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Old 02-24-2019, 03:09 AM   #1
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Default Inverter Question

Please help me out on this one. I've noticed that many of you have inverters in your electrical systems and, since I don't, I've wondered about the practicality of adding one. I have a 97 PW with 100ah cabin battery and 100w solar. No generator. In thinking about this I'm wondering:
1. What capabilities having an inverter would afford me. What do most of you use your inverters for?
2. Given my existing system what would I be able to do with an inverter? Enough juice, for example, to run a microwave?

Additional info: Most of my outings are for 4-5 days. I don't have any desire to watch TV......outings are my escapes. I watch movies and series on my ipad at night. I seem to have enough power to recharge my ipad and iphone via 12v.

Thanks for any advice you can give me.

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Old 02-24-2019, 12:31 PM   #2
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I run the fridge on 110V while traveling using an inverter. I think you get a bit better cooling than when on 12V and no worries about running the fridge on propane when driving. The load caused by the fridge also pulls down the system voltage somewhat reducing the negative effects of overcharging the batteries on long drives particularly if starting the day with fully charged batteries.

It is very unlikely that you'd be able to run the microwave oven off a single 100Ah battery unless the van's engine is also running (assuming all associated wiring and fusing supports the load). Typically microwave ovens seem to consume about 1.5 X their cooking power. 600W cooking power microwave oven = 900W power consumption. You'd probably need a battery bank / that could deliver 90A at 12VDC for that example.

Maybe 15 years ago or more Wilton Hart ran his microwave oven with the van engine running - 1000 Watt Inverter for a Roadtrek - he chose to run it off the engine battery. I prefer running it off the house battery but that would likely require upgrading the wiring, fusing & isolator in your van. It's easy to see why Wilton used the engine battery.

Two bikes on sliding cargo box: & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications:
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Old 02-24-2019, 02:36 PM   #3
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Seems you're well situated without an inverter. Yet, an inverter allows flexibility for the unforeseen - - for example, we have this cute little Hamilton Beach coffee bean grinder . . . runs on 120vac. Then there's our portable TV antenna and preamp (we don't use it much either) . . . like most small electric appliances, it comes with a 120vac supply. While some of our small 'book readers' and tablets come with 'combo' 120vac/USB chargers, others only provide a 120vac power adapter. Having at least a small (sine wave) inverter would avoid the not infrequent hassle of having to acquire/provision a separate 12v power adapter.

But we come with a bias. Our DIY Promaster is an "all electric" design - - no LP gas. The center piece of our system is a Magnum 2812 charger/inverter that powers 9 duplex outlets throughout the (inside and outside) of the van. 'Electricwise', living in the van is little different than living at home.
2016 159" High Top DIY ProMaster with 500ah Starlight Solar/Elite LiFePo4, 810watt Kyocera Solar w/MidNite Solar Classic MPPT, Magnum 2812/MMP250-60S Charger/PSW w/remote, Nations 280amp 2nd Alternator with Balmar regulator, NovaCool R4500 12/120v frig, 2 burner TruInduction cookstop, SMEV 8005 sink, FloJet R4426143 pump. No A/C or indoor washroom.
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Old 02-24-2019, 03:40 PM   #4
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Since a "normal" inverter won't run anything of size or power, you'd only need one if you had something vital you need to run off 120v. And only then if you could not secure a 12v power adapter.

In our three trips last year, we never turned on our inverter (we have 12v TV/DVR combo & 12v powered fans, etc.). Glad we have it just in case, but I wouldn't add it if I didn't already have it.
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Old 02-25-2019, 03:21 AM   #5
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Thanks to all. I'll probably stay where I am. Marcopolo: Having gone through a lot of testing/work on my old Dometic 3-way, I too wondered if it would be better to run the fridge off of the 120v via an inverter. My tests showed, as most of you know, that the 12v option was the least effective. Even though I'm not a full timer, I tend to go out somewhere every month. That's the advantage of being in the southwest. At this time of year it's easy to have the fridge on it's lowest setting for 120v and have it be too cold. But the summer is when it sounds real attractive to have a compressor.
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Old 03-03-2019, 06:13 PM   #6
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There are two varieties of inverters: Sine wave and so-called modified sine wave (MSW). You can think of these as expensive vs cheap. Sine wave inverters provide AC just like from the power company. Anything you power from a sine wave inverter will be happy.

Modified sine wave inverters produce a waveform that resembles Frankenstein's monster compared to the Mona Lisa a sine wave inverter puts out. Electronic devices may or may not be happy with a modified sine wave.

We run our small microwave off a MSW inverter. The microwave runs at about half the power it puts out on shore power (measured by heating water).

Our particular inverter often cannot increase its output rapidly enough from standby to the microwave's starting demand for the microwave to start its microwave emitter. The microwave stutters and stops. To some degree this depends on the battery's state of charge. So I play a trick: I switch our fridge to AC. That puts a 15 amp AC load on the inverter. Then I start the microwave.

Regarding your 3-way fridge, you will probably get better results by installing fans to force air over the coils than by running it on AC from an inverter when you are driving. The fridge in our Roadtrek 200 never worked well. Roadtrek simply does not install them properly. The fridge needs a tall chimney above it to induce natural convection. Without that, air flow over the coils is inadequate. I installed a bank of computer fans to blow air through the outside compartment. It works fantastically. We can drive all day in the southwest with the fridge on 12V and it stays cold. The fridge consumes a lot less electricity as well. I don't worry about leaving it on 12v when we park for an hour or two. (Full disclosure we have a 200 AH house battery.)

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Old 03-06-2019, 01:09 AM   #7
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Default Inverter

We have the RT Supplied 750 Watt TrippLite inverter/charger. I initially considered installing a larger unit but since that involved more battery power I was worried about the weight. We have 2 six volt 232 Amp-hour golf cart batteries which gives us about 120 useable amp-hours. We cannot run the microwave but it does have sufficient capacity to run a small drip coffeemaker (4 cup Black and Decker) and a toaster (not simultaneously) which fills our needs quite well as we can wake up and make breakfast without starting the gennie.

Our TV/DVD player is direct 12 volts, which I would advise over running the inverter for the TV.
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Old 03-06-2019, 03:46 AM   #8
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Thanks to all of you responding. I've written off the idea of an inverter. From your comments it's obvious that I don't have the battery power. I'll stick with my drip cone for coffee. Works well. Can heat water off the propane stove. I can see why many of you enjoy the slow cooker and microwave. We usually have meals like bacon and pancakes for breakfast (we pre-cook bacon at home) and dinners like chicken with mashed potatoes and carrots or tamales....all cooked in advance at home and reheated on the stove. But that works because our trips are usually short. I can see how it's harder if you're out for months on the road.

Best to all of you and thanks again for the advice.

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