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Old 10-02-2014, 10:35 PM   #1
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110V mini-fridge and microwave install?

1999 Chevy Quigley 4x4 3500.

My first RV/sport vehicle. It's already a conversion vehicle with tv and vcr, fold down bed..etc. And I don't know too much right now about hard wiring an appliance into a vehicle.

What I want to do is use a mini-fridge and microwave we have had not being used. Can and how, what's the best way to be able to use these in my vehicle? I was thinking of trying to build a little cabinet for them. How would I wire it in?

I don't need the fridge to be operating 24/7. Mainly just looking for it to keep drinks and stuff relatively cool. So I thought the time I'm driving would be enough to cool things down enough so that when we stop to picnic or camp we'd have some cold drinks or sandwhich meats.

I thought of eventually adding a rear bumper generator. Would that make it easier or more helpful?
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Old 10-04-2014, 10:15 AM   #2
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Re: 110V mini-fridge and microwave install?

Damian: You'll need an inverter........and a house battery or two. How many watts is your microwave?

It's quite likely that your microwave is a rather large size for a van; let's say it's a 1200W microwave, that's it's output power. Since everything is less than 100% efficient, it will draw say 1500W of 110V input power. The input power requirements for both the micro and the fridge are on their data labels.

This means that you will need a inverter rated at least 1500W. If you want to run the micro and the fridge at the same time you'll need an even larger inverter, like 2000W. These inverters need a lot of 12V amperage so that's why many of us have one (or more) large deep cycle house batteries.

It is possible to wire your inverter to your van starting battery and run these things while the engine is running, but you will rapidly deplete your starting battery running these while parked.

These appliances could be run off of shore power with no issues, but that may not be what you want.......

The fact that your mini-fridge is 110V also means that you will waste a fair bit of 12V power running it. Let's assume that your shiny new 2000W inverter is 90% efficient. That means that 10% of the power drawn from your battery gets wasted just powering the inverter to then power the fridge. That's why many of us here buy 12V fridges, like a Truckfridge or an Engel. Doing this skips the inefficiencies of 12V-110V-12V conversions (or just the 12V-110V inefficiencies)

Buying a 2000W inverter to support something that you have laying around may or may not make sense, as you can buy a smaller microwave with the $$ saved from buying a smaller inverter. For my build, I picked up a used 1000W inverter and bought a small 700W microwave at Best Buy for $69. Smaller inverter=less power from your battery.

Inverters are available in two flavors: True sine wave and modified sine wave (MSW). Either if these will power your stuff; MSW inverters are cheaper. Some inverters (typically for RV use) also have battery charging functionality built-in to allow battery charging while on shore power.

Do a search here for "inverter" there is lots of info.

One final note.....fridges are available in 12V but microwaves are not.
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Old 10-04-2014, 10:31 AM   #3
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Re: 110V mini-fridge and microwave install?

As BoyWonder said, the thing about electrical is that it's a whole system, if you don't want to be plugged in to shore power or driving or running a generator at all times (if you do, then it's simple).

If you want to be able to use these things when parked away from shore power and not running a generator at all times, then things get a bit more to the "it's all connected" level. Batteries provide power, so you need enough of those. Then you need a way to put the power back into the batteries (generator/charger, solar, etc.). And a way to see how the batteries are doing (like a gas gauge). Wiring that's heavy enough for the jobs at hand, with overcurrent protection to match. Etc. So at that point it's good to step back and take a look at the whole system so it will do what you want, is relatively balanced, etc.

So a big part of it is knowing how you want to be able to use the van, then going from there.

My '97 had a minimal system, and I had to live accordingly. Small house bank, and no real way to put amps back in except driving or plugging in. And no inverter. So no microwave use unless plugged in, and the refrigerator was a bit of a "tyrant" because I had to keep it going (by either plugging in or driving). On my current rig ('98/'99), I'm going to upgrade the electrical system to support my uses better. I don't really use a microwave or house Air-conditioning, so for me the main big draw will be the refrigerator, and is what is driving the whole upgrade, really (well that and my laptop ).

An entire system is not cheap, so it's good to have a plan laid out so you end up with a system that will give you what you want.

There are loads of knowledgeable, helpful people here, so if you say what you'd like to do (camping style, etc.) and what you already have (charger type, battery bank size and type, etc.) you'll get lots of good input. You have said some, but there are some blanks still.
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Old 10-04-2014, 06:30 PM   #4
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Re: 110V mini-fridge and microwave install?

So my microwave is a small one. I looked on the inside and back label and don't see anything that says how many watts is produces. Where should I be looking? I did see 2450mHz.
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Old 10-04-2014, 09:00 PM   #5
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Re: 110V mini-fridge and microwave install?

Re-reading my last post, it could have been more clear perhaps. Basically, to me it comes down to two things:

1) How do you want to use the van? Do you want to "a," be plugged in, driving, or running the generator all the time (i.e. one of the three)? Or do you want to "b," get away and be able to sustain your usage when camped away from it all?

2) What do you want/need to run? I've spent weeks off the grid with no power at all (sailing, back in the day) and that worked fine because I had no "needs," either. There was no Internet, no cell phones, no digital cameras, etc., and we had kerosene lights, and icebox, and non-electric pumps. But nowadays, most folks (including me) have things -- electrical things -- they want to run. But everyone is different, and if you fall into category "b," you'll want to have some idea how much "stuff" you need to support.


- Lights... LED or not?
- Microwave? Or not.
- Other appliances? Or not.
- Computer? Or not.

Etc. etc. Some people van camp like they were in a hard tent; others like they were in a suite at the Ritz. Just depends on what you like. You can come up with a system to do either (mostly).

It all comes at a cost, when "you are your own power department" (category "b"). Once you figure out what you want/need to run, and if you are more an A or a B, then you can plan out a system. Folks here can help.
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Old 10-04-2014, 10:45 PM   #6
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Re: 110V mini-fridge and microwave install?

This van is going to be a family weekend camper and support vehicle for a dirtbike motorcycle tour business. So I just need to occasionally use the microwave to heat up some drinks or a dish now and again when on an over nighter.

The fridge will be the same. Just need to keep some drinks cool for a day or two camp trip now and again, and no big deal if they aren't cool 100% of the time.

Let's say I install an inverter. Can I use the microwave, how many times, with the engine NOT running?

Eventually I'd like to have a generator installed on a bumper hitch or something where I would run the appliances off of it. What is meant by "shore" power? Is that running off of extra batteries or running off the van's batter/alternator setup?
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Old 10-05-2014, 12:23 AM   #7
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Re: 110V mini-fridge and microwave install?

I'd say take stock of what you have for starters:

1) Size of house bank (amp hours). You can draw the batteries down to 50% charge without unduly shortening their lives.

2) Draw of your projected appliances (you can convert to amps).

3) Duty cycle of refrigerator (depends on your climate).

Microwave... I don't know. With a small battery bank, I don't think you could run it off of an inverter, but I'm not sure. It's a pretty hefty draw though. Others here can probably speak to that better than I can, as I don't use a microwave. For occasional heating up of drinks, in a 12-volt world with a typical non-upgraded electrical system, I'd be thinking about a portable butane stove (bonus: can set outside on picnic table when desired).

With the refrigerator the thing is it will keep running until your batteries get down to basically nothing, which will drastically shorten their lives (bummer). If you put in a battery monitor (very good thing anyway), you could then shut the refrigerator off when they get down to 50%, and turn it back on when you drive again, or plug in again. Or carry a cooler and ice (might be easiest).

Shore power means plugging in to an outlet, basically. So then you can do things pretty much like "at home."

If you upgrade your system (charger/generator, solar panels, charge controller, battery bank, cabling etc.) then you still can't live without a care, like at home, but you can do a lot more. Such as run a small 12-volt refrigerator pretty much full time. It's a relatively big investment in time and/or money though -- might be worth it to you or might not.
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Old 10-05-2014, 10:40 PM   #8
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Re: 110V mini-fridge and microwave install?

Ok thanks for all this info and insight fellas. For now here is what I think I want to do. Tell me if this will work?


1. Hardwire an inverter (what size will I need to power a small 110v fridge and small microwave?) to the van battery.

2. Install shore power 30 amp plug via an outside, rearward driver side.


INVERTER THINKING:
My thinking is if I'm out and about camping and there is no power to plug into and I REALLY need to heat something up, I can turn the van on and use the microwave. The fridge doesn't have to be going nonstop, just as I'm driving, it'll do well enough to keep some items cool for a short time after I stop.

SHORE POWER THINKING:
If I'm in a spot where I can plug into power I can easily use my fridge and microwave and other items without a problem.


What do you think? Also, seeing as how I would have an inverter with appliances plugged into it while I'm on the road; is there a way to make it convenient (a quick switch) where I could swap back and forth between the inverter and shore power interior sockets without having to unplug and plug-in the microwave and fridge cords?
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Old 10-06-2014, 08:25 PM   #9
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Re: 110V mini-fridge and microwave install?

Quote:
Originally Posted by Damian
Ok thanks for all this info and insight fellas. For now here is what I think I want to do. Tell me if this will work?


1. Hardwire an inverter (what size will I need to power a small 110v fridge and small microwave?) to the van battery.

2. Install shore power 30 amp plug via an outside, rearward driver side.


INVERTER THINKING:
My thinking is if I'm out and about camping and there is no power to plug into and I REALLY need to heat something up, I can turn the van on and use the microwave. The fridge doesn't have to be going nonstop, just as I'm driving, it'll do well enough to keep some items cool for a short time after I stop.

SHORE POWER THINKING:
If I'm in a spot where I can plug into power I can easily use my fridge and microwave and other items without a problem.


What do you think? Also, seeing as how I would have an inverter with appliances plugged into it while I'm on the road; is there a way to make it convenient (a quick switch) where I could swap back and forth between the inverter and shore power interior sockets without having to unplug and plug-in the microwave and fridge cords?
If you purchase the correct inverter it will pass through AC shore power when it senses it. Dump the idea of a 110AC only fridge and look at something like a Engel or similar.
To run a fridge you'll need enough amp hours to supply it. Say you have a 100AH battery. That's fine for the fridge over night in most cases but to run the microwave you'll have to provide enough amperage to keep from draining the battery by running the engine. Most alternators will only supplement the actual draw being pulled out of the battery so long run times pulling 60+ amps out of the battery takes running the engine much longer to re-charge the battery if the alternator is only putting 5-10 amps back in. (This all depends on the vehicle, the vehicles alternator and the vehicles system load). You might need to run a larger alternator to supply more amps to better offset what is being pulled out of the battery. Kind of a reason why most SMB's with microwaves are outfitted with a 210 AH house battery, a solar array of 130W+ and a 1500w-2000w inverter as a standard build. The idea of using the vans starting battery is a poor choice for a number of reasons. A starting battery is not designed for anything other that starting and running the engine. Chances are that you'll end up stuck with a dead battery and shorten the life of the starting battery. There is a reason why RV's have separate battery systems.



A standard system is nice but costly. There are a few ways to cut corners though. Just depends on how far you want/need to go. For example you can buy a real basic inverter and just wire in a single 20A AC outlet and 30A shore power plug and just plug in the microwave to either the inside shore outlet or the inverter when needed. Most inverters have a dual 110 outlet and a power strip could be used for the lighter loads.

Then you could go this route. I don't know how well this MW works and heard they had issues but were resolved. Guess you can research it.

12v MW

ArKPak
Note that the ArkPak is not really designed to run a AC microwave and to hook up the power hunt MW might require some modification. But there is a load chart at the site. It has a 50A Anderson DC outlet but the power hunt is rated at 55A. Perhaps you can use a lower setting. Give them a call.

You still need to figure the load, AH rating, and charge time. Expecting to run a microwave for 20 min from a small battery just won't work. I can run my MW for a few minutes and not pull too much off my bank but I have two 220AH batteries that cost upwards of a thousand bucks. Figure in a 2000w inverter at about 1200 dollars, a battery separator, fuse panels and wiring along with a high amp alternator, things add up quick. You can probably build a simple system for a fraction of the cost.
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Old 10-06-2014, 08:30 PM   #10
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Re: 110V mini-fridge and microwave install?

Ok you guys got me convinced to go the route of a 12V cooler/fridge.

I still want a cheap way to use a small microwave without spending $1000 bucks.
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