Wire gauge from one battery to another

[Tiny Metal Tube]

So let's say your battery bank has more than one battery.  How do you decide on the gauge of the wires that go from one battery to the next battery? How could you possibly know how much amperage will flow there?

I'm getting two Odyssey PC1800-FTs for now.
https://www.amazon.com/gp/product/B00M1X3BSW

 

[Canine]

I used 2/0 which was bigger than I needed, but since the wires are so short, I went ahead and spent the extra money on the much larger gauge.

Wires that are the same length also helps.

If you can borrow an amp clamp, that will let you know how much is flowing. Not many amps will be flowing unless you are powering something like a microwave.

 

[Tiny Metal Tube]

Not many amps will be flowing unless you are powering something like a microwave.

I did get a 3000W inverter so I can run an induction cooktop and some other stuff. Let's say I'm running the cooktop at 1000W. Will the inverter pull 1000W or 3000W from the battery bank?

 

[highdesertranger]

the inverter will pull at least 10% more and could pull 30% more it all depends on the inverter. put a Kill-a-watt on the induction plate to see how much that draws then add 30% for safety. a 3,000 watt inverter can pull close to 400 amps if you max it out. that means huge cables, make sure to us a calculator, Blue Sea has a good one,

http://circuitwizard.bluesea.com/

highdesertranger

 

[John61CT]

Cranking the engine is a huge amp load, but usually under 2 sec so not much chance to heat up.

Using a winch can be a lot, best while alt is running to support the bank.

Probably better and cheaper to order from genuinedealz.com

If you're going to DIY, read this HowTo closely https://marinehowto.com/making-your-own-battery-cables/ Everything at that site is worth reading, couple other crimping / wiring articles, battery monitors, etc.

I use 00 (2/0) because I bought 100' but 0 (1/0) should be fine for most setups.

 

[Canine]

I, too, have a 3000 watt inverter. It's bigger than I need, but was able to get it for less than a 2000 watt, so that's why I bought it. Most any equipment that is being used at its limit will fail faster. A 1000 watt inverter is technically big enough for my needs, but it would probably buzz and get hot and not last as long. Do what HDR said and add a percentage, but I always err on the high side, so go 20% or 30% more.

The inverter will only pull enough energy to power the device that is plugged in plus the 30% loss. Using a 3000 watt inverter with a 1000 watt device plugged in plus 30% loss will be 1300 watts total. If the induction cook top is capable of 1800 watts on the highest setting, but you turn it up only to 1000 watts at the medium setting, the total energy used will be 1300 watts max.

 

[Tiny Metal Tube]

^ Cool. I ordered a 300A circuit breaker, I figure that'll be plenty, since nothing else will be on that run from the batteries. I may run the cooktop (stove?) at 1800W once in a while but I'm sure a lower setting will be plenty for most of my needs. 

Then there's the question of what to do when the wire is thicker than the connector. My math says I should have at least 1/0 gauge wire running to the inverter, but the connectors looked like they're around 8 gauge... And the included wires in the picture look like 10-12 gauge. Kinda scary.  

They should be arriving some time this week. I'll double check and make sure something can be done there.

 

[highdesertranger]

there is no way a 3,000 watt inverter can run off 8 gauge wire. what brand inverter is this? got a link? highdesertranger

 

[Tiny Metal Tube]

^ https://www.amazon.com/gp/product/B076KP71SJ

4.5 stars after 109 reviews seemed pretty good to me. Maybe they just didn't make the picture to scale.

 

[Tiny Metal Tube]

(deleted)

 

[Canine]

6 gauge wire. That isn't big enough. I use 4/0 but that's what I had lying around. I would have used 2/0 if I had to buy it. 1/0 minimum for me. 1awg according to a chart I consulted. I can't understand why they would include 6 awg wire when it is way too small. You could use the 6 awg to connect a fuse block.

I just looked some more. The manufacturer made a comment that recommended 1/0 at no more than 6 feet long with a 350 amp fuse on the hot side.

 

[B and C]

There are two big studs on the back (red and black) for connecting your 12V cables to. The small connectors on the front next to the 110V plugs are for hardwiring AC plugs in your vehicle.

 

[John61CT]

^ Cool. I ordered a 300A circuit breaker

Link? That size I'd recommend a fuse.

IMO can't rely on just Amazon reviews for specialized stuff like this.

wrt wire sizing, get to know the Circuit Wizard app and actually calculate yourself, conservatively.

Going from big wires to small termination if needed, already covered asymmetric butt connectors elsewhere right?

 

[highdesertranger]

yep that has studs on the back to hook up the 12v. that's a very good way to hook up the 12v you can hook up any size wire you want. make sure to use the appropriate size. the 2 short red and black wires shown in the first pic appear to be way to small, notice they are doubled up. seems kinda mickey mouse. highdesertranger

 

[Tiny Metal Tube]

Link? That size I'd recommend a fuse.

https://www.amazon.com/gp/product/B074SSH85T

> already covered asymmetric butt connectors elsewhere right?

Huh?

 

[highdesertranger]

well I wouldn't trust a no-name circuit breaker. I would go with a Blue Sea or Bussmann. anytime they advertise for car audio it's a red flag for me. highdesertranger

 

[John61CT]

+1 squared

Like propane fittings, circuit protection not an area to pinch pennies.

Might work OK as a switch for a while, at say 20% of its rated ampacity.

Anything over say 50A go with a simple fuse

 

[John61CT]

> already covered asymmetric butt connectors elsewhere right?

Huh?

Looks like you don't need it, but
https://vanlivingforum.com/showthread.php?pid=377915#pid377915

 

[Canine]

The circuit breaker you chose is likely for intermittent use. It will get hot if you use it long enough with enough amps, which isn't long. If you want something rated continuous duty, you will pay more. At least $40 more. That may never be an issue for you, but it is good to know.