Extending 650VA UPS discharge time.

[Achor123]

I have a 650VA UPS which I use to power my PC and a 30watt tube.The battery of the UPS during power failure lasts for not more than 20 minutes with the PC and tube on.I want to extend the length of time(autonomy time) of the UPS during power outage to at least 10 hours with all the loads on.I have about 20 12volts 20amphour dry cell batteries in place which(the UPS originally had a 12volt,7amphour dry cell) I intend to connect in paralell to the UPS thus increasing the amp hour of the system for charging and discharging.However,with this connection,the UPS heats up and goes off after working for about 1 hour.What design do I need to add to this to make it work?

Thanks

 

[mpparent]

What may be a better solution is to add a small standby generator. I don't believe there is a solution to the way you are trying to cobble up your existing "system". You could also get a larger UPS, eg one that has battery expansion cabinets (I believe you can small single phase units from Liebert or any other UPS manufacturer), but it may not be practical as the UPS/battery cabinet combination will be fairly large.

Mike

PS I believe your UPS is heating up because the batteries need charging current, and the amount required is not able to be handled by the rectifier circuit. Just a guess on that.

 

[itsmoked]

Achor123;

1) You do not have drycells in your UPS. Drycells are like flashlight batteries. You have GELCELLs!

2) To get 10 hrs out of batteries would require about 2 batteries the size of the largest car battery you've ever seen. But they would have to be, NOT automotive batteries, but deep cycle batteries. They would weigh at least 70lbs a piece. You would not want them in your house as they can give off some nasty stuff when being charged.

3) Hooking these in parallel to your UPS battery means your UPS's battery charger circuit would have to charge them also. It is not designed to do this and would probably toast.

4) Your UPS is over heating because you are essentially using it in a continuous mode that it wasn't designed to do. Most of the cheaper UPS's are designed VERY tightly so that they cost the absolute least amount of money to build, the UPS market is fierce!

mpparent is correct. If you want more than 30 - 40 minutes get a much larger rated UPS and don't increase your load or use a generator. The very best generator for your type load would be the smallest *inverter* type. These are very small, generally very quiet as they synthesize the AC power. The engine runs only at the speed needed to supply the connected load. This lets them idle along.

Honda makes the best ones.

http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=eu1000i

 

[Achor123]

I really apprecitae your coments mpparent and itsmoked.I probably have to get a standby generator except that I hate any form of noise.

 

[dwftx34]

Archor123
I agree with the comments above you will burn up the rectifier in your UPS because its only rated to charge the battery sized with the unit.
you could use a 12vDC booster battery made for jumpstarting cars and a inverter. i have used this setup to run a laptop and equipment for up too 8 hrs. using 17ah battery using an 400watt inverter. this will not give you UPS protection but in the event of a power outage you would not be in the dark. And its all quiet. There are some systems for sale here in my area through Frys Electritronics that should be avilable anywhere.

http://www.wagan.com/htmls/powersupp.html

http://www.xantrex.com/web/id/61/p/1/pt/29/product.asp

 

[itsmoked]

Alternatively Achor123, here's what else you can do.

Buy a large inverter making sure it has the charger function built in. Buy 2 or 4 deep cycle batteries like Trojan 6 volts (you hook them in series). Then you wire up the inverter to 120VAC or, whatever you have, and run its output to a power strip, which you run your lamp, PC, etc., with. The inverter passes thru the power and keeps the batteries properly charged and instantly switches to the batteries if mains power is lost.

My buddy has done this in in his office. Has a 2000 watt inverter and four deep cycles.

Inverter:

http://www.westmarine.com/webapp/wc...=10001&classNum=678&subdeptNum=544&storeNum=9

Batteries:

http://www.trojan-battery.com/Products/GolfCart.aspx

 

[ruggedscot]

If you wanted to continue to use your own UPS unit you could always alter it internally - Id be looking to do the following mods...

set up a battery and charger combo - as said before deep cycle batteries and associated charger this will give you a +vcc bus to feed your inverter with, how ever run this through some form of diode branch to prevent you toasting the battery in the UPS and also to prevent you from toasting the in built charger. If the internal battery to the UPS is higher voltage than the external units then it will pull from this first and drop the voltage until it matches the external cells - then you will pull from them. Ensure the blocking diodes can handle the power being used.

Over heating problems ? is this from the battery charger function of the UPS or from the UPS being used to supply a load when it is designed for short use only ? Think on ways to cool the unit bigger heatsinks - better forced ventilation - water cooled heatsinks anything to take away that excess heat....

Rugged