Connect with us

Extra battery wire in UPS. Voltage-sense? or what?

Discussion in 'Electronic Repair' started by mc, May 31, 2007.

Scroll to continue with content
  1. mc

    mc Guest

    I'm replacing the batteries (2 x 12V, in series) in a Best power supply from
    the early 1990s.

    Obviously, I have a negative lead, a jumper to put the two batteries in
    series, and a positive lead.

    Attached (with tape) to the red positive lead is a white wire with a smaller
    female spade connector on the end of it. The person who previously replaced
    the batteries did not connect the white wire to anything. What should it go
  2. JR North

    JR North Guest

    It should connect to a temp sensor buried between the cells and used to
    detect an overcharge condition.
  3. mc

    mc Guest

    Thanks. I was thinking temperature sensor but didn't see one. I'll look
    more closely. It's possible the previous person discarded it. (Maybe it
    was stuck to a battery and was discarded with the battery.) That, in turn,
    may be why the batteries lasted only 3 years in light use.
  4. mc

    mc Guest

    I found the battery replacement instructions on and they
    say not to connect the white wire to anything at all -- which leaves
    completely open the question of what it was originally for.

    Its connection on the circuit board is labeled SM or WS depending on whether
    you read it right-side-up or upside-down.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day