Old UPS - trying to see if it works

[ckucia_apc]

This was originally posted on APC forums on 1/26/2016

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I have a Smart UPS 3000xl that was here at my employer when I started last March.  Nothing was connected to it and it wouldn't power up. 

Have a little bit of time now and am trying to determine if it is usable or should be scrapped.  Has an external battery pack.  I know it's a discontinued model, and I'd rather get a new one, but frankly, disposing of it would be quite the pain.  If I can get it to work even for non-production use, it'd be better than trying to get rid of it.

UPS is SU3000RMXL3U

External battery is SUA48RMXLBP3U

First thing I did was check all the batteries - they were all dead.

So I bought 8 batteries on ebay and replaced all the batteries in the internal 48VDC pack, disconnected the external battery pack.  Unit still wouldn't power up.  Verified AC power and checked breaker.  Checked voltage on battery pack and it's around 50VDC.

So I took off the top cover.

When I trace the wiring for the internal battery pack, the blue connector that the internal battery plugs into is attached to some heavy gauge cable.  The black ground runs from the front connector to a similar blue connector (one of a pair) in the rear of the unit.  Red hot takes a similar path, although has some device inline (fuse?).  I checked voltage at the rear blue connector, and it's 50VDC.

The odd thing is this voltage never gets to the internal UPS circuitry.  I don't see how the internal batteries could ever power the unit, much less get charged.  The internal circuitry is connected to another blue connector on the back of the unit, right next to the one that connects to the internal battery pack.  I could plug an external pack into this second connector after replacing its batteries, but that still doesn't explain how the internal battery pack connects to the UPS circuitry.  I checked the two blue connectors in back and they are isolated from each other.

Is there supposed to be some sort of jumper across the two blue connectors in the back?  I don't see how else the internal battery pack would ever power anything.  The user manuals for the UPS and for the external battery pack don't even note the second connector being there or speak of a jumper.

Any ideas?

[ckucia_apc]

This was originally posted on APC forums on 1/26/2016

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So, I noticed the blue connector on the internal battery pack matched the blue connector on the back of the UPS where the external battery pack plugs in.

So I pulled the internal battery pack, hauled it around to the back of the unit, and plugged it in.

Fans cycled, and the UPS fired right up after pressing the on button.

So, the good news is the UPS works, and I can take the 8 batteries out of the internal battery pack, use them to replace one bank of the external battery pack, and get 8 more for the second bank of the external pack.

Bad news is I still haven't figured out how to actually connect the internal battery pack to the UPS.  The way it's looking now, the unit shipped with batteries and they were never used - they just slowly discharged over time because the internal pack isn't wired to anything internally when you plug it into it's blue connector on the front.

[voidstar_apc]

This was originally posted on APC forums on 1/26/2016

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The internal and external battery connectors should be connected in parallel. Maybe there's a blown fuse.

[ckucia_apc]

This was originally posted on APC forums on 1/26/2016

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I found a blue plug on ebay that appears to be some sort of jumper that would span the two rear plugs and connect the internal battery pack back into the UPS unit.

(Here's a link, although it expires in about 8 hours: http://www.ebay.com/itm/161358457554?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

The diagrams in the user manual for the external battery pack show what appears to be a double plug with four wires (presumably twohots and two grounds) plugging into the two plugs on the back of the UPS unit simultaneously.  It also states that the last battery pack needs to have the plug cover (jumper) on it. 

From this, it sounds to me like the UPS I have jumpers the internal battery externally using this jumper, either at the back of the unit, or at the back of the last external battery.  The second pair of wires are used to jumper the internal battery.  My external battery pack doesn't have provisions for this - it only has a two wire plug and a similar receiving plug for another external battery.  No place for a dual-plug jumper to relocate.

Unfortunately, there's no one at the company who was here when this thing was purchased (around 2006).  It sounds to me like there was a design change and the UPS and external battery are a mismatch.

[voidstar_apc · Accepted solution]

This was originally posted on APC forums on 1/26/2016

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I think you're right. It looks like SUA48RMXLBP3U has a connector on the back for daisy chaining additional battery packs, although using it for what's supposed to be the internal battery would be a bit funny.