Gjac wrote:
pianotuna wrote:
Keep the voltage as high as possible without reaching the gassing voltage. If you are getting one bubble per second you are at the gassing voltage.
That sounds like a good rule of thumb, but isn't the chemical reaction still taking place at lets say 13.2v without gassing and if so isn't there some plate loss?
At 13.2 V there should be no sulfate building on plate surfaces since that voltage is still returning sulfate back into the electrolyte. A bit higher voltage, as referenced in the previous post, allows that to happen more efficiently.
I'd say, in a broad sense, that any voltage above 12.8 V ******* sulfation onto plates but in some batteries that may be occurring around some plate surfaces. Not all are built the same. A float voltage, as Pianotuna states, just below an excessive gassing point, is probably desirable. FWIW, I have my float voltage on the solar controller set at 13.6 V for two GC2 6v's. In the Winter, that will rise to 13.8 V, observable. I live in Southern MN where temps are low during the Winter.
There is also plate shedding where the positive plate of the battery looses material from the plate. This is an ongoing process as the battery ages. The electrolyte is causing the material to dissolve. Raising voltages causes this to happen faster. A short duration of higher voltages like the 14.5V delivered by a vehicle alternator after starting the motor is not going to harm the battery as it is trying to recover from the large draw that was but upon it to turn the starter.
Charging the batteries continuously at that voltage in warm weather when the electrolyte is at full value is going to cause electrolyte to boil off and more plate shedding can occur. Charging at that higher voltage when electrolyte is at a lower specific gravity like when the battery has been discharged may be a good value, however.
A battery user should be aware that a lead acid battery does have a limited life. There is just so much material available in the battery and the chemical reaction, at some point, is going to stop. I'd like that to be as long in age as I can make it since buying batteries isn't one of my happy times. FWIW, I replaced my truck battery a couple of years ago. It was 10 yrs, one month old when that happened. I consider that extraordinary value since I made it work to power all the truck's electrical needs and the 2000 W (maximum of the two amplifiers) of sound system I have installed. I bought the same Motorcraft battery.
If I can get anywhere close to the truck's battery age of replacement with my RV batteries, I will consider the exercise of tweaking the solar controller and having temp compensation a good exercise.