question

barclay-89 avatar image

Motorhome power confusion, looking for help please

im currently in the process of converting a 26t lorry into a motorhome

I want to run normal household 240v things such as a tv, led lights, plug sockets for phone charging, hair dryer, fridge/freezer, microwave and I will have a gas oven and hob.

some places I will be taking it to will have a power supply to plug into which Is great however some places will not have this. My initial thought to resolve this is to have a silent generator, however how would I keep things powered such as the fridge whilst the truck is travelling around??

so do I need to run batteries and somehow convert them to 240v if that’s possible? and charge these via the generator?

thanks in advance for any help

Multiplus-IIinstallation
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4 Answers
spirou avatar image
spirou answered ·

Why even bother converting everything to AC mains then back to low voltage DC? Other than microwave, everything else will happily run on 12V DC.

Anyway, if you're starting from 0 knowledge, it's probably best to leave this to someone who knows what they're doing. Because there is just far too much to explain and far too much to go wrong. But you can start learning by watching victron van install video.

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Trina avatar image
Trina answered ·

You'll want to not use standard household appliances for a mobile build. Aside from the microwave (and that too has "low amp draw" versions you can find links or advice for in the mobile living communities (including truck drivers and boating people); everything would be best on 12v -or 24v if needed (but that is far more complex vs a tiny bit of expense for slightly bigger wire for things) .


I would consider this

4x 100a decent mono solar panels to get started with a decent bit of MC4 cable (12 AWG if possible but 14 is pretty common and usually fine)

2x parallel "Y" branch MC4 connectors to wire the panels with some flexibility to change over time (in less than ideal sun I find the higher voltage of series allows more power into recharging your batteries but the "Y" branch connectors will give you some flexibility to experiment over time or add a portable panel (if your MPPT can handle it).

Victron Smartsolar 100/30 MPPT minimum (you could go bigger if you think you want to ad more later but it's usually more cost effective in mobile situations to just add a second charge controller). With just 200w the 75/15 will work fine if money is tight.

Victron BMV702 or 712 (has the Bluetooth built in) battery monitor. You CAN skip a battery monitor IF you get the Bluetooth versions of things.and a lifepo4 battery but it is usually the FIRST thing to buy after a battery. If you go with the Tracer or EPEVER/Outback (not as good for a mobile install IMHO) they sell kits with a decent battery monitor included and they are VERY good budget things but victron is better really -the small caveats and cons won't affect you in a mobile build and all the excellent functions will definitely be highly useful.

If you can afford it, get a good 100ah LifePo4 12v battery. I'd say this should be TOP of the list to spend extra on! Lifepo4 is absolutely incredible for mobile power solutions.

For recharging while driving there are some standard setups the "RV" crowd outlines using the vehicles built-in alternator that would only possibly take a few hours of head scratching and YouTube to figure out and install. Probably the most important part is finding out how many "amps" your alternator in the vehicle can put out (you will want at least a 70a version absolute minimum (100a better) for most things - people in hot places get twice that output frequently.

I'd recommend a portable fridge -in the states we can get smallish ice-chest sized ones online that fit between the front seats and hold 42L to 60L+ and can easily run off any good 85ah or more capacity battery for a day or more in temperate climates. Amazon here has good reviews and expect to pay 300EU or more for a decent one.

For lights use LED small bulb replacements and tiny 12v auto and RV solutions -here in the states we use Amazon for cheap bulk packs.

For AC power you'll need to size your amp requirements, realizing that having too big an inverter is as bad as having too small a one and you don't want to run it unless you need to (so having a small 300watt one to do a few things in a pinch and a separate 1200w or bigger ones JUST for a microwave would be a good way to do things if you plan on using AC power frequently). Lifepo4 is very robust though so you could use a cheaper microwave and get a better inverter..

For recharging from a mains if you find the solar won't do it or parked somewhere longer and need it, the simplest solution is adding a Victron Smart BLUE 240vac charger in whatever amps your battery would best like (you can "stack" them as well -use more than one at a time just like the solar charge controllers) with the wonderful bonus in Lifepo4 that it can handle fast big-amp charging! You can plug the BLUE charger into the mains or if you wind up buying yet another piece of gear (I recommend Honda inverter-generators for gas generators really if nothing else than they put out highly regulated power and far more effectively-and this built in inverter in the generator is different from the one you'd have installed in the mobile) thi you can plug it directly into your gas generator and this would be the most effective way to do that!

Also you might want to look at victron's inverter-charger stuff. I don't need it so I used the simpler gear here. Everything I have will fit on half the dining table and does everything when I travel


If you are just getting started this would be a highly effective system pending sunlight and how much you drain down or use and then recharge your battery, and lifepo4 is far more tolerant of abuse than the old heavy batteries and worth the extra cost.

Probably the most important part to understand is you want to be running off DC power as much as possible when NOT plugged into the mains. And for simplicity and cost you want to have a really good idea of how much power you need -really need- at any given time and then again likely over a day or two and also a week so you can plan on how best to solve that need in your budget.

The best gear out there is Victron and Tracer/Outback (and then Bogart Engineering for solar charge controllers and monitors with any decent no-cloud sun) and for inverters Samlex and Victron brands. Engel and the Dometics and some of the Chinese companies make good RV mobile fridges (make sure if you get a dual AC or DC capable one you get the 240vac version vs the 120vac we get in the states). Honda and Yamaha make decent gas generators. In the USA we love Battleborn or Renogy lifepo4 batteries for their long warranty and excellent BMV's but I hear good things also about victron stuff from some of my friends. Cheap solar panels will work almost as good as expensive ones if you stick with monocrystaline (check YouTube for reviews) but if your mobile has a BIG roof you could get dirt cheap used grade b or c panels and use the savings to buy a second solar charge controller

The charging from vehicle part is vehicle make particular but victron is a standby for the battery stuff to route it to your housebattery while driving. Get on the RV forums and youtube, fuse wires between things and keep a fire extinguisher handy and you'll be fine. None of it's hard to do just takes time and wire and some money, a few tools, patience, and an some video watching.

Anyway. Hope that helps forgive any typos -I'm using my phone sitting watching the sunrise from my build using the above gear after years of trial and error, research and use!

:P



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JohnC avatar image
JohnC answered ·

Hi @Barclay-89

I bypassed this because I thought it was answered. But your question re AC appliances wasn't really considered. I share your desire to use them, and I'm mobile too (20m boat).

Yes, you'll need batteries. And an inverter/charger like the Multiplus. Batt charging from alternator maybe with an Orion dc/dc unit.

That's the minimum, but it's always nice to have a genny, and solar is great. But it all costs, and it's up to you how comfortable you prefer to be.

This is Victron's specialty, and the options are mind blowing. Just some examples: https://www.victronenergy.com/upload/documents/Brochure-Off-Grid-backup-and-island-systems_EN_web.pdf

Do your research further before spending. And good luck choosing..



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Trina avatar image
Trina answered ·

P.s. Victron makes the Orion TR (?) which I think is a 1-stop unit for the vehicle-alternator charging solution. Check it out!

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