Try this and see if there's any answers for you.
http://www.uuhome.de/william.darden/carfaq.htm

"Eric Lang" wrote in message
news

I have been using a battery charger that is around 30 years old. Seems
like it has been working well the last few years, but I wonder if
getting a new one will give me a better charge.
Is a battery charger just a battery charger, or is there a difference?
Thanks!