What maximum power inverter for 1G alternator

[Gary Lewis]

What size of wire did you use?

I used 6Ga wire (big pipeline to not loose current, long 14’ run).

I think the second model would fit nice.

Gary, why not install this fuse at the other end, in the cabin, instead of weather/dirt engine compartment?

The fuse needs to be as close as is reasonable to the source of the power. It protects the wire downstream of it. So if you put it in the cab and have a short between there and the starter relay the fuse won't blow and the wire will burn - and maybe even catch the truck on fire.

The smaller fuse holders have #10 wire on them, and that's a lot smaller than your #6 wire. It would work if you keep the wires to it short, but it isn't ideal. The Wirebarn calculator says that your choice of #6 will give more than a 2% voltage drop with your 28' of wire run - you have to include supply and return. At 40A #6 is only good for 17' at a 2% drop, although at a 5% drop it is good for 44'. So interpolating it looks like each % gets 9', making a 3% drop good for 26', which is still a bit shy of your 28'. And the #10 wire in the fuse won't help that.

Personally I'd be more interested in the first stud-style holder and this 40A fuse to go in it. You should be able to use the existing ring-tongue terminal on the wire to connect to the stud of the fuse, and then make a short jumper from the other stud to the relay. That way you won't have to cut into your existing wire nor try to connect #6 to #10. And you can mount the fuse holder right by the relay to make it clean.

[BigBrother-84]

The fuse needs to be as close as is reasonable to the source of the power. It protects the wire downstream of it. So if you put it in the cab and have a short between there and the starter relay the fuse won't blow and the wire will burn - and maybe even catch the truck on fire.

The smaller fuse holders have #10 wire on them, and that's a lot smaller than your #6 wire. It would work if you keep the wires to it short, but it isn't ideal. The Wirebarn calculator says that your choice of #6 will give more than a 2% voltage drop with your 28' of wire run - you have to include supply and return. At 40A #6 is only good for 17' at a 2% drop, although at a 5% drop it is good for 44'. So interpolating it looks like each % gets 9', making a 3% drop good for 26', which is still a bit shy of your 28'. And the #10 wire in the fuse won't help that.

Personally I'd be more interested in the first stud-style holder and this 40A fuse to go in it. You should be able to use the existing ring-tongue terminal on the wire to connect to the stud of the fuse, and then make a short jumper from the other stud to the relay. That way you won't have to cut into your existing wire nor try to connect #6 to #10. And you can mount the fuse holder right by the relay to make it clean.

Ok, got it, thanks!

Will proceed in the engine compartment.

[ArdWrknTrk]

Ok, got it, thanks!

Will proceed in the engine compartment.

There's still the option of a waterproof 40A circuit breaker like id originally mentioned.

These are intended for trolling motors popular with fishing kayaks and very robust from what I've seen.

Amazon, for $20 US (offshore) to $45 for top of the line Blue Seas brand.

Never worry about keeping a spare or having to unbolt a blown fuse on an always hot battery connection.

Just flip the lever back up

 

[Gary Lewis]

There's still the option of a waterproof 40A circuit breaker like id originally mentioned.

These are intended for trolling motors popular with fishing kayaks and very robust from what I've seen.

Amazon, for $20 US (offshore) to $45 for top of the line Blue Seas brand.

Never worry about keeping a spare or having to unbolt a blown fuse on an always hot battery connection.

Just flip the lever back up

I like that, Jim. Much better than a fuse.

[grumpin]

There's still the option of a waterproof 40A circuit breaker like id originally mentioned.

These are intended for trolling motors popular with fishing kayaks and very robust from what I've seen.

Amazon, for $20 US (offshore) to $45 for top of the line Blue Seas brand.

Never worry about keeping a spare or having to unbolt a blown fuse on an always hot battery connection.

Just flip the lever back up

Those are slick!

[BigBrother-84]

There's still the option of a waterproof 40A circuit breaker like id originally mentioned.

These are intended for trolling motors popular with fishing kayaks and very robust from what I've seen.

Amazon, for $20 US (offshore) to $45 for top of the line Blue Seas brand.

Never worry about keeping a spare or having to unbolt a blown fuse on an always hot battery connection.

Just flip the lever back up

Really interesting!

Thanks Jim!

[BigBrother-84]

I like that, Jim. Much better than a fuse.

Gentlemen, I completed the inverter installation yesterday.

I installed a 40A fuse holder (6ga) at the battery end of the positive inverter line. The only solution available locally fast.

I hope this wire can feed a bigger inverter, in case I decide to upgrade Big Brother’s alternator in the future (not in my plans but who knows).

The inverter is located behind the rear bench seat, passenger side. I left about 3’ of free wire, to be able to move around the inverter, if needed.

 

[Gary Lewis]

Gentlemen, I completed the inverter installation yesterday.

I installed a 40A fuse holder (6ga) at the battery end of the positive inverter line. The only solution available locally fast.

I hope this wire can feed a bigger inverter, in case I decide to upgrade Big Brother’s alternator in the future (not in my plans but who knows).

The inverter is located behind the rear bench seat, passenger side. I left about 3’ of free wire, to be able to move around the inverter, if needed.

Jeff - That should work nicely. But are you going to secure the inverter some way so it doesn't slide around?

As for that wire powering a larger inverter, yes and no. Using the wirebarn calculator your #6 wire is good for up to 80A and 22' of wire with a 5% voltage drop. But if I remember correctly you said you have 14' of wire for both positive and negative sides, for a total of 28'. However, you also said you left an extra 3' of wire, presumably both hot and ground, so if you trimmed that off you'd be right down to 22'.

But, speaking of grounds, the way I wired my 3KW inverter was to use the frame as ground. In other words, I have maybe 18" of wire from the inverter to the frame, and the frame is grounded in many places to the engine and both batteries - as shown below.

I'm not suggesting you need to do that much grounding. Nor really change anything right now. But if you do want a larger inverter you can cut your wire run by about 50% by using the frame as ground and ensuring your battery is well connected to the frame.

[BigBrother-84]

Jeff - That should work nicely. But are you going to secure the inverter some way so it doesn't slide around?

Yep, I bought commercial quality Velcro (with very strong sticky backing).

I’m confident that this inverter (it’s quite lightweight and doesn’t come hot) will stay in place.

And if needed, I can detach it and move it.

But if you do want a larger inverter you can cut your wire run by about 50% by using the frame as ground and ensuring your battery is well connected to the frame.

Interesting strategy!

I take note of it!

[Gary Lewis]

Jeff - That should work nicely. But are you going to secure the inverter some way so it doesn't slide around?

Yep, I bought commercial quality Velcro (with very strong sticky backing).

I’m confident that this inverter (it’s quite lightweight and doesn’t come hot) will stay in place.

And if needed, I can detach it and move it.

But if you do want a larger inverter you can cut your wire run by about 50% by using the frame as ground and ensuring your battery is well connected to the frame.

Interesting strategy!

I take note of it!