I have a solar panel rated at 5.2W (8V open voltage and 650mA short circuit) which I want to use for a weather station.
As lithium type batteries are not suited for cold weather conditions I want to use some other type (e.g. car battery or the like).
However, I could not find a suitable solar charger. I heard that car batteries or NiMh batteries have different charging characteristics than LiPos and therefore I cannot use a solar lipo charger.
Can anyone recommend a suitable charger?
Unlike lithium batteries, it is easy and safe to charge NiCD, NiMH and lead acid batteries. A few seconds with Google will turn up lots of circuits.
Who told you that lithium batteries are unsuitable? They are (generally) the best type for low temperature.
Lead-acid gel-cells are very forgiving. I would just attach a small 6v battery to that panel directly. No charger required. You will need a diode to prevent the battery from discharging into the solar cell at night but that may be included in the solar cell.
@jremington: I was indeed able to find several diy circuits before posting my question. However, I'd like to buy a ready-to-use product.
@MorganS: I found this article stating that lithium-ion batteries must not be charge at freezing temperatures: BU-410: Charging at High and Low Temperatures - Battery University
Why can I just directly attach a non-lithium battery to a solar panel? Isn't there a chance to overcharge the battery?