High battery charging voltage fix.
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,572
Likes: 486
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
High battery charging voltage fix.
Car was charging my old battery at 15.0 to 15.5 volts which was worrying me that I was damaging it especially on long trips. Would like to see around 14.2-14.4 volts charging on a standard lead acid battery. Tried several things that did not work:
1. New battery...n/c.
2. Replacement new aftermarket external relay type regulator...actually got worse - saw as high as 16 volts.
3. New alternator...n/c.
4. Verified all regulator and alternator connections and voltages (including ground) with meter....all OK.
5. Cleaned all connections with wire brush at the regulator and alternator...n/c.
In desperation I finally ordered and installed a new solid state regulator (Transpo D9212) and also a new noise capacitor. Battery is now charging properly at 14.2 volts.
Redvette2
1. New battery...n/c.
2. Replacement new aftermarket external relay type regulator...actually got worse - saw as high as 16 volts.
3. New alternator...n/c.
4. Verified all regulator and alternator connections and voltages (including ground) with meter....all OK.
5. Cleaned all connections with wire brush at the regulator and alternator...n/c.
In desperation I finally ordered and installed a new solid state regulator (Transpo D9212) and also a new noise capacitor. Battery is now charging properly at 14.2 volts.
Redvette2
Drifting
Joined: Nov 2013
Posts: 1,547
Likes: 282
From: Scottsdale Arizona
I had the same problem with my 68. The alternator was putting out nearly 17 volts and was causing the battery to boil over. I converted the original voltage regulator to electronic and it fixed it. Now it’s at 14.5 volts so no more overcharging and boiling the battery.
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,572
Likes: 486
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
It still bugs me that I could not fix the original charging system that the car came with. The only thing I found that was not quite right was that the measured resistance between the short F(B) and R(ST) wires between the alternator and the regulator were about .3 ohms. The wires and crimp lugs were a bit crusty but it does not seem like that slight increase would be enough to cause the voltages to rise so much. I even opened up both regulators and looked for the mythical voltage adjust screw but am sure it was not present on both of them. Perhaps the car's original alternator was electrically different and worked better with this relay type regulator.
Oh well...on to my door rebuild project now.
Redvette2
Oh well...on to my door rebuild project now.
Redvette2
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
You bend the tab on one of the springs. Doesn't take much to adjust the voltage. You're better off with the electronic regulator. Unless it's changed, you can put the cover from the mechanical regulator onto the electronic one to "hide" it.
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,572
Likes: 486
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
After driving the car on a long trip today I agree....the voltage stays with-in a much tighter range and never got over 14.5 volts during the whole trip. I have a cigarette lighter plug-in LED voltage meter that I don't need to pay so much attention to now. I will just use it to monitor the battery voltage during the longer non-op periods.
Redvette2
Redvette2
