I think there is a short burst like starting and winching to some extent they can handle more. Of course if you crank a starter for 10min s*** gets hot.
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- #2,902
I don't know how length plays into it. There'd definitely be less resistance built into a shorter cable, but I don't think it's amperage rating goes up if it's short because the cross sectional surface area of the wire isn't any different.
I wish I was an ee!
You're totally right, the duration matters a lot. Don't want the fuse too low, but on the other hand, if you fuse more than the wire can handle and you have an unexpected long duration draw, then you're in trouble. The unexpected long duration draw being the dead short scenario.
Cruiserdrew
On the way there
No-You fuse to the capacity (ampacity) of the wire. For 1/0, I'd use 250-300 amp fuses. And this is always the principle. You fuse to protect the wire, not the device.
@concretejungle had a near disaster recently and hopefully he will post his pictures to show the utility of fusing wires that can carry a large current in a short. He melted 2 gauge wire and insulation when a winch lead shorted near the battery.
I don't fuse my winches, but they are all on disconnects with large Power Poles. So if I need to winch, I connect the power poles. Othewise there is no power in the leads.
But any lead from the + terminal of any battery, needs an appropriate fuse. In an ideal world, even your main starter lead would be fused. Manufacturers don't to save a few $$ but also because they have professional engineers making sure the wire paths and tie downs are very low risk.
@concretejungle had a near disaster recently and hopefully he will post his pictures to show the utility of fusing wires that can carry a large current in a short. He melted 2 gauge wire and insulation when a winch lead shorted near the battery.
I don't fuse my winches, but they are all on disconnects with large Power Poles. So if I need to winch, I connect the power poles. Othewise there is no power in the leads.
But any lead from the + terminal of any battery, needs an appropriate fuse. In an ideal world, even your main starter lead would be fused. Manufacturers don't to save a few $$ but also because they have professional engineers making sure the wire paths and tie downs are very low risk.
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- #2,904
I can jive with that argument. It makes a lot of sense. It'd introduce a lot of terminals, and therefore failure points, but I see what you're saying. There'd be four different large fuses needed for my setup then, meaning 8 extra connections. Do we really think that my new cable routes are high risk though?
The next big question is where do you get your amp rating for the fuses? The charts I see rate 1/0 wires at 170 amps @90*C.
The next big question is where do you get your amp rating for the fuses? The charts I see rate 1/0 wires at 170 amps @90*C.
Cruiserdrew
On the way there
I'm not trying to be difficult either, but the wiring shown is not safe, or even close to safe. With fuses you have a very safe system, without, it's 2000 amps just waiting for a chance to be an arc welder.
You only need 2 fuses. The grounds do not need to be fused. Fuse the big 1/0 lead you show close to both + battery terminals.
Lots of ampacity tables out there. Most wire is rated to 105C. I like the Blue Sea tables on their website as they are easy to read and very conservative.
You only need 2 fuses. The grounds do not need to be fused. Fuse the big 1/0 lead you show close to both + battery terminals.
Lots of ampacity tables out there. Most wire is rated to 105C. I like the Blue Sea tables on their website as they are easy to read and very conservative.
TLC Norway
woodwelder
Just to add to the confusion...I'm running 24v, and never had any luck with big fuses on the winch or starter.
Winch would eat 350 fuses up to 500A, witch will be similar to 700 A on 12v.
And on my starter, it would kill a 400A fuse if engine cold on a really cold day.
So I got tired of fuses, and added a main ground switch for winch and straight power for starter.
Wish there was some clever solution after all, like a slow fuse that you can reset, not have to carry spares...
Sent from my SM-G388F
Winch would eat 350 fuses up to 500A, witch will be similar to 700 A on 12v.
And on my starter, it would kill a 400A fuse if engine cold on a really cold day.
So I got tired of fuses, and added a main ground switch for winch and straight power for starter.
Wish there was some clever solution after all, like a slow fuse that you can reset, not have to carry spares...
Sent from my SM-G388F
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- #2,907
Why is there so much stress over the two battery cables and not the starter cable or the alternator cable? I was taking those two into account in my list, not the grounds.
Is it because we think the wire path has a high risk of abrasion?
Cruiserdrew
On the way there
One of the nice aspects of ANL fuses is that they are not "fast blow" and are made with cabling and motor start up surge currents in mind.
In contrast ANN fuses or Type T fuses that come up to 750 amps I think, are much faster blow. Mega fuses, another alternative, I think top out at 300amps. I just standardized on ANL fuses but others will work fine. The fuses themselves are cheap, and a 4 pack of spares is like $8 on ebay.
Alternator wires should actually be fused and usually are with a fusible link somewhere in the system-again at the + terminal of the battery. That way if the alternator wire shorts against the motor or other ground, it blows the fusible link. They are usually not fused in the other direction but that's a risk vs benefit decision. Low risk, max 100 amps or so probably factors in the decision.
And the stress for me is that your 1/0 gauge cable is in a very exposed location subject to to all kinds of vibration and wear.
In contrast ANN fuses or Type T fuses that come up to 750 amps I think, are much faster blow. Mega fuses, another alternative, I think top out at 300amps. I just standardized on ANL fuses but others will work fine. The fuses themselves are cheap, and a 4 pack of spares is like $8 on ebay.
Alternator wires should actually be fused and usually are with a fusible link somewhere in the system-again at the + terminal of the battery. That way if the alternator wire shorts against the motor or other ground, it blows the fusible link. They are usually not fused in the other direction but that's a risk vs benefit decision. Low risk, max 100 amps or so probably factors in the decision.
And the stress for me is that your 1/0 gauge cable is in a very exposed location subject to to all kinds of vibration and wear.
I'm worried about that wire across the radiator/front support as it could easily get pinched in a front end crunch. But ANY routing and I would still put a fuse in. When I get around to MY dual battery set-up I will use fuses.
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- #2,910
Gotcha, so the risk is both the high amperage capability of that circuit (930CCA x2) and that there is a high risk of abrasion. I hadn't thought of the high amperage potential, just the abrasion risk, which wouldn't be hard to correct on its own.
I'm sold. Fuses are cheap and it won't look too messy.
A pair of 300A fuses should do the trick. A couple of these and the accompanying fuse holders:
http://www.amazon.com/Blue-Sea-Syst...1&ie=UTF8&qid=1448392580&sr=8-3&keywords=300A
I'm sold. Fuses are cheap and it won't look too messy.
A pair of 300A fuses should do the trick. A couple of these and the accompanying fuse holders:
http://www.amazon.com/Blue-Sea-Syst...1&ie=UTF8&qid=1448392580&sr=8-3&keywords=300A
Cruiserdrew
On the way there
I use the Blue Sea Fuse holders, but the Cheaper ANL fuses from Amazon.
But no doubt, the BussmanCooper/Blue Sea fuses are the best.
But no doubt, the BussmanCooper/Blue Sea fuses are the best.
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- #2,913
I've got no clue. I'm still learning!
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- #2,917
I'm using these for my dual battery install. One per es terminal.
That's a lot more compact than the ANL fuses. I might go that route.
Cruiserdrew
On the way there
Looks like a good solution. Be sure to have 1 or 2 spare fuses because they will be quite uncommon in the field.
With that said, I've never blown one of the high amp fuses-that's a very uncommon event.
With that said, I've never blown one of the high amp fuses-that's a very uncommon event.
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- #2,919
Thanks for your help and taking the time to explain this all out @Cruiserdrew 
