solar car battery chargers

Honest John Back Room » Technical matters
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Wed 2 Jul 2003 01:47
solar car battery chargers - bangerman
I'd like a second opinion on the solar battery chargers sold by various mail-order outlets. My measurements on two of them show maximum charging currents of about 50 milliamps under optimum conditions, viz. bright summer sunlight, with the unit angled to face the sun. In dull conditions, the current is much less, typically 10 to 20 milliamps. These currents are surely much too low to have any noticeable effect on a car battery. Discuss.
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Wed 2 Jul 2003 07:22
solar car battery chargers - David Lacey
OK I suppose as a means of battery power top-up during extended periods of the car/bike being laid up I guess........aslong as it is sunny!
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Wed 2 Jul 2003 09:18
solar car battery chargers - teabelly
I have one and used it for a while a few years ago. It is designed just to stop the battery getting flatter rather than actually charging it up.. I used to find when I didn't use the car very often the battery would be flat in about 6 weeks. With the solar charger on I didn't get another battery problem as far as I remember. It does work best if you charge the battery fully before attaching the solar charger for the first time though.
teabelly
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Wed 2 Jul 2003 13:07
solar car battery chargers - volvoman
Hi Bangerman- co-incidentally I started a thread on this subject in 'Discussion' this morning too so you may want to read the responses there. All I can tell you is that my solar panel produces 80mAmps/1 watt and a battery which had needed charging up several times over the last few months has worked fine ever since. It only cost £15 a I think it was well worth it.
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Sun 6 Jul 2003 14:59
solar car battery chargers - alapppy
HI

Do these only work if the lighter is powered up when the ignition is off

thanks
alan
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Sun 6 Jul 2003 15:03
solar car battery chargers - volvoman
You can wire mine direct to the battery if you have that problem. See the 'solar battery topper upper' threadin discussion.
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Sun 6 Jul 2003 15:36
solar car battery chargers - Marcos{P}
How do you fit the thing?
Does it just sit on the dash or do you fix it to a window?
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Sun 6 Jul 2003 18:46
solar car battery chargers - volvoman
Well mine just sits on the dash in my wife's car at the moment but I guess it could be more securely mounted elsewhere. Bear in mind that if it's mounted vertically it probably won't generate quite the same amount of charge. The unit's only about 12"x4" so it doesn't need a great deal of room on the dashboard and in Mrs V's car you'd hardly notice it was there aside from the connection to the cigarette lighter. How long's it gonna be before someone come up with a solar sunroof ?
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Sun 6 Jul 2003 20:22
solar car battery chargers - Marcos{P}
I think the Passat has solar panels in the sunroof to operate small fans to circulate the air if its left standing in sunlight.
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Sun 6 Jul 2003 20:17
solar car battery chargers - timp
I bought one of these when my car was used very little during the winter (short journeys once a week). During a sunny week, it was able to restore the battery charge sufficiently to change the colour of the indicator eye on the battery from red to green and maintain it on green. Made a noticeable improvement to the effect of switching on lights etc. on the speed of the ventilation fan, and the rate at which the heated windscreen and rear window demisted.

This was a 1.8 Watt solar panel and the car was facing south.

Tim
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