Battery not charging fully while idleing

[OldGuard60]

Just had AAA come out and check my battery on my 280SL (71) and he said at idle, it's not charging the battery.  Only does it when we revved it up to 2K+.  Does this imply the alternator (and/or battery) is going bad?
Here are the results:
Test Data:
Overall Result: CAUTION
The battery may be serviceable but with decreased capability to start the engine.
State of Health: 83%
State of Charge: 93%
Voltage: 12.54 V

Battery Details:
Type: FLOODED
Set Capacity: 730 CCA/SAE
Measure Capacity: 610 CCA/SAE

System Details:
Starter Voltage: NORMAL / 11.08 V
Idle Voltage: LOW / 12.22 V
Idle (with load) Voltage: LOW / 12.29 V
Diode Ripple: NORMAL / 0.07 V

Thanks in advance.
OG

[Vander]

How old is the battery? How long has the car been sitting?

Also you can do a trickle charge on the battery for 1-2 days, then re-test.

[OldGuard60]

I will have to look at it and get the date.  I drive it every fee weeks depending on weather.

Guess I better get a trickle charger....

[lpeterssen]

Dear OG:

Also go for a new external voltage regulator.  The BERU brand seems to be recommended by many members here in the forum and has an attractive price point.   On my personal preference I tend to eliminate the external voltage regulator and go for a modern more serviceable alternator that can be sourced everywhere as Bosch AL69X.

Having a voltage value of just 12.2 is too low.  Your voltage when running the car the car should be above 13.5 volts at idle and about 14 volts when rpm are high

Best regards
Eng. Leonardo Peterssen
Www.wiredoktor.com

Ps. Buy also a standby battery charger as suggested by other members.

[OldGuard60]

Thank you very much for this information.  I am NOT a mechanic and though I can do some "stuff" with my cars, I don't want to touch this ORIGINAL 280SL.  I just want to drive it in the neighborhood to keep it running and then in a few months, I am going to have a Master Mechanic who specializes on these cars work on anything that needs to be done.  I just don't want to do any harm to the car. 

[Jonny B]

As an aside, I would recommend that you get some amount of full run time on the car. Just trundling along in the neighborhood does not get the oil fully heated to drive off the water etc products of combustion. The cars need some time at speed to stay in fettle.

[OldGuard60]

Will do!  Thanks for that.