proper operation of voltage regulator

[SteveO_71]

Thought I would check my battery voltage the other day to see if the VR was working.

At idle 600-700 rpm i see 14.6v at the battery. Which I think is OK. When the engine is revved up 1500 or so, I see 15.4v on the battery. Should it jump when revved up?

Is the VR working properly?

Thanks!

 

[midlife]

It is not regulating...should see no more than 14.5 or 14.6 at full RPM.

 

[SteveO_71]

Thanks for the info! I was guessing as much.

I believe that this VR behavior is just recent.

Can the higher voltage damage the battery ( think the max called for is 15v ) or will that only happen after prolonged period of over charging like that?

 

[Don C]

It won't immediately hurt the battery. People usually don't realize they have a bad regulator until the battery boils over, not only damaging the battery but everything under the hood that the acid comes into contact with.

 

[c9zx]

It will harm/fail an AGM battery pretty quickly. Chuck

 

[SteveO_71]

Fortunately I received an electronic VR last week from Virginia Mustangs. Installed that to day and the voltage is now around 14.2 - 14.4 idle and revved.

My battery is a sealed AGM so no acid was splattered around. Its an Autolite replica one which not only costs more than the usual ones but also they seem to have a long lead time to be delivered , for whatever reason.

My battery tender wasnt acting correctly which caused me to start checking things.

What happens if the battery was damaged by the overvoltage? Not taking a charge and eventually needing replacement?

Thanks!

 

[Don C]

I forgot reading that you have an AGM battery. Because they have very thin plates and the acid is contained within the glass mat there isn't any free liquid to carry the heat away from the plates. Depending on how much and long they were overcharged they may now have reduced capacity and life. You might try a load test type battery tester and see how well it holds up to a load, and how much the voltage drops in 10 seconds.

 

[c9zx]

My AGM battery (Autolite from Va. Mustang) became weaker and weaker until it wouldn't start the engine when at operating temperature. Strange thing is it load tested good. New el cheapo from Wal-Mart and all was good. I also removed the "concours correct" Marti works regulator and replaced it with a solid state regulator. Overall I'm not impressed with the quality of many of the reproduction parts available from the large vendors. Chuck

 

[Don C]

I decided some time ago to not try AGM batteries. Too many conflicting reports and too many real world experiences like Chuck's, as well as too expensive for an old fogey.

The latest battery technology appears to be lead-crystal batteries, a lot of manufacturer claims about how good they are, we'll wait and see.

Maybe Elon Musk will come up with a new battery technology that is affordable and viable