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USB batteries

RogerS

RogerS

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I have an APC Smart 750 UPSand the Replace battery light has been intermittently coming on with an audible alarm. I power cycled it and the alarm light went off and it was OK for a couple of weeks. But the alarm has come back on again....beeps for about 10 seconds then goes out. Few minutes later, comes back on again.

Two 12v batteries connected in series. One reads 13.06 v and the other 13.07.

Not sure what tests I can do.
 
RogerS":148ejdg0 said:
I have an APC Smart 750 UPSand the Replace battery light has been intermittently coming on with an audible alarm. I power cycled it and the alarm light went off and it was OK for a couple of weeks. But the alarm has come back on again....beeps for about 10 seconds then goes out. Few minutes later, comes back on again.

Two 12v batteries connected in series. One reads 13.06 v and the other 13.07.

Not sure what tests I can do.
Click to expand...

Correcting the subject might be a good start :lol:
 
More constructively, the voltages look a bit low for float charging so does that mean there is a degree of self discharge going on and the UPS is sensing this? Voltage match is good though.
Maybe the charger has a problem - low probability
If it is a clever UPS, then it might be measuring internal resistance as part of its BITE.

I think mine can be connected to a pc to run health checks and download history. It ran for 2-3 hours the other night as we had a power cut but I've not bothered to connect to it to download the data.

You could also run some internal resistance tests on the batteries when removed from the UPS.
The acid test, no pun intended, would be to see how long it will run the load it is designed to protect.

Here is mine (12v based) floating at 13.5v in red, at no measurable current in blue

UPS.jpg

Bob
 
Thanks, Bob, for the information. I've come to the conclusion that it's a binary choice !

Either the electronic circuitry inside has thrown and wobbler and thinks that the batteries are faulty when they are not OR the batteries are faulty.

If the former then I stand no chance of fixing it. If the latter then a replacement battery pack (but not from APC!) is worth a gamble. Especially as the voltage is on the low side as you suggested.

So new batteries, I think.

I can't find any s/w on the APC site for Macs.

Only caveat is that since the batteries have been taken out, the voltage has increased in both of them marginally (13.21 and 13.17v) ...no idea what that means.
 
9fingers":188ulzck said:
RogerS":188ulzck said:
Only caveat is that since the batteries have been taken out, the voltage has increased in both of them marginally (13.21 and 13.17v) ...no idea what that means.
Click to expand...

That's a bit strange. I'd do a test on load first and see how it performs before shelling out?
Bob
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LOL...you're assuming that I have a suitable load and/or know where my bits and pieces are such as croc clips, wire et al !
 
How old are the batteries? They're classified as a serviceable part and should be changed every two years iirc. We've loads of them, after market is significantly cheaper than oem. Some have been neglected in the past and we've had to drill out the pop rivets on the frame top get them out as they've swollen.
 
greeno":1autbb4t said:
How old are the batteries? They're classified as a serviceable part and should be changed every two years iirc. We've loads of them, after market is significantly cheaper than oem. Some have been neglected in the past and we've had to drill out the pop rivets on the frame top get them out as they've swollen.
Click to expand...


Quite a few years TBH...probably more than 4 years.
 
RogerS":1ubn3n1n said:
LOL...you're assuming that I have a suitable load and/or know where my bits and pieces are such as croc clips, wire et al !
Click to expand...

Sooo much easier than that. Pop the batteries back into the ups, plug in a computer and then cut the mains input off and time how long the UPS will run the computer.

maybe with a voltmeter attached to the batteries for interest.

Bob
 
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