Ideal electrical set up???

[v-lux]

Additionally, I have just noticed that the figures quoted for the 550ah set up are incorrect.
When two batteries are linked in series this does not affect the capacity, so 2x 6V 240ah batteries linked in series = 12V at 240ah.

Capacity is only increased when cells are linked in parallel.

As much as I agree that traction batteries from whatever manufacturer are very good for their intended application, they are only as good as the charging system that is maintaining them.

Without 'proper' charging any battery no matter how expensive will fail prematurely. So statements such as 'months without charging' will become an expensive approach.

It's also worth considering with any set up in a van what your goals are. Mine were to run everything I possibly can from 12v. I didnt want anything but cooking running from gas to cut down on condensation and lessen the chances of the fridge ever not running if the gas runs out. Your engine will always make more power for you, but gas isn't always easy to find.
This is why I have invested my money in the charging set up and consumers. It's worth noting that I run my fridge almost non stop these days so have an almost permanent drain on my 300ah's which I have never seen drop lower than 12.3v (this is whilst using lighting, eberspacher, laptop, phones, etc....

[ghost123uk]

The batteries i can get are used, ie second hand.... however...

They have spent their life to date sat in a cabinet on constant charge and have almost never been discharged. They are used for mission critical back up systems for telecommunication set ups.
Basically meaning they are only there for if there's a power failure, which there very rarely is.

Periodically these batteries are replaced as part of a maintenance schedule, there's absolutely nothing wrong with them but they have to be replaced due to legislation.

So this is why the batteries are available at this price, which is a MASSIVE saving over what they would cost if you were to try and buy them brand new. (they're not all that far off the price of the trojans at retail)

In case you're wondering, the reason i can get these is because it's the job i do. I work with battery testing, maintenance and install for utility companies.

I use these too, pulled from large commercial UPS's (Uninteruptable Power Supplies) as used in computer systems in banks, supermarkets, hospitals etc. Because of the requirement to swap them out every 2 years regardless of whether they need it or not, the market is flooded with them.

They come in a variety of sizes, many around the size of a motorbike battery and they CAN be wired in parallel, as many as you wish (some big UPS's have 48 or so of them !!) to get the required amp rating. They charge up fine off the ~14Volts from the vans split charger.

Companies have to PAY to have them re-cycled and so if you offer to "take them off their hands" they are usually only to happy to see the back of them. I get them so cheap, or free, that I can swap out any that show signs of not being in good enough condition. They don't appear on Ebay very often because of the cost of shipping such heavy items. Many computer re-cycle centres have them, just a case of finding the location and visiting with some beer money !

No where near as good as a good quality traction battery though, (Trojan or otherwise) but suits me, esp at the price

[trentjim]

If anyone is interested I can get hold of the 100ah telecommunications batteries for £50 each....

the market is flooded with them... just a case of finding the location and visiting with some beer money !

cheers guys - good useful info for me

I'm planning on incorporating 100w of solar into my system - CTEC D250S has (I think)the sort of functionality I'm after but its only 20A

To what extent is the Stirlings regulation of the input voltage (from the alternator)important? would it throw a wobbly if fed with a regulated 15v from solar that it couldn't change? - if not then a switching circuit to feed either alternator or solar juice as appropriate (which is what the CTEC does) would be relatively simple to rig up, be better than the CTEC and at lower cost

[ghost123uk]

If anyone is interested I can get hold of the 100ah telecommunications batteries for £50 each....

the market is flooded with them... just a case of finding the location and visiting with some beer money !

I should point out that the batteries I get for peanuts are not as big as v-lux's 100ah ones, more like 20Ah, I wire them in parallel as required.

Re the Sterling, I am pretty sure it would be fine with 15 volts as some alternators chuck out a tad over 14 volts and so there will be a safe headroom built in (source = 40 years of experience with electronics)

[v-lux]

Something worth noting here whilst the subject of solar has come up is what sort of charge rate you will gain bs the cost of the system.

Solar is a lovely thing and provides some power whilst the van is parked up, however the cost of installing a solar set up doesn't necessarily give you the best £/amperage charging.
Don't get me wrong, I'd really like a solar set up, but I opted to spend the money on sterling a-b charger due to the far higher amperage charge rate for the money spent.

My set up will push in anything up to approx 80A (peak) whilst the engine is running and is capable up to 160A if I get a different alternator. For the £130 it cost me, this is very good amperage per £.
With a solar set up, the best approximate amperage you'll get out of a solar setup will be around 6-7A, it's fairly obvious which of these setups will charge a battery faster.

My ideal would be the system I have with a solar panel also, but I decided to go for the better charging option to begin with.

[dash]

What's the merits of going for an alternator-battery sterling rather than a battery-battery?

As far as I can tell, you seem to get a higher current rating with the a-b units, and pay slightly less for the unit itself, but the wiring looks like more hassle/expense.

Is there any more to it than that?

[v-lux]

Not an awful lot of difference really, the cabling is slightly easier with the b-b version, but it's still very simple with the a-b to be honest.

The a-b version handles higher current as you say.

The a-b version tend to come up for sale second hand more often as I think they are generally more popular.

[dash]

Cheers for that.

One of these days I'll manage to stop spending money on the running gear of the Doka (gearbox done, a bit of faffing with the cooling system hopefully sorted, exhaust still needs replacing) and be able to get stuck into doing the cab setup. Planning on going down the sterling charger/compressor fridge route and avoiding 240V entirely, at least to start with. Very rare for us to park up somewhere for more than a few days without moving, and as someone said, those few quid a night for not taking a hookup all start to add up if you do enough camping.

[trentjim]

Something worth noting here whilst the subject of solar has come up is what sort of charge rate you will gain bs the cost of the system.
Solar is a lovely thing and provides some power whilst the van is parked up, however the cost of installing a solar set up doesn't necessarily give you the best £/amperage charging.
.

I'll mostly go fishing in it so it wont see a hookup too often.
I see the value of solar as a means of extending the battery life (or from another perspective, reducing battery requirement), and perhaps more importantly as a "auto maintenance" system which keeps the batteries topped up whilst the van isn't being used (take the van out on friday, park up, 50% the batteries by Sunday, drive six miles home, park up on the drive and still be confident that I can do the same on the following friday without needing to plug into anything... Van sits unused for 3 weeks in December, battery is still ready to go if needed... surplus energy during the winter gets dumped to a small dehumidifier standing in the sink... that kind of thing)

in terms of cost I reckon that £200 should see me with 100w of solar
However, I also like the idea of using a self adhesive vinyl backing sheet to a high top, then a bed of silicone to adhere trimmed down broken solar cells, building a diy solar array that conforms to the roof line - sealed with more clear vinyl over the top. Broken cells are cheap and salvagable & can possibly be cut using a rotary diamond tile cutter... even allowing for a lot of wastage in cutting to size (to keep it looking neat) I think I could go well over 100w for less than £100 including ancillaries - would be experimental and might not pay off, but i'm very interested & it would be a cool project. Cover the whole roof and it would be worth looking at connecting it to the grid and the pay back from feed in tarrifs LOL!
http://www.ecrater.co.uk/p/5702025/453x ... olar-cells

[kevtherev]

de-humidifier, in a draughty old van seems pointless as it will be constantly trying to remove water vapour from this planets atmosphere,
Unless you intend on sealing it from the outside air?

power usage is a well tackled subject here, in a nut shell :-
Reducing power use is a cheaper way of making batteries last
modern technology has enabled lighting power to be almost removed from the equation.
media players that use 2 amps which is a fraction of what DVD players use.
12 Volt TV's that run at ridiculously low amperage compared to older sets

I found during the spring summer and autumn months power usage is quite minimal, as we're mostly out doors, enough so, to use a starter battery for my leisure needs. which without charge comfortably lasts a three night weekend.
Only the luxury of a propex heater in the winter requires a battery capable of supplying a constant amperage on top of my usual needs.

There is some overkill in your suggestions unless you're a heavy power user?

[trentjim]

playstation3, tv, fridge, laptop and heater in winter would be the biggies - not saying that they would all be on a lot, but doubtless the weekend would come when the fish werent biting, the wind and rain were lashing down & I might well hunker down and finish a game or two...
I'd like a system that would cope moderately well with that once or twice a year extreme use scenario... and that could avoid deep cycling the batteries on almost every other trip to maximise their life.

re dehumidifier, just a hairbrained idea of what I might do with surplus solar. yep, its probably unneccessary, and at <100 watts probably ineffective... got no idea how one would go about calculating the air changes through a locked up van to know for sure!

[poshbuggers]

I am reading this thread with interest as I shall soon be kitting the van out with electrickery.

My ideal setup would be hookup, consumer unit. The ability to charge from hookup and enough power to run a good fridge for 2-3 days.

When we go out it's normally a weekender or a week/fortnight with trips out. The van is only ever off grid/without being ran for those 2-3 days at the most.

I'd like to fit some 12v lighting, a DVD/TV setup w/Freeview and a few power sockets for games chargers/phone chargers etc.

The big stickler always seems to be the fridge/coolbox. Most of these turn off when the bttery gets below a certain voltage and on the usual batteries this doesn't take long.

Can anyone advise on a good battery/charger setup and a fridge portable enough to be fitted within a removable kuchenblock style unit that won't kill it?

[v-lux]

The best way to determine your battery size is to add together the consumption of the consumers.

In your case on a fishing weekend the highest users look like they would probably be heating and refrigeration. The other stuff will obviously have an effect, but with sporadic use you can just keep an eye on voltages and stop using them and/or run your engine a little to bump it up.

This will tell you what your continuous load will be, times that by how many hours you need it to last and that will tell you how much power you need on tap. (more the merrier though remember, better to have a larger battery and not run it right down)

In terms of charging a simple (rough) equation is 1.5xbattery capacity divided by the amps your charging set up gives, for example...

220ah battery bank with a 7a charge controller with solar panel. 220x1.5 = 330 divided by 7 = 47.1hrs for a full charge from complete discharge (meaning no lower than 11v - or its bye bye battery)

If it were me, i think i would opt for a big(ish) battery bank, with a decent 240v charger. Plug it in when the van is laid up at home so you know its brimming when you arrive at your swim, use the power whilst there (2 days max presumably?) then plug in again once its at home.
For example...
220x1.5 = 330 divided by 25A (ctek M300) = 13.2hrs (this will give a far better/fuller charge than a solar panel due to the clever trickery 7 stage stuff it does)

As an example my battery (300ah) gives me enough power to run my compressor fridge (constant running), eberspacher, led lighting, laptop, stereo and phone charging for at least 5 days without putting anything back in.

The most important piece of kit you can install with any battery set up is a voltmeter so you can monitor the level, without this you will run it down too far and destroy it. Great cheap LCD voltmeters on ebay, well documented on here via a search.

[kevtherev]

playstation3, tv, fridge, laptop and heater in winter would be the biggies -

well i can see that the fridge is out of the equation as it runs on gas.
lappy can be charged when the van is running
The inverter is the biggest drain so the play station would be removed from the equation for me.... unless I had a battery to sustain it's power requirements.

[centro]

Which Trojans do you have in your van Kev ?