12v wire thickness

[timelinex]

I have a 2kw inverter and will be getting a 100a converter for my 2 100ah lifepo4 batteries. Currently I'm just using whatever ga wires came with everything (a bix of 4/6/8).

I am planning on changing everything to connect through a BUS BAR and upgrade all the cabling to heavier ga. I want to future proof it to handle a 3kw inverter.

It's been REALLY confusing figuring out what wires I need. ALMOST everything online "(forums and articles) tell me I need something like a 4/0 guage, which is HUGE. That makes sense considering 3kw can reach 200-250 amps. Except the fact that no OEM items come with something nearly this thick.

I think the reason all these recommendations may be wrong is they do not account for length of wire being very short in our use cases.

Can anyone confirm?

I've found this site, which DOES take into account length:

http://www.offroaders.com/technical/12-volt-wiring-tech-gauge-to-amps/

It looks like considering everything is definitely under 4ft, I won't need anything over 4ga. On the other hand, I'm pretty sure that ampacity is over max 4ga rating when you look it up.

Using this calculator: https://baymarinesupply.com/calculator I get 2ga for my 2kw and 1/0 minimum for the 3kw. If this is the case I would likely go with 2ga to save money and more importantly because I don't even think the 1/0 would fit in the current inverters lugs.

Can anyone make any recommendations based on actual knowledge and not just heresay or making best guesses?

[enblethen]

Wiree size is commonly in the owner's manual.

[Boomerweps]

TurnThePage wrote:
No room for 2 wires from post to post.

I just replaced all my battery terminal screws with slightly longer stainless steel bolts, with a lock and regular washers. They are all M8s for thread size and diameter. This is to allow two large terminals to be stacked for paralleling my batteries and allow plenty of thread engagement. Each battery has two connections per terminal, on one end battery is the inverter, and the other, the lines to the buss bars and battery cutoff.

[Bobbo]

Here is a hydraulic crimper for less than $40. Hydraulic Crimper on Amazon

[deltabravo]

ktmrfs wrote:
Hydraulic crimper and 20 seconds and your done with a long lasting gas tight seal.

Once I get to an 8ga or smaller wire, out comes the hydraulic crimper.

A few years ago I installed a Victron inverter in my truck camper.
I bought a Temco hydraulic crimper. I built all of my own cables.


Video about my Temco Crimper

Another video: Building Battery Cables with TEMco Industrial TH0005 Crimper

[deltabravo]

ktmrfs wrote:
exactly. a 2KW inverter will draw 200A or more, 4ga isn't even adequate for a 1KW inverter if you intend to run anything near rated output for more than 15 seconds or so.

YEP!
Back in the 90s, (1991-1999) I worked for Heart Interface, the predecessor to Xantrex.
All of the 2kw and bigger inverters had 2/0 cables.

[ktmrfs]

deltabravo wrote:

timelinex wrote:
It looks like considering everything is definitely under 4ft, I won't need anything over 4ga.

Smoke (and flames) will escape from the wiring if you use wire that small and a 2kw inverter.

exactly. a 2KW inverter will draw 200A or more, 4ga isn't even adequate for a 1KW inverter if you intend to run anything near rated output for more than 15 seconds or so.

[ktmrfs]

Grit dog wrote:
^Great, you have a shop that provides you good deals on cables. I work on a lot of vehicles and never needed that many cables over the years.
Still doesn’t make any sense why they would “need” to be hydraulically crimped as you said above, though.

you probably could get by w/o a hydraulic crimper, but lots more work and time to get a good crimp. Hydraulic crimper and 20 seconds and your done with a long lasting gas tight seal.

Once I get to an 8ga or smaller wire, out comes the hydraulic crimper.

[deltabravo]

timelinex wrote:
It looks like considering everything is definitely under 4ft, I won't need anything over 4ga.

Smoke (and flames) will escape from the wiring if you use wire that small and a 2kw inverter.

[enblethen]

There is no reason why you could not use lugs like this sized for your selected cable. If you aluminum lugs like these insure you use a de-ox compound.
electrical lugs

[Grit_dog]

^Great, you have a shop that provides you good deals on cables. I work on a lot of vehicles and never needed that many cables over the years.
Still doesn’t make any sense why they would “need” to be hydraulically crimped as you said above, though.

[ktmrfs]

Grit dog wrote:

ktmrfs wrote:
go to a welding shop and buy the length of welding cable in the gauge you want and have them put logs on it for you. Many shops can do that.

Otherwise you'll need a hybraulic crimper. And based on what I've done I'd suggest and least 2/0 wire if not 3/0. Most inverters have a low voltage shutoff and a few tenths of a volt drop can make the difference in inverter running and inverter shutting down.

And make sure you use the correct fuse to the inverter. they are big, bulky but meant to protect under the high load conditions.

Welding cable has lots of very fine wire so it is very flexible and easy to route.

OP, you don’t need anything elaborate like having cables prefabricated or a hyd crimper.
You can buy any number of clamping or solder/crimp lugs that can be attached with basic hand tools. But you “can” make elaborate cables if you wish.
Regarding wire size, the responses are all over the board here. Many who just think bigger is better. (It is, but doesn’t mean it’s necessary) I used a wire size calculator real quick to provide my recommendation. You should do the same. You have the data. It’s that easy.

around here welding cable is very reasonably priced, pay by the foot, lugs are sold individually and the shops I deal with will crimp for free if you buy the cable and lugs. makes it easy peasy, and quick. And usually cable is available in red or black, from AWG 6 down to 4/0. Quick, easy, affordable and your good to go.

[TurnThePage]

You can always run extra cables if you initially chose too small. I ran 0 gauge for my 3000 watt inverter. I've been able to run the air conditioner on that with no cable heating at all. If I need more capacity, I will likely just add another run of 0 gauge since I have plenty of it. Now I'll likely increase the gauge for the wires between the batteries if I have to. No room for 2 wires from post to post. Oh, and I ordered welding cable on line. Very flexible and easy to work with.

[Grit_dog]

ktmrfs wrote:
go to a welding shop and buy the length of welding cable in the gauge you want and have them put logs on it for you. Many shops can do that.

Otherwise you'll need a hybraulic crimper. And based on what I've done I'd suggest and least 2/0 wire if not 3/0. Most inverters have a low voltage shutoff and a few tenths of a volt drop can make the difference in inverter running and inverter shutting down.

And make sure you use the correct fuse to the inverter. they are big, bulky but meant to protect under the high load conditions.

Welding cable has lots of very fine wire so it is very flexible and easy to route.

OP, you don’t need anything elaborate like having cables prefabricated or a hyd crimper.
You can buy any number of clamping or solder/crimp lugs that can be attached with basic hand tools. But you “can” make elaborate cables if you wish.
Regarding wire size, the responses are all over the board here. Many who just think bigger is better. (It is, but doesn’t mean it’s necessary) I used a wire size calculator real quick to provide my recommendation. You should do the same. You have the data. It’s that easy.

[valhalla360]

CA Traveler wrote:
Goog suggestion but I've never seen 4/O jumper cables, maybe from a tow truck?

Check jumper cablles as you want solid copper and notf copper coated alumiinum,

4' will limit the cost,

Problem is home depot was selling cable in 6ft lengths.

The 4 gauge was in the auto section and at 50amps, not too critical.