Losing charge through a Sunsaver controller?

Andy I think the Morningstar SunSaver solar regulator SS10 is draining my batteries at night. Every night I read the volts on the solar side -.04, -.09, -.16 ; No load on 2 x 85amp leisure Batteries in parellel.  Batteries increase around .25 volts a day and topped out at 13.29 yesterday night then dropped to 13.09 tonight.

What's your verdict?

What are the best batteries to use with the Kyocera 130 watt solar panel?

best regards, Scott

Hi Scott,

If they are only dropping to 13.09V there is nothing to worry about! Anything above 12.8V for a 12V battery is basically as fully charged as you can get it. Although the voltage will rise slightly above that during the day while charging is happening, it's quite natural for it to settle slightly overnight even if there is no load on the battery. If it was going down to 12.5 or so without any load on the batteries I would think there was a problem - but over 13 is a very healthy battery!

You do always measure a small negative voltage on the solar terminals when they are not receiving charge - if you actually measure the current along that wire however you should find it is negligible.

Standard leisure batteries like you are using are absolutely fine for use with that panel. They should last at around 5 years or so if they are kept well charged - which it sounds like yours are. 'Sealed' or 'gel' batteries would last longer - but they are so much more expensive that it's not really worth it.

A bank of 2 85Ah batteries is fine, but on the smaller end of the bank size I would recommend - you could easily add another couple of batteries if you want to have a bit more reserve for times when you are using the power heavily.

Hope that helps,

all the best,
Andy