Join Date: Apr 2006
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Re: Stupid solar question
The cheap charge controller is just a regulator. What it will do is lop off any extra voltage coming from the panels, which might put out 22 volts unregulated at their max. So the charge controller is making sure the panels don't cook the battery, but it is set to 14.2 volts, and that might still cook a battery in extended use. If the battery is never getting fully charged, no problem, 14.2 should be fine for bulk charging wet lead cells.
the charger also apparently has a cut-off, so that it will prevent the battery from pushing back into the solar panel in low light conditions, which saves you from needing a diode to do that.
Instead of lopping off excess voltage, an MPPT controller convertes it to lower voltage at higher amerage, so you may see 10-20% more charging power from the panel but you've got to balance that against the higher cost for an MPPT controller.
On the amp ratings, you're OK where you are. Odds are that if the battery is never getting fully charged, you're just not getting enough power from that one panel and lop-off controller.
If you have conventional lighting on board, replacing it with LED lighting can sometimes do more for your charging needs than spending the same amount of money on anything else.