Re: Setting 3rd brush generator output
Posted by Owen_Dyneto On 2018/3/9 15:04:31
How does one know when he has the correct setting for the third brush?
A very easy question to answer but with a short answer that's not particularly helpful. The correct setting is the one that neither overcharges the battery (as indicated by frequent need to top up the water) nor undercharges it (as indicated by slow starting).
Forget the voltmeter, it's got everything to do with amps. In a practical sense you want to have a charging rate just a few amps on the positive side for any particular load. And you may need several settings depending on driving situations. Here's how I've done my '34 for the past 50 years. Almost all of my driving is daytime driving, without any electric accessories, just running the ignition system, brake lights, etc. For this I set the 3rd brush to just compensate for the load, an ammeter reading of just positive by no more than 5 amps at average road speeds. Doing this, I rarely add water to the battery, and get about 7-8 years from a lead/acid battery.
When the occasion occurs that I'll be driving at night, I'll adjust the 3rd brush so the ammeter is again just a few amps positive with all the lights on and whatever other electrical accessories you want want active.
If your driving is almost exclusively very short trips with lots of restarts, you'll want a little higher rate. If it's long stretches of highway driving with few restarts, then a little lower.
As you can see, the object is have a charging rate that compensates for whatever load you've imposed plus enough to replace what was used in starting, but by a small margin to prevent overcharging.
In the day when folks found that whatever conditions they were in resulted in overcharging but they didn't want to change the 3rd brush, they simply drove with the headlights on to eat up the excess current - a pretty common practice in the days of 3rd brush generators.
The cutout should open when the generator voltage is less than the battery voltage, visa versa for when it should open. Can't help with your other questions. Curious about the CD-840, my Owen-Dyneto listing doesn't show this unit ever used on a Packard.
If you want to discuss getting a solid state generator control, I can't think of anyone better to speak with than Jason at AER.
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A very easy question to answer but with a short answer that's not particularly helpful. The correct setting is the one that neither overcharges the battery (as indicated by frequent need to top up the water) nor undercharges it (as indicated by slow starting).
Forget the voltmeter, it's got everything to do with amps. In a practical sense you want to have a charging rate just a few amps on the positive side for any particular load. And you may need several settings depending on driving situations. Here's how I've done my '34 for the past 50 years. Almost all of my driving is daytime driving, without any electric accessories, just running the ignition system, brake lights, etc. For this I set the 3rd brush to just compensate for the load, an ammeter reading of just positive by no more than 5 amps at average road speeds. Doing this, I rarely add water to the battery, and get about 7-8 years from a lead/acid battery.
When the occasion occurs that I'll be driving at night, I'll adjust the 3rd brush so the ammeter is again just a few amps positive with all the lights on and whatever other electrical accessories you want want active.
If your driving is almost exclusively very short trips with lots of restarts, you'll want a little higher rate. If it's long stretches of highway driving with few restarts, then a little lower.
As you can see, the object is have a charging rate that compensates for whatever load you've imposed plus enough to replace what was used in starting, but by a small margin to prevent overcharging.
In the day when folks found that whatever conditions they were in resulted in overcharging but they didn't want to change the 3rd brush, they simply drove with the headlights on to eat up the excess current - a pretty common practice in the days of 3rd brush generators.
The cutout should open when the generator voltage is less than the battery voltage, visa versa for when it should open. Can't help with your other questions. Curious about the CD-840, my Owen-Dyneto listing doesn't show this unit ever used on a Packard.
If you want to discuss getting a solid state generator control, I can't think of anyone better to speak with than Jason at AER.
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