# Oh no, another inverter question....



## daveandcarol (May 21, 2005)

Hi all!

We've ordered our new Burstner and I've been considering the various options for the electrical system.

The van is fitted with 2x 110ah batteries as standard, I was thinking of fitting a 1000w inverter to power things like laptop, video camera charger and the dreaded wifes hair dryer (240v 800w).

I'm looking to buy a 2kw generator to power the roof top air con (we're hoping to spend some time wild camping) and keep the batteries topped up.

Does this sound reasonable?

Is 800w too much to pull from the two batteries and if that's the case is there any point in buying a large inverter?

I may want to run a microwave, but I suspect I would have to run the generator for that?

I read somewhere that we should only draw about about 22 amps from the batteries, 22a x 12v = 264w does this mean that there's no point in buying an inverter any bigger than 300w ???

Regards, Dave and Carol.

P.S. Please don't post loads of replies complaining about noisey generators, we only intend using it when we're wild camping away from other people!


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## 88724 (May 9, 2005)

Hi

The hairdryer pulls around 73 Amps through an invertor, so will use up around 12 Amp hours for every 10 Mins of use.

A Microwave uses just under 7.5 Amp Hours for a 5 Minute warm. An 800w Microwave needs about 1200w of input power so a larger Invertor would be in order to runthe Microwave

Here is a brief run down on using gennies 
Web Page on 12v vs 2490 microwaves

On the question of drain per battery, its true that 10% of ah rating is the best for batteries long term health, but if you use a proper charger as opposed to the normal onboard one then that will more than make up for the higher drain for short periods.

Do beware of Invertor ratings Sterling Invertors are rated truthfully in that if you buy a 800w sterling invertor it will supply 800w 24/7 even up to 40 Degrees ambient as far as I am aware all other manufacturers "massage" the figures

Some 800w invertors are for only short periods and at lower temeratures,all of these things effect the invertors ability to perform, so do pop a name up here before buying and someone will give you the TRUE accurate rating.

Are the burstner batteries standard lead acid? beware if they are gel total waste of space (IMHO, backed by facts)


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## daveandcarol (May 21, 2005)

*Thanks George!*

Thanks George

Very interesting reading.

Maybe we'll ditch the microwave idea, we'll be full timing so why the rush!

Must try and convince the wife to cut her hair short, not looking forward to firing up the generator every time she wants to dry her hair! :roll:

I believe the Burstner batteries are standard lead acid and Varta too. I take it that gel batteries are not recommended??

Regards, dave and Carol.


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## Road_Runner_644 (May 9, 2005)

Hi Dave & Carol 

the dreaded hairdryer was the reason for our first invertor, and the microwave was the reason for our second. 

The first invertor was 1000w and ran the 850w hairdryer no prob, but the microwave was 850w, but pulled something like 1200w, which the invertor just about managed, but it was it was screaming for its life. 

So if we were down on power, i had to run the 1k genny, to charge the batteries, to stop the invertor screaming. 

So - next van round - 2 x 110ah batteries, 2k invertor. No probs from hairdryer, or microwave, except when you get lazy and plug the electric kettle in at the same time. 

The point is - I would go for a 2k invertor - it covers more possibilities, for not too much more money. 

You don't want to be running out setting up the genny just to run the microwave. 

Like when the gas bottle runs out, and it's raining, and you want a cuppa. 

Just be lazy, turn on the invertor, plug the kettle in, and get a sausage roll in the microwave. 

Invertors usually stop working long before the batteries are critical, so maybe one night you lose your wild camping mains, but the lights and tv still work, the water system still works, and you can get the charge back into the batteries when you run up the vehicle next day. 


Dave


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## BERTHA (May 21, 2005)

Dave and Carol

Looking at your photo you are buying a 747 we have just received ours and found that all the 12volt fuses installed are wrong compared to book and what is on front panel.
Thankfully, the fuses installed are lower than the written limit. So, where there should have been 8 x 25amp fuses installed we 10amp.

I have just insalled a 110amp Battery which runs a 500 watt Invertor. I run a 2nd Invertor which is plugged in to the van 180watt ciger type socket in the front dash this then runs the 80watt Air Cooler we purchased from B&Q because we can't use the mains roof Air Con. But we also run the charger for the 110amp battery so this receives a charge while travelling.
While on site we plug the charger in to the mains socket.

The Invertor from the new 110amp battery runs the addtional TV and DVD in the rear bedroom and also a normal domestic fridge purchased from Comet in the rear garage

This does not then over tax the orginally installed van batteries and charger which is running the lights, pump etc.

I have housed my installation in the side locker behind the drivers door

Let me know how you get on with your new van

Best of luck

B


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## 88726 (May 9, 2005)

hi bertha

just got to say , fridge in the garage ? :lol: :lol: :lol: :lol: 

a proper home from home ! :lol:


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## daveandcarol (May 21, 2005)

Dave, are you sayng that you'll run a 2000w inverter from 2x 110ah batteries? A bit much isn't it? 8O 

Can anyone recommend the largest inverter that is reasonable to use with 2x 110ah batteries?

Thanks, Dave and Carol.


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## 88724 (May 9, 2005)

Hi Dave

Its do-able with two good batteries a good charger and used for very short periods (at full tilt) I would definately want more batteries though.


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## johnsandywhite (May 9, 2005)

8O It's not the size of the invertor that is the drain on the battery. It is the actual load applied to the invertor. It will certainly run a 2000 or 5000 for that matter. But you would not be able to pull 5000W from it for very long with only the 2 x 110ah batteries.


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## daveandcarol (May 21, 2005)

*Fridge in garage...*

Hi B!

We have just ordered a 748 (basically same as 747) but it won't be delivered until March 2006! Then we'll be going full timing around Europe.

Just out of curiosity, what make/model of fridge are you using, what is the power consumption?

Regards, Dave and Carol.


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## 88724 (May 9, 2005)

Hi Dave 

I run a mains fridge, it averages around 3 Amps an hour, 72 Amps a day, which because I like wild camping I have 10 X 110 AH batteries. This will run the fridge for 8 days without reaching half drain on the battery bank


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## johnsandywhite (May 9, 2005)

So *George* what is your opinion of 6V Golf Cart batteries as opposed to 12V Leisure?


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## daveandcarol (May 21, 2005)

Hi George, wow 10 batteries that's some weight and space taken up. 8O 

I assume you also run a generator from time to time to top them up?

Dave and Carol.


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## 88724 (May 9, 2005)

Hi John

6v Golfs are better than 12v Leisures, best overall are full traction batteries.

Hi Dave

That was the initial Idea, but with a 30A Sterling Charger one day on hook up per week will fully charge. I do have an EV3600 Honda whisper quiet permenant on board genny, dead quiet and remote control, but I am still undecided whethor I will fit it or not. Bigger Charger and small genny would be able to charge them up in sub 12 hours all depends on what you want to spend and timescale you want to charge within. I assumed one day a week on site would be ok.

The battery bank weighs 1/3 of a tonne.


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## Road_Runner_644 (May 9, 2005)

Hi Dave and Carol. 

Quote 
"Dave, are you saying that you'll run a 2000w inverter from 2x 110ah batteries? A bit much isn't it? Shocked 

Can anyone recommend the largest inverter that is reasonable to use with 2x 110ah batteries?" 

I see it more as having the capacity to pull up to 2000w rather than a setup short of batteries. I can run at full tilt for an hour (2000w @ 12.5v) and take 160 amps out, somewhere around this point the invertor cuts out, and whats left in the batteries is only useful for the lights and the TV. 

But, i don't see how i could ever use this amount of power even in a day. The microwave would be used for 15 mins max, the kettle 5 mins per boil, the hairdryer 10 mins. 

I have a "smart" split charge relay from the alternator, that pumps out about 60amps, as soon as the vehicle battery reaches 13.5v, and this has proved to be brilliant in getting the bulk of the charge back in to the batteries as soon as we get going again. 

The test this year was running the setup at Peterborough, where we deliberately used the electric kettle, microwave, hoover and anything else we could think of to see how far the batteries would last under real conditions. 

The result was that we couldn't run the batteries out in 3 days, and the bit of top up from the solar panel helped as the sun was out all day long. 

So, If i could afford the space, and my target of 3 days without running the engine or genny was longer, I'd probably put another 110 in there, but i assure you, you'd be pushed to use the power up, unless you start using a George Formby grill for breakfast dinner and tea. 

The other point to remember is that you usually go into economy mode as soon as the hookup disappears, and use gas for cooking and kettle boiling, turn of anything you don't need and generally watch your power usage. 

But it's brilliant to be able to draw on the thing when you need to, and not have to either start the engine or put the genny on just because you want a couple of kilowatts for 10 mins or so. 

Cheers 

Dave


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## daveandcarol (May 21, 2005)

Hi Dave

Very interesting, thanks for the info and taking the time to reply.

Regards, Dave and Carol.


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## JustRadio (May 21, 2005)

I HAVE NOW POSTED THIS AS A SEPARATE THREAD UNDER THE TITLE, "A fast low voltage charging option?". PLEASE RESPOND THERE - Thanks
John

Would this be useful? It seems to me that 12v charging is much more effective than the low voltage charge available from a standard genny, and probably more effective than the charge from a big mains genny via the on-board charger, (not sure what their output is).

Buying a "Battery Set" used to be commonplace for cruising yachtsmen, little green Stuart Turners for the small boat, Petter single cylinder diesel for the larger, but I thought nothing like it was available on the market. I've been looking for ages.

Now I found this 
http://www.macgen.com/honda/batterycharger.html

Unfortunately it's in Australia, and judging by the alternator it's locally put together, but I have mailed them. Now wouldn't a handy little suitcase generator that kicked out 45 amps solve the occasional mains problem via an invertor, better sustain life away from a mains plug, and be much cheaper than a fixed installation?

I think so and I like to hear all opinions. I'm so keen to know I may make this a separate post!! Converted from Ozzie dollars this one would be £460 there.

Thanks
John


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