Electrical absorption at start up

Wolf_Tm250 · Post by **Wolf_Tm250** » Thu Dec 30, 2004 1:15 am

Hello,

I moved my battery to the trunk, and I like to put a fuse for the positive... just to avoid dangerous short circuits.

Does anyone have an idea of how big has to be the fuse ?
I imagine there should be high absorption in a cold start up of the engine.

TIA, bye.

deaf_rattle · Post by **deaf_rattle** » Thu Dec 30, 2004 9:00 am

i have a 120amp circuit breaker in my car (battery in boot)
its a ma61 with 7mgte

i never had the circuit breaker pop at start up.

hope this helps

Wolf_Tm250 · Post by **Wolf_Tm250** » Thu Dec 30, 2004 9:38 am

Thank you M8s !

Lloyd · Post by **Lloyd** » Thu Dec 30, 2004 2:15 pm

140A breaker on mine and never had any issues

MrOizo · Post by **MrOizo** » Thu Sep 11, 2008 9:58 pm

Thought i would bring this back from the basement...

Where do you get these fuses from? Something that was suitable for a battery in the boot installation.

Cheers.

bluemaumau · Post by **bluemaumau** » Thu Sep 11, 2008 10:08 pm

im sure jaycar will sell em

Alex B · Post by **Alex B** » Thu Sep 11, 2008 10:54 pm

They do indeed, got some resettable ones.

method · Post by **method** » Fri Sep 12, 2008 12:00 am

I have a 120amp circuit breaker lying around if you want one?

I also have a few 250amp blade fuses with holder to go with 0/1ga wire.

MrOizo · Post by **MrOizo** » Fri Sep 12, 2008 11:02 am

method wrote:I have a 120amp circuit breaker lying around if you want one?

I also have a few 250amp blade fuses with holder to go with 0/1ga wire.

oooOOooo could be keen. how much you looking at for the 120amp? got one from Jaycar this morning but looks a little on the tacky chinese side.

Rumad · Post by **Rumad** » Thu Sep 18, 2008 9:25 pm

For those that arent sure what size fuse to use in these type of applications all you need to do is add up the total of the fuses at the front end of the car where the battery used to be connected (From the main battery terminal follow every cable off it until you hit a fuse and so on with all the others, tally them all up & hey presto

Easiest way...)

If people are looking for an inexpensive alternative to buying a big (read pricey... say $120+ usually for the manual-reset ones) circuit breaker style fuse, i have a couple of pics of a setup i did on a mates car which does the job perfectly for less than half the price

Just paralleled these together on a 'common bar' so to speak (similar in principle to running an extra bank of injectors for fuel instead of one set of massive ones)

Note: I used automatic ' thermal' reset ones rated to about 40amps each one but you can get manual reset versions of the same thing easy as

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ChaosAD · Post by **ChaosAD** » Thu Sep 18, 2008 10:36 pm

I think youll find the starter has a direct feed without a fuse.
If you have a sick battery the starter can draw a lot more current than usual trying to crank over the engine. The volt drop of the cable from the boot to the engine bay makes things worse.

Scotty · Post by **Scotty** » Thu Sep 18, 2008 11:02 pm

You are actually meant to be fusing for the cable so that if it shorts out, it blows the fuse/circuit breaker stoping your car from bursting into flame, not to protect anything on the other end. Here is the maximum size fuse you should be using for each size of cable, anything under (aslong as you dont need to draw more current) will be fine.

Code: Select all

Wire Gauge Current Capacity Amperage (amps)
1/0              350
2                 225
4                 150
8                 100
10                 60
12                 40

You should be able to find something to fit your needs at a marine or car audio shop

Rumad · Post by **Rumad** » Thu Sep 18, 2008 11:05 pm

Youll find every wire has either a fuse or a fusible link at the battery end of the cable, even the starter cable... this is the only thing protecting the battery from ' dead shorting' to the chassis

JRS · Post by **JRS** » Fri Sep 19, 2008 7:54 pm

Rumad wrote:even the starter cable...

name one common car that has this.