Author Topic: Negative effects of AGM battery on charging system  (Read 7945 times)

jcochran@cox.net

  • Full Member
  • Regular
  • **
  • USA, VA, Newport News
  • Posts: 51
Negative effects of AGM battery on charging system
« on: September 05, 2014, 02:15:30 »
Hi,
 I installed an AGM battery from Antique Auto Battery earlier in the year and I'm very pleased with it's original appearance and performance however it seems to be adversely affecting the voltage regulator. A digital voltmeter is showing swings up to 16 vdc on a new voltage regulator (I replaced the original a month or two after installing the new battery because it seemed to be failing) and my understanding is that older charging systems sometimes have a problem recognizing the true voltage on an AGM battery. I am concerned that the high charging voltage will damage the battery and that one day I may be stranded due to battery/charging failure. Does anyone have experience with this and if someone knows the part number for a proper Bosch battery it would help as I expect the battery will be for show only. Also please know that I am very happy with Antique Auto Battery's product and service.

Thanks for your help,
Jim Cochran

Mike K

  • Inactive
  • Silver
  • ****
  • South Africa, Gauteng, Johannesburg
  • Posts: 351
    • Mike Kirkinis
Re: Negative effects of AGM battery on charging system
« Reply #1 on: September 05, 2014, 06:21:58 »
Earlier this week I replaced my battery with a Bosch battery. I installed the S4 005 which was readily available.
Here's a screen shot from the Bosch website indicating suitable batteries for our cars.

Best,

Mike
Feb. 1971 Mercedes 280SL Auto  LHD (Last of W113 Series)
Aug. 1989 Mercedes R107 300SL RHD (Last of R107 Series)
http://michali.zenfolio.com
http://www.lebombo-safaris.com

ejboyd5

  • Associate Member
  • Gold
  • *****
  • Southold, NY
  • Posts: 510
Re: Negative effects of AGM battery on charging system
« Reply #2 on: September 05, 2014, 12:21:08 »
I replaced the original a month or two after installing the new battery because it seemed to be failing.
How did it seem to be "failing?"  I would reinstall the old regulator to see if the problem goes away.

Jonny B

  • Pagoda SL Board
  • Platinum
  • ******
  • USA, CA, San Marcos
  • Posts: 4190
Re: Negative effects of AGM battery on charging system
« Reply #3 on: September 05, 2014, 14:15:54 »
What AGM battery did you get from them? I had checked their web site some years back, and there was no listing for an MB application.
Jonny B
1967 250 SL Auto, DB 568
1970 280 SL Auto, DB 904
1966 Morris Mini Minor

rb6667

  • Guest
Re: Negative effects of AGM battery on charging system
« Reply #4 on: September 05, 2014, 20:56:10 »
Hello Jim, I have not actually bought this battery yet, so the part # may have changed.  24-F  is the Bosch battery that is acceptable for use in our cars.  You might check out the width, height and length specified in the tech manual for batteries   A little research on the web should point you in the right direction size wise if the 24 F part number has been updated.  Pep Boys and many others can order a Bosch Battery.  I've attached a picture  (Not Mine) that I saved from one of our members that installed it in his car.   







 

Raymond

  • Full Member
  • Platinum
  • ******
  • USA, FL, Jacksonville
  • Posts: 1204
    • GemstoneMediaInc.com
Re: Negative effects of AGM battery on charging system
« Reply #5 on: September 06, 2014, 16:08:51 »
I don't believe the battery is your problem.  Voltage and amperage are just that regardless of the source.  I had relay problems with the car when I had a lead-acid battery.  That was solved before April of 2010 when I decided to move the battery to the trunk of my Pagoda.  I installed two 6-volt AGM batteries in series and have had no trouble whatsoever.  I have a friend with an AGM in his '71 280 SE and it has been trouble free for 8 years.  The Optima in BK's VW lasted almost 11 years.  The one in her truck is more than 7 years old. 

Ray
'68 280SL 5-spd "California" Coupe

66andBlue

  • Full Member
  • Platinum
  • ******
  • USA, CA, Solana Beach
  • Posts: 4733
Re: Negative effects of AGM battery on charging system
« Reply #6 on: September 06, 2014, 17:39:21 »
Same here. The Optima in my 230SL is now 8 years old and still going strong.
http://www.sl113.org/forums/index.php?topic=8627.msg56216#msg56216
Alfred
1964 230SL manual 4-speed 568H signal red
1966 230SL automatic 334G light blue (sold)
1968 280SL automatic (now 904G midnight blue)

jcochran@cox.net

  • Full Member
  • Regular
  • **
  • USA, VA, Newport News
  • Posts: 51
Re: Negative effects of AGM battery on charging system
« Reply #7 on: September 14, 2014, 02:10:40 »
Hi,
 I replaced the voltage regulator and still have the voltage fluctuations; I'll replace the alternator and see what happens. I'm beginning to wonder if the "Odyssey" battery charger I use to keep the battery topped off is adversely affecting the charging system??? In any case thanks for your help and Cochran's "Conservation of Difficulty" law apparently still applies.

Thanks again,
Jim

66andBlue

  • Full Member
  • Platinum
  • ******
  • USA, CA, Solana Beach
  • Posts: 4733
Re: Negative effects of AGM battery on charging system
« Reply #8 on: September 14, 2014, 02:57:16 »
In your first post you wrote:  A digital voltmeter is showing swings up to 16 vdc on a new voltage regulator
What prompted you monitor the voltage, was there something wrong?
Also how do you measure the voltage and when do you notice the fluctuations?
Is the engine idling or at some speed?
And finally what happens when you turn the headlights on, do the fluctuations go away and what is the charging voltage now?
Alfred
1964 230SL manual 4-speed 568H signal red
1966 230SL automatic 334G light blue (sold)
1968 280SL automatic (now 904G midnight blue)

jcochran@cox.net

  • Full Member
  • Regular
  • **
  • USA, VA, Newport News
  • Posts: 51
Re: Negative effects of AGM battery on charging system
« Reply #9 on: September 15, 2014, 15:02:09 »
66andBlue

1) I checked the voltage because the headlights were fluctuating slightly in intensity and the charging light in the dash was pulsing.
2) I measured the voltage across the battery posts and the voltage fluctuates at all speeds and electrical loads.
3) Idling and at speed in park.
4) Voltage fluctuations do not change with lights on or off.
5) Also please know that the battery is being charged and shows 100% charged when I return from driving the vehicle but I'm concerned the spikes could eventually harm the AGM battery (anything above 15 vdc is potentially harmful) and the headlight/charging light fluctuation can be a bit of a distraction.

Thanks for your help,
Jim

garymand

  • Inactive
  • Gold
  • *****
  • USA, CA, Meadow Vista
  • Posts: 537
Re: Negative effects of AGM battery on charging system
« Reply #10 on: September 15, 2014, 16:42:43 »
Go to a auto parts store and ask them to check your charging system.  They can at least eliminate the battery and maybe the regulator.  The regulator is supposed keep the voltage constant, but the voltage from the alternator needs stay above 12 Volts, too.  I doubt if a battery would cause the syptoms you describe.  It could be intermittent voltage from the alternator or the regulator. 

The simple fact that your charging light is flickering tells be the voltage from the alternator is dropping below the battery voltage.  Recap: rpm doesn't matter, load doesn't matter, battery is charged, voltage is dropping below battery voltage. 

That all points to alternator, regulator, or wiring intermitent, either a bad/intermitent connection to the voltage or a bad connection to ground.  The intermittent connection can be in the wiring, regulator or alternator.  You said you swapped out a regulator: if the problom doesn't change with the regulator, that leaves what?  alternator/wiring.  Do you have a substitute battery, just incase I'm wrong about the battery?  You can swap batteries to see that it is not the battery.  With the meter connected, wiggle all the wires and connection around the battery, alternator and regulator.
Gary
Early 250SL German version owned since 71, C320, R350, 89 Porsche 944 Turbo S

Jonny B

  • Pagoda SL Board
  • Platinum
  • ******
  • USA, CA, San Marcos
  • Posts: 4190
Re: Negative effects of AGM battery on charging system
« Reply #11 on: September 17, 2014, 15:54:27 »
I would definitely recommend you check the wiring. I had an issue with my alternator, and we found that the wiring right at the alternator had an intermittent short. Corrected that, and no issues.
Jonny B
1967 250 SL Auto, DB 568
1970 280 SL Auto, DB 904
1966 Morris Mini Minor

garymand

  • Inactive
  • Gold
  • *****
  • USA, CA, Meadow Vista
  • Posts: 537
Re: Negative effects of AGM battery on charging system
« Reply #12 on: September 17, 2014, 19:23:08 »
Sorry, couldn't resist.  A short is the oposite of an open.  An open disconnects power to what ever is supposed to turn on.  Opens are failsafe: what everever should work just stops working.

A Short is what you see on submerines when they want drama in a movie.  Shorts heat stuf up real fast, causes sparks, causes fires and replacement of wires that loose insulation or repainting of hoods when the hood SHORTS the battery posts.  BTW, subs have banks of circuit breakers, as do airplanes, circut breakers open to prevent shorts from setting fire to subs.  Your house has breakers in your 'fuse box' to prevent shorts from burning down your house.

An intermittent short is what you have when you first learn to arc weld and the stinger keeps getting stuck on the thing you are welding.  It is more likely that your intermitent was an open, as in a flashlight that keeps going out and you bang it to get the light to come back on; the electricity was not flowing while the circuit was open.  Hmm, I think that is why we say the switch opens the circuit.

 ::)  I just get tired of people calling opens shorts as in the guy pulls into the garage and says my right tail light is out, I think I got a short circuit somewhere!

If the light is out because of a short, the fuse would be blown and more than one light, the whole circuit would be out because of the open fuse. (Sorry, I understand that might be confusing to some)  If only one light is out, the filiment is probably open, or in our old cars, the connection at the socket has oxidized open. 
Gary
Early 250SL German version owned since 71, C320, R350, 89 Porsche 944 Turbo S

UJJ

  • Full Member
  • Silver
  • ****
  • USA, CA, Grass Valley
  • Posts: 327
Re: Negative effects of AGM battery on charging system
« Reply #13 on: September 18, 2014, 12:13:25 »
Thanks Gary, well said!
Same problem with the bolt and screw definition, kinda
Urban
Urban Janssen
Grass Valley, CA
1968 280 SL - 4speed manual
173 anthracite grey