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Battery Charge/Use question


MCTFisher9120

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Bought a solar panel thing the other week to charge up my Deep Cycle battery for the boat motor. Now, it comes with both clips and rings to attach it to the battery.

 

My question is, is it "safe" to have the rings on the battery...then a wing nut then the boat motor clips using the battery at the same time. The panel was $30 and it says it has overcharge protection on it. Just the most sun ut would get would be while I'm out fishing.

 

Or on the other side my arms are not big enough to carry a battery a few hundred meters to charge it every other day :P

 

Thanks,

MTBF

Edited by Mike The Bass Fisher
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Ya but the thing was from CT and like the size of a ruler long..maybe 5"wide. I saw another guy at my campground using it(his was screwed to his dock) and whenever he was in he attached his stuff...seemed to keep his Bass Tracker going....I have a good Motormaster charger also, just wanted to try the lazy mans way of things

Edited by Mike The Bass Fisher
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Okay, here's the simple formula, not 100% accurate, but close enough that will make you understand the math of recharging with solar. Everyone is trying to charge a 12volt battery, nominal fully charged after a 12-24 hour period of rest with nothing attached to a new battery is 12.6 to 12.65 volts, period. I know, a lot will say mine reads 13.2 or somewhere around there..12.6V to 12.65v is fully charged, read with a good quality voltmeter, digital or analog or with a temperature corrected hydrometer. By the time you drop to around 11.7v to 12.0v you're pretty much discharged. Now for the solar panel formula. A 15 watt solar panel, like the ones at CTC or Wmart will put out about 14-17.5 VOLTS(NOT AMPS) and put out a max of about 1(ONE) amp/hr in the most ideal condtions of full sunlight with the panel perpendicular to the sun and following the sun around during peak hours of about 10am to 4pm, befroe and after those hours, amp output is less, dropping off to less than .5 or 1/2 an amp. So at best you may see about 8-10 amps for the whole sunny day, much less on cloudy days or when your panel is in the shade or not "pointing" at the sun. Formula is Volts divided by Watts = Amps ie, 12V/15W= approx 1 Amp, under ideal conditions.

Those 5 watt panels barely put out 0.4Amp or 400mA. Then you must take into account parasitic draws such as radios/CD players(in boats/cars/etc) that use a small amount of power for memory, subtract that from your input. Don't forget that batteries also have a small static discharge rate, more in warmer weather, less in cool weather. So after a day on the water with your electric trolling motor, don't think for minute that a solar panel will recharge it with any efficiency, maybe a 2-3 15 watt high quality panels, but even those take time.

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