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Author Topic: Using PV to charge campervan leisure battery  (Read 5049 times)
skutter2k
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« on: April 02, 2016, 10:00:07 PM »

Hi,

I'm new to the world of PV and interested in finding a solution to top up / maintain my campervan leisure battery. I am aware of the various fitters out there but very sceptical of the huge variances in price and quality so I am weighing up the options and considering doing it myself. So, what am I trying to achieve?

I would like to fit a system that would keep the leisure battery topped up when the van is parked up outside the house and which I can then use to help keep the battery going while "wild camping".

What I envisage is a panel mounted on the roof that is flat when parked outside the house (I don't really want people to see it and it only needs to trickle charge the battery at this point) which I will then lift up to face the sun when I get to a camp site (I presume this will help increase the output).

I presume I will need a panel and some kind of charging system (12v). The van already has a charging system from the alternator (woefully inefficient and noisy) and from the mains hookup when available.

Do I need to use 12v panels or do people use standard panels (which seem cheaper and more powerful) and drop the voltage down? Are there any pitfalls that I need to be aware of?

Many thanks for any advice.

Ritchie
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biff
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« Reply #1 on: April 02, 2016, 10:43:45 PM »

Hi Richie,
          If you have a peep into the Navitron shop you will see battery charging PV panels.
     Now if it is only a camper battery,,something like a 100ah battery, you can get what you call a suitcase charger,,13amp i think,
   It opens out in two halfs and comes with a little controller that protects your battery from overcharging.
    I don,t know if Maplins still do them but they used to cost 60 sterling one time.
    I hope this helps.
                             Biff
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skutter2k
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« Reply #2 on: April 02, 2016, 11:18:06 PM »

Hi Biff,

Thanks, I noticed the 12v panels. I presume I still need some kind of system to stop them overcharging the battery?

I have pretty much ruled out the suitcase style systems as I would like the battery to be trickle charged while the van is not being used. Being as the van is parked outside the house I may even use it to keep all my various gadgets charged too, seems silly to have a panel sat there doing nothing when there is always a phone/laptop/camera/torch/tablet that needs charging.

Ritchie
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Scruff
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« Reply #3 on: April 03, 2016, 02:53:19 AM »

Welcome to the forum Ritchie.

How good would you like the system?  Grin
On a scale from 8 month electrical autonomy to occasional single overnight weekend use?

36cell modules are better suited for 12volt systems. You can use cheaper (by the watt) more powerful 72 cell but you either need MPPT that's far more expensive or an involved isolated 24v system. Tilting makes a significant difference alright especially in the late Autumn/ early Spring when the sun is low.

Dear Biff, respectfully..no...those suitcase trinkets are overpriced and underperforming...
« Last Edit: April 03, 2016, 03:48:43 AM by Scruff » Logged
dhaslam
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« Reply #4 on: April 03, 2016, 03:36:04 AM »

I used 10 watts pv panels  per battery on a boat without any controller.    One battery was used for engine starting and the other for sailing instruments but the boat was only used at weekends.   The batteries are 70 amp hour  and were well charged after a week.   
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biff
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« Reply #5 on: April 03, 2016, 09:19:15 AM »

Good morning all,
            Scruff, I beg to differ, As trickle chargers the 13watt suitcase chargers were an excellent investment for me some 8 years ago. I actually use them. I have one looking after my 2 x 130ah truck batteries that raise and lower our wind turbine tower and I have another sitting inside the windscreen of a vehicle since last november.
    These are trickle chargers with their own little controller, Back then they were 60.00 each..They were money well spent.
                                                                                     Biff,
           
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biff
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« Reply #6 on: April 03, 2016, 09:40:28 AM »



 One of my suitcase trickle chargers.

 No 2 . I must trim the ivy once again.

    No 2 has been trickle charging this 12v x 260 ah winch battery.
                                                                                              Biff
   These chargers came with a small controller and simple instructions, The controllers did 12v, 9volt, 6volt and something like 4.5volt. The leads opened out to 6 metres.
  
« Last Edit: April 03, 2016, 09:44:42 AM by biff » Logged

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fourfootfarm
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« Reply #7 on: April 03, 2016, 10:48:59 AM »

Hi Ritchie,

To get things back on course a little.

If you are only after a trickle charger to keep the battery happy while the the camper is not in use than a controller is not necessary as a tiny solar panel just doesn't have the beans to do anything nasty to a battery (anything in the 10-50w range will do)

If you want something a little more useful, say for making sure you can keep the lights on in your camper for a long weekend away without firing up the engine then you'll need something a little more sophisticated.

The kit available from navitron is all good stuff but I'm afraid its rather out of my budget.

http://www.navitron.org.uk/store/off-grid/chargers-load-controllers

http://www.navitron.org.uk/store/solar-panels/solar-pv-for-battery-charging?p=3

If you're a bit flush with cash and don't mind supporting our generous forum benefactors then I would go with them. But their range is a bit limited.

If you scout round ebay/gumtree you can find used 80 to 120w panels for fairly cheap. I've seen 120w for 50 quid each. If you're handy with a multimeter you can check then in bright sunshine and check if they actually still work.

You're looking for panels with a Voc (open circuit) of about 20 and a Vmp (maximum power) of about 18 these are what '12v' panels are.

Controllers. I am a dirty peasant and buy cheap rubbish ebay stuff. Its erm, okay. But Morningstar are an excellent brand and do a range of relatively inexpensive and very hardy PWM controllers. Depending on how many panels you have you'll have to size your controller accordingly. The SunSaver range can also act as a load controller and will cut you off if you're damaging the battery.

Well thats my 0.02 anyway!
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biff
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« Reply #8 on: April 03, 2016, 01:46:51 PM »

It would be extremely foolish to stick a 50watt solar panel on a 12 volt battery without a controller.
 You might get away with it if you kept the battery out in the open where they cannot do any harm to the surroundings, but a 50watt panel can boil a 100ah battery dry if a controller is not used.
  You cannot walk away and leave it unattended.
  It takes time and that is what catches people out,,They forget and the fluid level drops, The sun can shine longer and stronger.It is simply not worth the risk.
 I take my job as moderator very seriously and the idea that some one would get information on here in Navitron that would lead to their camper or house burning down does not sit well with me.
  So unless you are absolutely sure of your facts, Please do not post any thing that could lead to a fire breaking out or loss of life.
                                                                     Biff
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« Reply #9 on: April 03, 2016, 02:01:51 PM »

I am presently working with a 330watt panel dumping directly into a 600ah x 48volt forklift batt,
  There is a controller present with a dump load of 1,5kw. Even with all the use I am giving it, the controller will register 60volts+
  I run grinders and drills,, pillar drills and saws of this outfit, come 2pm and the batts are burbling nicely.
  My 330watt panel can still deliver 450watt+ 
  Your 50watt panel will deliver 75watt+,
  I often boost a 2 ton bank by bypassing one of the dump loads and waiting for an hour till the voltage climbs to 145vdc,
 The 60 cells bubble and hiss and then when ready, I reconnect the dump load .
  The controller is the only thing that will give you peace of mind and even then you can get caught out. Be carefull.
                                                 Biff
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fourfootfarm
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« Reply #10 on: April 03, 2016, 03:23:58 PM »

Really Biff? A 50w panel mounted horizontally would put out about 2-3 amps maximum for about an hour or two a day. That wouldn't even touch the sides of a big leisure battery.
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Outback FM60. EPsolar 30a MPPT and a bunch of Tristar 45's. Hodge Podge of solar ~ 4500w. Various generators and 1000ah 24v forklift battery.

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biff
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« Reply #11 on: April 03, 2016, 07:09:13 PM »

The best thing you can do FF is to go and try it,
  You will not buy a 50 watt panels that says they are safe to use without a controller, I will dump PV into a forklift pack all day long while I am working with it,
    But I either disconnect it or put it through the controller if I am not about, You are fully depending on the Battery to cope with the unnecessary overcharge.,
  You can get away with it for long enough until circumstances come together to cause trouble.
   I have had forklift banks that could hold down the voltage on these two 165watt panels to below60volts for hours on end, but then i put them on other forklift packs and instead of stopping at 60volts,they began climbing , I shut down the system after passing 62 volts.
  I am guessing that the pack was faulty and that the internal Battery resistance was failing,
  They sell controllers with the panels. The wise thing is to use them even if they cost a few bob more.
                              Biff
« Last Edit: April 03, 2016, 08:00:46 PM by biff » Logged

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Tiff
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« Reply #12 on: April 03, 2016, 07:52:05 PM »


Controllers. I am a dirty peasant and buy cheap rubbish ebay stuff. Its erm, okay. But Morningstar are an excellent brand and do a range of relatively inexpensive and very hardy PWM controllers. Depending on how many panels you have you'll have to size your controller accordingly. The SunSaver range can also act as a load controller and will cut you off if you're damaging the battery.


Over the years I've bought quite a few controllers from ebay, they are ok if you know what you are getting. Probably the biggest con on ebay is the controllers being sold as MPPT when they are not. Some are, some are not - I have some basic controllers, 2 different brands of real MPPT and two fake MPPTs which are sort of ok as a basic controller but have no MPPT ability at all.

I have a couple of full size panels charging a 12v system via a MPPT controller.

Everything sold on Navitron is excellent kit, intended for some serious off gridding.

Pay attention to fuses and ensuring decent size wiring and secure connections.
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guydewdney
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« Reply #13 on: April 03, 2016, 09:16:13 PM »

how does one tell the cheap mppt vs pwm's when the description says its mppt?

i had a pwm controller, a german brand beginning with S, and it fried my leisures (4 x 80Ah's) as it sits for so long (months) unused.

i bought a better chinese version, that i hope is real mppt, for my boat, also long term unused, but with a larger panel:battery ratio. currently hoping it wont fry that (it is a bit more basic tho' and one battery isnt scary to replace)

i now have a brand name controller dping my Trojan golf cart battery bank in the camper. hoping to hell that wont fry it.
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skutter2k
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« Reply #14 on: April 03, 2016, 09:39:45 PM »

I've had a day in work and only just had chance to catch up on this.  Thanks for all your replies, it's all very useful to a newbie like me.

I'm looking for something that will keep it topped up when I don't use the van for a few weeks or sometimes months but will also be useful when we go away off grid for a week or so at a time. This van has more reliance on the 12v system than our previous one and I need to be able to charge gadgets without worrying about killing the battery. It seems foolish to get a low powered panel, I'd rather have too much juice and find ways to make us of it (like I said, charging stuff from the house if I can!).

While Googling I noticed the MorningStar controllers seem quite popular and there is a model that can charge two batteries which would be great as I could ensure both the main van battery and leisure battery are topped up at all times.

I think the highest powered 12v panel I have seen is 150w, what rating of charge controller would I need?  Do I need to be concerned about the other chargers that are hooked up to the battery (alternator and mains)?

Many thanks

Ritchie
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