Originally Posted by GaryJ
Trying to fly before my time,put my trainer into a low altitude stall.Plane nose dived into the ground from about 20ft up did some structural damage that was easily fixed.After getting home put battery on charger to "top it off" and all I get on the charger are 3 blinking red lites.Could the crash really have made my battery bad?
If you have access to a digital multimeter, put it to use by checking the battery power terminals, and the battery balance cables.
Generally, those balance cables have a black wire on one side, and a red wire on the other side. Check the back side of the balance connector, and locate the "Locking Pins" for each terminal. With your digital multimeter's black wire, LIGHTLY press it against the black balance connector wires locking pin. (If you press to hard, you can bend that locking pin, resulting in the pin falling out of the housing. It takes a magnifying glass and a sharp knife blade to bend those locking pins back.) Then, measure the next adjacent wire. It should be around 3.6-4.0 volts DC, depending on charge level. If its good, then move both your meter leads one notch over to the next cell and repeat.
There is really no reason not to have one of those digital multimeters now days. Harbor Freight has a useable one for under $5.00. I've got two or three of them, and for our model airplanes, they work as good as my $350 Fluke 87V meters. I feel safe using that $$$$ Fluke meter on a 440 VAC switch panel, but that is NOT the case with the Harbor Freight meter!
Take a look at how to use these meters: