Ok What Am I doing Wrong!!

With the two sets of wires you get two negs, which both go to the Trimetric shunt. That means the single fat wire from the shunt to the battery neg post has to be really fat to take all the amps that the two share plus any amps from the other negs going to that shunt.

Buying a 3000w inverter when you only need a 2000 happens when the 3000 is on sale for half price making it way cheaper than the 2000 :)

Got It! Thanks guys, turned off converter plugged in the camper cord to it and everything works, went with #1gauge wires and hooked up neg last, barely any spark not like the fireworks when I hooked up the up the pos last! Thanks

I recommend a single 4/0 wire. Link for custom cable posted above.
OK... if the inverter actually has terminals for parallel wire I would go #2 and 200 amp fuse for each. #1 would be better.
Not sure it matters that much depending on use and the limited battery.
Just seems odd to get 3000 watts and connect it like it was 1000 watts.

shepstone wrote:
So.. should I be running 4 of the#4 gauge or 4 of the #1gauge? I measured the lengths and need 2 @18" &2 @36" long

In theory it is ok to have different lengths for the pos and neg in a circuit because it is the total resistance that counts. However with the inverter and the way it seems to split the load inside it, never mind how the wires share things, IMO go for the two sets of #1 (two short,two longer) so there will be some margin for however the electrons really get around with this inverter.

My biggest load is a 1000w microwave that wants 1550w 120v input when on household power (like PSW inverter power) This would pull 150amps from the battery bank with a PSW inverter. However,with MSW inverter the same microwave runs at and draws less power so it takes a little longer to heat things up (but it works ok) and I only see 115 amps draw. So in my case I could get away with thinner wire than needed for 3000w. I have no trouble running that MW with the 15a receptacle in the inverter plus a few other smaller loads.

If you wire with really fat wires for the inverter to handle 3000w where that is a 300 amps draw, then you can't even do that with the one 15a receptacle, so you would be wanting to use other loads in the other two receptacles somehow.

OK I found the specs for the 3000w inverter:

"If connected with loads of over 1000w, two sets of same size wirings must be connected to the same battery....And it may damage the inverter if using one set of wiring only or connecting two sets of wirings to different batteries separately"

It does not say how fat the cables should be! :( ( I do know the optional cable set for it is two sets of 3ft #4)

My Vector 2000w inverter users manual says for their 3000w MSW inverter:

ANL fuse rating 500a (Vector spec uses the surge 6000w as what to match for)

-up to 6ft one way 2/0
-up to 10ft 250mcm

Those are way fat compared with the specs for some other brand inverters which just use their normal rating for wires, not the surge rating.

I'll check the Cobra next. Ok the Cobra 2575 is similar with the two sets of terminals but is a bit vague on wire size. Says minimum is #4 at 4 ft. Says 250a fuse.

http://s3.amazonaws.com/szmanuals/ec75fe649bf72e875f441fe6df79943a

Go-Power wiring kit for 2600-3000w inverter is single set of 10ft long 4/0 with a 400a fuse.

So there are variations! IMO use your common sense and wire and fuse for the ampacity of the biggest amp draw you will ever do. Use the divide by 10 rule so that say 1500w will pull 150 amps.

Seems you need fatter wire for longer distances. (over three or four feet) Fuse for protecting the gauge of wire you actually use.

So.. should I be running 4 of the#4 gauge or 4 of the #1gauge? I measured the lengths and need 2 @18" &2 @36" long

OP has 3000 watts...

I would stay tight on the fuse if the wire is small. If the wire has the proper ampacity for the device then you are mostly protecting for a dead short so a larger fuse is fine.

JMHO

time2roll wrote:
4 or 4/0? With #4 I would not have larger than 125 amp ANL fuse. Still under size. What do the instructions call for?

Two sets of #4 3 ft long is the same as the wire kit that is for the Vector 2000w inverter. Cobra inverters are similar. It is equivalent to whatever fat # single wire set the spec says.

With a single set you might have say a 300a ANL, but with two thinner pos wires you put a 150ANL on each wire to the pos battery post.

I don't have the specs handy.

4 or 4/0? With #4 I would not have larger than 125 amp ANL fuse. Still under size. What do the instructions call for?

shepstone wrote:
This one
but I paid $240 for it as a store clearance. Also I see that there is a small grounding post under the main terminals on the right hand side, should that be grounded to the rv chassis? (installation instructions are pretty much worthless and don't mention anything about the grounding post)

I have that inverter. It does a good job. It does spark, don't worry about it.

It has two sets of terminals. you use two sets of #4 no more than 3 ft long. (sometimes sold by CanTire with that inverter as part of the deal) One set of #4 is not enough. Even so, I like to use the fatter blue #1 cable CanTire sells for my inverter/battery instead of those #4s

If you use one set of fatter wire on one set of terminals, that is still wrong, because inside the inverter it is in two halves sort of, so if your load is over about 1000w then that one "side" will be overloaded even though the wires are fat.

Use a length of #8 to go from the chassis ground to the frame directly. DO NOT bring that wire around to the neg input terminal of the inverter as a way to eventually reach the frame using that path. Go direct to frame independent of other negs.

You need a least four batteries to run big loads like a microwave.

You can plug the RV cord via 30/15 adapter into one of the three 15a receptacles and turn off the converter (to not have a "loop") Put the fridge and water heater on gas. Unplug the television when not watching it since the tv is always on when plugged in and drawing from the battery via inverter. You are now doing "whole house" same as if plugged into a 15a pedestal, but you must use "power management" not to pop the inverter's breaker for that one receptacle.

You can get more power up to the 3000 by plugging something into another of the three receptacles.

I always turn the inverter off with that remote when not running any 120v loads. It is hard to see that dim green light in the remote that shows inverter is on. I stick my three-light tester (which has brighter light) into a receptacle to show that the inverter is on. You could use one of those night -light things instead.

This one
but I paid $240 for it as a store clearance. Also I see that there is a small grounding post under the main terminals on the right hand side, should that be grounded to the rv chassis? (installation instructions are pretty much worthless and don't mention anything about the grounding post)