low quiescent draw charge controller

[tirebiter]

I have a 1.5 Watt panel. Is there a low power 12 Volt controller that is known for it's small amount of drain on a battery when the sun is not shining. I have a 10 amp controller but the drain at night is apparently too much. More than the panel by itself, drained it at night. The battery never got to full charge over several days of using the charge controller. It was fully charged when I first tried the controller. I'd rather not increase the panel size/output if possible.

If you want more info, I posted on the show and tell forum explaining about my coffee grinder that is solar powered.

 

[kernel]

Morningstar solar has a Sun Guard 4a charge control with low power draw (6 milliamp)
There are probably some postage stamp size ones out there.

 

[tirebiter]

I looked at the data sheet and cannot find any rating for how much currect it draws at night when no sun is shining. AT this time, I am testing a small MPPT solar charge controller board but it's confusing me as to how the make a couple of trim-pot adjustments on it. At least it didn't seem to drain the battery overnight although it does not seem to be charging the battery up as much as the PV panel did by itself when wired directly to the battery.

 

[SolarRat]

although it does not seem to be charging the battery up as much as the PV panel did by itself when wired directly to the battery.

14.x volts will never charge as fast as 18+ volts. But it will save your battery.

 

[kernel]

I would call or email morningstar solar and ask. They will likely be happy to answer. 6mA is described in the literature as self consumption. I would assume it to be without power applied which would consume more power as it moduletes more, but could just as well be max power draw max power modulation.... assume theres problems with assumptions.

Another assumption is that you likely want a 200-300mA control. Led indicators and relays or other power control capable of handling an amp or 4 may use too much of your panel output?

 

[rin67630]

I have a 1.5 Watt panel. Is there a low power 12 Volt controller that is known for it's small amount of drain on a battery when the sun is not shining.

I found out that the best with small panels (which are mainly designed to peak at 16-17v wo load) is to feed them through a Schottky diode directly to the battery.
If you run some kind of programmable device from it, you may measure the battery voltage and switch a load whenever the battery voltage exceeds 14,5V until it dropped to 13,8 again.
Every MPPT device i've found drains more energy than the useful load does!

The advantage of that process is that it needs no energy fo itself when power is scarce and you get every mA onto the battery.
In bright sun, once the battery is fully loaded anyhow, you have got too much of it.
On bigger panels, up to 10W it is good enough, above the MPPT are better.