Generator Charge Rates Tips & Tricks

Apr 3, 2024 Tips & Tricks

Generator Charge Rates Tips & Tricks

Installing my new Voltage Regulator is a very worthwhile upgrade to the standard or diode cutout – it will keep your battery topped off without overcharging it.  But there are some things to keep in mind when looking at different cars & equipment on those cars.

Original Ford Model T’s really had only a few devices that draw power from the battery:

  • Buzzboxes/coils
  • Headlights
  • Brake Lights
  • Horn

That’s it.  Headlights might draw 5A while they’re on & coils 2-3A, so you could see 7-8A more or less of battery draw at night.  So you might think well, I’ll just set my generator’s 3rd brush for 10A output and all will be fine.  Not so.

The Model T generator is rated for a maximum 100 watts of Power calculated as follows (Power = Voltage * Current).  so, 6.4V x 10A = 64w  or 64% of the generators maximum 100w rated output.  And 100 watts of output is assuming a brand new generator with new field coils, a new armature, new brushes, etc, NOT that 100+ year old unit in your car.  So, at 60watts of output today,  that might be 100% of what your generator is capable of, so it won’t be very long before you’re buying another one after yours gives up the ghost, depending on how much you drive your car.

A much better solution is to lower your charge rate to 5A, and let the battery recharge more slowly over time as you drive the car, putting less stress on your entire charging system.  Of course if you only drive your car at night (highly unlikely) this won’t work, but for the vast majority of us who tour our cars and occasionally use our headlights, it works very well.