UPS turning off even when the battery voltage is 13v

ketoneenergies

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Why ups is turning off even when the voltage of the battery is 13v. the cut-off voltage of the ups is 10v. But ups is turning off within minutes without using the battery charge. it even turns off even on very low load like 10w within in minutes. Any idea?
 

daromer

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What battery? What UPS?

A LA battery dont stay at 13V resting so is it at charge or is it lithium? Can the battery handle the load so it doesnt dip?
 

ketoneenergies

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daromer said:
What battery? What UPS?

A LA battery dont stay at 13V resting so is it at charge or is it lithium? Can the battery handle the load so it doesnt dip?
it is lifepo4. it is handling load without dipping. but it getting turned off like a timer is set. after particular time it is turning off.
 

Korishan

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It would help to know what UPS you are using.

Also, "time" each incidence to verify if it is a timer being used. And do the test with different loads, charging a phone/tablet, small heater load like a hair dryer on low, and then on high.

One possible reason this could happen is that a capacitor has gone bad in the UPS and would need to be replaced.
 

daromer

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You are aware of that UPS systems are ment to only run a short amount of time? Ie using an UPS as inverter may not work in some cases. Like some cheaper versions have a max run time since they basically expect the battery to be dead after that

This may not be the case for you but you have left out alot of details on whats going on and how you connected it all up.
 

Korishan

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Agreed with Daromer. However if the UPS is a server grade unit, then they are designed to run basically hours on end w/o let up.

Cheap house units are like he says, designed to only run about 30mins or less as they will heat up a LOT. I found this out when my power was out a few years ago for about 2 weeks. I had a small 500VA APC dumb unit. It was connected to a 12V Lead Acid car battery. It ran pretty good. However, the board warped a little, and discolored at some of the FETs and the poor cheap digital voltmeter I had laying on top there was a hole melted through the case where it was sitting on top of the FETs. Fortunately nothing actually stopped functioning. But I don't run it on long loads like that now. It only serves to keep my server/router from getting knocked out when our power blips. It's connected to a lawn mower battery now, though
 

Overmind

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I will do similar testing with LiFePo4s and 12V UPSes. My BMSs just arrived.
When I get some spare time I'll make the 1st build/upgrade.
 

Redpacket

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Some UPS are intended to (or can be set to) only run for a set time.
They may have a link to a PC/server to signal device shutdown, PC shutdown takes eg 2mins, UPS runs for eg 3mins, then shuts off = "safe shutdown".
 

daromer

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Garolds: What?
 

Korishan

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daromer said:
Garolds: What?

Was a spammer. He went back to previous posts and inserted unrelated urls
 

daromer

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Ah was to Quick hehe
 

kc8adu

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many cheap and nasty ups units have a timer in firmware.
its not designed to run beyond its stock battery capacity.
best ones are the old metal case apc and best power units.
i usually set up a fan that runs from the logic so it runs in inverter mode only.
metal case= probably good.
plastic case= probably junk.
 

Overmind

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The case logic may be generally good.
There can also be the issue of drawn current.

In my 1st LiFePo4 test I used a Mustek Powermust 848 which worked extremely well with 2P4S 6AH 26700 cells.
Let it run for 25 min under high performance laptop load and the cells maintained voltage extremely close to each other. Same when recharging. I did add a BMS though.

Problem in initial test: test connection had a too thin wire --> insufficient current --> UPS not working on batteries.
 
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