PSW Inverter - No Load Current

Just tested my PMX2000 for no-load. Spec says 1.5 amps or less.

Trimetric with inverter off, 00.4 amps then with inverter on but nothing plugged into it, 1.0 amps. So 00.6 amps no- load.

In real life, with the shore cord plugged into the inverter, there is a small load as mentioned previously. So not sure what use a no-load figure is. Anyway that's what I got.

Since there is room for only two batteries, consider moving to 12 volt jars. AGM would be my choice.

By doubling the number of cells, the load per cell is reduced to 50%. It would be important to use thick wire and balance the wiring.

Many rv'ers use a small inverter for little loads. Best bang for the buck is a Victron 350 watt.

This is what is balanced and best for twin twelve volt batteries.



As it often doesn't cost a dime more to do this, I think it is worth the trouble.

If you wish to understand the "why" surf here:

correctly interconnecting multiple twelve volt batteries

Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?

Thanks for all the replies!

Good to hear the Prowatt 2000 will power some microwaves. I believe the microwave in our new camper is supposed to be 1150w line (700w cooking), so fortunately it's at the lower end of the microwave power scale. Have plans to use 4/0 cable with a ~5 ft. run and two GC2 batteries, so hopefully minimal voltage drop (~.06v at 115 amps).

FWIW, I only mentioned using the Prowatt 2000 because of the low, no-load rating (.8a) vs. its 1800/3000w power out capability---price had no bearing. I would have no problems spending a lot more money for a true 2000w (4000w surge) inverter that legitimately (without a power-save function) offered <1a no load current. As far as I know no such animal exists.

Although I've never used an inverter with a "power-save" function, I'm getting the impression many power-savers have trouble recognizing smaller loads, like say a cell phone charger. Have to turn the power-save function off in order for the inverter to recognize a smaller load. Maybe I've got it all wrong, don't know.

BFL13 mentioned the PowerMax 2000w PSW inverter. That has to be the best bang for the buck out there. Less than $220 on Amazon. Unfortunately 1.5a of no-load.

As for solar, our camper will come OEM with 100w of solar. No immediate plans to add more panels--maybe down the road. We're not dry campers per se. Just need power for the occasional 12-18 hr stop while we're on the road.

I guess for now the Xantrex Prowatt 2000 looks like the best candidate.

You asked about any others. I have this one, which has been working great. You can get the remote on/off for it as an option. Spec no-load is 1.5 amps or less, if you leave it on.

I have not measured for that, since my "whole house" set-up means when it is on, there is always some small load, like the microwave panel lights, and a phone charger or two. Even your camper's GFCI receptacle has a small draw.

At least one other member here has the same inverter and is happy with it last I heard.

https://www.amazon.com/PowerMax-PMX-2000-Pure-Sine-Inverter/dp/B07DQTW1SW/ref=sr_1_3?ie=UTF8&qid=1549559913&sr=8-3&keywords=PowerMax+inverter

Generally, you can only get away with two batteries for this work if the batts are near full at the time. If they are below 75% SOC, you will likely hit the inverter's (any brand) low voltage stop.

With the truck camper we had, and a 2000w inverter, I put two batteries in the front of the truck bed wheel well and then slid the camper in. Before it was all the way in, I hooked up the wiring to the two batteries in the camper, so that made four batteries in the bank.

Some solar is always good to add to that for when there is some sunshine. if there is, you don't have to worry about small draws like inverter no-loads. You can just turn the inverter on and leave it on till you next get shore power.

Check out tripp-lite products
The have PSW and MSW inverters with load sense
That you can adjust, this brings the idle no load current down to around 200Ma,
Adjust it so the smallest load you will use turns it on

I love them
Be warned they are big and heavy, but much sturdier than the prowatt
The 1250w model will carry that all day, carry 50% over load for 10 minutes
And 3600 surge for 10 seconds not milliseconds

That thing will run an A/C if you have the batteries

Prowatt is fine. I would not consider it top line but should serve you well. Two batteries is a bit light for 1500+ watts.

This how I ended up with two inverters. The 2000 was installed to run the MW and one added outlet for use as needed. The 2 amp draw was a bit much or it was constantly monitored to turn off as needed. A few years later added a 300w inverter to power the rest of the outlets. This one just stays on for the small stuff and the 1/4 amp is not a big deal. Then came the solar.....

otrfun wrote:
Our in-bed camper will only hold two batteries. Wanting to power the microwave, TV, satellite and laptops. Thinking a 2000w PSW inverter would be the right size. Noticed most 2000w inverters have no load current approaching 2 amps. A bit high. Don't want to be constantly turning the inverter off and on during the day to conserve. The Xantrex Prowatt 2000 is the only "2000w" PSW inverter I've found so far with less than 1 amp of no load current. Of course, in reality it's only 1800w continuous with only 3000w surge (typically surge is double the continuous) which may explain the lower no-load. Does the Prowatt 2000 have a good track record powering microwaves? Other 2000w PSW inverters with =< 1a of no load current I may have missed? Thanks.

My former inverter was a ProWatt PSW 2000 and it had no problem running our 1500w microwave...I used two 6v GC’s...But to start, the battery cables were too smallish (creating a bottleneck) and the low voltage alarm would shutdown the inverter (Performance limited by cable size and lengths). So I upsized to 0004 ought AWG cable, and eventually swapped out the home-sized 1500w oven for a better and far more ‘system optimized’ 850w SS Panasonic, and ordered a SS MW oven trim kit (google) to tidy-up the gap - looks uber Professional!...To avoid wasting power, you can order a remote hardwired off-on switch for the ProWatt...

BTW, I also agree with 2oldman on the solar!...As for the two 6v GC’s, no problem running the Panasonic 850w....

3 tons

A bit of solar would alleviate those concerns. Worrying about a bit of no-load current is not my idea of a good time. As for the comment above, your water pump doesn't take any power when it's not pumping.

I am way too fussy about power consumption and am always turning off stuff. I don't like my water pump on unless using it. Even my LED lighting gets shut off when I am not in the coach for more than a few minutes.

I think it comes from my Dad cruising around the house turning off lights when I was a kid.

The simple (to me) solution would be to get a ca. 250-500W inverter for the TV etc. and a separate higher powered one for the microwave, and switch the larger one on and off only for microwave use. If you put a remote switch next to the microwave that would not seem to be a very burdensome additional step.