# How many Ahs?



## grizzlyj (Oct 14, 2008)

Hi folks

Just to ask this old chestnut from possibly a different point of view (possibly buying new), a few of the new campers we've been looking at seem a little under equipped in the battery department!

So, with

three halogen 10W spots
three fluro tubes (not sure of size, but only compact ones twin tubes)
compressor fridge 1Ah average in use
diesel fired webasto 18 to 42 watts depending on setting, not more than half way though
water pump for sink, no shower
nothing else was used over the weekend we borrowed it.

What size lead acid battery would give a reliable 3 days without hook up and without discharging too far to eat into its lifespan?

One or two 80W solar panels are certainly on the cards, as is a second battery, but the installed one at 135Ah seems insufficient for whats in there now? Maybe with gas heating and fridge, but everything on 12v needs more oomph!?

Our current camper has 255Ah at 24v, and to my knowledge has never been below 80% even with the bigger loads imposed, and at 8 years old work fine. The above set up would seem to suggest big discharges and a short service life, or am I missing something?

Hoping to be corrected!

Cheers

Jason


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## teemyob (Nov 22, 2005)

*Batteries*

Hello,

I am not that certain about your requirements.

But we have 440ah. Lots of Halogens and a lot of new LED's. Fridge on Gas, use of TV's, DVD, water pump, heating water pump and so on.

We could go at least 3 days in winter with 50% of the 440ah

TM


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## rosalan (Aug 24, 2009)

Are you missing the alarm system?
Alan


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## andrewball1000 (Oct 16, 2009)

Hi Jason,

I dont the answer to your question either, but if you increase the solar to 240w you can cut down the battery to say 2x110ah and not worry any more, ever! I would also separate the batteries so you always have a full one.


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## erneboy (Feb 8, 2007)

Surely not worry ever except in Winter Andrew? Alan.


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## andrewball1000 (Oct 16, 2009)

erneboy said:


> Surely not worry ever except in Winter Andrew? Alan.


Alan, mine has gone 2 winters (and summers) without plugging in to EHU. The panels still produce enough to keep the batteries topped up!

I believe that if you are going to do solar, then don't mess about, put up enough. The "fitting" cost is not much more.


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## erneboy (Feb 8, 2007)

We have 405w of solar and it can't cope for more than a few days in winter, low sun and short days Andrew.

All our lighting is led etc., we use around 60/80 ah daily.

Given around 7 to 8 hours of daylight we would need to be seeing close to 10 amps to replace that, it never gets near that figure, Alan.


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## andrewball1000 (Oct 16, 2009)

erneboy said:


> We have 405w of solar and it can't cope for more than a few days in winter, low sun and short days Andrew.
> 
> All our lighting is led etc., we use around 60/80 ah daily.
> 
> Given around 7 to 8 hours of daylight we would need to be seeing close to 10 amps to replace that, it never gets near that figure, Alan.


Fair enough Alan, it therefore does come down to what each individual uses in AHs. Obviously my consumption is a lot less that yours. I have never bothered to work mine out as I have never need to since I installed the solar. The Ops question still stands therefore.


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## grizzlyj (Oct 14, 2008)

Thank you for the replies 

To clarify, the small van my wife and I borrowed was a demonstrator had a 135Ah leisure battery and was equipped as above. We were told that once charged there is enough power to run the heater on low all night, be careful but not silly with the usage, and we would only need hook up every 3 days. No-one specified driving was required in the mean time.


But the fridge as described will use 24Ah, the heater on half heat for about six hours of its output will use 12Ah, and good practice suggests not going below 80% charge. But just those two will get me down to 100Ah from a theoretically full battery at room temperature.

Their monitor says the leisure is in "good" condition down to 11.9 volts, then fair, then poor, so I think I have a more conservative approach than the manufacturers!

Added to that small Camping Gaz bottles are usually fitted. Monday morning was freezing outside, 3 deg inside, and the electric system cut out when the heater was put on at 7am since the battery was too flat, which also created too low a voltage for the fridge which also cut out. A few degrees colder and the butane wouldn't come out of the bottle?!?

Perversely, had we kept the heating on its lowest setting all night rather than off, the batteries would have been warmer and may have been OK all night?

According to the display there is a 0.1 amp drain when the water pump is on standby, isolate that and it says there is no leakage. What the monitor/Sargent box of tricks itself takes though?

Anyhow, saying you don't need hook up is probably true with a decent battery in the summer with a reasonable drive every day, there is too much drain in my opinion for a battery that size to last more than a night otherwise. So two batteries and two maybe three panels seems sensible.

Cheers

Jason


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## erneboy (Feb 8, 2007)

So Jason 36ah plus some lighting, pumps etc. No telly?

You will need a fair bit of solar to give that in winter. I would be lucky to get half that.

There is a solar calculator on here I believe. I will see if I can find it, Alan.

Here it is: http://www.motorhomefacts.com/modules.php?name=SolarCalc


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## erneboy (Feb 8, 2007)

In mid December it gives my max out put as 4.8amps at solar noon and my daily output as 14.2ah.

Nowhere enough for either of us Jason. I t won't do for me even with 400w worth of solar between October and March. The rest of the year it's fine, Alan.


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## Spacerunner (Mar 18, 2006)

I'm out of my depth here, but here goes.

I've actually cut down on my battery bank and replaced 2 x 110 ah with a single Elecsol 125 ah.
I have 140 watts of solar panel, which seems fairly ineffective during a UK winter.

The two 110's never seemed to fully charge even in good conditions in summer. Is it too much capacity for the solar panels?

So with the same solar panels I'm hoping that the Elecsol 125 will fully charge in a shorter time.

I have charged the two 110's off the van and they seem perfectly ok and have held a full charge (12.8 ) for over a month.

Is there a formula of solar size to battery capacity?


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## erneboy (Feb 8, 2007)

Spacerunner, not too much battery capacity for your panel. More likely just not enough charge going in to replace what you have used. Whether you have one or two batteries won't alter that.

There is no formula other than checking that the power you get from your panels is sufficient to recharge your batteries, Alan.


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## grizzlyj (Oct 14, 2008)

Alan that is a smashing little calulator! And no, no telly! We did take a laptop and a few films but it was too cold having turned the heater off early evening. I'm sure the everyday drivability will more than compensate for a soft sided pop that we seem to be heading for! :? 

So today the 220W panels on my current camper produced a theoretical 17.3 amps in total! Gosh.

But in August near St Tropez a few years back they kept the two 255Ah lumps totally full for I think the 5 days we got burned on the beach, no EHU and the compressor fridge working overtime 

Solar panels do seem to boil down to putting as much as you can afford up there, unless you like northern latitudes in winter only!


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## Addie (Aug 5, 2008)

Electric fridge is a terrible idea, 24amps a day!?

Even the smallest van will have room for a small underslung LPG tank somewhere which will consume say half a litre a day. A better option when off-grid, surely?

We have 2x 86AH batteries in our Twin, LED lights throughout. We spent 2 days parked up outside Athens waiting for the storms and strikes to pass running the heating (blown air) and powering our Laptop for 48 hours straight using a 12v charger as we had fast Wifi and was grabbing some telly for later. This was the only time we've ever drained our batteries (control panel cuts power) and I don't think they would have been full when we arrived.

You can squeeze a few amps by going full LED but the fridge seems to be the main culprit and the easiest fix? 

P.S. What van did you borrow?


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## grizzlyj (Oct 14, 2008)

Addie said:


> Electric fridge is a terrible idea, 24amps a day!?
> 
> Even the smallest van will have room for a small underslung LPG tank somewhere which will consume say half a litre a day. A better option when off-grid, surely?
> 
> We have 2x 86AH batteries in our Twin, LED lights throughout. We spent 2 days parked up outside Athens waiting for the storms and strikes to pass running the heating (blown air) and powering our Laptop for 48 hours straight using a 12v charger as we had fast Wifi and was grabbing some telly for later. This was the only time we've ever drained our batteries (control panel cuts power) and I don't think they would have been full when we arrived.


Depends where off grid perhaps? The little camper we hired first from a company in Inverness said they can't get refills for instance.

We had to leave our own UK 13kg Calor propane bottle in Morocco and pay deposit and fill for a new local butane one this year after staying longer than we planned, and thats despite a compressor fridge leaving the hob as the only gas user. Back in the UK I'll have to pay for another Calor bottle and fill all too soon. In the summer there were posts on MHF from a Brit hiring a German van coming on hols from the USA, and he was looking at forking out for a new pair of big bottles in just about every country he wanted to visit to keep him and his family warm.

If you know you will be able to get your bottle type or a fill where you're going then gas everything is fine. But our bottle has lasted up to 6 months. If you don't know that then a bigger Ah capacity is much more flexible if the suns shining or you can plug in! There are plenty of big truck campers being built for world travel with huge electric systems and no gas at all, in some cases due to a perceived safety advantage, and partly because the further you go the bigger an issue gas resupply will become. So possibly a good informed choice, with enough Ah.



Edited to add, while we were visiting Wellhouse leisure they kindly jacked up an i800 to have a look if a gas tank will fit, and no there wasn't room. They can fit gaslow, but then you're stuck needing to fill it and no room to store that bottle if you have to buy another when you can't.


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## andrewball1000 (Oct 16, 2009)

Addie said:


> Electric fridge is a terrible idea, 24amps a day!?....the fridge seems to be the main culprit and the easiest fix?


I agree with Addie on this.

you might also consider separating two batteries with a mechanical (1,2,both & off) switch as 1 battery is quicker to fully charge than two. Also you get a warning when one is flat and can reduce consumption to essentials and switch to the other. I use the solar to charge the one that I am not drawing the supply from. That is my emergency reserve.


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## Addie (Aug 5, 2008)

grizzlyj said:


> Addie said:
> 
> 
> > Electric fridge is a terrible idea, 24amps a day!?
> ...


Where will you be going in this new van, anywhere in Europe LPG is obtainable except for Finland and I can't see an i800 doing a full overland back to Asia and the roof isn't big enough for much solar to support your fridges amp addiction 

The third party stories you quote sound a bit dramatic to me and hinge on poor preparation on their part rather than a reason to avoid gas, you can 'feed in' using any bottle / reg combo with the right setup. What size is the bottle locker - 6kg?

Appreciate in overland vehicles and benefits of nil gas but an i800 already has gas requirement for hob/grill - this is a shopping trolley with a mattress in comparison to those trucks! 

Some of the Roy Wood Transit range is worth a look at 5.2m but not low-line and I suspect you'd have to order new to get an Auto box.


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## grizzlyj (Oct 14, 2008)

Addie

I want to downsize from our current 12 ton gross wee beasty to something my wife can commute in, 2m tall.

We've been to see I think 8 different versions of different campers of about the i800s size.

The i800 for instance can hold either one 7kg butane, one 6kg Calor bottle or one 6kg gaslow, no room to undersling. 

Danbury for instance can/will only fit Camping Gaz for some reason, which as far as I'm aware is butane only. 

Another can take 2 Camping Gaz 907s, or one Calor 4.5kg butane, or one 3.9kg Calor if I want propane. 

So if I head off to Europe in the next month or so as I'm hoping to it will be cold, we will aim to camp at the top of things so butane only is probably silly. I don't see any point in having Gaslow only as that becomes too restricting and won't fit on most anyway. 

If I had a 6kg or bigger Gaslow bottle and a similarly sized space for another locally sourced bottle then maybe, but I won't. 3.9kg of propane won't last long if its running the fridge too, and where do I find one of those easily outside the UK?

I can fit a second battery though, and 240W of solar at least.


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## Addie (Aug 5, 2008)

I wouldn't say refillable is 'restrictive' - certainly not in comparison to calor bottles but I guess fairly pointless for just grill / hob.

We used to have a 6kg Gaslow in our Compass Suntor and could last about 10-14 day as that fridge was pretty economical, given we needed diesel at least once in that period it was no hardship to squeeze in LPG at the same time.

It sounds like you only 'need' solar for the fridge and in my mind could ruin what would be quite a nice looking lowline pop-top van with a massive solar array on the top.

Can you re-locate the spare and go for a doughnut lpg tank if they do such a thing for domestic usage? Locate a small underslung style tank inside somewhere and reclaim the gas 'locker' for other uses?

Just trying to provide an alternate viewpoint - 25amps a day is a fair old whack to compensate for in a small van.


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## grizzlyj (Oct 14, 2008)

Hi Addie

A refillable tank would be restrictive if it took up all of the only gas bottle storage space as on the i800, and we then went somewhere like Morocco where perhaps you can't refill. No space in such a small camper to cart round a redundant gaslow bottle having then had to buy a local bottle.

There is nothing massive about low line flexy panels that Wellhouse leisure and other sub 2m tall converters offer other than the cost. On a Bilbos roof they are still lower than the poptops stiffenings ribs from what I saw. The one drawback is of course their comparitive inefficiency, but the only actual figures I've seen suggest 10% less in ideal conditions. Not enough to get excited over if that the difference between a van that does what we want or not.

This would also most likely be on a new van. Any converter will not likely want to chop up his gas bottle cupboard to provide more room, and then find a suitable gas fridge to easily fit in the compressor fridges current home. If I did it then their warranty for the bits I'd changed would be void. Fitting a gas fridge requires ventilation, cutting holes in the side of a shiny new van will probably void the manufacturers corrosion warranty at least in that area. I may be wrong but doesn't a gas fridge need to be fairly flat to work too? I've never had one so don't know. So I also then need levelling blocks which I've not bothered with for the last 3 years? 

I will have to cut down on the number of spare socks I take if we bought a van of this size, so I doubt I'll find an alternative hole for a spare tyre! In the nice big gas fridge perhaps?! 

Jason


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## peejay (May 10, 2005)

Hi Jason;

Just wondering about the efficiency of solars on a pop top roof when its raised, generally how much of a power loss is there when its facing away from the sun?

Have you had a look at a Bilbos yet? If so i'd be interested in your opinion of them?

Pete


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## grizzlyj (Oct 14, 2008)

Hiya

You would lose some with the panels facing away from the sun, but it would be an ideal scenario to have the pop up and it facing south while camped 

Bilbos were helpful. Some of the older ones for sale had better condition furniture than the original VW stuff in the cab. They all seem a simpler or more basic layout than the Autosleeper T5s also for sale 2nd hand. Less fussy plastic bits anyhow. Not cheap though!


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## grizzlyj (Oct 14, 2008)

Addie said:


> Can you re-locate the spare and go for a doughnut lpg tank if they do such a thing for domestic usage? Locate a small underslung style tank inside somewhere and reclaim the gas 'locker' for other uses?


I remembered last night that I did see a Transporter a few months ago with a rear swing-away type spare wheel carrier mounted upright on the rear pillar. That would get in the way of both opening the tailgate (which you need to do to turn the gas on normally), as well as most likely clashing with any bike rack, but still a possibility.

I could then just use a mounted lpg tank as you suggest, leaving an empty gas locker (apart from spare socks) for a local bottle if ever needed for another Moroccan trip.

8)


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## andrewball1000 (Oct 16, 2009)

grizzlyj said:


> Fitting a gas fridge requires ventilation, cutting holes in the side of a shiny new van will probably void the manufacturers corrosion warranty at least in that area.


Hi Jason, could you fit something more portable like this. http://www.mobilegas.co.uk/mobilecoolbox/gasfridgefreezerunit/combicool.htm.

Then at night in winter when there is insufficient solar you can just switch it off and move it outside into the cold. The top entry design may be more efficient than a front entry one which spills all the cold every time you open the door. Not sure what ventilation it needs. Just a thought.


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