Hello,
I have a small 500va uninterruptible power supply labelled IBM OP500. I am wayyy over my head but if I let the smoke out it is not a big deal.
I've had this thing 20 years or so. It's on its 4th battery, I believe. The battery light started flashing a few months back so I ordered a replacement.
I put it in and gave it a couple days and the battery light still flashes bad battery. It does not carry a load when line voltage is removed.
I threw it on the bench yesterday and determined that it is charging - which I assumed because it got acceptably warm when I changed the battery.
My question is if anyone can give me a direction to a chip to look around.
I am certainly charging. How do these charge and sense battery voltage at the same time?
It does switch to battery when line voltage is removed but it isn't enough to carry a load. I had a 200w 12v power supply on the bench (idle) I used for a makeshift load and it was getting 24vac, I believe. So it is switching and trying, but not getting any current. I did not test output without a load.
My thinking is the same pathway that senses the battery voltage has a considerable voltage drop.
I don't have the board out to get pictures yet.