Low Voltage
Thread Starter
Senior Member
Joined: Sep 2007
Posts: 368
Likes: 11
From: Iowa
2019 S450
Low Voltage
At cruise speed voltage is 13.96 VDC steady.
Engine off its 12.05
Heater in Residiual heat mode it drops to 11.7 VDC at once and in less than 5 min it is down to 11.50VDC. At that time the battery insignia shows up in the heater control window and it shuts off..
I am looking hard at the battery.. I put 100 Amp load on it for about 15 seconds and it held on at about 11.21 VDC..
Is it the battery or could it be the alternator is not bringing it to full charge with only 13.96 VDC max charge voltage ?
Thanks for the help..
Engine off its 12.05
Heater in Residiual heat mode it drops to 11.7 VDC at once and in less than 5 min it is down to 11.50VDC. At that time the battery insignia shows up in the heater control window and it shuts off..
I am looking hard at the battery.. I put 100 Amp load on it for about 15 seconds and it held on at about 11.21 VDC..
Is it the battery or could it be the alternator is not bringing it to full charge with only 13.96 VDC max charge voltage ?
Thanks for the help..
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 377
From: San Jose area
'19 E63S sedan
At cruise speed voltage is 13.96 VDC steady.
Engine off its 12.05
Heater in Residiual heat mode it drops to 11.7 VDC at once and in less than 5 min it is down to 11.50VDC. At that time the battery insignia shows up in the heater control window and it shuts off..
I am looking hard at the battery.. I put 100 Amp load on it for about 15 seconds and it held on at about 11.21 VDC..
Is it the battery or could it be the alternator is not bringing it to full charge with only 13.96 VDC max charge voltage ?
Thanks for the help..
Engine off its 12.05
Heater in Residiual heat mode it drops to 11.7 VDC at once and in less than 5 min it is down to 11.50VDC. At that time the battery insignia shows up in the heater control window and it shuts off..
I am looking hard at the battery.. I put 100 Amp load on it for about 15 seconds and it held on at about 11.21 VDC..
Is it the battery or could it be the alternator is not bringing it to full charge with only 13.96 VDC max charge voltage ?
Thanks for the help..
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From: Boston, MA USA
03 E320 -wife's car now; 07 Porsche Boxster S - my toy
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paul...
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Joined: Nov 2001
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From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
To me looks like a bad or marginal battery. Could also be the wrong spec battery since its not OEM. Replace the battery with the correct spec battery and it should be OK.
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Joined: Jan 2007
Posts: 1,152
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From: Sydney, Australia
190D 2.5 (x2), 190E 2.6, W202 C240,W202 C43 (C55), W210 E55, W212 E250CDI
A S600 has alot of electronics running in the background so a high capacity battery in crucial.
Go get yourself a MB AGM battery of the largest size about 860-950A or equivilent (dry cell) and you won't have to think about it for at least 5 years.
Go get yourself a MB AGM battery of the largest size about 860-950A or equivilent (dry cell) and you won't have to think about it for at least 5 years.
