[AT] Batteries charged backwards

[Frank DeWitt]

With so much traffic I guess I should jump in.

Years ago (1970) I had a 1948 chevy  (Long story)  I also had no money 
and needed a battery.
My boss had a huge 6 volt battery out of his dozer with a crack in the 
side from freezing.  He gave it to me.

I patched up the crack with RTV and thought about charging it.  I 
reasoned that because one cell was drained the best way to have all the 
cells match was to drain them all.  I did that and filled them with 
plain water.  I didn't have a battery charger so I built  a 24 volt 
power supply from junk.  (A 24 volt AC secondary transformer and a full 
wave rectifier)  (4 diodes)   I connected this to a Variac  (Adjustable 
auto transformer)   I connected the output of the powersupply to the 
battery and turned it up to 24 volts.  I read less then .5 amp.  
Remember this is a dead battery with plane water in it.   I checked it 
every few hours and adjusted the AC to get about 4 amps output.    After 
charging 24 hrs a day for a full weekend I had 6 volt output with some 
current behind it.  I put the battery in the chevy and it worked. I 
drove the car for about a week before it finally stopped charging.    
That was the last batter I put in that car.  It would crank the engine 
for as long as it took. One day after work it was so cold and windy my 
car was the only one that would start.  I couldn't give anyone a jump 
because I only had 6 volts.   Ended up giving the boss a ride into town 
to borrow a truck and go back and get every one else started.

Having a charger that I had full control of was so handy I packaged the 
whole thing in a box with a amp meter and used it for many years.

Frank