solar panel

[steve]

just got a 15Watt solar charger to use on trip to keys/dry tortugas.won't be hard wired into system so i can move the panel when i want/need to.but my real question is..... how much of a chance of "cooking" my batteries.i have two... deep cycle/marine/gel type......i guess i could just keep using stuff like fans/radio/blender if i'm over charging.anyone have a solor panel? any problems? thanks,stevemac 26x "heard the call"

 

[Gord May]

Watts or Amps ?

A 15 WATT Panel will NOT likely "cook" your batteries (< 2 Amp output).A 15 AMP Panel (>150Watts) WILL likely "cook" your batteries, if left unregulated.Solar Panels are usually rated in Maximum WATTS Output. [Watts = Amps x Volts] & [Amps = Watts / Volts]Regards,Gord

 

[steve]

watts.... not amps....sorry.... i should have known better...it's just my silly ole keyboard....

 

[ross]

You could monitor your voltage and

disconnect when your battery voltage reaches 14.4 volts. If you plan to leave it hooked up unattended for any length of time I would suggest a charge controller. You can get a good controller for around 35.00.

 

[Brad]

Monitoring likely to be of little value

As Gord said, it's not likely that a 15 watt panel will cook anything. If you are monitoring the voltage, you will only get an accurate reading after waiting a while after taking the charger off the curcuit...at least an hour. With a 15 watt charger, that's probably a precious hour. Check it first think in the morning before the sun comes up (actually, you might want to disconnect at night anyway so you don't get any drain from the panel), but, again, you aren't likely to overcharge if you are using anything electrical during the trip.Enjoy the voyage.Brad on the Willy T

 

[Dan McGuire]

How big are Batteries?

You can generally charge your batteries at a rate up to 2% of battery capacity without hurting them. It is generally better to keep it down to about 1%. Your 15 watt solar panels put out about 1.25A assuming that they are 12V panels. This means you can charge up to 62.5AH batteries safely(1.25/.02). If these are type 24 batteries, about 70AH, charging them individually is pressing your luck. Type 27 batteries, about 100AH, should be fine. Charging both batteries at the same time should be OK as long as their combined capacity is at least 62.5AH. I have a 10Watt panel which I use to keep my type 24 battery charged. It does an excellent job. I just replaced the battery after three years continually on the solar panel. Also as long as the batteries are at least 62.5AH batteries, a controller should not be required. Disconnecting the solar panel when you are sure the batteries are fully charged will prolong your battery life.

 

[ross]

monitoring your voltage

will tell you quite a bit about the state of charge of your batteries when your panel is producing power. With a 15 watt charge source and gel cell batteries, when your battery voltage gets above 14 volts with no other drain, you are close to fully charged. Gel cell batteries do not like to be overcharged.