The 17 to 19 volts panel output is what drives most people crazy! They erronously percieve that same voltage is present when the panels are hooked to their battery bank. Realizing load concept for most people does not happen. I am done with this as we have done it before and results the same. Chief
A typical boat battery would likely never attain max panel voltage because as we increase voltage the battery accepts more current, even a full battery, but this is very bad for the battery.. We can't over look what the video is showing.
220Ah Lifeline AGM Battery Bank -
*Charged to full with charge controller and 12W solar panel
*Solar controller removed and 12W panel left unregulated
*Battery voltage is now pushed to 15.1V with .72A of current flowing into it
*Once full this battery is experiencing excessive levels of daily over charging even with a 12W panel.
*Battery voltage should be regulated to 13.4V for this battery once current has dropped to 0.5% at 14.4V.
The reason the voltage stoped at approx 15.1V on this 220Ah bank is because with .72A, at that SOC, 15.1V is creating that much current acceptance. Voltage is pressure and as we increase it more current can flow into the battery. In this case MUCH, MUCH more than should be. If we raised the current to 1A (a 15W panel) voltage would go higher.
125Ah Flooded Battery
*Charged to full with charge controller and 12W solar panel
*Solar controller removed and 12W panel left unregulated
*Battery voltage is now pushed to 15.48V with .71A of current flowing into it
*Battery experiencing excessive levels of daily over charging.
*Battery voltage should be regulated to 13.6V for this battery. The switch from absorption voltage to float is to occur when charge current at absorption voltage ceases to drop by more than 0.1A in one hour. This tends to be at about 0.4% Ah capacity in tail current where the absorption to float transition needs to occur. In other words when the battery is accepting 0.32A at 14.6V it needs to be dropped to float voltage. The 12W panel was capable of continually driving upwards of .72A into the battery and this is why voltage hit 15.48V. Pushing the battery to 15.48V is an
equalizing voltage essentially every day for 3-5 hours.
Equalize your batteries every day for 3-4 hours and see how they hold up...(grin)
The reason the voltage stopped at approx 15.48V on this 125Ah bank is because with .71A, at that SOC, 15.48V is allowing .71A of current acceptance. Voltage is pressure and as we increase voltage more current can flow into the battery. In this case MUCH, MUCH more current than there should be at 100% SOC. If we raised the current to 1A (a 15W panel) voltage would go even higher.