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Author Topic: leisure v car battery - camping use  (Read 5402 times)
chasfromnorfolk
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« on: August 13, 2013, 01:00:26 PM »

this may be a bit lightweight for these threads but I'm looking for affirmation from someone that my 'observation' seems likely before I decide what battery to buy next:

I have a small submersible pump (rated consumption unknown but apparently tiny) powering a camping shower that until recently was hooked to a 110 leisure battery. The battery has finally given up - won't hold charge, but it's 10 years old - and I'm currently using a spare (used) car battery. I used to charge the leisure battery 'from time to time', probably once a week, relying on the "fully charged" indicator to tell me when it was, well, fully charged, but not particularly noticing how long that might have taken.

Anxious that the car battery doesn't fail in operation. I've been monitoring its charge more carefully and find that even after say a week's use (10 showers?) it still shows green in the charge window and 12 volts on a meter, reverting to 13 volts and fully charged after maybe half an hour on the charger, sometimes less.

So, does the light usage/regular light charging regime 'suit' the car battery better and did I hasten the end of the deep-cycle leisure battery by light charging too frequently? Might I just as well carry on with the car battery?

The thing is, I have a couple of decent spare car batteries, so keeping one ready charged is no problem as insurance and would save the expense of a new leisure one if my use and charging regime is going to be injurious...

Chas, with other things to spend his pension on, mainly Rioja and IPA.
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knighty
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« Reply #1 on: August 13, 2013, 01:12:03 PM »

how are you charging them ?  do you have to take them away somewhere or are you doing it in situ ?

if you have other old/spare batteries which hold a charge ok... you could connect them all up in parallel, so they'd last a lot longer between charges

if you need to keep moving them to charge... I'd be tempted to add a solar panel to keep them charged / topped up :-)


EDIT:
actually, is it a camper van/caravan ? and you're running the engine to charge the batteries ? sounds like it could be... in which case I'd still go with more batteries and a solar panel :-)
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julian
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« Reply #2 on: August 13, 2013, 01:12:31 PM »

You may find this an interesting, and money saving read -

http://www.sterling-power.com/support-faq-2.htm

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martin
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« Reply #3 on: August 13, 2013, 01:28:54 PM »

Where to start? I've got a similar setup in my touring caravan - from memory, the shower pump is probably drawing about 8 amps when running, which is a fairly hefty draw to be taking from a car battery, so you need to do all you can to keep it in good nick (charge it regularly and fully), or it'll give up the ghost relatively quickly-  it isn't a good idea to run the battery very low (ever) - my suggestion would be to get yourself a small solar panel and regulator, bung the panel in the sun, and keep the charge well up all the time (it's a helluva lot cheaper than buying new batteries)
Something like this - http://www.navitron.org.uk/product_detail.php?proID=734&catID=133 and an el cheapo pwm controller off Fleabay for around a tenner would probably do the job admirably (around 30-35 the lot), certainly spring-autumn.
The built-in charge indicators on batteries are next door to useless-  a voltmeter is invaluable- with a little experience, it can tell you a lot about your battery condition using one. A flooded lead acid battery (like a car battery) can be charged to well over 14 volts (it's actually good for it), and a fully charged battery should be showing over 12.7 volts (and that's after having let it "rest" after charging)
I really would look at the solar charge idea - it's pretty cheap and effective.
Not a "lightweight" question at all-  a small battery system needs care in it's design and running, every much as a big system!
« Last Edit: August 13, 2013, 01:38:46 PM by martin » Logged

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chasfromnorfolk
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« Reply #4 on: August 13, 2013, 02:47:05 PM »

Apologies for lack of detail, my first post read ok from my end, but then I know the set-up... thanks for the info so far.

the battery supplying the shower is 'stand alone' - not in a vehicle, doesn't supply anything else, and because of the permanent, shady position under trees, solar charging isn't easily arranged... plus, as I need the reassurance the shower won't conk out with soapy complainant in there, I sort of accept my weekly trudge with a wheelbarrow back and forth to the workshop with it (the battery, not the soapy complainant) as an opportunity to make sure it's ok.
The charger is a mains 'Halfords' one with 'charging' and 'charged and maintaining' indicators. I'm currently testing it with a good 'Fluke' meter as well to get volts.

Chas
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oliver90owner
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« Reply #5 on: August 13, 2013, 03:18:53 PM »

Automotive batteries are designed differently to deep discharge variants.  The car battery is designed to provide a huge amount of current for a small period of time and then be recharged to 14.4 volts soon afterwards, by the vehicle alternator. They will not stand up long to deep discharge or being left under-charged for long periods.  Deep discharge batteries will not supply starter motor currents for long, if at all, but will supply lower currents and withstand longer periods of partial discharge than automotive batteries. The whole spectrum is from automotive through leisure and traction (fork lifts, milk floats, etc) to the really heavy duty deep discharge cells for duties such as marine back-up power.

Life of battery, weight and cost (much more lead in the better batteries) are prime design factors, as you don't need to be using fuel to cart around a huge battery which is basically only needed for starting the engine.

Fifty years ago cars were still regularly parked overnight with the lights on.  Modern batteries would not cope with that on a regular basis.

For your application the difference may be a battery lifespan of two or three years for the automotive battery compared to the longer life for the leisure battery.  Using up available battery capacity can be quite lucrative as long as you don't mind changing it more regularly, and reliability is not too much of factor.  Keeping your battery on a float charger would be better than intermittent charging from a discharged state and as Martin says an option is a suitable solar panel and a small controller.

I would not be putting used batteries in series.  One battery is likly to drag down the other unless of the same age and type.

RAB
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daftlad
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« Reply #6 on: August 13, 2013, 03:24:35 PM »

The little 10 pound solar charge controllers do tell you the state of the battery so you will only need to wheel to the charger if it tells you to and the battery will last an awful lot longer with daily charges.
car batteries are ok if you get them second hand and cheap (or free) but will die much more quickly.

is the shower solar thermal?

peas
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Tiff
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« Reply #7 on: August 13, 2013, 03:31:55 PM »

I think the answer is simple - use the car batteries until they die, then get a leisure battery.

As you have the car batteries anyway, the cost is not an issue. if they are just sitting on a shelf they will be slowly degrading anyway, especially if they are not being kept charged on a regular basis. I would put them to good use.

I would then spend some of the saved cash on a small PV panel and charge controller, even if it just helps maintain the battery and reduces the number of trips with the barrow its got to be a good thing. Ensure there is enough change left over for a pint of IPA.
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chasfromnorfolk
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« Reply #8 on: August 13, 2013, 07:00:46 PM »

Well, I'm certainly attracted to the idea of using my car batteries, and may well end up with a solar panel trickle charging them and a punchy leisure battery when they give up - but I'm still a tad uncertain: I thought leisure battery = deep cycle battery. Isn't a deep cycle battery one that should be discharged deeply before recharge?

If I draw tiny amounts of current (so small a mains charger could rectify it within minutes) and trickle charge with a solar panel, isn't all this 'shallow' use going to compromise the life of the deep cycle battery? Which is sort of where I came in...

Chas



 
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martin
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« Reply #9 on: August 13, 2013, 07:08:03 PM »

"Isn't a deep cycle battery one that should be discharged deeply before recharge" -NO!!!!!!!  - "shallow use" is what you need to aim for in all "lead" batteries- if you can contrive it to only ever discharge by 10 or 20% of it's capacity before recharge, they should last very well indeed.......

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knighty
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« Reply #10 on: August 13, 2013, 09:34:05 PM »

is there anywhere close you could put the solar panel ?

it doesn't need to be very big... and it's one of those things where when you get it, you'll wonder how you ever did without it!

is the water heated, or just cold ?
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chasfromnorfolk
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« Reply #11 on: August 13, 2013, 11:29:21 PM »

is there anywhere close you could put the solar panel ?

it doesn't need to be very big... and it's one of those things where when you get it, you'll wonder how you ever did without it!

is the water heated, or just cold ?

Yeah, I'm sure you're right, and this thread's convinced me... I'm swung onto the trickle-charge panel idea.

The water starts cold, in a barrel, pumped through by the battery and heated by calorgas to warmish via a Kampa 'Geyser' unit. Hardly renewable or very sustainable, but the best option for the woodland setting and occasional use. Of course solar thermal is attractive, but lack of piped water supply, anywhere to site it in the sun and cost counted against it. I'd favour experimentation and bodge, but I'm in a minority of one, domestically. The other voters want a reasonably reliable shower.

Chas
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martin
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« Reply #12 on: August 13, 2013, 11:40:11 PM »

Here's one in a "sustainable conference centre" I went to a couple of years ago, which made very effective use of a boiler codsed up from 2 rads and assorted other bits and bobs - fed on old pallet wood, logs etc...........





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biff
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« Reply #13 on: August 14, 2013, 08:44:29 AM »

But definatly a solar pv charger is a "must"for your batteries,
                               Even a 40watt pv panel that you could move about on the end of a 30ft lead would be bound to catch enough sunlight to charge a couple of 100ah batteries during the summer months(between the trees).
  PV is the ultimate charging method,quiet,effecient and no hassle.
                                    Biff
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chasfromnorfolk
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« Reply #14 on: August 14, 2013, 09:00:39 AM »

Here's one in a "sustainable conference centre" I went to a couple of years ago, which made very effective use of a boiler codsed up from 2 rads and assorted other bits and bobs - fed on old pallet wood, logs etc...........

Neat, and exactly the sort of highly-developed solution the family fear I might come up with. Can't think why they don't embrace it...

Chas
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