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W124 E300 12v 1992 and a 2009 Crown Victoria
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Discussion Starter #1 (Edited)
Greeting Everyone,

Two days ago my car, the 124 not the Crown Victoria :), turned off in a check point after getting stuck for about an hour as millions of people come for pilgrimage from all over the world . Man, it is not my fault that I work beyond that check point :mad:. I still consider my self lucky being stuck for just an hour.

The symptoms before stopping for good were great drop in RPM and oil pressure and the ABS light showing up alone (shouldn't the battery light be?) when I hit the breaks with the gear engaged on D. All lights were on, the radio, the A/C and I was charging my mobile with the lighter. When I let go of the breaks, thing went fine.

When it turned off, I tried to turn it on but I only heard the ignition ticking. All electric parts worked fine with reduced output.

I tested the battery and it was dead and had to be changed. It was an electric 88Amp battery and changed it with a traditional non-electric 88Amp one.

My questions are:

1- Looking at those symptoms and the situation I was in, is shutting off like this normal?

2- In a last moment test after changing the battery, when disconnecting the battery while the engine is on, I noticed a momentarily drop in RPM then it came back to normal. Does this proof any thing? Please note that when I tested the charging of the batter, the device showed 13 (don't remember the unit) and the mechanic said it should be like this if the alternator is working fine.

I'm asking these questions to clear all possibilities that the problem was battery related only and the charging with all related electrical parts are working fine.

Sorry for elaborating so much and thank for reading.
 

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W124 E300 12v 1992 and a 2009 Crown Victoria
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1,056 Posts
Discussion Starter #2
Guys, further to boring story up there and after some search I found that the voltage test should be 13v on an idle engine with no load and 12v with heavy load.

Went to a battery store, borrowed their voltameter (if the name is correct), and tested the out put and had those exact results. The heavy load was with the A/C and headlamps on and the gear on D.

This gives me piece of mind and means problem solved as per my analysis.

Regards.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,467 Posts
You lost me in this....you determined the battery was bad, replaced it and all is well? Yes, if the alternator is working properly if as you accelerate at idle, the voltage should slightly increase (measured across the battery terminals). Even at idle though, it should measure 13 volts or better.

Anymore weirdness and you should replace your OVP....should be replaced anyway with the newest style for peace of mind. You were right there when you were fooling with the battery.

Kevin
 

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1988 W124 300E
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242 Posts
You lost me in this....you determined the battery was bad, replaced it and all is well? Yes, if the alternator is working properly if as you accelerate at idle, the voltage should slightly increase (measured across the battery terminals). Even at idle though, it should measure 13 volts or better.

Anymore weirdness and you should replace your OVP....should be replaced anyway with the newest style for peace of mind. You were right there when you were fooling with the battery.

Kevin
maybe also check the voltage regulator with the brush. it could be very worn and not contact the rotor properly and causing not charging.
cheap component with 2 min installation though.:D
 

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1993 300E 2.8 (sold), 2012 C250 (wife's), 2004 C230 (sold), 2005 E320 (sister-in-law's)
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257 Posts
Battery disconnected for few days and now engine can NOT start

Dear all, we have a similar problem here.

After we disconnected the battery (93 300E 2.8) for few days (disconnect the negative only), now we found that the battery seems to be discharged and we can't start the engine at all. Here are my questions:

  • Should a car battery always be connected to avoid discharge by itself? I don't know much about how it works with the car battery (sorry about the newbie question here)
  • In this case, would "jump start" help to start the engine again? And once it started, how long should we keep the engine running to get the battery fully charged?
Thanks!
 

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W124 E300 12v 1992 and a 2009 Crown Victoria
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1,056 Posts
Discussion Starter #6 (Edited)
I my self got lost and mixed up in this. I edited no. 2, sorry for the confusion. I thought if the battery dies, the engine does not shut down as the alternator is charging. So when it happened, I thought something was wrong with some charging component. The test proved I was wrong. I wonder why it did shut down even though the test showed good results. It happened to me once with my previous Crown Victoria by the way. The battery then was electronic as well. Could this be an electronic battery specific problem? have I mentioned that the battery was done for for good? It couldn't recharge.

I'll keep checking the charging behavior once a day for some time and depending on the results I'll think of the next step. Even if there is a slight misbehavior I'll do something about it.

And Ohman, I know that the positive pole is the one to be disconnected when storing the car. I just picked up this info with no actual experience. Lets hear what the professionals say about it. As for recharging, I suggest a jump start then taking it to a battery shop for an appropriate recharge so you can hit the other bird as well which is making sure the battery is still physically fine. What ever drained the power could have possibly harmed the internal parts as well.

Oh yeah, thanks guys for your kind comments.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,467 Posts
I my self got lost and mixed up in this. I edited no. 2, sorry for the confusion. I thought if the battery dies, the engine does not shut down as the alternator is charging. So when it happened, I thought something was wrong with some charging component. The test proved I was wrong. I wonder why it did shut down even though the test showed good results. It happened to me once with my previous Crown Victoria by the way. The battery then was electronic as well. Could this be an electronic battery specific problem? have I mentioned that the battery was done for for good? It couldn't recharge.

I'll keep checking the charging behavior once a day for some time and depending on the results I'll think of the next step. Even if there is a slight misbehavior I'll do something about it.

And Ohman, I know that the positive pole is the one to be disconnected when storing the car. I just picked up this info with no actual experience. Lets hear what the professionals say about it. As for recharging, I suggest a jump start then taking it to a battery shop for an appropriate recharge so you can hit the other bird as well which is making sure the battery is still physically fine. What ever drained the power could have possibly harmed the internal parts as well.

Oh yeah, thanks guys for your kind comments.
Doesn't matter what the old battery did...it's now what is going on with the NEW battery. If I read this right, you momentarily disconnected the battery when the engine was running...WHY? Never do that with computers and FI....a real NO-NO.:( Your asking for trouble doing that.

There are two small screws on the back of your alternator-that is the regulator (with two brushes). Check the amount of brush life left with the engine OFF. Very easy to find and replace the regulator, if necessary. It was my understanding from your OP, that a mechanic had checked this-so I didn't suggest it. If that's not it and any weirdness still remains, replace your OVP. Which as I told you earlier, should be replaced with a newer style anyway, if it hasn't been done.

You should be trying to establish a baseline by doing basic checks/repairs, so that only the exotic problems remain, if any.

Kevin
 

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W124 E300 12v 1992 and a 2009 Crown Victoria
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Discussion Starter #8
Thanks again Kevin.

I realized that disconnecting the battery while the engine is on is a grave mistake after doing some research. Luckily nothing bad happened when I did it as everything is working just fine. The reason I believe is that if the battery is disconnected, the alternator will generate too much power that won't find a container, the battery, causing computers to overload with power and explode, figuratively.

Nothing weird is showing so far, but I'll take your advice gratefully and check, or directly change, the parts you mentioned.

With regards.
 

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'90 124.128
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241 Posts
NEVER disconnect Alternator/Battery with engine running

Why?
It'll BLOW out the Diode(S) in the Alternator(AND then you'll be most unhappy)

DO NOT JUMP START (AND then attempt to charge the DEAD battery with the Alternator)
a TOTALLY dead battery [Anything below 12. Volts].The Alternator is designed to run
all the electrical equipment on the car AND use a small charge to restore the battery from
cranking.Using the Alternator to charge a TOTALLY DEAD Battery WILL SHORTEN THE
ALTERNATOR"S LIFE SPAN VERY QUICKLY.
If the Battery's DEAD put it on a SLOW charge overnight WITH A BATTERY CHARGER (24Hrs) @ 2 AMPS.

OHMAN,

Disconnecting the Negative Cable from the Battery is the PROPER way to disconnect the Battery.(Our MB s are Negative Grounded [through the Chassis back to the Battery's Negative Pole.)

If the Negative Cable was disconnected (AND prevented from contacting the Negative Pole on the Battery) Zomezing Else WEIRD is going on with your Battery.(Or it was already ILL.)

My Favorite Electrical Testing instructions:
http://assets.fluke.com/appnotes/automotive/beatbook.pdf
 

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1988 M-BENZ 300E | 1991 FORD PROBE GT TURBO | 2003 FORD EXPLORER 4x4
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684 Posts
Ok, this is a problem in many vehicle, they do not charge well at idle and you sat idle too long and ran the battery dead.

The alternator should be putting out 14 volts with a low load, if it's not I'd slap a new regulator on it.

In the future, when sitting in a traffic line for long periods of time, if you must have your a/c and lights on then put the car in park and hold the rpm's at about 1200.

Never disconnect the battery with the car running, it will fry the OVP Relay.
 

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W124 E300 12v 1992 and a 2009 Crown Victoria
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Discussion Starter #11
Thank you guys for elaborating.

I don't wanna hurt my beloved baby :(
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,467 Posts
Why?
It'll BLOW out the Diode(S) in the Alternator(AND then you'll be most unhappy)

DO NOT JUMP START (AND then attempt to charge the DEAD battery with the Alternator)
a TOTALLY dead battery [Anything below 12. Volts].The Alternator is designed to run
all the electrical equipment on the car AND use a small charge to restore the battery from
cranking.Using the Alternator to charge a TOTALLY DEAD Battery WILL SHORTEN THE
ALTERNATOR"S LIFE SPAN VERY QUICKLY.
If the Battery's DEAD put it on a SLOW charge overnight WITH A BATTERY CHARGER (24Hrs) @ 2 AMPS.

OHMAN,

Disconnecting the Negative Cable from the Battery is the PROPER way to disconnect the Battery.(Our MB s are Negative Grounded [through the Chassis back to the Battery's Negative Pole.)

If the Negative Cable was disconnected (AND prevented from contacting the Negative Pole on the Battery) Zomezing Else WEIRD is going on with your Battery.(Or it was already ILL.)

My Favorite Electrical Testing instructions:
http://assets.fluke.com/appnotes/automotive/beatbook.pdf
Great link thanks; big diagrams, easy to understand....even for those of us that HATE car electrical systems.:rolleyes:

Kevin
 
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