Inverter install question

[Jokaj]

I plan on installing a 3000w inverter in my micro Minnie 2225rl. It appears I will need to use 4/0 cables. The cables currently on the battery are 4 gauge. Do I need to replace those cables to 4/0?
Also the negative battery cable connects to the battery monitor shunt (B-) and a cable from shunt (P-) goes to the frame. Can I ground my inverter to the (P-) or should I run it directly to the frame?

Thanks for any help.

[GaryKowal1]

You need the heavier battery cables. I hope you have substantially upgraded your batteries. Why a 3000? What are you going to power with it. What is battery capacity? Funny enough I am installing a Victron 3000 in my sons 5the wheel this week. But we upgraded batteries first.

[Jokaj]

Originally Posted by GaryKowal1

You need the heavier battery cables. I hope you have substantially upgraded your batteries. Why a 3000? What are you going to power with it. What is battery capacity? Funny enough I am installing a Victron 3000 in my sons 5the wheel this week. But we upgraded batteries first.

Thanks. We upgraded to LiFEPo 200 aH. Don't plan on using it on anything crazy. Just microwave and coffee maker when we don't have shore power. Also to run the fridge when we are on the road.

[creativepart]

The negative from the inverter must go to the shunt. All loads must pass through the shunt.

The inverter needs to be installed as close to the batteries as possible. Running the 110v cable a long distance is not a problem due to the higher voltage involved.

A 3000w inverter will need about 250 amps hours of usable battery capacity. Do you have that many amp hours? With lead acid batteries that would require over 500 amp hours to provide that much usable amps.

How about detailing all of your plans so we can better answer your questions.

[creativepart]

Originally Posted by Jokaj

Thanks. We upgraded to LiFEPo 200 aH. Don't plan on using it on anything crazy. Just microwave and coffee maker when we don't have shore power. Also to run the fridge when we are on the road.

With one 200ah lithium you’d be better off with a 2000w inverter. Keep in mind those are heavy loads and even with LiPo batteries you will deplete them fairly quickly with heavy loads. So, you’ll need a substantial way to recharge them after such heavy use.

[Jokaj]

Originally Posted by creativepart

With one 200ah lithium you’d be better off with a 2000w inverter. Keep in mind those are heavy loads and even with LiPo batteries you will deplete them fairly quickly with heavy loads. So, you’ll need a substantial way to recharge them after such heavy use.

Thanks. I bought the 3000w during black friday/lightning deal which was the same cost as the 2000w. I didn't have much time to think about it and pushed the button .
Do you happen to know what fuse I will need? I can't seem to find anything online except for a goPower class t 400amp. The ANL don't seem to be able to handle 4/0 wires and the circuit breakers are only rated for 300 amps.

[creativepart]

I don’t know what fuse you’ll need. My RV came with 400 amp fuses for both the inverter and the main 12v power feed - they are separate on my motorhome. But the cabling is 3/0.

I have 400ah of LiPo batteries and a 2000w inverter.

[Marine359]

Unless you plan to upgrade to 400ah of battery you should consider sending the 3000w unit back unopened for refund. Seems a 2000w model would suffice, and it only needs 200ah, and smaller cable can be used. 4/0 is difficult to work with, expensive, and don’t even try to install your own terminals without buying expensive tools.

I used 1/0 cable pre- made with terminals, short distance between inverter and battery, and 250amp fuse. All loads, including inverter, must be wired to shunt negative load side. The inverter will have a separate grounding connection which should be wired to chassis.
You can buy a 30ft rv power cable, cut it in half, and run the two cables from the inverter to the panel through the floor and along the frame rails, then back up under the sink, if that’s close to the panel in your floorplan. Curious whether you are installing a plain vanilla psw inverter or a hybrid inverter/charger, as that may change your installation somewhat.

Rarely if ever run microwave off the inverter, but it does work. Don’t know what brand you’ve bought, but advise Victron or Xantrex as they both will pass through a full 30amps from shore power.

[Jokaj]

Thanks Marine. I have a Renogy pure sine 3000w inverter. I am also looking at a transfer switch go power ts-30.

[fringemtm]

For that inverter, the recommendation is a 300a fuse. Now for using 4/0 wire, this inverter can push out up to 9000w for one second, and handle 3600 for 10 seconds. Also not knowing the distance between the batteries and the inverter is another reason for recommending 4/0 wire. You can use 2/0 wire, but the distance needs to be below 5 ft between battery and inverter. This will allow up to 330 amps with less than 3% voltage drop. The no-load rating is about 30w which is around 10w higher than the 2000w inverter. As others have noted, you really need more battery than 200ah. If you use the inverter for any high power appliances, it will drain the 200ah battery quickly which will shorten its life.

[Jokaj]

Thanks fringemtm. Good info.

[powercat_ras]

1. Inverter needs to be super close to batteries, within 3'. You can tolerate longer wire runs on the AC side so long as you use properly sized AC wiring.

2. Put a 300 amp ANL fuse in series with pos cable

3. Use 0 gauge wire for both positive and negative, don't try to pass current thru chassis

4. Buy pre-made cables or buy/borrow a hydraulic terminal crimper or buy/borrow one of the large wire terminal crimpers that you hit a crimping plunger with a 3 lb. head heavy hammer to make a good terminal crimp.

Even if you don't plan to use the full 3000 watts, the big gauge will make the whole setup work better. You need to minimize the voltage drop between the batteries and the inverter 12 volt terminals.

[BobC]

The 3000A inverter won't draw any more from your batteries than a 2000A inverter (ignoring efficiency differences) as long as you don't try to run more watts worth of appliances at any one time.

Jokaj, I think you understand this but, for the benefit of others reading this thread: As far as wire sizes goes, be careful and make sure you understand the differences between the various ways of specifying wire gauges. For example 4 gauge (or 4 AWG) wire is 0.2043" in diameter while 4/0 (or 0000) wire is 0.46" in diameter (despite the ".UK", the chart is for American wire sizes:

https://meters.co.uk/wp-content/uplo.../CHART-1-w.jpg

Also, here's a link to a page with a calculator for wire size vs. voltage/amps/distance:

DC Electrical Wire Calculators

[creativepart]

I agree with Randy on all points in his post.

My RV came from the factory with a 2000w Magnum inverter and it is mounted (upside down on the ceiling) in a compartment directly opposite the battery bank. The cabling is 3/0 between the inverter and the batteries. The negative cable is separate of the chassis ground and was connected directly to a mid-point negative battery post all it’s own. There is a 400 amp fuse on the positive cable.

I say the negative “was” connected to the battery bank because now it’s connected to a negative buss bar to pass through my shunt before connecting to the battery bank.

[Jokaj]

Thanks all. Currently my negative post connects to the shunt and the opposite end of the shunt goes to the chassis. Is this a problem? The dealer installed the LiFEPO when I purchased the TT.

[Marine359]

When you say, goes to chassis, do you mean chassis ground? No bueno.
The other side of the shunt is for negative loads only. If all loads are connected to the shunt “load side” you’ll get an accurate measure. I have found it easier to connect everything by using bus bars.

[creativepart]

All negative loads - every one of them including the chassis ground - goes to the load side of the shunt. The battery side of the shunt goes directly to the main negative battery post of your battery bank.

[Jokaj]

I attached a picture. The B- is connected to my negative post. The P- connects to the chassis. I hope this is more clear than my ramblings so, this is okay? Thanks

[creativepart]

Assuming you only have one negative load - the chassis ground - and that your B- indicator on your shunt means it goes to the battery ground - then everything is good.

But when you add the inverter the negative cable from the inverter must go to that load side (I guess that's P- on your shunt??) of the shunt and not to the chassis. If you have solar then the negative of the solar controller needs to go to the P- side of the shunt. Even if your shunt has a negative lead attached to the battery you need to relocate that to the P- side of the shunt.

Every negative load must terminate at the shunt.

[Jokaj]

Thanks. I think I got it. I did some more researched based upon this thread and found my system. Wish the dealer would have given me everything. But anyways, you are correct about the P-.