This is probably a dumb question…what would happen if I charged the Exide batteries w/ a 6 volt 4-amp charger?
The Battery Charger would say that the battery was already charged or fault (most likly fault if that is an option). Unless of course you severly discharged the battery to the point where the voltage was below 6V (way past usable on a robot). Think of volage as the force or pressure on the electrons. A battery charger works b/c it has higher voltage or force than the battery so it forces electrons backward through the battery, thus charging it. When the voltage of the charger is equal to the battery, it is fully charged. If the battery voltage is higher than the charger (like if you hook up a 6V charger to the 12V battery), the battery will try to “charge” the charger. This could damage the battery charger (I can smell the smoke). Two 6V chargers in series (6+6=12) might worK:D
In all likelyhood, your battery would try to discharge into the battery charger. Depending on the the state of your battery, this could be very exciting, melting wires, burning up the charger and making the battery very upset. Or if it is a very well designed charger, then nothing would happen.
Makes that clear as mud doesn’t it? Best not to try.
Good Luck
Baisically what would happen is that the battery would be charging the charger 
The battery has a higher voltage than the charger thus the charger would be taking from the battery. Thats is my understanding at least, im not an electrician by any means
Not on our FIRST batteries but on some other, smaller batteries we have hanging around (approx. 1/8 size in terms of Amp-Hours and volume), one of our team members accidently crossed the leads on the charger and went home for the night.
The next day the battery was REVERSE CHARGED! Really! Black was at a higher potential than red. It was very confusing until we realized what happened (luckily our curcuits are usually automotive type deals that have reverse battery protection).
Anyway, we hooked it up to the charger (red to red, black to black) left it over night again and now it is fine.
I would not recommend that you kids try this at home, but at least in this one case, we got away with it.
Joe J.
That’s better than what happened to our team Joe, last year a battery was left on an automotive (high power 10A) charger overnight, The switch on the front was set to start for boosting a battery to start a car (didn’t go to trickle). Needless to say we are lucky to still have an A building at the tech center and that battery is about 1/3 larger than it used to be. From then on only 4A or less automatic chargers are allowed on our team.
Joe,
This is the first I have heard of a battery reverse charging. Does it still work OK? Did it have the full terminal voltage? Was the battery hot?
Matt, any cracks in the case, leaking? And yes you are very lucky.
Al
I don’t know if Ron actually pulled a load from the battery. What I kwow for sure is that the battery showed that it was reversed charged when it was hooked up to a multimeter.
The reverse battery protection on our circuit board would have prevented us from drawing anything but a few milliAmps.
It was a brand new 1.2 Amp-Hour sealed lead acid battery (Yuasa model NP1.2-12).
I think the battery is just fine now.
Very strange indeed. To be honest I had no idea that the chemistry could be made to work the other way round – learn something new every day.
Joe J.