for a good earth connection (use the origanal earth wire) ....... what i did in my mk1 anyway!!!

 

[calum001]

managed to get most of it sorted now (not bothering with a fuse at the engine bay end) but the only thing i'm stuck on is what fuse to run at the battery end

anyone know if a 300A fuse would be adequate and do the job or would it blow due to the 680 cranking amp ?

 

[Jonny1*2]

you shouldn't need one mate. I was going to use a 250amp on the ALT/Starter wire, but i'm just keeping the one in there. Just run the wire direct from the battery to the kill switch, and straight to the junction box. Should be fine. what stuff you using? I've got all the stuff to do this, but still haven't got round to it.

 

[calum001]

cheers mate, i've just been speaking to one of the guys at my work (electrics side of things) and we've just been talking about how a 300/350A fuse would be fairly pointless as all you would be protecting the car from would be a power surge from the battery over the 680A and it's very unlikely, it would never run that high apart from in the first 5 seconds but any smaller fuse and it might blow, looks like i might just be going without

i got my junction box and kill switch from Demon Tweeks and i'm going to order the cable, connectors and battery charger (Ctek) from Car Audio Direct, battery from burp

what about you ?

 

[Dink]

you would be off your tits to run without a fuse at the battery at least (i'd have one from the alternator aswell)

you state in the image above that the short circuit of the batt is 1800A which is about 21kW of power

that will set light to some plastic/cloth very very quickly

i'd get a 300A fuse inline as it will not operate til about 450A

 

[bmh.01]

cheers mate, i've just been speaking to one of the guys at my work (electrics side of things) and we've just been talking about how a 300/350A fuse would be fairly pointless as all you would be protecting the car from would be a power surge from the battery over the 680A and it's very unlikely,

Wrong, the fuse is to protect the cable not the car. If the cable was shorted without being fused or breaker'd then its a fire/battery explosion waiting to happen. 680A is a lot of current. 125% wants to be fused and as close to the battery as practicably possible.

A standard battery is 420A CCC so i'd fit the smallest fuse you can get away with, probably just have to try various until you find one that holds unless you can get hold of a 12v dc ammeter that'll read that high.

 

[calum001]

cheers gents that was the type of answer i was looking for, as admitted earlier my knowledge on electrics is extremely limited !

my reason for saying it could have been fairly pointless was due to the fact that the battery will only be running at anywhere near 680A when starting (but i appreciate its a very high current so should be)

i'll try a 300A inline fuse, would try a 350A but i can't seen to find one in ANL fitment, i don't think i would get away with any less than 300A (would love to be proved wrong if anyone knows otherwise though)

would i need to go for the same size fuse at the alternator aswell or could i get away with a smaller one than the one at the battery ?

Cheers

 

[Dink]

my reason for saying it could have been fairly pointless was due to the fact that the battery will only be running at anywhere near 680A when starting (but i appreciate its a very high current so should be)

the battery will output current whenever it is shown a load

so if you get a fault it's basiclly a load with nearly no resistance so it's current will be massive (well above 680A)

yeah you could get away with about 100A on the feed from the alternator

 

[Jonny1*2]

try the bay mate. I think there is a company on there that does them. can't remember what I searched for though :S

I've got the odyssesy 25 and ctek indicator. Didnt' get the charger yet, but if it flashes red i'll just start her up I spoke to Jay (burp) about the fuse bit and he said so long as you keep the fuse on the alt/starter which is currently there it should be fine. I got a BMW 3series junction box for mine. I'll be doing a little guide when I finally get round to doing mine. No idea when though as yet. :S

 

[calum001]

perfect thats great cheers again mate !

yeh i was thinking about just keeping the fuse that's already on the alternator/starter cable (that way it's not different than normal apart from the fuse isn't right at the battery?)

i've done another diagram that i'll get loaded up soon

 

[wallop]

Some interesting reading in this post....

When dealing with electrics there are usually 2 ways to do it, the adequate/safe route, or the performance route....

The current, (pun intended lol), electrical loom is designed with cost over safety in mind....So can be labelled as adequate....

I did a pic a while back, which I think was ignored by most, (probably too expensive lol), which I based on my Cav....Will search later....

 

[wallop]

Found it...

When starting the car always depress the clutch pedal, this reduces the load on the starting circuit....

Cable sizes;

Batt to Fused Distribution Block--- 0awg
Fused Distribution Block to Starter Motor--- 4awg minimum
Alternator to Fused Distribution Block--- 4awg minimum, (Depends on ALT output & cable size used)

Please Note; This is how I would wire a relocated battery in my car, your car may require some alterations to fuses, cable sizes etc....

 

[Tiags]

Sorry to bring up an old thread but I am confused, all I need to buy is some 0gauge battery cable and run it direct from the positive bay terminal. Then Use the existing earth cable wherever I wish to locate the battery. Meaning I do not need to purchase a fuse, only the battery cable ?