I have 7 of these HF float chargers / automatic maintainers and they all work great. They do an excellent job of maintaining my batteries at about 13.2 Vdc. I also verified that they shut off charging current once they reach that state, but will pulse the batteries intermittently to maintain them at that level. There is a two color (red & green) LED on the charger that indicates what it's doing. The LED flashes red when it is disconnected from the battery or connected wrong, stays solid red when it is charging (about 750 mA), flashes solid green when it is nearly fully charged (still charging at 750 mA) and then flashes green when it is maintaining (intermittent pulses approx. 200 - 500 mA on DVM). As I said, they all work good EXCEPT on three of the chargers the green portion of the LED no longer functions, the red portion is fine. I verified that the charger(s) itself is still working, only the green portion of the LED is not.
The circuit board is very cramped (the LED is particularly hard to get at) but I was able to manage to "ohm out" both parts of the LED. Each side (red or green) reads about the same: 2.4M (ohms) one direction and 4.3M the other direction. None of the chips on the dual sided PCB are labeled. Following traces is impossible as many of the traces are covered by components and/or pass through to the other side of the PCB. A thorough visual inspections reveals no obvious things like cold solder joints, bad traces, burnt components, etc. Because this has happened on three chargers so far, I suspect that the LED (based on the ohm readings) itself is good but that there is some sort of driver chip or transistor that might be bad.
Any chance anyone has a schematic for this (can't find anything via Google) or has done any hacking on these? I maintain quite a few batteries in the winter and it's really handy just glancing at the equipment to see if the green LED is lit, if it's not, then I have to make sure nothing got knocked loose, unplugged, etc. Thanks!
The circuit board is very cramped (the LED is particularly hard to get at) but I was able to manage to "ohm out" both parts of the LED. Each side (red or green) reads about the same: 2.4M (ohms) one direction and 4.3M the other direction. None of the chips on the dual sided PCB are labeled. Following traces is impossible as many of the traces are covered by components and/or pass through to the other side of the PCB. A thorough visual inspections reveals no obvious things like cold solder joints, bad traces, burnt components, etc. Because this has happened on three chargers so far, I suspect that the LED (based on the ohm readings) itself is good but that there is some sort of driver chip or transistor that might be bad.
Any chance anyone has a schematic for this (can't find anything via Google) or has done any hacking on these? I maintain quite a few batteries in the winter and it's really handy just glancing at the equipment to see if the green LED is lit, if it's not, then I have to make sure nothing got knocked loose, unplugged, etc. Thanks!