House batteries to use with large inverter

[Unicorn1108]

We're planning some camping where generator use is restricted, so I want to make sure my batteries will hold up between charges. We'll usually draw less than 25 amps, but I'd like the option of running the microwave with my 2000W inverter, which I expect will draw at least 150A. If not for the microwave, I'd avoid marine batteries or any battery with specs for cranking amps, but is running the microwave similar to starting an engine? Should I get a dual-purpose battery, or just make sure I have enough deep discharge batteries to supply 150A?

[pianotuna]

If a tall group 29 will work look for Dynasty UPS12-490MR. These may be available used as 'take outs' from cell phone tower battery back ups. They replace them more or less every year.

Do check the dimensions carefully.

[Unicorn1108]

I've only got room for 2 batteries, unless I start welding, and I foolishly left that equipment behind, so I think I'll go with a pair of 12V AGM batteries. I've been parked and plugged in for more than a week, so I'm going to measure the maintenance voltage that my converter is applying to my current batteries, and find a pair of AGMs to match, so I don't have to upgrade the converter too (I don't even know where it is).

Thanks for all the ideas!

[ktmrfs]

wa8yxm wrote:
The MINIMUM per Xantrex is 1pair GC2 (or equal) per 1,000 watts.. For boondocking might be a good idea to double that.

1,000 watt Minimum 1 pair (230 amp hour) double 2 pair (460 amp hour)

3,000 watt Minimum 3 pair 690 amp hour Boondocking six pair

Of course more battery is always better.

agree completely. my experience is that 1000W 1 pair GC2 is IMHO the absolute minimum and likely to mean inverter dropout at around 80% or less SOC, while 4 GC2 will work down to around 50% SOC

I'd say for 1000W the "RECOMENDED" should be 4 GC2.

the downside to GC2 batteries, very high current draw= very high voltage drop. 12V big advantage in this case

[wa8yxm]

The MINIMUM per Xantrex is 1pair GC2 (or equal) per 1,000 watts.. For boondocking might be a good idea to double that.

1,000 watt Minimum 1 pair (230 amp hour) double 2 pair (460 amp hour)

3,000 watt Minimum 3 pair 690 amp hour Boondocking six pair

Of course more battery is always better.

[grizzzman]

Almot wrote:

MEXICOWANDERER wrote:

Cook spud in campfire. Foil wrap with three teaspoons of water No square wave round hole issue.

You can't count on a cook spud in campfire, with all these campfire bans lately. There is more modern way to do this - though probably 100-something years old. Look for "double boiler" aka "Bain Marie pot" on Amazon etc. Slow, takes 15-20 minutes to reheat a plate of meal, and zero amp-hours. Not much fun in a hot weather since you have to run propane stove for 20 minutes on low, but on a hot day without A/C you don't have craving for hot lunch and only need a hot breakfast and supper.

Then you don't know how to cook and check a spud in a campfire.
As far as a fire ban goes I use a barbecue that hangs on the side of the trailer and hooks to the trailers propane supply. Keeps the heat OUTSIDE where it belongs 🙂

[Almot]

MEXICOWANDERER wrote:

Cook spud in campfire. Foil wrap with three teaspoons of water No square wave round hole issue.

You can't count on a cook spud in campfire, with all these campfire bans lately. There is more modern way to do this - though probably 100-something years old. Look for "double boiler" aka "Bain Marie pot" on Amazon etc. Slow, takes 15-20 minutes to reheat a plate of meal, and zero amp-hours. Not much fun in a hot weather since you have to run propane stove for 20 minutes on low, but on a hot day without A/C you don't have craving for hot lunch and only need a hot breakfast and supper.

[NinerBikes]

Replace with AGM batteries, or if budget allows, LiFePO4 batteries. Both of them flow a lot of current.

[Unicorn1108]

Wow, that's interesting about the variable power microwaves. I only know the kind that cycles between 100% and 0%. I'll definitely look into that, since I'm not that attached to the current one, except that I know it fits. 🙂

[ktmrfs]

my experience running a 1000W inverter to run our true variable input power panasonic microwave.

Use 4 golf carts, or go with 12V. with two GC you'll need to keep the batteries in the 80% or higher state of charge, or the inverter will drop out.

GC have many many advantages for trailer use, but high current draw is NOT one of them. the design tradeoffs for long life, etc. mean fewer thicker plates which equals more internal resistance and voltage drop under load.

with 4 GC I can run the microwave when the batteries are near 50%.

And another hint. unless you are REALLY attached to your current microwave, toss it out, pay about $125 and install one of the panasonic true variable power microwaves. unlike others that cycle between 100% and 0% for less than full power (and hence draw full power under load), the panasonic does vary magnetron power and input power with selected power level. our 1000W panasonic draws about 1300VA at 100% power and about 700VA at 50% power and down around 400VA by the time your down to 10%.

that way (a) you don' need a 2000W inverter to run them, and (b) when running on a generator etc. at < 100% power the generator isn't continually hunting between no load and high load as the microwave cycles. and (c) when on battery power, you can drop the load and reduce the battery load, yes it does take longer to heat, but 50% power doesn't mean 2x as long, about 1.5x as long to say heat water.

[Golden_HVAC]

The Trojan golf cart battery is rated at 75 amp draw. That is a lot of power to put on a battery for a long time, such as cooking for 8 minutes. Even most drives that I do in the golf carts at my work involve picking up speed to 13 MPH, and then running part throttle, until there might be a hill. Uphill can draw max amps for a few seconds (20 seconds and you are at the top of the hill where I work), but downhill can actually charge the battery. Most drives are less than 1/2 mile, or about 2 minutes. (at 15 MPH you would drive it would take 4 minutes to drive 1 mile).

SO the Trojan T-105 that we use will last about 105 minutes at 75 amps draw before reaching 5.0 volts.

I would recommend a set of T-125 batteries, same size as the T-105, but a little more lead, and thus can hold about 20% more power. I have 4 T-105's. I used my microwave on my Trace M1512 inverter/charger, and it no longer cooks nearly as quickly, so it had to be replaced. Now I just run the generator while microwaving, or bake it in the propane oven.

I also have a 415 watt solar system to recharge the batteries. This keeps them nearly full all day long. It will help a lot when cooking at night. But like I said, I would rather bake it or cook on the propane stove.

I hate listening to my generator!

Good luck,

Fred.

[Canadian_Rainbi]

We use our 4 GC batteries (484 AH) and a Xantrex Prosine 2.0 pure sinewave inverter with our micro-convection oven regularly. It pulls about 150-160 Amps from the batteries, (75-80A each) Cables are 4/0 about 3 feet long.

For those thinking about purchasing a microwave for use with an inverter, consider a microwave that uses inverter technology for power control such as Panasonic and GE. (Note that the inverter of an Inverter Microwave oven has nothing to do with running it from batteries via an inverter. The inverter technology in those microwaves use an inverter to control the power level. For example, an inverter microwave oven at 50% power really only draws half of the full power while running. An NON inverter microwave oven at 50% power level draws 100% power but for half the time. The first method is much better for the batteries.

[Unicorn1108]

pianotuna wrote:
What do you plan to reheat? If your times are 5 minutes and under a small battery bank can do the deed.

It's mostly five minute type operations, a couple of times each day, to be replenished by generator. The places we're thinking about allow generator use twice or three times each day, so recharging shouldn't be a concern. If I were trying to recharge with solar alone it would be a different story.

Secondary is when we have the RV serviced, it can be a few days before we get it back, so I want to be sure the propane fridge will keep going. That should be very minimal, but with my current batteries, a week of fridge and other small loads was enough to kill the batteries.

[Unicorn1108]

The space I have to work with is about 19 inches wide, 14 inches deep, and 12 inches high. I don't think I can get four batteries in there, but I think I have room for a couple of size 31 batteries. I saw some from Fullriver that claim 45 minutes at 75 amps, 115 AH with smaller loads. Not very long, but I was glad to see it even mentioned that they could deliver 75 amps.

Now I have to measure the voltage produced by my converter, to see which batteries I can use.

[MEXICOWANDERER]

RGM will work great with the microwave. I have a MSW Trace and I use it a lot to prepare fish and frozen vegetables. With the fish it's 8.5 minutes instead of five four minutes to reheat a large mug of coffee instead of two minutes. There's few PITAs more intense than "Ooops if I do this then I can't do that" decision. Get as many amp hours as it takes to make your life comfortable. AGM batteries have that wonderful high wattage capability that inverters/microwaves love. Sounds like you are on the right track.