The trickle cells probably won't overtop the batteries, toasting them. Probably.    I added a pair between the solar cells and batteries last year, when I replaced a faulty cell.   One lives in the battery box by the V berth, next to the main switch.  The other is in the little storage nook under the companionway.   I looked at it as an inexpensive way to add a voltage gauge and USB ports for phone or IPad (Navionics) charger.   The negative is parasitic drain during winter layup.   I did the math, the milliamps added up from November to April.    The manufacturer cautions that a solar cell hooked to the controller but not to a batter would damage the controller.   I covered my solar cells and disconnected the batteries.  A smarter person would have wired in a switch.

Alex



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Alex Cole
S/V Lark
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