Help - Solar Powered Battery Savers

[aard]

Hi,

This was suggested as a solution to my earlier thread.

Any idea which one will be sufficient for the battery on a Griff?

Also, will they work in a well lit underground car park, or do they require real sunshine?

fyi - have found details of two, blurb below. Are either of these any good?

Thanks all in advance!

1. =========
Battery Saver SE 2W
The Batter Saver SE 2W is a solar powered car battery maintainer that will trickle charge a 12V battery. Ideal for cars, small boats, tractors and other vehicles. Not for outdoor use.
Rated at 2W (135mAmps@15V).
Measures 394x127x20mm; weighs 41g.
5 year warranty on panel output.
Price (incl. VAT) £24.99 UK Delivery £6.45
==========
2.========

Battery Saver SE 6W
Larger vehicles such as pick-ups, vans, RV's, or small boats have larger batteries and larger battery drains simply because they have more electronics. The BatterySAVER SE 6W slowly charges larger 12V deep-cycle batteries, helping to protect them during storage periods.
Helps maintain 12V batteries and reduce battery loss caused by key off electronic drains and natural voltage losses.
Weatherproof and designed for outdoor use.
Amorphous silicon panel works well under overcast conditions.
Comes with battery clamps and ring connectors, extension cable (10ft), 12V plug and socket cables and mounting screws.
Maximum power 6Wp.
Nominal current: 400mA @ 15V in full sun Suitable for all 12V batteries.
Suitable for all 12V batteries.
Dimensions: 375 x 360 x 26 mm, 1.5kg.
Price (incl. VAT) £69.99 UK Delivery £6.45
============

[SpielBoy]

I got one of these ... and stuck it on the roof of the garage

www.selectsolar.co.uk/pics/batterysaver6w.html

Battery still tended to go flat when left for 2 1/2 weeks plus however ...

I think it might be because there is secondary immobiliser on the car in addition to the normal Meta one and it couldn't supply sufficient current

... have now got an battery isolater fitted.

According to what was said on the packaging normal ambient sunshine (ie it doesn't have to be sunny) should be enough for the thing to work - though I would have thought an underground car park might cause problems!!

[JR]

Sure this guy will know www.actproducts.co.uk/accessories.php

[steve-v8s]

If you plan to leave the car with alarm and immobiliser active I don’t think either of these would produce adequate output to keep the battery topped up. Really you need to lift one of your battery leads and measure the current, which I guess will be at least 150ma and have a supply that is capable of a bit more than that with a 13.8v load attached. The quoted solar cell current will probably be the short circuit output not the current when charging a battery. They would probably provide a fair charge into a flat battery but not into one that is close to charged.

In overcast conditions the output will probably be a lot less and inside will be next to nothing. Photo voltaic cells don’t tend to work well from artificial lights because the frequency of the light is different and the power of the light is a lot less.

Will help to counter the losses but not be up to a mains powered unit.

[aard]

Thanks for all your detailed replies and help.

I've found this one on eBay:

http://cgi.ebay.co.uk/Solar-Powered-C

I asked if it would work in an underground carpark and the owners reply was:

"Well lit underground carpark is Very good, I have my car under a streetlamp, IT works like that too, Kind Regards"

Is this porkies then??? (Apologies in advance to the owner if its not - the info just seems to be conflicting)

[GreenV8S]

The panels I've seen have all been far too small to even make a dent in the leakage current under typical overcast winter conditions. I suspect that they will work just as well under a street light, or an underground car park, or in the cupboard under the stairs. You probably don't even need to take it out of the wrapping. :

[shadowninja]

My Chimaera lasted 2.5 weeks with one of those basic panels, just sitting on my drive, panel resting on the "parcel shelf". (It may have lasted longer but I had returned from holiday.)

[Al 450]

Maplins do them for £10.00 on special offer (or did a couple of weeks ago), they will only work properly outside. Man made light isn't bright enough I'm afraid.