Solar cell tricke battery charger - PeachParts Mercedes-Benz Forum

JHZR2 · #1 01-11-2004, 10:27 PM

Hi,

I was driving by my local VW dealer, and I noted that in all the cars in the lot, there was a solar cell array suction cupped to the windshield. I believe it must be a setup that is used to keep a tricke charge to the battery.
This would probably be useful for people with our cars in cold climates, since the battery's power drops with the temp. This way you always have a full charge.

I am interested in getting one or two of these if they arent cost-prohibitive. Does anyone know about these units?

Thanks,

JMH

kerry · #2 01-11-2004, 11:15 PM

I think JC Whitney sells them.

JHZR2 · #3 01-11-2004, 11:49 PM

Do you know if they are usable through the cigarette lighter in our cars, since it is not powered without the key? I assume that if an outlet is not powered without the key, the charger must be directly attached to the battery?

JMH

#4 01-12-2004, 01:11 AM

I don't see why one could not just cut off the cig lighter end and splice a connector to the battery with an on/off switch or quick disconnects.

Kestas · #5 01-12-2004, 08:36 AM

Can anyone comment on whether overcharging is a concern and if these units are designed to protect from overcharging?

Russo 85300tD · #6 01-12-2004, 08:45 AM

They dont have enough current capacity to overcharge a big diesel battery. Just make sure they have a blocking diode built in otherwise your battery can discharge thru the panel at night

Russ

#7 01-12-2004, 12:24 PM

I have two of them. They work great. Their capacity is only a few milliamps, so it will not overcharge your battery. They will NOT charge up a dead one either. Since the cigarette lighter plug is not powered, you would have to modify it to tap into the fuse box. Personally, I'd get the correct cigarette lighter plug from rat shack and tap it in that way. Since the Dodge sits for quite a while between uses now, using the solar charger has made a noticeable difference in starter speed when starting the truck.

I bought mine off of Ebay cheap. I'd put in a search for solar chargers. There are always a couple of dozen to pick from.

JHZR2 · #8 01-12-2004, 12:29 PM

Im looking at the VW model... Has 4 nice suction cups to put it on the windshield. The specs are:

Part number: 1C0 915 687.

Max. Power: 3.2w

Voltage @ Max Power: 18.8v

Current @ Max Power: 170mA

Why is the voltage at max power so high? Shoudl this be an issue, i.e. should I consider a charger that does more like 14v at max power, like the alternator in the car?

Also, is 170mA too high? I assume these things only put into the battery what the draw is. Once the voltage of the cell equals the voltage of the battery, it stops charging. Thing is, 18.8V is nowhere near the voltage of our or any battery. My chevy truck is somewhere near 15V because its a slightly different battery type, but thats as high as Ive seen them.

Should I overlook this one? I have to assume that VWs use a 12V system, so dont quite understand why it would put out such high voltage.

Thanks,

JMH

Russo 85300tD · #9 01-12-2004, 12:41 PM

The 18 volt is the open circuit voltage for the solar panel. When loaded with a battery and delivering the full 170 MA the panel voltage will drop to between 14 & 12 volts depending on the load. This typical of solar panels. My 100 watt panels run 21 to 22 volts open circuit with no load. At 3+ amps output the voltage is 14.5 volts or so

Russ

JHZR2 · #10 01-28-2004, 04:32 PM

OK, so I did something really stupid. Today there was a break in the weather, and I wanted to do my fuel filters and diesel purge, in preparation for replacing some of my glow plugs... And not thinking, I didnt unplug the panels (I had wired in a constantly on outlet as suggested above). There was no smoke or odd smells, fortunately.

It seems to me that a couple of the panels are aq purplish hue, whereas the rest are blue (I dont recall if they were this way before) Also, testing in very indirect 415pm sunlight, I was only getting ~7.5V when testing via my multimeter (Is solar cell voltage a function of sunlight intensity, or is just amperage/power output a function of intensity, with the voltage always the same?) and 19+V when I laid it on my incandescent light, so that all the light was directed onto th solar cells.

So, did I ruin the panel? It states explicitly on the back that 'the panel MUST be unplugged prior to starting'
If I busted the panel, and am only getting 7.5V (Ill test it in bright light tomorrow), then the panel will still work, but will only keep a battery at ~7V, right?

What might I have busted by leaving it plugges with the car on?

Thanks,

JMH

#11 01-28-2004, 09:13 PM

Your incandescent light test sounds like you didn't do any harm. I'd double check it in full sunlight, like you suggested that you are going to do. If the voltage is still 18v, then don't worry about it. You just don't want to have the thing plugged in while driving down the road.

Russo 85300tD · #12 01-29-2004, 07:59 AM

Output voltage & current are a function of the amount of sunlight that falls on the panel. Try measuring it in bright sunlight and I bet the voltage output returns to normal. Incandesent light sources usually only provide a minimal output from solar panels due to the limited spectrum and intensity of light

Russ

shoe · #13 01-29-2004, 12:13 PM

We have used them in limited instances on our fleet vehicles. Ones that sit alot. Try this website http://www.pulsetech.net it is for the solargizer brand.