Maine, I put 3 Kyocera 140 watt panels on our boat with 3 Genasun controllers. We have a 6 golf cart house bank left over from the bad old days. Batts are fully charged and on trickle by noon,1 ish on cloudy days. Too good to be true? Am I hurting house bank by never discharging below about 75-80%? Also, I am not equalizing. Will all this cut into battery life?
Not equalizing can cut into battery life but shallow cycles, once broken in, will only help lead to longer life. Keep in mind that with three controllers, at high states of charge, one controller will win out in voltage supremacy thus essentially shutting the other two down. For a while you will get ping-ponging where voltage comes up with all three then one or two two shut down and voltage falls and all three kick back in only to ping-pong again. Once at an SOC where one controller/panel can supply the current to hold the voltage you will be running on the controller/panel with the highest voltage set point.
To confirm your SOC by noon shut down the solar input (Genasun controllers need to be broken on the output + wire to the batteries) and fire up the motor. Turn off all DC loads and run the RPM at about 1800 - 2000 depending upon your alt.. Note the battery terminal voltage and current flowing into the battery bank. If this is less than 2% of the banks overall capacity then your solar is doing what you think it is. If the accepted current is more then you are simply being tricked. You should see less than 2% current at 14.4V for a bank to be deemed "full"...
But lets do the math anyway. You have a 675 Ah bank. If you drop to 80% SOC you then need to replace 135Ah's + about 15% for charge inefficiency or approx 150Ah's to get to full from 80%..
If we figure your solar output only really begins getting good at 9:00 am then you would need 50A of charge current sustained for three hours to be "full" by noon. Three 140W Kyocera's are only capable of about 24A or about 8A per panel...... So if you are really dropping to 80% SOC then there is no physical way you are "full" by noon. It is however likely that you are still in bulk and the voltage is still climbing at noon thus tricking you into thinking you are in float.
