50Traveler Posted June 12, 2011 Share Posted June 12, 2011 I am not talking about a big metal box that hums and can push a steam-roller by the starter, but one of those low amp solar chargers that sits on the dash in hope that the clouds will part. I bought one some time ago and have used it successfully on low batteries that I wanted to give an extra boost. Since the amps are so low I wondered if they would harm a 6 volt battery.Are there any electrical gurus out there that can interrupt their chanting of "Ohm" long enough to answer this?Thanks as always,Justin Link to comment Share on other sites More sharing options...
24T42 Posted June 13, 2011 Share Posted June 13, 2011 My husband is an electrical engineer. He said no. I can't repeat his explanation but it made sense while he was saying it. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted June 13, 2011 Share Posted June 13, 2011 Add a 6 volt Zener diode in series, or a Runtz voltage drop resistor.Or, If you have 2 6 volt batteries connect them in series and charge like 1 12 volt battery. Link to comment Share on other sites More sharing options...
MCHinson Posted June 13, 2011 Share Posted June 13, 2011 Or the easy thing to do is to buy a cheap 6/12 switchable charger. I think I got mine years ago at Walmart. Link to comment Share on other sites More sharing options...
ply33 Posted June 13, 2011 Share Posted June 13, 2011 The solar panel is made up of multiple cells and, I believe, each cell puts out about 0.5v. I'd guess that the cells in your 12v panel are wired in series. It might be possible to cut the conductors that wire them together and change it to a series/parallel combination to have the panel put out 6v.Or you could purchase individual cells from an electrical hobbyist supply and wire up enough of them to provide 6v to make up your own panel rather than modify one designed for 12v. Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted June 13, 2011 Share Posted June 13, 2011 To answer your original question (I have finished the chantting of "Ohm"). You can - yet the purist will say no but I have one and use it to "trickle" charge my battery. I am guessing your solar charger is less than 1 amp max output. Your battery will use a little more water in the couse of a year. All other lights and radio should be off but when a load is thrown on the solar charger - the volts it produces will quickly drop in the "overload condition" so you will still be safe. The electic clock will not care. A single little light bulb will glow more brightly and burn out sooner. A headlight will overload and drop the voltage so no harm. Radio is overload as well.The use of series of diodes is needed to make the purist happy - each one drops the voltage 1.5 volts - so you will need several to drop the voltage to 7.5 to charge with. How many do you need - in bright light with no load measure the volts of the solar charger and subtract until you get to around 7.5 volts.If used in less than bright sunlight - I would not loose sleep over it. In a shop or garage - it may not even put out 7.5 volts to charge with anyways - use a meter and see.Ron Link to comment Share on other sites More sharing options...
50Traveler Posted June 13, 2011 Author Share Posted June 13, 2011 Thank you for that very enlightening response. The solar charger is rated at 1.8 watt / 125 mA (milliamps?)I have several other battery chargers of the plug in kind but hoped I could use this on sunny car show days when I am doubtful of the cars charge. Maybe I'll attach a clamp to each end of a hotdog and get ready for lunch.Justin Link to comment Share on other sites More sharing options...
Guest De Soto Frank Posted June 13, 2011 Share Posted June 13, 2011 Justin - Try wiring a 6-volt bulb ( say a #63 license light bulb) in series with one of the charger leads ( doesn't matter whether + or - )... that should drop the voltage down to 6 volts... Link to comment Share on other sites More sharing options...
ply33 Posted June 13, 2011 Share Posted June 13, 2011 Justin - Try wiring a 6-volt bulb ( say a #63 license light bulb) in series with one of the charger leads ( doesn't matter whether + or - )... that should drop the voltage down to 6 volts...Good idea. Except I think he'd need a bulb that is rated to draw .125 amps at 6 volts if his charger is .125 amps. And the #63 would actually be too low a resistance. Google tells me that DigiKey has something that might work but I can't open the DigiKey page at the moment to verify it. Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted June 14, 2011 Share Posted June 14, 2011 Two watts is not worth messing with except in the long term storage sense to maintain a battery.You would need at least 5 amps over a period of several hours to hope to start a car with a marginal battery even in direct sunlight - even more if the weather is cold.I "lug" a spare battery around in my 6 volt 49 Olds 98 just to be safe and 25 foot jumper cables to avoid a 12 volt jump.The battery is wired in to charge when the engine is running and it runs my 6 volt a/c system so that the regular battery does not get drained in slow traffic.Ron Link to comment Share on other sites More sharing options...
Guest Posted June 14, 2011 Share Posted June 14, 2011 Thank you for that very enlightening response. The solar charger is rated at 1.8 watt / 125 mA (milliamps?)I have several other battery chargers of the plug in kind but hoped I could use this on sunny car show days when I am doubtful of the cars charge. Maybe I'll attach a clamp to each end of a hotdog and get ready for lunch.Justin---------------------------------------------------------------------------I can understand having a battery charger for cars that are not in daily use, but I can't understand why you would need a charger at a show with a car that has no battery drain, passes a load test, and a charging system that is in good order. Those conditions are a prerequisite before my cars leave my garage in the first place. Link to comment Share on other sites More sharing options...
Guest Albert Posted June 18, 2011 Share Posted June 18, 2011 use a 6V dash light,, in series with the charger, and it will light if the battery is charged, or the solar cells are putting out too much current,, Link to comment Share on other sites More sharing options...
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