UPS not detecting load and wont run off Batteries

Martin SMITH Member

Hi

I have an SMT1000rmi2u and yesterday it starting chirping saying to connect batteries. I reset the unit and it detected the bateries, but now doesn't detect a load and does not run on batteries (if the A/C input is cut, so is the output) I tested the four batteries and 3 were between 11-13v, one was 9.31. Could the one battery be causeing that? why would it not detect any load even when there was one?

Grateful for any help
Ta
Smudge

Martin SMITH, 2024-11-24 10:25:33 +00:00

#99

NB-23 Member Warrington

Howdy
thanks for writing.
I think one of the cells is bad - the 9.31V one you've metered.
IF the cells are new, repalce just that one.
If the cells are older than say 2.5 years, replace all of them. If you have reason to believe the cells have been deep discharged or abused, replace them all.

Not detecting a load is different - thats a sign of a fault.

UPS do need a good cell bank to work at all (wont turn on without a certain DC voltage supplied) so it could be related to that, but you wont know till you get a good cell pack in it. My gut is its two things you are seeing, battery problem + UPS either having a one off problem, or fault.

If you order the cells from us and find its the UPS, we'd sell you a UPS core at roughly the cost of the UPS minus the cells you have already bought - this lets you try the cells first, with the back up plan of replacing the UPS too if needed.

If you have little time you can go ahead and order straight off another of the UPS with new cells. These are reasonably priced and currently on sale.

https://secure.ups-trader.co.uk/rack-ups/175-smt1000rmi2u-no-front.html?search_query=smt1000rmi2u&results=7

NB-23, 2024-11-25 12:21:11 +00:00

#104

NB-23 Member Warrington

Noting your follow up email gives the details of the order - its one of ours from may 2020 (circa 4.5 years old) - this makes me certain the cells are needing replacement. I'd say give new cells a whirl and see where that gets you, unless you need a rapid solution in which case go for the above UPS with cells.

This is the link to the 4x cells to rebuild your existing pack.

https://secure.ups-trader.co.uk/rebuild-kits/284-rbc132-rebuild-kit.html

You mention checking fuese - I dont think thats it.

NB-23, 2024-11-25 12:24:10 +00:00

#105

Martin SMITH Member

Hi NB

Replied to mail as well. last night it was detecting load and said batteries were 100% which makes me think the UPS actually has a fault. Why would the UPS say the battery was 100% if the cells were at fault? as an electrician, that makes no sense to me so I am gen interested in how that works?. If the batteries are 12v each and are kicking out 11-13V with the exception of the 9.31V one, I would expect the UPS to record a less than 100% reading? this machine has had one power failure a year ago and the batteries kicked in straight away and obviously the % went down, are they kept trickle charged? I dont just want to buy four new batteries only to find that the core itself is faulty.

Martin SMITH, 2024-11-25 12:59:43 +00:00

#106

NB-23 Member Warrington

Howdy,

noting you are an electrician.
The UPS is charging the cells at the same time as checking their capacity - the voltage you'll read on the whole pack when connected to the UPS is probably lifted from what you measure with the cell pack out of the case?

The UPS is using this to guess charge capacity.
Normally, when the cells have some life, when it does a blip test it notices a voltage drop higher than normal and says "batteries dead". Sometimes the cells are so bad it doesnt have time, and turns off instead, and then you might struggle to restart the UPS.

Quick version - its hard for the UPS to know cell charge capacity when the batteries are being chagred, and espeically if the UPS has just been turnd on.

I still think its new cells time.

I've covered how we help if it does turn out you have two problems (dead cells and a faulty UPS) in my first reply. We dont leave you in the lurch!

NB-23, 2024-11-25 13:38:59 +00:00

#107

Martin SMITH Member

NB-23 Member Warrington

NB-23 Member Warrington

Martin SMITH Member

NB-23 Member Warrington

Report Post

Write your reason