Powering questions

[J Mac]

Hi everyone, I’m new on here, I’m about to embark on a camper van conversion, and hoping for a little advice on a few matters, for now I’m trying to get my head round best way to go with regards power.

So some of the things I’m intending including in my build, a oven, hob, kitchen sink with hot water, shower with hot water, fridge.

I had originally thought I would use lpg for powering most of the above (exception of fridge) with solar panels to provide the power for all the 12v devices (lights, fans, charging devices, etc...) the more I have been looking at things the more I’m wondering if it might be possible to go big on the solar panels and batteries and use these to power everything.

looks like I’d need at least a 3000w inverter for all these high powered devices and even then seems I would need to make sure I only use one at once.

From looking seems like most of these high wattage inverters are 24v so my thoughts were maybe rig 2 batteries in series and use these solely for the inverter powered appliances and another 12v battery to power everything else.

So my question is does this sound like a feasible option? If so does 3 batteries sound enough? What about solar panels what would be sufficient and how would you connect them would you completely separate the two sides of the electricity supply so maybe have 3 panels, 2 for the 24v and one for the 12v? Does having a 24v setup mean it can’t also be connected to the alternator (van battery) for split charging?

Well I’m really excited about joining the camper van world and looking forward to hopefully hearing some of your views, any help and advice will be much appreciated.

thanks.

 

[addoaddo]

Unlikely to have enough storage capacity to run all these items for long. General advise is if possible run anything associated with heat to use gas rather than electricity. Nothin wrong with 24v system apart from charging. The engine generates 12v an most solar produce 12v

 

[J Mac]

Thanks Addoaddo for your reply and input, I’d kind of thought if maybe I looked on the basis that in total maybe 40minutes of cooking and 20minutes of heating water a day (this is what I figured as a worst case scenario) so I figured 3000w/24v would mean 125ah so for an hours use would that mean a 125ah battery would work for an hour? I’m probably making an error in my calculations there or I’m not taking into account something but I thought if that was the case with 2 batteries I’d have about 2 days use and if so it was whether the solar panels could keep up with this demand? But I appreciate your thoughts which at present is certainly making me more inclined to go with plan A and gas.
It’s a shame though as I really liked the thought of it being more environmentally friendly and liked the idea of having one less thing that requires attention as in having gas bottles, lpg tanks refilled,

 

[Spriddler]

Can't advise but if you do a search in the a self-build forum you'll probably find similar FAQ's or you can re- post your question there:

Self-Build Motorhomes

DIYers talk about Self builds here.

www.motorhomefun.co.uk

Good luck with the project.

 

[Tombola]

start with working out how many amps you think you will use in a day, then plan your system around that with some leeway

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[pappajohn]

so I figured 3000w/24v would mean 125ah so for an hours use would that mean a 125ah battery would work for an hour?

A pair of 125ah batteries in series will give 125amps at 24v.
You should only discharge to 50% so you would need four batteries, two pairs in parallel to give 250amp (per pair) at 12v and connect each pair in series to give 24v.
Two 125ah batteries in parallel will give you 1 hour of inverter use at full load.
More importantly you need to recharge what you take out.... It'll take quite a long time to put 250 amps back in.

 

[WillH]

Use gas for cooking, most energy efficient.

 

[J Mac]

Can't advise but if you do a search in the a self-build forum you'll probably find similar FAQ's or you can re- post your question there:

Self-Build Motorhomes

DIYers talk about Self builds here.

www.motorhomefun.co.uk

Good luck with the project.

Thank you Spriddler

 

[J Mac]

start with working out how many amps you think you will use in a day, then plan your system around that with some leeway

Thanks Tombola, yes I thought I did that 3000w for about an hour.

 

[J Mac]

A pair of 125ah batteries in series will give 125amps at 24v.
You should only discharge to 50% so you would need four batteries, two pairs in parallel to give 250amp (per pair) at 12v and connect each pair in series to give 24v.
Two 125ah batteries in parallel will give you 1 hour of inverter use at full load.
More importantly you need to recharge what you take out.... It'll take quite a long time to put 250 amps back in.

Thanks pappaJohn that's very useful information, definitely learned something there, I spent day watching random camper conversions on youtube and there was quite a few that had gone down this route, none went in to much detail on the set up though or amount of batteries/solar power wattage etc also most I think may have potentially been from sunnier climates, seems like it's not the way to go from everyones opinion so back to cooking on gas

So with cooking and water heating off gas, just fridge, lighting, fans and charging devices off batteries, I'd be really interested on what amount of wattage solar panels and battery set ups all the completely off grid folks have in theirs.

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[CamperManLez]

I think you will find an electric oven will be a very heavy load, not much will be cooked in less than 1/2 an hour. Suggest you stick to gas for cooking and just the small 6kg bottle. My van is all electric except the hob (no oven I use a remoska) but I use sites with hook up so no issue. For the solar have a look at domestic panels, they can run at 24v , Panasonic make some very good ones.

 

[autorouter]

You might find this recent thread of interest.

Wildax replace gas with lithium

Watched the 2021 model virtual launch yesterday from the factory, interesting to see them now offer a ‘gas free’ option, but also what they think is a workable specification. It includes, diesel/electric truma 2 x 100 amp lithium 2 x 150 solar 50 amp b2b 3000w inverter wired to all sockets 2 x...

www.motorhomefun.co.uk

The basic problem is that, weight for weight, a kilogram of gas or diesel contains about 40 times more energy than a kilogram of battery. In addition, solar power is good in summer when you don't need it, and scarce in winter when you do. Most MHs would struggle to fit 1000W of solar panel, but in winter you'd need ten times that for all your heating and cooking.

Having said that, there is scope for your idea of 3kW inverter, lots of batteries and a big B2B charger with lots of solar, with a diesel heater and water heater, and maybe a good old barbecue for cooking.

 

[Reallyretired]

You can get a diesel hob too I think, has been mentioned somewhere on this site.

 

[funflair]

Thanks Tombola, yes I thought I did that 3000w for about an hour.

So by the time you factor in inverter efficiency and a bit of a safety margin you might as well call that 300ah out of 12v batteries, OK that would be just possible for one day with say 320ah LiFePO4 with these physical attributes below, so now you have used your days allocation of power so you need to think about the next day when you want the same power, well it isn't there unless you have put it back and lets face it solar is unreliable so you need at least another days storage and possibly two so you are realistically looking at 900ah of LiFePO4, lead acid would just be too heavy, then what about your budget as you have just give or take £10k. We will very soon have 420ah LiFePO4 and I fully intend to use all our 240v stuff like kettle, microwave, oven, induction hob etc etc BUT I would not want to do this without the backup of being able to sit out a few days of rubbish weather and go back to using gas for at the very least cooking while nursing the battery capacity.

• • 160ah
  • Dimensions (LxWxH)
    417 x 227 x 314 mm / 16.4” x 8.9” x 12.4”
  • Weight
    26.9 kg / 59.3 lbs
  • Case material

 

[ChrisL]

If I was building my own van I would be going for diesel for heating and cooking, also remember if you have a separate diesel tank for domestic use you could run it on red diesel where available, which will save some money. It's worth looking into, boats have been using diesel for many years.

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