I think if you use rechargeable batteries you will be very close to the battery low threshold - it is not measured in a precision fashion just using a simple resistive voltage divider and a couple of transistors. With a 1.2V (nominal) battery this would give 4.8V at the terminals when fully charged, with zero current draw. The stated threshold in the ref manual is 4.2V +/- 0.1V so it is pretty close and with the age etc might well of moved around. When I have use rechargeables the light always comes on so I tend to feel they are generous with their calculations. Any significant current draw can pull the terminal voltage down as the internal resistance of the battery is quite high. Even a small current draw could drop the terminal voltage by ~200mV. They have an internal impedance of 25ohm @1KHz at least according to the spec. So that could easily push the batteries below the threshold voltage.
If the memory backup battery was a dead short there is a 1.8K resistor in the charge path which would limit the current to ~3mA which should not impact the overall current draw. There could be some abnormal drain on the board but again the parts are all 35yo and I would not be surprised if the leakage currents are now out of spec. If the LCD is starting to fail it will draw quite a lot (relatively) of current which might not help. You could re-check that all the new caps are installed correctly and there are no small solder bridges or any corrosion that could act as a high resistance bridge. On 6/6/20, 2:11 AM, "M100 on behalf of Erik van der Tier" <[email protected] on behalf of [email protected]> wrote: >Duracel 2500mAh rechargeables
