The Noco Genius 1 uses an IC charge profile, Once it gets the battery up to 14.7ish at 3 different amperage levels, declining as battery voltage rises, it shuts off and only restarts once battery voltage drops to 12.69v, at least on teh AGM setting, when i tested my dad's
Others prefer a maintenance charger that holds the battery at 13.2 or 13.6v, always
Ideal float voltage depends on the battery, and its temperature. Too low and self discharge can occur, or parasitic loads can allow it to discharge, too high and positive plate corrosion and excessive water usage can enter the picture.
Bay area temperature swings not being extreme make for the latter being less problematic. The Noco might have its user complain that it is not holding the battery at a constant voltage as they expect.
While this certainly is not a solution for every user, and this should not be applied to a well depleted battery, One can adjust the voltage that it holds the battery at.
I think a power supply which brings the battery to 14.1 to 14.5v for 5 to 15 minutes a day is what i would do for long term battery storage in a place where temperature extremes are a consideration.
There are many different versions of the LED power supply above. I had a 22$ one which I played with. It was rated at 30 amps but a depleted healthy battery would accept 36+ amps from it, and above 36 amps it made an unpleasant noise. It does not have the ability to limit amperage, only voltage. Some of the clones of this product, will claim to have the ability to limit amperage. Grain of salt.....
I modified it with a better fan and more heatsinking and a better voltage adjustment potentiometer, but had to manipulate the voltage, manually, in stages to keep amperage below 36 when charging a depleted battery.
When this became irritating, I set it to 14.8v, hooked it to a depleted battery and 36+ amps flowed from it into battery, for 17 minutes, until it released its magic smoke.
I then ordered a Meanwell rsp-500-15 adjustable voltage power supply. rated for 500 watts, it delivers upto 623watts . I modified it too, with a better voltage adjustment potentiometer, quiet Noctua fans, and additional heatsinking on case exterior adjacent to heat producing transistors. it will output 40 amps all day long at any voltage I choose between 13.12 and 19.23. Its been my primary plug in charger since september 2014 and has many thousands of hours of use on it.
I've also added a 50 amp 'Ideal Diode' (only a 0.04 drop across it) and a shunted ammeter which displays amp hours and watt hours passed, SO I can easily dial in the voltage I want, and see how much amperage the battery accepts, and over a period of time how much watt hours or amp hours the battery accepted. Well, I often have DC loads on the battery so the total AH/WH figures also include those DC loads.
There are benchtop adjustable voltage, adjustable amperage power supplies which will allow a precision no 'maintainer' can hope to match, but it requires that a human control it properly. Perhaps raspberry Pi control for those capable of such.
