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A friend works for a company that, when the battery goes bad in a computer UPS, (uninterruptible power supply), throws the UPS out, since the price of a new battery is about two thirds of the price of a new UPS.
Since he knows I am a collector of marginally useful stuff, he brought me three of them.
I called the manufacturer and asked the technician about the charger used to keep the UPS battery charged. He said that it was a float charger.
So I made some jumper cables to extend the battery wires in the UPS, and hooked them to my battery. The UPS was plugged in to a Kill-A-Watt meter, set on watts, so I could monitor the current.
The battery was at 12.6 V (resting) to start, and when I connected the UPS, it drew about 11 watts. I let it run over night, and the voltage increased to 13.7 V, with the charger connected, and the watts dropped to 3 or 4. (The meter jumps back and forth between the two.)
Everything I have been able to glean from the Internet suggests that a float charge for a flooded cell lead acid battery is 13.5 to 13.8 V, with the voltage going up as the temperature goes down. The float voltage for a AGM battery is a bit higher, but it would seem that the voltage put out by this UPS would keep either one in the float charge range.
Depending on the electricity cost in your neighborhood, it would cost about a penny a day to keep your battery fully charged over the winter. You might check the acid level every month or so, just to make sure that everything is OK. Electronics don't always act as they should.
If you try this, I would suggest that you check the voltages for a day or two, so that you can determine if your UPS is working as it should, and in the correct voltage range.
CZ
Since he knows I am a collector of marginally useful stuff, he brought me three of them.
I called the manufacturer and asked the technician about the charger used to keep the UPS battery charged. He said that it was a float charger.
So I made some jumper cables to extend the battery wires in the UPS, and hooked them to my battery. The UPS was plugged in to a Kill-A-Watt meter, set on watts, so I could monitor the current.
The battery was at 12.6 V (resting) to start, and when I connected the UPS, it drew about 11 watts. I let it run over night, and the voltage increased to 13.7 V, with the charger connected, and the watts dropped to 3 or 4. (The meter jumps back and forth between the two.)
Everything I have been able to glean from the Internet suggests that a float charge for a flooded cell lead acid battery is 13.5 to 13.8 V, with the voltage going up as the temperature goes down. The float voltage for a AGM battery is a bit higher, but it would seem that the voltage put out by this UPS would keep either one in the float charge range.
Depending on the electricity cost in your neighborhood, it would cost about a penny a day to keep your battery fully charged over the winter. You might check the acid level every month or so, just to make sure that everything is OK. Electronics don't always act as they should.
If you try this, I would suggest that you check the voltages for a day or two, so that you can determine if your UPS is working as it should, and in the correct voltage range.
CZ
Thanks for the info.
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