Back-UPS CS 650 hangs with "no battery" light on

[Anonymous user]

After some time of no use, I plugged in my Back-UPS CS 650 and it unfortunately does not do anything. The "No Battery" light remains on but nothing happens, either with or without the battery. I am measuring 5.86 V on the terminals so it looks like an electrical failure somewhere. Where do I start?

I already know that, officially, the battery is the only user replaceable part, so no need to remind me of that. I am an engineering and I am looking for solutions

[BillP · Accepted solution]

When you mean the replace battery LED is on "but nothing happens either with or without the battery" - what are you expecting to happen? I am not sure what you mean by that. this LED comes solid on when the UPS fails itself test. when it is flashing, it means the battery is disconnected. If you measured 5.86VDC on the battery terminals, i am surprised that it is not flashing and indicating battery disconnected.

How old is the battery? when did this stop working properly? could it be just that this battery is really old and does not charge up anymore?