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Fuse on rear battery main cable
https://www.ausmini.com/forums/viewtopic.php?f=5&t=100066		 Page 1 of 1
Author:  dubbomini [ Sat Jun 06, 2020 10:56 pm ]
Post subject:  Fuse on rear battery main cable
Hi,
I wish to use a fuse on the main battery cable next to the battery. What size (in AmPS) and type are everyone using?
Thankyou
Author:  fuzzy-hair-man [ Sun Jun 07, 2020 5:33 pm ]
Post subject:  Re: Fuse on rear battery main cable
I think the circiut breaker I put on mine was 150 amps, it may be just as good or better to put it on the negative as just about the only thing it wouldn't trip on is a spanner or wheel brace across both the battery terminals.
I'm not an electrian so maybe someone else will come in.
My mini is not A series powered but I don't know that it'll make much difference.
Author:  9YaTaH [ Sun Jun 07, 2020 5:44 pm ]
Post subject:  Re: Fuse on rear battery main cable
fuzzy-hair-man wrote:
I think the circiut breaker I put on mine was 150 amps, it may be just as good or better to put it on the negative as just about the only thing it wouldn't trip on is a spanner or wheel brace across both the battery terminals.
I'm not an electrian so maybe someone else will come in.
My mini is not A series powered but I don't know that it'll make much difference.


Miserable black, rainy night outside Bankstown Aerodrome...heading East...outside lane...suddenly it all goes black and no engine...somehow I got over to the kerb...ran to the boot to disconnect the battery...and found the jack welded across the battery terminals...

The cardboard cover rubber thingy had broken...it took an almighty reef to pull the jack off the battery...then the ignition and lights came back on :roll:
Author:  winabbey [ Sun Jun 07, 2020 6:27 pm ]
Post subject:  Re: Fuse on rear battery main cable
9YaTaH wrote:
..it took an almighty reef to pull the jack off the battery...then the ignition and lights came back on :roll:

Good old Lucas :wink:
Author:  Morbo28 [ Sun Jun 07, 2020 6:43 pm ]
Post subject:  Re: Fuse on rear battery main cable
I have a 250A fusible link in a holder right near the battery. Both from Jaycar. In case main lead is shorted.

I also run one of those battery cutoff switches right near the battery on the negative terminal.
ImageImageImage

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Author:  FNQ [ Sun Jun 07, 2020 8:38 pm ]
Post subject:  Re: Fuse on rear battery main cable
Wouldn't the current rating of your main cable determine the best fuse/breaker size?

This is a very good question and one that makes me question my limited understanding
My brain says
Cable size 4 ( battery cable) is rated at 135 amp, so i might put a 120 amp fuse in. But i see how 250 amp would stop armaggedon.

BUT i would love to hear from an auto electrician
Author:  fuzzy-hair-man [ Sun Jun 07, 2020 8:47 pm ]
Post subject:  Re: Fuse on rear battery main cable
Well I did ask the auto electrician I bought my circuit breaker from what he suggested, it was either 120A or 150A if you use a circuit breaker you get a battery isolation switch in there as well.
I ended up putting rubber grommet things over the terminals as well.
Author:  Morbo28 [ Mon Jun 08, 2020 10:34 am ]
Post subject:  Re: Fuse on rear battery main cable
Yeah mine is just armageddon prevention, given the length of positive cable under the car. Failsafe for a short, not for being overloaded from components.

Also the form factor influenced my decision to buy the 250A. Solid case, covered, bolt down, easily remove and replace fusible link etc.

Sent from my Pixel 3 XL using Tapatalk
Author:  FNQ [ Mon Jun 08, 2020 4:12 pm ]
Post subject:  Re: Fuse on rear battery main cable
thanks Fuzzy and morbo, just confirming my thinking . Ta
Author:  9YaTaH [ Mon Jun 08, 2020 6:51 pm ]
Post subject:  Re: Fuse on rear battery main cable
FNQ wrote:
Wouldn't the current rating of your main cable determine the best fuse/breaker size?

This is a very good question and one that makes me question my limited understanding
My brain says
Cable size 4 ( battery cable) is rated at 135 amp, so i might put a 120 amp fuse in. But i see how 250 amp would stop armaggedon.

BUT i would love to hear from an auto electrician


No...the battery cable should have a safety factor over and above the amperage actually used by the system and particularly the peak current drawn under starting conditions...
Author:  dubbomini [ Mon Jun 08, 2020 10:15 pm ]
Post subject:  Re: Fuse on rear battery main cable
Thanks everyone. I’ll go down the jay car route
Author:  AJ [ Mon Aug 10, 2020 6:20 pm ]
Post subject:  Re: Fuse on rear battery main cable
If your cable is rated at 135 Amps and you have a 250 Amp fuse , the fuse will not provide any protection , your battery cable will melt before the fuse will blow , causing all sorts of damage and possibly catch fire :shock:
Fuse size is always dependent on cable Amperage rating , the fuse or circuit breaker rating should be smaller than the cable rating to protect the cable
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