Hi, my 1960 3.8L MK2 Auto has some charging issues I believe.
Static Battery Volts 12.97, when I start engine from cold & it's running on the auto choke I have 14.09 Volts.
Once the choke cuts out & running on normal idle of 900rpm it drops to 13.4 Volts.
If increase rpm the volts increase marginally up to 13.8 Volts
Fan belt is not loose.
The Amp Meter needle has always just flickered off vertical into Charge on idle
Is there a problem here?
For info, the Battery is 5 years old, car starts & runs OK.
R
Peter

 

Looks fine to me but is it converted to alternator, with negative earth, Peter?

I presume you're checking the voltage with a small, hand-held multimeter like most of us do, I have five multimeters gathered up over the years and they all read differently so I have little labels stuck on the backs that say 'point 65 volts low' or ' point 9 volts low' so when using them I have to mentally add it on to the reading to find the corrected voltage. One voltmeter, mounted under the speedo on a bike I regularly use, is a whole volt low right through the range. This is an easy adjustment to make when I need to drop a gear to get the alternator back on the right side of the battery voltage.

It took me several years to discover that new multimeters that I'd bought, because I felt the old one was maybe no longer accurate, was also untrustworthy. I hooked them all together in parallel on a decent battery and got my son in law, who's an electrician, to check them all against his big calibrated industrial one. This enabled me to mark mine up with their various plus or miinus corrections. I have no idea if his was exactly right either, (what do I trust?) but these adjustments have worked for me just about daily ever since.

Ray

 

Hi Ray, thanks for your reply.
Still running the original generator on negative earth.
Yes, just a handheld multi meter, but given your detailed response (ha,ha great love it), I think I'll change the battery in my meter
& then run the car down to the local garage & get them to check output with their meter against mine & then do just what you describe, record any variation.
Any clues on the amp meter lazy reading Ray?
regards
Peter

 

The values sound acceptable to me as well. Unlike yours, my ammeter always moved to mild discharge at idle, but my car idled much slower at 500 to 550 rpm.

 

Thanks Peter3442. Yeah, my Rev counter is playing up now which apparently does happen after fitting an electronic ignition recently ! Another issue to remedy.
Being automatic the idle prior to this change was more like 700rpm not 900 rpm as per the rev counter & I don't believe this has changed.
Peter

 

It may be the regulator that causes the ammeter to have a slow response, which is why I asked if it's been updated to an alternator. Alternators have the rectifier/regulator unit built in so have a much sharper response to demands for current as well as a superior charging rate. If it still has the old mechanical Lucas regulator., I expect, like me, its getting a bit tired and worn up. Even if it has it's points and settings attended to when needed, they don't respond like a modern electronic replacement does.

On my dynamo-equipped bikes, I put a new electronic regulator unit inside the old Lucas control box so it still looks original..

Ray