Hi! This is my first post on the forum. I looked around here and found info that helped me get to the point where I am, so it made sense to post here when I got stuck.
I'm stuck because I can't figure out if there is a point at which there will be too much internal resistance for my charger to charge my batteries.
Basically, my question is, is there a limit to how many 12v batteries wired in parallel I can charge with a single 50w solar panel? If so, how do I calculate it, and does it depend on how many amp-hrs the batteries are rated for?
The panel has the following ratings: Maximum Power Voltage: 17.5V; Open Circuit Voltage: 22V; Maximum Power Current: 2.86A. An Amazon comment from another purchaser said he measured 18.9v DC from this panel in an area on the olympic peninsula and measured 18.9vdc in "a shaded area on overcast days".
Based on my calculations for location and necessary reserve time, the bare minimum I can get by with is probably around a 110 amp-hour battery, but to be safe, I want to use a bank of either two 115 amp-hr batteries, or two 80 amp-hr batteries.
More specific details about my system in case it's relevant:
I have a system I want to deploy for about 3-5 years with minimal maintenance. My conservative estimate is that it will draw about 1 amp continuously, but the real average draw is about 0.5 amps, and I can make it shut off at night if I have to. It's being deployed on the North Olympic Peninsula (Washington State, in the United? States), where there's pretty crappy insolation in the winter, so I want a good margin of safety.
I am building a small long-term timelapse system that connects a canon camera running CHDK with an Eye-Fi card to a Verizon mifi 2200 cellular router. I've got a little microcontroller that cycles power periodically, and a board that splits 12v down to the voltage required for the camera and the router.
Thanks for any help you can give,