Wiring + Fuse Q

[msommers]

I will be running two seperate amps. One for the components up front and one for the 10" sub in the back. The one amp will be doing the almost full capacity for the fronts, 150RMS X 2, this amp has 1 40AMP fuse on it. The other(coustic 400SE) is for a small 10" JL sub which is 125RMS. Not sure on the fuse size but there are two of them if that makes any difference(don't have the amp yet to see what fuse size, sorry). Anyways, I have a 4AWG amp kit now and could pick up a bit of 8AWG for each amp from the distro block. Will this be sufficient?

As for the main fuse(s), what size should I be using? The kit came with a 60 AMP fuse. The battery I'm using isn't high end at all, its the 2 highest level at CDN tire. 750 CCA at 38º C and 675CCA at 0ºC. Reserve capacity of 120 minutes. Not sure if any of that information will help, when I was reading the online manual for the coustic, it said something about a fuse at roughly 50% of the amp hour rating, I don't know what this is.

Any help appreciated, thanks!

[spike98]

That would be more than enough for your system. But you will have to upgrade if you go over 1000wrms.

[gordguide]

" ... The kit came with a 60 AMP fuse. ... 750 CCA at 38º C and 675CCA at 0ºC. Reserve capacity of 120 minutes. ... the online manual for the coustic, it said something about a fuse at roughly 50% of the amp hour rating, ..."


The short answer: the 60 AMP fuse is big enough.

The long answer:
Coustic's reference to AH is completely unhelpful, if you live in North America. To measure that particular property, we use Reserve Capacity (RC) which is:
The number of minutes a fully charged battery at 80° F (26.7° C) can be discharged at a constant 25 amps until the voltage falls below 10.5 volts.

Even though they measure the same property of a battery, they cannot be converted; unless Canadian Tire provides you with a spec for that battery, it's useless to you to go by AH to determine the fuse you need.

I also see some wierdness in the numbers you did give; they don't make sense.

CCA is measured at 0 F or -18 C, not 0 C.
The other value cannot be CCA, it must be Cranking Amps (CA) which is the same as Marine Cranking Amps (MCA), or it could be Hot Cranking Amps (HCA), which are measured at 80 F or 26.7 C.

I have no idea what 38 C refers to; it's not a temp any battery, in Canada, the US, Europe or Asia is measured at. Also, HCA, the closest temp, is rarely spec'ed anymore; in Canada we typically see CCA , CA, and RC specified, but not AH or HCA.

So, we're left to guessing. Thankfully, that's not too difficult; the largest batteries used as starting batteries in cars and trucks max out at around 125 AH, so a 60 AMP fuse should be as big as you need to go. If it blows while listening to music, you need to look at some expensive mods to your charging and starting system, or get used to turning it down.