Smart-UPS 750 Not Powering

[geeked_apc]

This was originally posted on APC forums on 3/14/2009

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I picked up a used Smart-UPS 750 from a company that was getting rid of it. They said that it didn't work. I still took it home optimistically hoping to use it on my computer at home (I thought that it might be a simple fix like buying a replacement battery). First things first; I'm new to this kind of UPS, and therefore I have several questions.

First - The UPS does not power on. No lights, no sound, nothing at all. I decided to pull out off the front cover and have a look inside. The battery looks great... In fact, the whole unit looks almost like new. I got out a multimeter and tested for continuity of the wires. The two middle wires connected fine. The two outside wires did not. Is this normal?

Second - On the back is a big plastic cover with the words under it "Battery Connector". I thought that all of the battery backup was handled inside the unit. I tried to open it up and couldn't. What is this used for? Do I have to use it? How am I supposed to open it up?

Third - Seeing that this is some kind of server UPS, would it work for a personal computer setup?

Is the entire UPS shot or is it just the battery?

~Chris

[BillP]

This reply was originally posted by Angela on APC forums on 3/14/2009

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First - The UPS does not power on. No lights, no sound, nothing at all. I decided to pull out off the front cover and have a look inside. The battery looks great... In fact, the whole unit looks almost like new. I got out a multimeter and tested for continuity of the wires. The two middle wires connected fine. The two outside wires did not. Is this normal?

I believe it is, i'd have to look to be sure. did you measure the voltage from these batteries? i believe this is a 24v battery system.

Second - On the back is a big plastic cover with the words under it "Battery Connector". I thought that all of the battery backup was handled inside the unit. I tried to open it up and couldn't. What is this used for? Do I have to use it? How am I supposed to open it up?

To confirm, are you talking about the triangular connector on the back?? If so. this is what is called the "quick battery disconnect." APC, per DOT regulations, is not allowed to ship any UPS batteries with the batteries connected for safety reasons. This quick disconnects opens the battery circuit so that the batteries are not connected to the system. This is done like this so a user can just reconnect this quick disconnect rather than having to open the front bezel, etc to get to the actual batteries and connecting them. The connector should just pop off and when its open, the batteries are disconnected internally. Once connected, the batteries are then connected, so you should have this connector connected like the following picture on the bottom left: [click here|http://www.apc.com/products/moreimages.cfm?partnum=SUA750&type=Back]

Third - Seeing that this is some kind of server UPS, would it work for a personal computer setup?

There are no issues with using this with your personal computer at all. It is great for any system and provides both serial and USB data connections to use with your computer, as well as the advanced LED display on the front which can give you most of your UPS status.

hope this helps!

[geeked_apc]

This was originally posted on APC forums on 3/14/2009

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Here is a diagram of my battery (actually it's two batteries):

Edit: Couldn't get my diagram to show up right.

I've ordered it like this:

1 - 3 - 4 - 2

1 and 4 are negative. 3 and 2 are positive.

1 is connected to 2 and 3 is connected to 4. When testing for continuity, 3 and 4 connect, but 1 and 2 do not. 1 and 2 lead to a connector seems to just slide into the UPS. 3 and 4 must connect the two batteries together.

Which set am I supposed to check the voltage with? Shouldn't both sets of wires make a circuit?

~Chris

Message was edited by: geeked

Message was edited by: geeked

[BillP · Accepted solution]

This reply was originally posted by Tim on APC forums on 3/16/2009

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You would want to take a measurement off the connector used to connect the battery to the UPS itself.