Help with batteries...Please

[altpwr]

I have recently purchased VW solar panels (3 of them).  I plan on using a splitter (in reverse) to combine all 3.  This will give me a total of 9.6 watts.  Should I put a charge controller between the panels and the battery??

I have heard that 10 Watts is the magic number where a charge controller is neccessary, but I can't figure out why I wouldn't want a charge controller for a small system that will go a week or more without discharge.

Thanks for any info in advance.

[Nando]

altpwr:

What is a splitter in this case ?.

What is VW panel, please explain you you get accurate help.

What is the voltage & current output of each section?>

What is the battery voltage.

Regards

Nando

[commanda]

I think it's the ratio of panel watts (and hence amps) to battery ampere-hours that determines whether you need a charge controller or not.

Amanda

[PaulJ]

   Battery type is also important. Flooded cells are far more forgiving than SLA's where over-voltage is concerned, as long as the electrolyte level is maintained.

   

[altpwr]

The info I have is  for each panel -  

Max Power: 3.2 Watts, 18.8 volts, and 170mA

Electrical ratings at 1000W/m Squared, AM 1.5, cell temp 25 C

Each panel has a one way diode and 12v male lighter end.

There will be three of these hooked into a 3 to 1 adapter 12 volt male lighter socket. From there, should I go to a charge controller, or straight to the battery?  

I am doing this to increase the wattage to 9.6 watts

I am new at this, so sorry for any extra, or lack of, info and again, thanks in advance for any help

altpwr

[Ungrounded Lightning Rod]

Since the panels have an integral diode, the three-way

cigarette-lightr adapter setup you describe should work

just fine.

There are two problems with overcharging a wet lead-acid battery:

The extra power goes into electrolyzing the water into gas (which

goes away) and into heating the battery (which can cause thermal

damage if the heat gets too great - and losing water also loses

cooling fluid that would otherwise help distribute the heat.)

But with only 3 * 0.17A = 0.51A in full sunlight, if you've got

a car-battery sized battery you definitely don't have to sweat

thermal runaway and molten lead or boiling water.  B-)

And with, say, 5 solar hours per day you only get about 2.5

amphours per day, so you'll be doing well to stay ahead of the

leakage.  If you check the water ever few months you don't have

to sweat it going dry.

So I wouldn't worry about a regulator.  Just check the water

from time to time.

If you have an 85 amphour deep-cycle battery and discharge it

down to 20 amphours (about 74% discharged) it will take it a month

or more of sunny days for the panels to bring it back to full

charge.  So undercharge, or sulfation from chronic undercharge,

might be more of an issue.

[altpwr]

Thanks for that info.  I take it you would recommend a wet battery opposed to a sealed battery?

Also, It sounds like I need to add a few more of these panels to make it even remotely usable - even though it is only for occasional usage.

Thanks again.