Advice Please: First hand experience using a microwave in van

[XERTYX]

So I'm thinking of having a microwave in my build. I know, I know.

Hella draw, peukert effect, voltage drop, pure sine wave inverter.

I was looking for info on them and I came across a video bob did 4 months ago on his microwave and his setup.

I know I'll likely need a 2kw pure sine wave inverter. I was considering a 1.5kw but I found a 2kw that I like on amazon for about the same price as a 1.5kw.

Bob has 4 golf carts so the puekert effect is a little less harsh. I was originally planning on 4 29DC 12v batteries from walmart, but I'm wondering if I can get by on 2 of them.

With 2 batteries I'm thinking the peukert effect will probably be pretty harsh. It would be less with 4.

How many people here use a microwave with 2 12v batteries? I'm not going with lithium. $400 is the cheapest lithium I've found and that's still too much.

Without getting too super technical and into quantum physics level math bob estimates roughly 2 amps per minute for the model he has. That seems about right based on some figures I ran thru a puekert calculator in the past trying to calculate another ~1kw  load.

I'm not committed to a microwave. In fact this winter I have used a microwave about 20 times. That's the first time I've used one in well over a year.

There are a couple other 1kw loads I'd like to consider so a microwave seems like a good base line to see if its reasonable to plan to use them.

I've been thinking of a 900 watt or less air fryer recently. That should be comparable to a microwave load, probably even less draw as the element gradually uses less than 900 watts after warming up.

I'm going to be putting 500 watts of solar on the roof, 750 would just about fit with very little overhang but I think 500 will do what i need. Especially if i only go with 2 12v batteries. 

I've just about narrowed down everything I'm going to include. Just waiting on my stimulus to make a few large purchases, fridge, panels, controller, batteries, mattress, inverter.

 

[Weight]

2000W sine wave Samlex inverter. 4 golf cart batteries, 460 ah @ 12 volt. 400W Renogy panels. 45 amp TriStar PWM CC. 1000W Panasonic microwave.
Four years. But not much in 2020.
No troubles.

 

[XERTYX]

Groovy, thank you. That's a more robust system, much like bob has. Those 4 batteries would make sense that it works.

Bob in that video specifically said 2 golf carts will not work. Too much voltage drop. I'm wondering if I'll have the same trouble with 2 12v deep cycles. He said in the video that as he understands it that 2 12v true deep cycles will work.

I'm starting to think 4 12v batteries is just too much. Too much weight, too much maintenance, too much temptation to take them to 50% and then not be able to get a full charge on rainy days. Too much $ to blow if I screw em up.

I've gotten a lot more experience with solar and caring for batteries since my days on the boat without a charge controller. Just straight wired and checking with a multimeter. D'oh. But I've killed a lot of batteries.

I have a micro bank setup and ready to use right now down on my family property. Been running strong for nearly a year, but I also dont run AC loads on it.

 

[tx2sturgis]

Never let physics or practicality get in the way of your dreams...I always say....or not.

Hey one thing to seriously consider when you are spending that big fat check:

Take a look at the Panasonic Inverter Microwave ovens. (this is the one I have: https://www.bestbuy.com/site/panasonic-0-8-cu-ft-microwave-stainless-steel/6115702.p?skuId=6115702)

I use one and it actually can cook (and reheat) at lower power levels, not cycling high power on and off like most other microwave ovens do. 
This should help ease the load on your system since it is likely to have some limits on power. You can run it at ACTUAL lower power levels. Yes they do cost a bit more. Yes they are worth it, in my opinion.

So there!

Now, 'scuse me, I gotta go heat up some fish sticks...

 

[XERTYX]

That's something to consider, thanks. I'm making a list and trimming the fat as much as possible. That's part of where I arrived at 2 29DC batteries instead of 4. I'm also considering going with a 20a controller and 2 100 watt polys from amazon instead of a 40a controller and 2 250 watt panels. Just to get everything up and running.

Then later when I get the 250w panels (hopefully I'll be able to source them without paying freight to the east coast from AZ) ill swap in the 40a controller and have 2 spare 100s and a controller, maybe as portables, maybe put it on my families property.

 

[PlethoraOfGuns]

My last setup I had 180w solar on MPPT controller and 2x100ah wet deep cycles. 1500w pure sine inverter running a 1000w 1990 Emerson microwave. Used to have 3 batteries, but one prematurely bit the dust. On three batteries it worked pretty good if using microwave shorter than 10 minutes. On 2 batteries, no way, 2 minutes running and then bad things started happening. I could also charge the batteries with engine alternator so I could run engine to give the batteries a little boost when running microwave. I love having a microwave. It dumps a lot of heat into food fast and efficient. I make a lot of leftovers in tupperware, so microwave is everything.

 

[jimindenver]

Three grp 27 or four 6 volt.

700 watt microwave uses 1070 watts of power.

Having the sun shining on your solar while you run it sure can make a big difference

 

[WalkaboutTed]

We set up Hubby's van around the ability to make coffee (electric kcup or drip-800w). And since he likes his coffee super hot after adding milk, a microwave was needed (700w).

In order to do it, two cups if he's by himself, four cups if I'm with him, this is his set up:

360w solar on top, 180w on the side which is either facing East in the Summer or facing South in the winter. Early in the morning the side panel can produce 20:1 as the top panels proportionally, usually they equalize watt production at about 1000-1100.

He has 450ah of AGM VMax Tanks (4x6v). He's never had a problem with them not being recharged by noon. The batteries are over three years old and still tolerate this treatment unless it's the second day of clouds-they sag a bit. In that case, he may run the engine while brewing and nuking. Or go for a drive in the morning.

The inverter is a el cheapo modified sine wave Kriëger. The microwave is the old fashioned manual dial, so it tolerates voltage drops easily.

The electric coffee machine and microwave are in addition to the 4.6cuft 12v fridge. And lots of small electronics, including a laptop.

Just as an aside, my old van had three group 27 Chinese UPG121000 (not true deep cycle). We tried running to microwave, just for yucks and it barely popped corn until I turned on the engine. The three batteries were not adequate.

 

[vgilbert]

Not smart enough to do all the solar math but I am smart enough to start a 2,000 watt inverter generator  :thumbsup:
Therefore I have a nice microwave/air fryer/convection combo unit in my rig and use it daily
Solar/battery set up cost large enough = ??? Reliability = ??
Generator cost = $450 plus $2.00 per day (running 12-16 hours per day) Reliability = very good

 

[jimindenver]

I design and build solar systems and even I will tell you that you still need the generator or some other form of alternate charging no matter what solar system you have. It will charge up your batteries a fair amount when the sun doesn't cooperate and provides power to run long term larger loads that your system can't. In fact, get the generator first.

That said, a generator has many limitations. There may be quiet times that you are not allowed to run it, you may find yourself around people that don't want to hear it. A 2000 watt generator will not come with a remote start feature so every time it needs to be turned on or off out the door you will go. You will need to protect it in the rain too.

A generator can grow legs so be careful about leaving it out. I would never put one out at a Walmart, a rest area or truck stop.

A generator is reliable as long as it is kept tuned up, has the gas run dry in between uses and only fresh gas put in it.

The last thing is using only a generator to keep your lead acid batteries charged is a guaranteed way of killing your batteries over time. Bringing lead acids up to 100% is essential for their health and it simply takes far to long to do it by running a generator all day.

 

[vgilbert]

Just saying mine has been great. However, I also realize a  generator may not be the right choice for everyone.
I have stayed at truck stops (Loves and Pilot) extensively over many states and run mine without issues. Of course I lock it to the frame of my rig. I am currently sitting in urban Yuma at a transmission shop (on the street) and have ran the generator for 2 days now. Also, I have a battery bank that I use overnight for my refrigerator, lights, phone, etc so quiet times are not an issue. Besides, it runs so quiet its really hard to hear from 20 ft away. I am sitting in my rig right now with the generator running and cannot hear it.
One more thing I like is the fact that I can just run down and get a gallon of gas when I need to, much faster than waiting out a few days of bad weather.
Generators can be stolen, break down, etc and solar can also be damaged, etc. I went with my generator for 1 primary reason - cost. When first starting out I wanted to keep cost under control while I made sure this lifestyle was right for me. The $450 initial investment has been well worth it to me.

Solar vs generator, both have pros and cons.

 

[66788]

I design and build solar systems and even I will tell you that you still need the generator or some other form of alternate charging no matter what solar system you have. It will charge up your batteries a fair amount when the sun doesn't cooperate and provides power to run long term larger loads that your system can't. In fact, get the generator first.

That said, a generator has many limitations. There may be quiet times that you are not allowed to run it, you may find yourself around people that don't want to hear it. A 2000 watt generator will not come with a remote start feature so every time it needs to be turned on or off out the door you will go. You will need to protect it in the rain too.

A generator can grow legs so be careful about leaving it out. I would never put one out at a Walmart, a rest area or truck stop.

A generator is reliable as long as it is kept tuned up, has the gas run dry in between uses and only fresh gas put in it.

The last thing is using only a generator to keep your lead acid batteries charged is a guaranteed way of killing your batteries over time. Bringing lead acids up to 100% is essential for their health and it simply takes far to long to do it by running a generator all day.

Words of wisdom born of experience.

The wise man learns from the experience and mistakes of others.

 

[Ravella and X]

"you may find yourself around people that don't want to hear it."

That would be me.

Also... Some of us don't actually need to consume power 24/7. My main use is an old and inneficent 110v mini fridge. When its going to be cloudy too long for my small solar set up, I turn off the inverter and get a block of ice for the fridge.

Oh! I forgot that I recently added a 3qt 700w instant pot. I'm content using it while the sun shines.

 

[VanForNow]

For people who want to avoid investing in a massive electrical upgrade to power a microwave, a stovetop Omnia Oven is the quick, easy, low-cost way to go. (Just sayin')

 

[user 37446]

Pretty much takes a full sized van, preferrably an extended model for enough solar roof real estate. You can get 400 watts on most any f.s. flat roof van Now for a minivan, you can't hardly fit more than 200 watts on its roof and the efficiencies of flat mounting knock that down by about 30%. Then there's the charge controller loss.

I did see one guy on YT with a small 700 watt (just over over 1K at startup) microwave on a 1500 watt PSW inverter and he had two 12v 100 amp hour group 31 marines thickly wired together. He said that he always fast idled his van while running the microwave. I don't know how long his batteries lasted, I remember something about them being less than 1 year old and he had 200 watts of solar as well as a c.d. solenoid.

A gennie, while nice, is kinda impractical in a minivan due to space considerations to carry it and the fuel. If you have a f.s. van with a cargo box for the propane or gas then that would be ok.

 

[abnorm]

^""Then there's the charge controller loss.""??????

 

[B and C]

^^^PWM charge controller.

 

[Weight]

Yes. I actually have experience. No guessing. Dodge B250. I started with 3 x 100 watt Renogy panels. 45 amp PWM, charging 6 x GC2 batteries. Ran my 100W microwave for 3 years until I upgraded to 400 watt solar panel. I did equalize my house bank every three or four months by plugging into shore power. Otherwise, solar handled Mr Coffee, toaster, and microwave every day.