Solar charger

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Mac

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Jun 7, 2006
436
MacGregor 25 KEUKA lake NY
Here is a new one, and I tried to archive it but no luck, my buddy gave me two 9volt solar chargers. I put the volt meter on one and indeed it kicks out 9 volts. Can I hook them in a series and get 18volts? Is this usable for my sailboat? I have one battery on it and only run the running lights and bilge pump once in awhile. Thanks, Mac
 
Jun 2, 2004
252
hunter 260 Ruedi Res.
whats the wattage on the panels??

They should work just fine wired in series for a 12 volt system. Most 12 volt panels are rated at 17-20 volts peak power output. If the output is much over 15 watts I would recommend a charge controller be used with them.
 
Aug 9, 2005
772
Hunter 28.5 Palm Coast, FL
No they won't work!!!

If they are indeed nine volt solar panels (which is a strange voltage) and you hook them together in series to get 18 volts you will damage a 12volt battey with too high a voltage, the best you can go is about 14.5-15 volts without damage.
 
Jul 1, 2004
567
Hunter 40 St. Petersburg
Actually,

the open voltage on each of our 110 watt Shell panels is in the 18 - 20 volt range. This is normal. Once hooked to the batteries the potential is reduced and you'll see lower voltages. The MPPT controllers now on the market actually promote wiring panels in series to get even higher voltages (30-50 volts) which they then convert to more battery friendly voltages and additional amperage. Having said all this, I would recommend doing more homework and contacting a knowledgeable source regarding your specifics before hooking things up. I would suggest John or Libby at: www.svhotwire.com
 

Mac

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Jun 7, 2006
436
MacGregor 25 KEUKA lake NY
yes

it was in full sun. A guy at work said it should work if I loop the two solar boards to the battery. He said I could block off some of the cells with tape, like 25% of each panel.
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
Mac

If one panel has an open circuit voltage of 9 v then it is probably meant to charge 6 v batteries. Have they got any markings which will allow you to look them up on the web? These units normally have a high internal impedance and need to be loaded down before they generate any worthwhile current. ie 9v to 6v or 22v to 14. I would suggest putting them in series will be fine BUT, just like any other solar panel they will overcharge your battery if left on indefinitely. However charge regulators are not dear. Normally you will only need one if the current output is more than one amp, otherwise they are just trickle chargers. I would advise against taping over some of the cells as this will reduce the output to almost nothing. Some panels have diodes across each cell to help them overcome shadows caused by rigging and ropes etc. Yours may have these so I suggest connecting up and monitoring the current. Then cause a shadow and see what happens to the charging current.
 
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