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Thread: SuperDooper computer UPS power (trick)

  1. #1
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    Default SuperDooper computer UPS power (trick)

    Ghetto hack for your UPS power system.

    I have 2 UPS for pc's that I wasn't using because I have a fast switching inverter in my home but it seems in my new clinic in santo domingo, we have a diesel generator. So when the lights go off and if there are no patients in the clinic, they would take as long as 15 minutes to turn on the generator. Sometimes they wouldn't turn it on for a long time. Mean while my computer would get turned off as my laptop battery is dead. I replaced the dead battery in the ups which I had connected with my internet modem/router and laptop but it only supplied me with 10 minutes of power, max. Then within 5 months the cheap toy battery just died inside the ups.
    So i started to read on the net about a hack in the ups which would give me more power and duration. remember, the UPS for computers is a small inverter and it also uses a 12 volt battery. All I had to do was replace the tiny battery inside with a bigger car battery connected on the outside. I simply took the power battery cables from inside of the ups and extended then outside of the case and connected them to a small sized car battery. Now I have a ups which will last me hours if the clinic decides not to turn on the generator. This battery will give me years of service as compared to the small tiny toy battery which came with the ups.
    Here is a picture of the setup, which is not mine but I pulled it off the net. I use only one car battery.

    http://www.dansdata.com/images/carba...arbatt1280.jpg

  2. #2
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    Been doing that for years and years Aftab, long before I ever came to the D.R.

    I had one of the old Tripp Lite UPS's which had a separate switch for operating the inverter portion and this is very handy.

    I could control whether the inverter activates or not on loss of A/C power. This feature is nice because it does not run the battery down when you are not using the UPS to power the computer. If you have long blackouts, the UPS would be dead just sitting there not powering anything otherwise.

    It's a shame they did away with that feature.


    Don

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    Correct me if I'm wrong, but those batteries are wired in series which means they are either 6 volt golf cart batteries or else that is a 24 volt UPS.

    I would recommend using inverter batteries over car batteries for this application, because we all know what happens to car batteries if they get drained real low.

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    Quote Originally Posted by MrMike View Post
    Correct me if I'm wrong, but those batteries are wired in series which means they are either 6 volt golf cart batteries or else that is a 24 volt UPS.

    I would recommend using inverter batteries over car batteries for this application, because we all know what happens to car batteries if they get drained real low.
    The picture is not my setup, its a picture from the net. My setup is exact but with a car battery. Now I do not think the inverter will drain the batteries to dead, because all inverters have a low voltage cut off setting. This means if the voltage goes down to like 11 volts (example), it will cut off the inverter. Now it seems my ups is constantly charging the batttery. I measured the battery and it measured like 12.67 volts, then 12.89 and then 13.1 volts. So what is the cut off level for charging? I hope it will not fry my battery dead.
    AZB

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    Quote Originally Posted by AZB View Post
    The picture is not my setup, its a picture from the net. My setup is exact but with a car battery. Now I do not think the inverter will drain the batteries to dead, because all inverters have a low voltage cut off setting. This means if the voltage goes down to like 11 volts (example), it will cut off the inverter. Now it seems my ups is constantly charging the batttery. I measured the battery and it measured like 12.67 volts, then 12.89 and then 13.1 volts. So what is the cut off level for charging? I hope it will not fry my battery dead.
    AZB
    Typical charge voltages for a 12 volt battery is 12.6 - 13.8 volts.
    There are basically two kinds of chargers, one is constant voltage and the the other is constant current. With the constant current one, the charge voltage will go down as the battery charges to capacity.

    The charger in your UPS is not designed for the high capacity of the large battery you are using, you should have no problems with over-charging. Make sure the water level is okay in the battery. I have been using one for about 3 years and it is still okay. Check the voltage on your car when the it is charging, you will probably see a voltage around the 13.8 volts or even higher if the battery has heavy sulfate.


    Don

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    Exclamation Caution and word of warning............

    ........FOR WHAT IT MAY BE WORTH................

    There seems to be some perils to keeping a car battery on "charge".

    Our story: (and luckily noone was killed).


    We had a large car battery that was connected to our diesel generator.

    Every time we wanted to turn it on, it was low etc...........so we used a "trickle" charger and permanently connected it to the battery and to the power outlet in the wall.......When the power was on, the battery would trickle charge........

    .......It worked for a long time, everytime we wanted to put the generator on, it started, then one day, the watchman went into the garage and flipped the switch and the battery blew up like a huge bomb and small pieces went flying all over the garage...........There was nothing left to the battery but the plates........

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    Quote Originally Posted by POP Bad Boy View Post
    ........FOR WHAT IT MAY BE WORTH................

    There seems to be some perils to keeping a car battery on "charge".

    Our story: (and luckily noone was killed).


    We had a large car battery that was connected to our diesel generator.

    Every time we wanted to turn it on, it was low etc...........so we used a "trickle" charger and permanently connected it to the battery and to the power outlet in the wall.......When the power was on, the battery would trickle charge........

    .......It worked for a long time, everytime we wanted to put the generator on, it started, then one day, the watchman went into the garage and flipped the switch and the battery blew up like a huge bomb and small pieces went flying all over the garage...........There was nothing left to the battery but the plates........
    This was likely the result of a spark or flame of some kind coming into contact with the flammable gasses that a lead-acid battery emits when charging.

    This is why its important to keep your batteries in a well ventilated area, to prevent the buildup of these gasses.

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    Quote Originally Posted by SantiagoDR View Post
    Typical charge voltages for a 12 volt battery is 12.6 - 13.8 volts.
    There are basically two kinds of chargers, one is constant voltage and the the other is constant current. With the constant current one, the charge voltage will go down as the battery charges to capacity.

    The charger in your UPS is not designed for the high capacity of the large battery you are using, you should have no problems with over-charging. Make sure the water level is okay in the battery. I have been using one for about 3 years and it is still okay. Check the voltage on your car when the it is charging, you will probably see a voltage around the 13.8 volts or even higher if the battery has heavy sulfate.


    Don
    But but, it reached 13+ volts and didn't cut off. does that mean it charges constantly at .5 amps (amp meter reading)? I am afraid it may kill my battery with constant over charge.
    AZB

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    On my alarm system I have a second 12v/7ah battery with a special constant voltage charger. I have that charger set at 13.5 volts (+/-). The battery lasted for more than 5 years. I picked 13.5 volts as that was what I read a fully charged sealed lead acid battery should be (2.25v per cell).

    A UPS system uses Sealed Lead Acid batteries.
    Sealed lead acid batteries require current limited constant voltage charging.
    I would therefore think the charger in the units are constant voltage chargers.

    A battery with a bad cell will never reach full charge voltage.


    Don

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