Help me extend the autonomy of an UPS

[maxer]

HI !

I have an UPS from TRUST model (TRUST 600 UPS)
It has an internal battery 12v 7 Ah and it last under full load 360w only 45 minutes.
I'm wondering whether i can connect to it a 80 Ah 12v battery or not.
Can the charger of the UPS handle it without beeing damaged? I want to extend the autonomy to about 5-6 hours.
What modifications could i make to it?


Anyone has the service manual or schematic for this??

Regards
Maxer

 

[haulm]

Re: UPS question!

I think the best way to your question is to ask the service of UPS's manufacturer.

 

[IanP]

Re: UPS question!

In normal circumstances battery inside a UPS unit is charged with limited current till it is "full" and then the charging mode is switched from "charge" to "trickle".
Connecting directly external 80Ah battery will most likely not damage the UPS and you have good chances that this combination of internal and external betteries may work well.
However, I wouldn't excercise this option and connect this battery through a, say, 10A diode, so it is only used when there is no external power, and cherge it with a proper battery charger when it is required. In this way you will have this huge backup, but in the same time you will not see its presence.
Regards,
IanP

 

[avino]

UPS question!

In normal circumstances battery inside a UPS unit is charged with limited current till it is "full" and then the charging mode is switched from "charge" to "trickle".
Connecting directly external 80Ah battery will most likely not damage the UPS and you have good chances that this combination of internal and external betteries may work well.
However, I wouldn't excercise this option and connect this battery through a, say, 10A diode, so it is only used when there is no external power, and cherge it with a proper battery charger when it is required. In this way you will have this huge backup, but in the same time you will not see its presence.
Regards,
IanP

I agree!!!

 

[rajudp]

Re: UPS question!

HI !

I have an UPS from TRUST model (TRUST 600 UPS)
It has an internal battery 12v 7 Ah and it last under full load 360w only 45 minutes.

Maxer

12v 7ah battery will not work for 45 minutes at 360w load, at 350w load it will work only works maximum 15 minutes

 

[bepobalote]

Re: UPS question!

In such type of cheap UPSs, transformer and electronics are underrated and are designed to work in NONCONTINUOUS mode.
If you will replace the 7.2Ah with a larger battery, the transformer (and the bridge mosfets) will reach dangerous temperatures (not mentioning cables) when in battery mode.
If you really want to use for several hours a cheap UPS, you have to use it at not more than 40% of its typical ratings (a lot depends on the quality of the transformer/efficiency) and be sure to keep the inner of the UPS well cooled/vented!

Regarding the charging of the 80Ah battery, you have to use an external battery charger, BUT in general you have also to disable the internal charger (there can be incompatibilities between the internal and the external one) which was not designed for a such high load!

Please also remember that (assuming a 80% efficiency at 360W) that the MEAN current flowing from the 12V battery is more than 35A. The maximum current will -without any trouble- be more than 100A...
A 10 A diode (as suggested) will die immediately!

 

[pranam77]

Re: UPS question!

I have an UPS from TRUST model (TRUST 600 UPS)
It has an internal battery 12v 7 Ah and it last under full load 360w only 45 minutes.
Maxer

12v 7ah battery will not work for 45 minutes at 360w load, at 350w load it will work only works maximum 15 minutes

Yes this was my thought too....Its is purely impractical to get a UPS backup for 45 minutes with 360 watts load with 12v 7 ah battery.

Ok..to extend the duration, you may increase the size of the present heat sinks by twice, as prolonged use will generate more heat than at present and Modify the battery charger section by thrice the present capacity, and then you may use a bigger battery as you have mentioned, but you'll have to replace the High current carrying wires too to suit the new batterys charging and discharging currents...Cheers

 

[rajudp]

UPS question!

i converted my inbuilt ups to an external one. i made an extra charging circuit for 12v 40AH battery. the transformer was good for external ( now a days they will using 75W transformer for 600VA UPS) So check the Size . a transformer with type 3 core with 2" to 2.5" tong width will work fine as external UPS. and you can add more heat sinks as pranam told