!!!UPS Modding!!! + >>>Increase Backup time Manyfold<<< I have done it....

[cyberaddict]

Hi Rollercoaster,
I need some help, I have "powersafe" (*www.powersafeups.com/line-interactive-specs.html) line interactive 600 va ups 3 yrs old with 12V/7AH battery, battary needs replacement and hence I think I can try out this mod. I am planning to attach 135AH to 150AH battery to this ups. since the internal charger will not be of help to charge this battery I will also get a external charger. The problem I am facing is in locating a internal charging circuit on UPS and placing a switch to enable disable it: I have basic knowledge of electronics circuits, but not enough to locate/modify the charger circuit on the UPS. Hence i think if I just put 1 diode in parallel with resister on the wire going to battery +ve terminal (anode of diode towards the +ve terminal of the battery pack) it will permanently disable the charging of batteries with internal charger. diode and resister ratnig I am planning to use are 2.2ohm/15W resister and diode rated for 150 amps. The idea here is resister will limit current to batteries during charge and during load current will flow through diode.
Please guide me if I am correct and if there are any problems with my diode/resistor ratings or any other problems?

 

[Rollercoaster]

From experience and more research I have determined that you dont have to disable the internal charger. you can let it running as is.

It is like attaching two power sources in parallel. So ur internal charger will give relatively negligible current and wont matter at all.

Also, when the battery is fully charged with the external charger the internal will also shut off as soon as it determines the proper voltage has been achieved.

Regarding you diode/resister Idea, if i understand correctly may work but it is not required and might be overkill.

Remember to mod the UPS for ventilation and cooling(fan) or it may burn out on extended usage.

 

[cyberaddict]

Thanks,
I have attached 120AH battery and use 6A external SMPS based charger. Added a fan and switch for cooling with some holes drilled for ventilation. My setup is working fine now. Not tested how long it will provide a backup. But it sure works for 50 minutes that I tested.
Thanks again for all the help and starting this thread.

 

[janitha]

Thanks,
I have attached 120AH battery and use 6A external SMPS based charger. Added a fan and switch for cooling with some holes drilled for ventilation. My setup is working fine now. Not tested how long it will provide a backup. But it sure works for 50 minutes that I tested.
Thanks again for all the help and starting this thread.

It will be better to use 12/10 A charger since lead acid batteries are generally charged @ 1/10th of the capacity. Anyway pl keep us informed.

 

[Rollercoaster]

It will be better to use 12/10 A charger since lead acid batteries are generally charged @ 1/10th of the capacity. Anyway pl keep us informed.

That is only a guideline. 6A is the standard in real world for 150AH and 10A chargers are not readily available.

 

[babu_mce]

hi
i am new here.i am thinking of modding my ups too (mine, too, is NUMERIC Digital 600 PLUS) . i have few suggestions.

Since this is a line interactive UPS we just have think about the battery.
what if we employ a switching circuit for connecting battery to the inverter section during LINE off using a comparator.

Also i am planning to make a 10A charger shown in www.sound.westhost.com for battery charging.although it lacks control circuit i think it wont make much of a problem since we have daily load shedding in my state.