Engineering is basically the art of compromise.
GE knew that fast charging was a selling point. The charger they designed was OVER 1000W (it varies with how low the batteries are) because most people in 1970 had 15 Amp outlets. The timer is all there is... BUT... remember, this is not a constant-current charger. Nor is it even really constant voltage, because the load is a major part of the circuit. The current is the limiting factor with low batteries, but eventually as the voltage goes to 42 or 44V, the current going into each battery has dropped, and the drain at the 120V outlet has gone down from 1000W. You can check this with a Hall-Effect current meter at the batteries, and at your plug.
It isn't bad for the application, and very good for a 1970 'cheap fix'.
From: Jeremy [mailto:nagidog starband net]
Sent: Sunday, April 27, 2003 3:28 PM
To: elec trak yahoo group
Subject: (ET) charger
I finally got my e-12 in working order and just mowed about an acre of hilly, very bumpy ground. It did great, really a tough machine. I have noticed that the charger really sucks the juice, about a 1000 watts when charging. This seems great if you just want a quick charge and get back to mowing, but must be very hard on the batteries and is too much of a load for my solar system. . . I can do it, but would bring down my available solar power 20% for just one hour of charging. Spread over time the load is not to big for my solar. I think a DC to DC converter putting out 200 or 300 watts would charge more efficiently and put less strain on my solar system. Also, my charging switch-dial has letters from a to G on it, but I have not noticed a difference in amperage depending on where the dial is set. Is this dial strictly a timer. What is the preferred method of charging using the onboard charger. Short spurts over time, one big long charge. Basically looking for the low down on charging technique.