Powering a Remoska

[Attila the Hen]

Help, I have purchased a 400W Remoska for use in our PVC and would like to be able to use it “off grid” using an inverter. The van has two new 120AH batteries which I think will give me enough power, the Remoska only being used for a maximum of 90 minutes (jacket spuds). The essential question is the size and type of inverter required and the cable size from the batteries to the inverter. You don’t get something for nothing- 240v & 400w comes out at around 1.8A so my calculation is that at 12v to feed in enough power for 400w i would need around 35A draw from the batteries. All the inverters I have looked at appear to have much smaller cable than 35A so where am I going wrong in my calculations? Any advice/experience would be greatly appreciate.
regards, Chris.

 

[Jimbohorlicks]

90 mins is a long long time, a 700 watt microwave takes 5 mins a spud, but I wouldn't keep mine on that long, ie 10 miins for 2 spuds, 3x 115ah batteries, 200 Watts solar and 1500watt inverter.

 

[Nostrovia]

I'm no expert, so if this doesn't help - sorry.

This is a link to a Victron 500w inverter instructions (the 12v 500w model), which states a 6-10mm cable (depending on cable length).

At the bottom of this page, is a calculator for cable size requirements. 1.8amps fits in with a 6mm cable.

So, I think you've overestimated draw and cable size requirement. Maybe someone else will correct me here, or add a bit more detail.

However, I think that 400 w for 90 mins through an inverter supported by your batteries is maybe asking too much.

 

[jongood]

We ve tried to so exactly this, but aborted it when the fan on the inverter was running virtually non-stop, Sterling 1000w inverter ( quasi sine wave)

 

[DBK]

12 volt cables rated at 35 amps will be pretty thin.

But you will be hammering your batteries and will probably struggle to recharge them.

Go low carb and forget the spuds. Or buy a van with an oven.

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[Nostrovia]

4.5mm cable is rated at 35 amps, so again - 6mm cable specified by Victron is correct.

 

[pappajohn]

For 90 minutes use you will draw a fraction under 50amps plus losses, call it 50 amps. (33 amps per hour)
But if memory serves the Ramoska is thermostatic so it isn't drawing current all the time.

 

[Minxy]

Jacket spuds are the one thing that we don't bother with in the camper/MH, they just take too long to cook, even in a double skillet pan they take about 45 mins. 90 mins IMV is way too long to be using any electrical appliance with such a high draw (even though by comparison to some stuff it is small).

 

[autorouter]

Maybe you are confusing the two ways to size a cable. It is usually described by Cross Sectional Area (CSA), for example 6 millimetres squared, abbreviated to 6mm2.

The diameter of 6mm2 wire is 2.8mm. That's the copper core - the insulation will be on top of that.

Unfortunately some people abbreviate too much, calling it 6mm cable, which can be confusing.

 

[nomade690]

You can buy ready-cooked frozen jacket potatoes and they take only 20 min in the Remoska or 5 min in a microwave.

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[pappajohn]

You can buy ready-cooked frozen jacket potatoes and they take only 20 min in the Remoska or 5 min in a microwave.

And resemble soggy sand wrapped in newspaper..... I've tried one.

 

[jongood]

And resemble soggy sand wrapped in newspaper..... I've tried one.

Oh well , nice idea while it lasted.

You can wrap JP's in foil and do them in BBQ coals if you really want one.

 

[pappajohn]

Now that's the proper way to bake them.
A bonfires as good but they're harder to find in the Ash and embers.

 

[Wh05apk]

You can buy ready-cooked frozen jacket potatoes and they take only 20 min in the Remoska or 5 min in a microwave.

Work well with crispy skin in a gas oven though.

 

[Just smiffy]

Now that's the proper way to bake them.
A bonfires as good but they're harder to find in the Ash and embers.

and that’s exactly Where they’ll cook if your wires are too thin...?

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[Ridgeway]

Double skillet on a gas hob ?

 

[Don Quixote]

The simple answer is NO it won't work. I'm not going to go into quility of wiring from batteries to inverter or how hot things are going to get.......
Firstly you will need a very large bank of batteries then there is the charging of batteries after you have taken out around 50/70/80 amps continuously Then there is the other items drawing power for the remainder of that day/night from your "two new 120AH batteries" Taking out 50+ amps is nearly discharging your batteries to near critical point and if off grid will distroy them as solar will not recharge them, which they will need if you don't want to replace them.

 

[autorouter]

The simple answer is NO it won't work. I'm not going to go into quility of wiring from batteries to inverter or how hot things are going to get.......
Firstly you will need a very large bank of batteries then there is the charging of batteries after you have taken out around 50/70/80 amps continuously Then there is the other items drawing power for the remainder of that day/night from your "two new 120AH batteries" Taking out 50+ amps is nearly discharging your batteries to near critical point and if off grid will distroy them as solar will not recharge them, which they will need if you don't want to replace them.

I don't think it's really as bad as that. 400 watts uses about 35 amps, so for 90 minutes (1.5 hours) it will use 35 x 1.5 = 53 amp-hours, which is about what pappajohn said.

Your two 120 amp-hour batteries will provide 120 amp-hours while discharging from full to 50%. So 53Ah is a sizeable chunk of the 120Ah of available energy, but not enough to be a big problem.

You then have to think of refilling the batteries. A single 100 watt solar panel on a long sunny summer day will struggle to give you 50 amp-hours. But with 200 or even 300 watts, you would probably do it on an average summer day.

Is it worth it, just for a baked potato? Only you can be the judge of that.

 

[Cheshirecat57]

Have you thought if a “portable” camping gas oven?

 

[Don Quixote]

I don't think it's really as bad as that. 400 watts uses about 35 amps, so for 90 minutes (1.5 hours) it will use 35 x 1.5 = 53 amp-hours, which is about what pappajohn said.

Your two 120 amp-hour batteries will provide 120 amp-hours while discharging from full to 50%. So 53Ah is a sizeable chunk of the 120Ah of available energy, but not enough to be a big problem.

You then have to think of refilling the batteries. A single 100 watt solar panel on a long sunny summer day will struggle to give you 50 amp-hours. But with 200 or even 300 watts, you would probably do it on an average summer day.

Is it worth it, just for a baked potato? Only you can be the judge of that.

It is as bad as that..........

Even a 300watt solar panel WILL NOT charge the batteries back to fully charged in 1 UK sunny day. There is no way a 100watt panel will give you more that 8amps with the sun directly over the panel (never happens in the UK) so at best 8amps for 1 hour then downwards from there or 300watts of solar 20+ for 1 hour then at best 6amps perhaps. Thats providing there is not a cloud in the sky................... Then there is the fact that the batteries are still supplying power to whatever is being used in the MH.......

The problem is 90% of MH owners fail to understand how the solar system works.

If you have nothing at all taking power ie: TV, Sat system, Computer, Chanrging phones, Shower, running water, fans, heating system etc etc etc etc then yes a 100watt or 300watt panel will do the job, but who these days has none of the above drawing the power out of the batteries..........

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[Richard n Ann]

Boil the potato in a saucepan for 10 minutes then bake in the gas oven ??
Times vary depending on size of course but boiling them first speeds up cooking a lot.

Absolutely no need to be faffing about with electric at all ?

 

[autorouter]

There is no way a 100watt panel will give you more that 8amps with the sun directly over the panel (never happens in the UK) so at best 8amps for 1 hour then downwards from there

On a long summer day, the sun will shine for maybe 15 hours. From a 100 watt panel, that's 6A for 3 hr, 5A for 2 hr, 4A for 2 hr, 3A for 2 hr, 2A for 2 hr, 1A for 2 hr, and we'll neglect the other 2 hours of sunshine.

That's 18Ah + 8Ah + 6Ah + 4 Ah + 2Ah = 38Ah

These figures are a bit pessimistic, but realistically they are quite possible. That's the reason I said 200 watts or 300 watts would be better if you wanted to replace 53Ah of energy.

 

[Don Quixote]

On a long summer day, the sun will shine for maybe 15 hours. From a 100 watt panel, that's 6A for 3 hr, 5A for 2 hr, 4A for 2 hr, 3A for 2 hr, 2A for 2 hr, 1A for 2 hr, and we'll neglect the other 2 hours of sunshine.

That's 18Ah + 8Ah + 6Ah + 4 Ah + 2Ah = 38Ah

These figures are a bit pessimistic, but realistically they are quite possible. That's the reason I said 200 watts or 300 watts would be better if you wanted to replace 53Ah of energy.

Again not realistically possable with a solar panel locked down flat on a MH roof in the UK. Perhaps in Spain were cloud cover is very rare and the sun is higher (over head, not at an angle to panel) in the sky over the FLAT panel.
I'm tired of explaining this over the years and as so many MH owners replace they batteries regularly clearly shows they don't know how to look after their batteries thinking that solar panels will FULLY recharge their batteries whilst off EHU or running engine charging system for 4 yours or more NOT 1hr run out to next stop over.............................

 

[iandsm]

Help, I have purchased a 400W Remoska for use in our PVC and would like to be able to use it “off grid” using an inverter. The van has two new 120AH batteries which I think will give me enough power, the Remoska only being used for a maximum of 90 minutes (jacket spuds). The essential question is the size and type of inverter required and the cable size from the batteries to the inverter. You don’t get something for nothing- 240v & 400w comes out at around 1.8A so my calculation is that at 12v to feed in enough power for 400w i would need around 35A draw from the batteries. All the inverters I have looked at appear to have much smaller cable than 35A so where am I going wrong in my calculations? Any advice/experience would be greatly appreciate.
regards, Chris.

From experience I wouldn't bother unless you have an oven or even better a barbecue with a lid like a Webber go anywhere or a Cobb, they are the best jackets for me.

 

[Shrimp]

I don’t think the Remoska has a thermostat. It has an on/off switch & that’s it!
You could run the Remoska whilst travelling, would have to be well wedged this, the lid gets very, very hot enough to burn thru it’s cable.

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[pappajohn]

I don’t think the Remoska has a thermostat

I wasn't referring to a user adjustable thermostat in my post but a fixed temperature stat.
Apologies if I'm wrong, but the interior would get extremely hot if the element was constant.

 

[iandsm]

I wasn't referring to a user adjustable thermostat in my post but a fixed temperature stat.
Apologies if I'm wrong, but the interior would get extremely hot if the element was constant.

I dont think your wrong, if there was no internal fixed thermostat it would simply keep heating until the element melted and failed.

 

[jongood]

So is anyone managing to run a remoska on an inverter for long enough to cook something?

 

[Just smiffy]

So is anyone managing to run a remoska on an inverter for long enough to cook something?

we do, what we cook is normally done in half hour max...