Solar Battery maintainer during storage
Just got back from a 3 month spell in Canada - during that time our caravan has been in at a CASSOA site. But we had to leave the battery installed etc so that the Caravan/s OEM alarm and tracker were active (because removing the battery might have invalidated the insurance).
Additionally we have a TK104 Tracker connected to the battery ( https://www.caravanclub.co.uk/club-together/discussions/information-technical-tips-advice/storage/how-we-know-our-caravan-is-still-at-the-storage/ ) that sleeps in standby for 23.5 hours/day then wakes up and sends up and sends us a sms message with current long/lat. But the power consumption of this should be tiny
Prior to departure, we found that after approx 4-6weeks the caravans standard Numax 105ah (DC31MF) battery was discharged to the level that the owners manual said would be "damaged" 11.3V (we've recharged and use it OK since)
So we needed to find a way to keep the battery installed etc but charged up throughout the typical British winter - we bought one of this 6W solar panel battery maintainer from Halfords http://www.halfords.com/workshop-tools/garage-equipment/battery-chargers-jump-starters/halfords-solar-battery-maintainer-12v-6w it comes with suckers that enabled us to install it inside the caravan on the underside of the sunroof - (i.e. no drilling holes etc) and the standard cables on the solar panel were long enough to span from the sunroof to the battery compartment.
It seems to have done a brilliant job - just checked the caravan and battery which has been untouched since beginning of January - battery was full at 12.6V - perfect - highly recommended
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I have no experience of Solar Panels but I notice the Solar Charger you mention is fitted with a male cigar-lighter type plug, would simply plugging this directly into one of the fixed female socket inside the van carry the charge to the battery or would there be other problems I would need to overcome?
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JCB, this is how they connect, but only low powered ones.
larger, roof or floor mounted panels of (say) 60w - 150w will need a regulator and be connected directly to the battery.
alarms, immobilisers, other 'systems' monitoring, all take a draw from the batteries, albeit a small one, but over time this will drag the battery down.
happened to us on our first MH (didnt realise this would happen) and got a flat battery....since then, always a roof mounted solar panel.
the bonus spin off is that, with a sufficiently large panel, off grid camping is easily doable, allowing pitching at places where EHU is not available, like some CLs, or temp hol sites....
good luck.
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Thanks BB,
I thought this was the case, As I am only considering one to keep the battery topped-up while the Van is in storage. what would be about the highest Solar Panel Output not needing a regulator?
Looks to like the one HillClimb is using might be ideal for my purpose
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JCB4x4 - yes the solar panel came with both a cigarette lighter and a pair of crocodile clips. I am using the crocodile clips directly on the battery terminals because the cable is long enough and the sunroof / battery close enough together.
I have trickled charged at least two cars in the past via the cigarette socket so it will probably work in your caravan too - I switch the main isolation switch on the fuse panel off (the alarm etc bypasses the panel - probably all the 12V circuits do) - so I guess the cigarette sockets are still active when the main switch is off
In terms of charging amperage and regulators - a battery charger normally provides 8-12amps when you start charging a flat battery, it will drop to 1-3 amps when topping up. Trickle charging is normally less than 1amp and that low an amperage doesn't do damage.
The Halfords solar maintainer that I use is 6W, so it provides a maximum of 0.5amp so unregulated should be fine.
Buying a 40, 80 or 120w solar panel mounted on the outside top of the roof would be a good solution if you wanted to regularly stay at non-EHU sites - even a 40W panel is capable of 3amps so would need a regulator
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Hello HillClimb,
Really just begun to put my thinking cap on with this one.
So it’s the usual Watts/Volts/Amps calculations with Solar Panels then.
As I’m used to Battery Chargers & Batteries being Amp rated I have just realised that I was confusing the Watt rating for Amps in this case and as you point out to many Amps input would fry the battery, so hence the need for a regulator at higher Wattage's.
Taking this a little further, remembering I really have no previous knowledge of Solar Panel out-put.
Why are they rated in Wattage?
Why would you use one with a High Wattage/Amp out-put when this would damage the Battery.
Does the Voltage out-put vary for instance ?
When Off-Grid, are all 12v circuits/appliances run from the Solar Panel via the Battery or are some run directly?
I'm beginning to find this topic more than a little interesting and feel I may be asking a few more questions here.
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have a look at this thread
plenty of advice on solar panels etc.
rated in wattage as this is a unit of power...
voltage putput will vary depending on the amount of sun. a small panel requires full sun to acheive a meaningful output...a large panel can still generate a healthy putput in cloudy conditions.
however, when a large panel is in full sun, it needs a refulator to restrict the amount of puut to avoid damage.
when off grid, all 12v appliances run from the battery, with the panel replenishing any used power.
good luck.
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Thanks BB,
I think I am now beginning to get the picture certainly looks like I will be able to keep myself busy reading through the thread you quote.(a few pages there)
Could end up with a few more pounds on the caravan roof and a few less in OHs Bank Account (well she says it hers) It's joint really, as in I put it in and she takes it out).Usually to waste on food electric/gas etc.
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without trying to get you to run before you can walk
, once you get into the off grid thing and perhaps have a largish panel that will keep you going 'indefinitely' in decent sunshine, you might start to think about what devices can be powered by that battery.obviously, the std 12v systems in your van like water pump, lights, heater pump/fan etc, but then there are the other gadgets that are taken for granted when on EHU.....mains type chargers for phones etc can be run from USB sockets on 12v, heating or hot water runs great on gas, as does the fridge.
the 'snags in the ointment' (as my old boss used to say) are the heating devices like hairdryers, microwaves etc....
in the thread i linked to, Merve uses a large inverter to convert 12v to 230v to run this type of device. however, they will use a fair slug of battery power in a short space of time.
small inverters are, perhaps, more common....we have a 500w one which runs our mains-only Sky+HD box when off ehu.
spunds like you're getting into this a bit....happy reading....
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It is possible to over complicate the question of non ehu use.
To simplify it.
Anything that requires heat isn't really suitable for 12v use.
Before rushing out and buy a solar panel make sure the your battery is good, you can generate all the power in the world but it is largely pointless if you have no where to put it. Also money spent on replacing standard lights with Leds is money well spent.
We have been on site since Thursday charging 3 smart phones and 3 tablets without any problems.
Finally you will use more gas than you can possibly imagine particularly in the colder months.
Finally with Solar panels they are more efficient freestanding than roof mounted because of the angle they deployed. We have a roof mounted panel simply because we use storage and it keeps the batteries charged.
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I have a solar roof panel that I have yet to fit due to a caravan change.
Originally I simply wanted a small panel to keep the battery topped up as the OP outlines. After thinking about it a bit and looking at prices I came to the conclusion that I might just as well fit a 100 watt regulated unit so that I will also have the facility of going off grid if I want as well as ensuring that the battery is charged correctly.
There is also the problem of Euro6 engines failing to recharge the battery whilst on the move due to the design of the latest alternater circuits to be considered and countered.
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Until recently I have been using a system of two 110ah batteries (one inherited at no cost, nothing untoward mind-you) and either the battery charging facilities at non-EHU sites or a small unit (cost £5, the normal price at time of purchase being £15) that allows safe charging of a second battery carried in the car while out for the day. I have spent a max of 11 continuous day’s off-grid using this system and it has shown the potential to supply enough 12v power to meet my requirements for an indefinite period. So I have no need to change this system. With regard to keeping the batteries charged during storage periods the van has been kept at home with easy access to 230v mains supply. However as with all things in life circumstances have changed and storage is no longer viable at home and I now no longer have access to 230v mains supply. Now with a couple of hours work and the price of some suitable cable I could link the two batteries together during these storage periods to give 220Ah capability but this would lead to extra work each time I stay off-grid, or it seems for about £35 I could simply buy a suitable plug-in ‘Solar battery- maintainer’.
None of the above diminishes my interest in understanding the technical details involved in generating 12v Solar Power or its useful application in the world of C&MH touring.
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Looks like you have a system that works for you for of grid. If a 6W battery maintener keeps the battery charged then that fine. The Halfords price seems a bit step but convenient. For the record I have a 150W roof mounted panel and my battery definitely stays charged in storage.
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Yes Boff, I do have a system that works but it has its beginnings in the somewhat dim (pun intended) & distant past when Solar Power was little more than a dream. It has come together and been refined over a number of years from equipment readily to hand but it now needs some further tweaking in order to meet my present day requirements. I can see that my present situation presents me with the opportunity to invest in Solar Technology and create a system that requires far less management and labour so I will be giving some time to further research whether such a move is really what I desire.
Thanks to all !!
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I didn't mean to be patronising. In life I believe that there are two types of system those that work for you and those that don't. The technological advance that I believe is a game changer is the advent of the led both for lighting and TVs. This is allied to the collapse in price of solar panels makes it a real practical proposition. Our first SP bought about 10 years ago was 43w and a real bargain at £156. The last one I bought about 18 months ago was £128 for a 150W panel. If you are serious about one I would look on eBay or amazon for prices. But fitting one in truth is a simple DIY job. Just takes a bit of nerve to drill a hole in the roof.
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I got the Aldi solar panel to keep the battery charged whilst stored.
It says it can be used inside and plugged into the 'cigarette lighter' socket. Just wondered does anyone do this and is it effective?Alternatively, how much do they cost to have fitted on the roof?
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Boff. Re: "I didn't mean to be patronising"
I apologise
if by the wording of my last post it seemed that I was implying that you were being patronising towards me, I assure you that nothing was further from my mind. I was just trying to say that because something works it does not mean it is the most suitable means to achieving the desired end. JCB4x4
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I think the fundamental questions for all owners are:
A. do you want to good off grid without EHU (for more than a weekend)
B. If no to A. then is off-grid overwinter storage with alarm etc still powered needed.
For the former, a large freestanding or roof mounted powerful panel is needed with a regulator. (Caravan covers is a contentious subject, but if you like covers overwinter in storage and want solar then it may be an extra complicator).
But if you normally EHU or offgrid only for a night or 2 then but need to maintain your battery overwinter without regular visits to swap out the battery then a small solar maintainer as I bought will suffice. I suspect if I hunted around on mail order I may have saved a few pounds or up'ed the spec; I initially installed the £25 2.4W version but mid winter it didn't produce enough power. Halfords kindly swapped it (plus some cash) for the 6W £39 version which seems to have done a great job of maintaining the battery. The 6W was much bigger, nearly as big as the sunroof and the ease/convenience & security installing the panel on the inside of the caravan was fantastic.
I have no doubt that there may have been some dull days where the panel allowed the battery to deplete slightly but I know my 110ah battery can survive a few weeks so on average over numerous days, even in the winter, the 6W panel produced enough juice. And regarding buying better/cheaper from another retailer - £39 isn't a fortune and the convenience of a Halfords branch 10 mins from the COSSOA site and confidence in that Halford won't quibble if it fails to perform in anyway so I wasn't inclined to bargain hunt. The SP that Aldi sells looks identical, exactly the same dimensions - I suspect they are identical and £9 cheaper at AldiI hope the recommendation is useful to others with similar requirements
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It is my understanding:
1)That in order to fully charge a 12v battery set the charging unit needs to be able to supply 14.7v (pulsed) at not <10% of the battery-set’s Ah rating.
Eg.: 220Ah requires 22Amp input and 110Ah requires 11Amp input.
2) That in order to protect the battery-set from damage during use and charging, the charging unit must be able to detect and meet the battery-set’s required charging needs throughout its use, particularly if the battery-set and the charging unit are to be left connected and un-monitored.
I know this is achievable using mains 230v Smart-chargers.
My question is- are Solar Panels with Controls able to meet these requirements?
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JCB4x4 regarding the info you've posted - some is, as far as I know, true but some I do not believe is correct.
Certainly the voltage of the charge must be greater than the voltage state of the battery. Although these batteries are nominally 12V, my brand new Numax DC31MF 105ah when seriously depleted will be 11V but after a long charge (i.e. its 100% full) then left to stand for a couple of days, then a volt meter across the terminals shows approx 13V.
When I connect my charger to this full battery the charger puts out a voltage of approx 14.5V (the key thing is it has to be greater than the battery in order to "push" the charge and "overcome" the batteries voltage state.
But I think your amperage info is very off. Figures like 105ah; 110ah even 220ah is amperage over a period of time - hours. To understand what kind of amperage a caravan battery might normally sustain, for comparison, according to my owners manual, the typical site ECU supply is typically 10amp and often 5amps on the continent. So, apologies but your "Charger must be capable of 22amps" calculation isn't realistic - the plug in the charger will be a 13amp fuse - so no - that isn't right.
Many typical battery smart chargers will initiate charging a flattish battery at 12V and perhaps 8 - 10amps. But as the charge state rises the voltage of the charger must similarly increase up to your 14.7V but the amperage from the charger will drop to <1amp. My Trickle charge is similar in terms of voltage profile, but it only puts out a fraction of an amp. Charger that are smart are able to monitor the charge state and in effect they temporally switch themselves off then either wake themselves up and charge until 100% again because the monitored charge state has dropped or perhaps a time based. Some smart smart chargers are also capable of attempting to de-sulphate a battery whose internal plates have sulphated (due to being left discharged for too long) - to do this chargers deliver a pulse charge. As far as I am aware chargers do not normally need to deliver a pulse charge.
So back to my solar maintainer - it also produces approx 14V, even in dull sunshine (this voltage ought not to fluctuate with sunshine, but the amperage will - until there just isn't enough sun and it shuts down). It is rated at 6W so I would expect in ideal sunshine with ideal panel point then it should produce 0.43amps. When I measured the amperage during a dull January day when I first connected it to a semi-depleted battery it output about 0.25amps if memory serves. So in the short winter days, the solar maintainer might only deliver 2amps/day. But my GPS/GSM tracker consumes <2ma - and I suspect that the OEM alarm system consumes similar - so I would expect the daily consumption to be <1amp/day. In comparison, from experience without the solar maintainer, the battery was still functioning but pretty run down (30%) after 2 months which suggests consumption was around 1.5amp/day. So my conclusion is 6W is clearly sufficient, but I only - the smaller one I initially installed (2.4W) didn't cut it (probably because it will only deliver about 1.25amp of charge during a winters day)
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I am quite surprised that a 6 Watt panel will keep the battery fully topped up. Much depends on how much power the alarm/Tracker takes, how much sunshine their is etc. No doubt this is covered in detail on the other thread but if it works then fine. Since this is really just a top-up charge it would certainly be advisable to fully recharge the battery with a leisure battery charger at the end of the storage period.
To recharge a sealed battery you need 14.4 volts and a multi-stage charger.
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I did mean to post some of my further thoughts & questions earlier, when I realised that I would be meeting up with a long-standing friend who has spent his working life as an Auto-electrician, in the car, truck, bus and caravan industry. He is also an ardent Off-grider and Solar Panel user. Having since spent some time on a one to one basis with him, I now find I have all the answers Re: Solar Power that I require.
Many Thanks!! to all who have contributed to answering the many questions I have raised throughout this thread.
JCB4X4
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