I think the reason for the long battery life in this case, is more likely
due to the quality of the batteries you're using.
What is the brand name and model number of the batteries?

--
Cheers,
WB
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wrote in message
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A charged but unused SLA should retain its charge for months. The
battery powered cars the grandkids love (got them on freecycle, not
new at $300 each) have 12 volt 10AH SLA batteries and typically get
charged twice a year (when the grandkids are here). I use a Black &
Decker charger that does 1 or2 amp charging (switch selected) and the
1 amp charge works well. The B&D charger is "smarter" than the
original charger which comes with a "do not charge more than X hours"
warning. Many UPS chargers are in the same category - they do a fast
charge to quickly replenish the battery after use, but there is no
"smart" monitoring. I've seen several different brands of small UPS
(300 watts or so) kill batteries in a year or less - even if unused.
The charging circuit simply cooks the battery.

Forget about using a UPS to charge a battery. Instead, buy a real
charger which won't destroy a bettery even if it's left on charge all
the time. For most UPS batteries, I would recommend the Black &
Decker Smart Battery Maintainer. It uses a switch mode power supply
and has LEDs for "charging" and "charge complete". The charger is $22
at amazon.com
http://www.amazon.com/Black-Decker-B.../dp/B000AMOEPA
and I've seen it for about $20 at Target and Walmart. If you can find
the older version with the 1amp/2amp charge level switch, it's even
better on the smaller batteries.

Keep an SLA battery properly charged and it will last a very long
time. The electric cars are typically driven until they no longer
move, so the batteries get a full discharge at relatively high current
(5 amps on level driveway; 15 amps uphill - more if two kids in one
car). These batteries have been in service two years and seem to have
close to their original capacity.

John