Solar Powered 12v 12w battery charger on offer.

salinia

salinia

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Just purchased one of these from Maplins -http://www.maplin.co.uk/solar-powered-12v-12w-battery-charger-217850

thought it was a good buy at £39.99. £30 off the usual price...on offer until the 17/05/11.

Picked up a solar charging controller M149 to go with it £15.99 perhaps not such a good price? Hopefully with this combo I won't have to keep taking the 75 amp leisure battery home for charging. Just need to ponder how its all going to connect up now it seems easy enough.
 
Very interesting.

Looking on the specification page it states:

Optimum working current: 680mA

Is this simple maths now ... 12 hours of daylight = 12 x 680 = > 8 amps (ah?) into the battery ?
 
. 12 hours of daylight = 12 x 680 = > 8 amps (ah?)
Click to expand...

yes, ah. You are multiplying amps x hours so result is amp hours (ah)

Actually 12 x .680 = 8.16 ah

Typical battery capacity = 72Ah, so 9 days will see it fully charged from fully flat - in theory.

In practice, initial current required to charge a near flat battery is probably more than .68A!
 
Brill. So for < £100 I can buy 2 plus the regulator and look forward to > 100 ah per week. (One of my service batteries is 220ah)

Mrs Bav CAN run her fridge :)
 
This is from their site:

Requires only daylight (not direct sunlight)
Amorphous solar panel charges even in cloudy and overcast weather
so I was hoping not to have to rely on actual sunlight.

Wot you fink?
 
Not to well up on electrickery but replies so far would seem that this piece of kit will serve us well (fingers crossed) thank you.
The new varta 12V 90ah(20h)75Ah(5h) we brought home after having served about 12 days and nights aboard using it for Garmin GMI 10 instruments about 8 hours and 8 hours cabin lights and a bit of lcd 7 inch screen tv 6 hours. 6 HP outboard charger tickled the battery for 2 hours. The Garmin GMI 10 instruments have a menu function that gives the battery voltage and just before disconnecting the battery and heading home this facility showed 11 volts...as this is a new boat to us we are still learning and hope to find out more about this function. Got the battery home and it took approx 12 hours to fully charge with the mains charger, hope this is of interest to anyone with a small sailboat.
 
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Bav34 said:
Very interesting.

Looking on the specification page it states:

Optimum working current: 680mA

Is this simple maths now ... 12 hours of daylight = 12 x 680 = > 8 amps (ah?) into the battery ?
Click to expand...
Unfortunately I think you will find the output will be more like 2-4 AHrs a day. In a good subtropical location you may get up to 6 or 7Ahrs in summer, but 8 is very optimistic.
 
Thanks for the heads up, I've just been and ordered one.

I've been looking for a cheap solar panel to avoid lugging the battery home to charge it. Like many small boat owners, the battery serves the VHF, depth/log, GPS, autotiller and cabin lighting, and I have no charging on the boat, not even from the outboard.

So hoping this will provide enough top up between trips.

Now lets be practical. "optimum current" 680mA so that's 8.16Ah as previously quoted (based on 12 hours sunlight)

But mine will only be in direct sunlight for a small part of the day. So lets say a more realistic charge is likely to be 3Ah per day.

So my 55Ah battery will take in excess of 18 days to charge fully from flat.

So this really is just a trickle charger.

The point I'm trying to get at, is with such a low current charge, I doubt it's really necessary to bother with the extra expense and complication of a charge regulator. Even a fully charged battery is not going to complain, overheat, or boil dry with a 680mA charge for part of the day, and a significantly lower charge for the rest of the day.

Do others agree?
 
ProDave said:
Thanks for the heads up, I've just been and ordered one.

I've been looking for a cheap solar panel to avoid lugging the battery home to charge it. Like many small boat owners, the battery serves the VHF, depth/log, GPS, autotiller and cabin lighting, and I have no charging on the boat, not even from the outboard.

So hoping this will provide enough top up between trips.

Now lets be practical. "optimum current" 680mA so that's 8.16Ah as previously quoted (based on 12 hours sunlight)

But mine will only be in direct sunlight for a small part of the day. So lets say a more realistic charge is likely to be 3Ah per day.

So my 55Ah battery will take in excess of 18 days to charge fully from flat.

So this really is just a trickle charger.

The point I'm trying to get at, is with such a low current charge, I doubt it's really necessary to bother with the extra expense and complication of a charge regulator. Even a fully charged battery is not going to complain, overheat, or boil dry with a 680mA charge for part of the day, and a significantly lower charge for the rest of the day.

Do others agree?
Click to expand...

At least with a regulator you'll also get protection in case the panel shorts out. Buying a new battery is a heck of a lot more than the £15 a regulator costs. Sure, it's an insurance policy, but worth it for the small premium, IMHO.
 
Prodave: I think for the sake of £15.99 stick the solar charging regulator in line along with the 10 amp fuse for peace of mind then if you don't get down to the boat in between times and we are blessed with "solar power" you will not be thinking is my battery boiling. Only my opinion nothing expert about it.:o
 
I've bought a similar 12w panel on eBay to run a small computer fan as an extractor in my garden shed which gets a bit hot and stuffy in the summer.
I've had it running on the window cill in my office for the past couple of weeks, and its amazing how the speed of the fan constantly changes during the day. Even the slightest cloud affects the output dramatically and the whine of the fan has been going up and down like a yo yo with little apparent change in the sunshine level.
I fear anyone expecting maximum output for 12 hours a day from a panel in our latitude is going to be very dissapointed.
I'll put one of our data loggers on it when I get a chance and log the output over a week or so.
 
When I get mine, I'm going to set it up on the boat, with a fuse, and isolating switch of course (it says it has a built in blocking diode, I will check the effectivenes of that)

I also plan to fit an ammeter, 1A full scale should be enough so I can monitor charging current.

I'll then form an opinion whether there's likely to be enough over charge to warrant fitting a regulator.
 
Well I've just ordered 2 plus a regulator and got £3 off for signing up to their newsletter = £92.97.

If I only get 3ah a day each that's still 42ah a week which means the fridge can run a further day and a half without having to head back for shore power or revert to our stock of Fray Bentos.

:D
 
ProDave said:
When I get mine, I'm going to set it up on the boat, with a fuse, and isolating switch of course (it says it has a built in blocking diode, I will check the effectivenes of that)

I also plan to fit an ammeter, 1A full scale should be enough so I can monitor charging current.

I'll then form an opinion whether there's likely to be enough over charge to warrant fitting a regulator.
Click to expand...

A commonly accepted rule of thumb is that up to 1 watt of solar power per 10 Ah of battery capacity needs no regulator, but it is generally recommeded that panels over 10 watts are fitted with a regulator anyway.

When I had a 5 watt pannel and a battery under 50Ah it need topping up now and then ( annually). Now I have a larger battery. Not topped it up in 4 years.

Fuses should be fitted in any circuit connected to the battery. The fuse should be located as close to the battery as practical. It should be rated less than the safe current carrying capacity of any of the wiring in the circuit connected to it.
 
I just got my solar panel delivered today. some initial findings and WARNINGS

First initial findings. It's 8:30PM on an overcast evening in the North of Scotland, so we wouldn't expect much power out of the panel. BUT I would expect some.

When placed right up to the window in my workshop the panel is producing an open circuit voltage of 12.39 volts. But my test battery also has a terminal voltage of 12.39 volts. So my multimeter in series records no current whatsoever into the battery.

Lets see what it does tomorrow when it's brighter.

But now A WARNING.

The solar panel has a long flying lead with a connector. they also provide 3 mating connectors, one terminating in a "cigar lighter" plug, one a pair of large croc clips to go directly on a battery, and one with a pair of small lugs.

The in line connector is of the sort with one exposed pin and one shielded pin when disconnected (both are shrouded when the mating halves are plugged together).

But the stupid buggers have only made it so that the exposed pin at the battery end is the POSITIVE one.

So, say you were using this in your car, connected to the cigar lighter socket. You unplug the panel but leave the cable in place. you now have an exposed POSITIVE pin just waiting to touch anything metalic and earthed and short out.

Less off a danger in a fibreglass boat, but still a hazard if it comes close to ANYTHING connected to ground.

Please please please MAKE SURE you connect a fuse between the supplied lead and battery positive so that if the unplugged lead should short out, the fuse will simply blow. No fuse and it could be very dangerous. (no fuses are fitted in the supplied leads)

Better still cut off the supplied in line connector and use something better.

I despair sometimes at the "engineers" that design such things. By simply wiring it the opposite polarity, you would have an exposed negative pin, which would present virtually no hazard.

I feel I must now contact Maplin and point out this very unsafe situation.
 
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salinia said:
Prodave very strange that. I have just tested mine and the exposed pin is negative looks like yours has beeen wired incorrectly at the manufacturers?
Click to expand...

Which end are you checking?

Yes the exposed pin from the panel is the negative.

But my point is the exposed pin on the short connecting lead is the POSITIVE.

So if you have one of the supplied short leads connected to your battery, and you unplug the panel, you then have an exposed POSITIVE connection from your battery, just waiting to short to some earthed point.

My guess is the designer decided best to have the negative lead from the panel as the exposed one, not realising that on the mating half that means it's the positive from the battery that is exposed.

Or yes, perhaps mine is wired wrong. Any other reports from other people with this same panel?

I have emailed my concern to Maplin, with the footnote that if you don't understand what I have described, you forward it to a qualified electronics engineer for his opinion.

P.S I'm getting about half a watt from the panel into my battery at the moment, looking at the window in my workshop. I'm sure that will increase considerably when the sun comes round to shine in the workshop window.
 
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Sorry I get you now. Yes mine is the same as yours and I can see your point.
Thanks for that. As you say not so much a problem on a fibreglass boat but still worth remembering that if disconected from the panel you don't want the exposed end touching the negative on the battery. I have mine in the garden at the moment charging my battery it is connected to the solar charger. I tested the output with my multimeter from the charger via the regulator and was initially disapointed with a low reading (I do not understand how these things work) however when connected to the battery all was fine and it was charging. I will make a video and post it here back in a few minutes.

http://www.youtube.com/watch?v=Er49hCKSNV0&feature=player_detailpage
 
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