UPS does not turn on at mains failure

[Tipu606]

my Sendon 600VA UPS will not turn on to run my computer when the mains supply goes off, instead it beeps continously.
The battery voltage is 13.85V and seems OK
The UPS when connected to the computer runs all right when mains is present.
Can anyone please advise what to check?
thanks !
the similar circuit diagram is attached

 

[Qaisar Azeemi]

you have to see for two possibilities:

1) Replace any kind of relay in the circuit of the UPS. carbonated or blown out terminals of the relay may cause that problem.

2) check the power transistors (Mosfets/Bjts) for short. for MOSFET if they are short the multimeter will show short(Or continuous beep if beep mod continuity is selected) between the source and Drain.

in case of BJT check the same procedure for emitter and base shortage.

Replace all if you find them short.

Regards

 

[Tipu606]

@Qaisar Azeemi
Hi ! thanks for your valuable suggestions.
The battery is two years old so i did the good old battery test with a automobile turn indicator 12V bulb and the bulb went off after a few seconds indicating a bad battery.
Now replaced the battery with a new made in China 12V 7.2AH battery and the UPS is working fine, but the new battery still needs 12 hours of charge.
regards

- - - Updated - - -

 

[Qaisar Azeemi]

i am glad that you have solved the issue. you didn't write about old battery. however it was battery fault. congratz...

 

[edpalmer42]

@Qaisar Azeemi
Hi ! thanks for your valuable suggestions.
The battery is two years old so i did the good old battery test with a automobile turn indicator 12V bulb and the bulb went off after a few seconds indicating a bad battery.
Now replaced the battery with a new made in China 12V 7.2AH battery and the UPS is working fine, but the new battery still needs 12 hours of charge.
regards

Two years isn't a very long life for your battery. You might want to measure the float voltage on the UPS to make sure it's correct. Too high or too low a voltage will shorten the battery's life. Most small lead acid batteries have the desired float voltage printed right on the battery.

Ed

 

[tpetar]

That batteries have life age of 3-5 years, declared by manufacturer in usage on 25C. In UPS case hot trafo is sticket together to this batteries which lower life age of them. :wink:

This is by time life age, also life age is linked with battery cycling which is in range about 300-500 times.

Chinese battery replicas/clones consider with 1/3 of declared.

 

[Qaisar Azeemi]

Two years isn't a very long life for your battery. You might want to measure the float voltage on the UPS to make sure it's correct. Too high or too low a voltage will shorten the battery's life. Most small lead acid batteries have the desired float voltage printed right on the battery.

Ed

In our south of Asia mostly tap water is used in the Batteries instead of Distilled water. since Tap water have impurities that cause the Reduction of life of the battery to 1 or 1.5 years. here this battery fault is common. However, if Distilled water was used then he might go with the above given method for battery; else i am sure the battery life was over.

 

[Tipu606]

That batteries have life age of 3-5 years, declared by manufacturer in usage on 25C. In UPS case hot trafo is sticket together to this batteries which lower life age of them. :wink:

This is by time life age, also life age is linked with battery cycling which is in range about 300-500 times.

Chinese battery replicas/clones consider with 1/3 of declared.

genuine branded 12V 7AH batteries are not available in the market, so what we get to buy are substandard cheap ones which do not last long

 

[tpetar]

genuine branded 12V 7AH batteries are not available in the market, so what we get to buy are substandard cheap ones which do not last long

Ammount of music according to the amount of money. ;-)