portable solar

[wncrasher]

I bought this portable panel this week:

Amazon.com: Go Power! GP-PSK-120 120W Portable Folding Solar Kit with 10 Amp Solar Controller: Automotive

My battery setup is 4 T-105's (500 amp hrs) and one SC-225 (130 amp hrs).
If I was down to 50% capacity, how long should it take this panel to recharge them?

The sales info says it does 6.7 amp DC per hour. Is it as simple as (225+65)/6.7=hrs?

[AirsDream]

Nothing is that simple. The literature assumes "standard conditons" - a certain latitude, altitude, cool panel temperature, perfect alignment, clean panel, etc. You won't have any of those things. There are also Peukert effects, battery age and condition considerations, wiring voltage drop, you name it.

So here's what you should do. Set it up where and as you plan to use it, hook the system up, and see what sort of charging rate you're ACTUALLY getting. Then you'll know more. But given the large size of your battery bank, it'll take a LONG time to charge those babies up if they're seriously run down.

[andreasduess]

I was thinking the same. Those are some serious batteries you've got in there.

I am currently learning about solar, so would also be interested in the opinions of those who know more than I do.

[RickDavis]

assuming full output from the panel you are looking at about 50 hours charge time In the real world it will be longer.

Basically, divide the number of amp hours needed ( 1/2 of total capacity in your case) by by the charge rate in amps (6.7) X about .9 since nothing is 100 % efficient.
In the real world it will be much longer than that as you will rarely see the full output of the panel.On the other hand based on typical use consuming 50 amp hours a day it would take many days to get discharged to 50% in the first place.

If you are conservative with your power use the panel will make a big difference but won't do it all.