Using 400W Remoska on 1500 W Inverter

[PJGWiltshire]

Going through some electrical changes on the van. Installing a 240W Solar Panel panel and thinking about adding an a 1500w Pure Sin inverter for the odd occasion when need 240v supply. One item we are thinking of buying to use on the inverter is the Remoska oven,this is a 400w unit. By chance is there anybody out there who have used this item on an inverter system and if so how much battery drain do you experience. Keeping in mind that hopefully the panels will be charging the batteries I hope that say a two hour use of the Remoska will not heavenly drain the batteries. Your input would be greatly appreciated

 

[Chockswahay]

I don't have a Remoska but for each 60 minutes of constant use it will be 33 amps

I'm thinking..... flat battery in 2 hours??

(just saw Scotjimlands post after the above edit )

 

[scotjimland]

400 watt on 12vdc will use 33 amps.. ie 33 ah

that would effectively flatten an 85ah battery in just over 30 mins

two hours will use 66ah

this is not allowing for the Remoska cutting in and out on the thermostat .. so it will be a little less.. but still a big load..

 

[PJGWiltshire]

I have two 100ah batteries, so is it the case that 2 hours will take out 66 ah leaving me ample to use other items and be recharged by the panels.

 

[maz]

The Remoska doesn't have a thermostat so it's a continuous load.

Great bit of kit but I only use mine on hook-up.

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[scotjimland]

The Remoska doesn't have a thermostat so it's a continuous load.

thanks Maz.. wasn't sure , don't have one

 

[makems]

We have a 1200W inverter and use the Remoska occasionally.
We have 2 x 100AH batteries and 400w of solar panels.
We only use it with the inverter for cooking lunch if the sun is shining strongly so the panels have a chance to recharge the batteries before nightfall. I wouldn't use it for cooking an evening meal because as said above you would risk flattening the batteries.
And we only use it for recipes that require 45 minutes max cooking time.
We have only used the Remoska off the inverter I. Sunnier climes ie Spain, Portugal, Morocco. Never tried it in the UK as the sun isn't usually reliable enough.
Some years ago We did once use the Remoska on the inverter while travelling to do some jacket potatoes thinking the alternator would keep up with charging the leisure batteries for a couple of hours while driving. WRONG!
I didn't realise that without an B2B device the alternator only gives out a trickle charge.
Result? 2 flat batteries on arrival that had to be replaced! Lesson learned.

 

[hilldweller]

I have two 100ah batteries, so is it the case that 2 hours will take out 66 ah leaving me ample to use other items and be recharged by the panels.

Unfortunately the rule is to use only 50% of the capacity. So your batteries are fully discharged and a 240W panel will very very rarely give 240W. Basically it is A_Bad_Plan.

Gas if best for off hookup heating.

 

[scotjimland]

I have two 100ah batteries, so is it the case that 2 hours will take out 66 ah leaving me ample to use other items and be recharged by the panels.

in theory.. yes.. you have 200ah.. so that is a useful 100ah.. so that would leave about 34ah

the other thing to consider is the type of battery.. leisure batteries are not designed for high currents for long periods.. using like that will shorten their life.
if you do go ahead I suggest you invest in traction batteries..

 

[maz]

I've got one of the older ones (slightly higher wattage) and it's a godsend on hook-up as I use it instead of the gas oven. I have an inverter that could power it off hook-up but that's when I'd rather use the gas.

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[PJGWiltshire]

in theory.. yes.. you have 200ah.. so that is a useful 100ah.. so that would leave about 34ah

the other thing to consider is the type of battery.. most leisure batteries are not designed for high currents for long periods.. using like that will shorten their life.
if you do go ahead I suggest you invest in traction batteries..

Thanks for this useful info, Now I can tell the good lady that she will have to carry on using the oven. Saves having another infrequently used piece of kitchen equipment taking up space. More room for my toys.

 

[SomeoneElse]

High power inverter are best for short term loads, like hair dryers, kettles, toasters and microwaves.
Inverters are at best 90% efficient, therefore a good rule of thumb is to divide the wattage at 230v by 10 to give the current from the battery.
Your 400W Remoska will take 40Amps out of your battery, therefore one hours use will use the all the recommended capacity of a leisure battery.
Two batteries will give you two hours use, but the proposed solar panel is likely to take most of a reasonable summer's day to replenish.
Tip do your cooking in the morning as the solar panel ain't much good at charging your batteries at night.

 

[Eamless]

We have a 400w remoska, 2x100 AGM batteries, 280w solar power, a 30amp Morningstar PMW controller and a waeco 1kw pure sine inverter. We have used our remoska continually off grid over the winter in Portugal Spain and Morocco. In Portugal it hardly stopped raining for a month. We used the remoska for about an hour to 90 mins in the evening , after sunset, with no problems. We still had enough juice in the batteries to watch tv or power the tech for the rest of the evening. Our batteries supply load is cut off before damage is caused. By the next evening we are generally fully powered up again. We have never used daily but we have used it on alternate days a lot. No issues.

 

[Dogsense]

May I jump in with diffrent item to use inverter for. What size inverter I should need to charge two 400wh electric bikes batteries, and how is the calculation for it?

Thanks to all clever funsteres.

 

[Old Soldier]

Some good tips. I tried the 400w remoska on my 400w inverter and wondered why it didn't work.....derrrr! And me being an ex army electrician too!!

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[scotjimland]

May I jump in with diffrent item to use inverter for. What size inverter I should need to charge two 400wh electric bikes batteries, and how is the calculation for it?

Thanks to all clever funsteres.

look on the charger data label for amps or watts

then get back to us..

inverters are rated in watts.. allow 20% on top of what the bike charger is rated at.. x 2 if you are going to charge both together..

but be aware, charging bike batteries will soon deplete a leisure battery if you don't have solar to charge..

that is the next calculation.. what size battery do you have.. and do you have solar ?

 

[Dogsense]

Thanks ScotJimland.
I will get the information and will come back to you.

 

[jonandshell]

It's not as simple as that!

Most leisure batteries are rated on a C20 or 20 hour discharge rating.
A 100Ah battery will only supply 5 amps for a 20 hr period to achieve that rating, at a 100% discharge.
Now, if you discharge it at 33 amps, the capacity of that same battery is much reduced.
Assuming a 50% depth of discharge and 33 amps drawn, you would possibly only get 40 minutes from it, or 22Ah from your 100 Ah battery!

 

[Dogsense]

Here is the information about the batteries and the charges for the Ebikes, what size inverter we will need to charge two batteries at the same time. We have (I think) two 100Ah and 80w solar panel.
Thanks for the use of your brain cells cleaver people.

 

[scotjimland]

The charger wattage is 230v x 1.5A = 345 watts

times two = 690 watt

allow 20% extra and the Inverter required = 828watt .. nearest size to that is probably 1,000 watt or 1kw

when charging starts the current drawn from your battery will be 690 watt / 12 = 58amps or 58amps per hour (ah)

you have 2 x100 ah batteries which gives you a useful capacity of 100ah .. so in less than 2 hours you have two flat batteries..

IF the sun is shining your 80 watt panel will only be putting back at best about 6A


This is all theory.. and the charger current will drop off during charging.. the best way to calculated is to actually measure the current drawn while on charge..

IMO .. This is not a viable proposition ..

a second opinion would be welcome from someone who actually uses an inverter to charge ebike batteries..


anyone ?

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[peterc10]

Jim, I think the better measure may be the output, i.e. 4A @ 36v = 144W, which is going to be the maximum I guess.

We have bikes from AS bikes which have 36V batteries and I spoke to the boss, Peter, about how to charge them without mains. He recommended quite a small inverter (think it was about 200W), and said it did not need to be pure sine wave. That was of course for only one bike. But we haven't yet tried to re-charge them using the inverter so can't be sure until we do.

Given the size and weight of the batteries on an electric bike I don't see them needing as much power as a 100Ah lead acid battery to charge them. If they did that would suggest we should all be using loots of those rather than lead acid batteries in the motorhome. But again that may just be a false impression.

 

[scotjimland]

Jim, I think the better measure may be the output, i.e. 4A @ 36v = 144W, which is going to be the maximum I guess.

quite possibly.. like I said.. no experience of them.. and an once of practical is worth a ton of theory.. the two bike chargers would need a minimum of a 300 watt inverter..

using that figure the current drain on the leisure battery would be 288watts / 12v = 24A .. so that would flatten a 200ah bank in ~ 4 hours ?

 

[scotjimland]

more pondering.. forget the amps , watts etc.. head is hurting

each bike battery holds 8.2 ah
the leisure battery total is 100ah

two bike batteries hold 16.4 ah ..

so in theory you could get about 6 charges from the leisure batteries before they were effectively flat..

is that correct ?

 

[Dogsense]

Thanks ScotJimland. A bit confused,
If we have 2x100ah batteries, why only useful capacity of 100ah?

Other opinions?

 

[scotjimland]

Thanks ScotJimland. A bit confused,
If we have 2x100ah batteries, why only useful capacity of 100ah?

Other opinions?

because you should only discharge to 50% capacity ..
going lower regularly will reduce the battery life considerably... this chart shows

Broken Link Removed

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[peterc10]

Like Jim says, keep it above 50%.

 

[peterc10]

more pondering.. forget the amps , watts etc.. head is hurting

each bike battery holds 8.2 ah
the leisure battery total is 100ah

two bike batteries hold 16.4 ah ..

so in theory you could get about 6 charges from the leisure batteries before they were effectively flat..

is that correct ?

Sounds good logic to me. But will need to allow for conversion losses in both inverter (to take it up to 230V AC) and the converter (to take it down again to 36V DC). I did ask AS bike if they had a charger for 12V socket and he said they didn't. But other bike manufacturers may well do.

 

[Wildman]

I have two 100ah batteries, so is it the case that 2 hours will take out 66 ah leaving me ample to use other items and be recharged by the panels.

as batteries should not be used below 50% capacity you effectively have one battery so work it out from there. 230W solar will take a while to replace 33amps even in full sunshine at midday. Probably at least 10 hours in midsummer

 

[PJGWiltshire]

Heading to Norway for the past part of the trip, looking to be in Artic circle from June through to July. Can look on the posative in the land of the midnight sun in June so hopefully should get a bit more charge in through panels. We decide to buy the Romoska having looked up the cooking times of various things using it. It appears that on average the use will be within the 30 min to 45min time. So should be Ok, just changing the two batteries to 2x 125 AH

 

[BONZO]

Why not treat you self to a Jenny run for 1hr you should have charge bikes. Or
Pay for EHU now and then.

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