Inverter and battery sizing to power my camper microwave

[LaneW]

So, I am getting all sorts of misinformation on this and hope someone can give me correct scoop.

I am planning to replace my LA battery in my truck camper with two, 100 ah Lithium batts (probably SOK). I also need to install an inverter, really just to run my microwave. It’s a 900 watt MW that draws 1350 w according to the manual. Looking at a couple of 2000 watt pure sine inverters. But I am getting conflicting info, even from the manufacturers, as to whether two 100ah lithiums and a 2000 w inverter will be adequate to run the microwave .

Does anyone have definitive information on this question, or can you point me to a truly reliable source for answers?

Thanks in advance!

[LaneW]

You folks are very helpful, thanks. I do get it about wiring and will plan to discard what comes with an inverter and oversize the cabling.

So you can run your air conditioner for over an hour? Wow. I don't plan on using the AC at all and we don't use the microwave much at all, so if this system plan can do that, wife will be happy.

But how do I find out about the inrush current matter? That's a bit concerning to me. I want to do all of this once only and get it right the first time.

[srschang]

I inrush current the same as surge capacity?

[otrfun]

We use a 200ah lifepo4 battery pack (equivalent to 2, 100ah lifepo4 batteries in parallel) and a 2000w inverter to power our 1050w (line input power) microwave and 11k btu a/c unit. Get about 85-90 min of continuous runtime when we're powering the a/c (similar runtime for microwave--although we rarely run it for more than 10-15 min.). When we're on the road we recharge the lifepo4 with a 40a dc to dc charger. It's all been working flawlessly now for almost 2 years.

Choosing a capable 2000w inverter is important. Not all 2000w inverters are created equal. Although most inverters can supply their continuous current rating, many fall short providing suitable amounts of inrush current. Inrush current is necessary to successfully start a/c units and microwaves. Unfortunately, very few manufacturers provide inrush current specs for their inverters.

Proper gauge wiring and quality connections are important, too. It can take 110-150a of 12vdc to power a typical microwave or RV a/c unit. That's a lot of current. It's one thing to simply power a microwave and/or a/c unit for a few minutes---it's another thing to do it continuously for an hour or so. Improper wiring and/or bad connections can cause significant voltage drop (and heat). Best case, you won't obtain full power from your inverter---worst case you could start a fire. Don't scrimp on the wiring.

Good luck!

[StirCrazy]

yes you should be fine. thats about the same amount of power as I have with four 6V batteries, infact probably more usable on a inverter. I never worry about a couple min here or there in the summer but I do have a fair bit of solar to make it up. In the winter I am a bit more conservitive with inverter use as I have to take the furnace into acount.

[Tom_Barb]

You should be fine. . .power wise.. but be certain that you have the proper alternators simply because the truck batteries will be lead acid, and the camper will be Latium. they charge at different voltage.
SO.. you will need a added charger for the Lithium side of the system.

[pianotuna]

Hi,

Inverter loses are about 12%

1350 x 1.12 = 1512 watts / 12v = 126 amps = no problem running microwave

Just choose a battery monitoring system that allows 100 amps to be drawn from the battery bank.

Do wire the batteries in a balanced manner.

[srschang]

I have 2 100ah lithium batteries and a 2000w Xantrex inverter. It runs the microwave no problem. Just don't try to make toast while microwaving something else. That didn't work.

[greenno]

Sure it will run your micro, it will just deplete your battery's.

Do the easy math. Theoretically here ya go. Not figuring the inverter loss while operating.

2 x 100ahr lithium batteries equals 200 hrs total availible at 100% discharge which you dont want to do.
I think 90% is acceptable but not recommended.

So you have 180ahrs availability right?

Microwave will draw 1350 max at 120vac still with me?

Inverter is rated for 2k so your good there.

Micro will draw max 11.25 amps at 120vac.

Inverter converting to DC you will use 112.5ahrs of battery capacity using the micro for 1 hr. And you only had 180ahrs.

So using the micro for like 15 minutes will deplete your battery's approx 28ahrs or so which would be about 15% capacity.

Now you will need a way to recharge those battery's to get back to full state. Either by battery charger , solar etc.

Good luck and dont burn the popcorn.