Originally Posted By: Pete
...How much voltage and power do the solar cell assemblies put out? Are you able to directly connect these solar cells to your batteries, or is there some sort of voltage converter that I'm not seeing? Did it just happen that the solar cells put out the right voltage for your needs, or are they actually designed to be the right zie for this job?...

I can only guess what are the panel's real specs are because everything goes through that tiny AC-AC adapter (voltage converter as you call it) pictured on the right side. It gives out 2 regulated voltages for 12V and 5V. The 5V one is 0.5A, nothing known about the 12V one. However, the AA battery pack is charged by the 6.4V dedicated outlet, which I believe is not regulated and most likely providing the raw PV power.

Originally Posted By: Pete

I've seen other people with larger battery charging systems for lead-acid batteries. And it usually seems that they need some sort of voltage or power converter to get everything matched up. So ... just wondering why you don't need that here.

For a lead acid battery charging the most important part is the automatic charger, which will control the charging current so not to overcharge the big battery and to provide the most efficient charging cycle. You definitely want one if you are going to charge your batteries unattended. Otherwise you have to monitor the battery voltage often. From other side, you might need to do that only once. Just note the necessary time for your particular battery, and charge it for the same time the next time. The regulated voltage is less important here, just keep it at 12-18 volt. Also for direct solar panel charging you might need to add a diode into the circuit to prevent a back flow current (from battery to PV) at night.

I think that this particular panel is not good for lead acids charging, because the 12V current should be quite low on its 12V port (0.4A or so). But that was expected. In fact, I've been looking for a thin folding panel to charge 4 NiMH fast enough to my applications and with USB out.