I have a project to decorate the family "Little Red Wagon" with Christmas lights. So I stated experimenting with LED light strings and battery combinations. I finally decided to use an Inverter and not cut up any light strings. The LED light set that I found has 80 lights and the specs state it uses 12 watts. So as a test I connected two 6v lantern batteries in series and ran the leads to the inverter (rated at 100watts), connected a lamp with 40 watt bulb.
The inverted started up and seemed to be working, but when I connected the lamp, the green led on the inverter turned to red and lamp glowed at 60% of what it should. The voltage from the battery dropped from
12.6 to 11.5v. I need a battery with less internal resistance.What would make a better 12v source ? Most NiCad drill batteries are up around 18v+ What is the voltage of battery in APC backups ?