ivp wrote:
> I appreciate this panel is not a high-tech charger, but surely there
> must be some risk of gassing and/or ruining a battery with excess
> voltage ? Although I note your "As long as the battery is sized big
> enough so that it can handle the maximum current even when full"
>
> Still seems unwise to me, 22V and a 6V battery

22V is the open circuit voltage, which is not relevant when connected to a
load that looks largely like a voltage source.  The short circuit current is
more relevant.  That will have a nicely guaranteed upper bound in full
sunlight.  As long as the battery can handle this current (actually the 6V
current, which should be a little less), there will be no problem.

As you say, lead acid batteries are charged most quickly with a constant
current until they get to a voltage, then hold at that float voltage.  This
solar panel won't charge the battery in the quickest possible time, and the
maximum possible energy won't be extracted from the panel, but it works fine
for many applications.  Lead acid batteries have no problem being charged
indefinitely at some current.  As long as the panel can not exceed that
current, then there won't be any problem.  Conversely, you have to use a
battery rated large enough to handle the panel's full sunlight current
indefinitely.


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