Battery Drain/Charge - PeachParts Mercedes-Benz Forum

zafarhayatkhan · #1 10-17-2005, 05:22 PM

Car: 94 E320

A few days back, ASR/Check Engine lights started coming on intermitently. Then the car failed to start, clicking noise. Replace battery. Everything was good for a few days.

Then the car failed to start again. Jump started, had the battery and alternater check at Advance Auto Parts: both good. Drove around, came back, started fine. In the morning, the car failed to start again.

Ordered a voltage regulater from Phil Today.

What is the most likely source for drain?

This morning heard the AC blower with the key on, PBU was in the off position. The sound was very faint, so not sure.

ray95e320se · #2 10-17-2005, 11:15 PM

Hi zafar,----You may have "hit the nail on the head" with the blower motor running with key off. You have lost some "serious amps"in about 8 to 10 hrs overnight out of that new battery.Where there is amps (current) flowing, there is heat. With a cold engine, (overnight) & battery charged ,windows open & hood open,doors & trunk closed, listen for anything running,possible blower regulator with a "sick" transistor running at low speed.Also feel the rear of the alt for heat, possible a shorted diode. I use an infared temp tool , it works great for this test.If nothing is detected from the above checks,it's time for a DVM set on 10 amps (auto range) in series with the negative post & the grd cable. Read the amps or milliamps , approx .50 MA is normal current draw for modern cars with ECMs, body modules, radio (keep alive) & all modules have gone to sleep mode,usually after 20 mins. Start removing all fuses , one at a time, when the current flow drops down to normal, that last fuse you removed is the problem circuit.Now you know what "street" to go down, so to speak.That 600-800 amps is going out of them cables some- where, when you open the circuit with the fuse or possibly a relay, same deal, one at a time,from relay panel(rear of fuse panel),you have stopped the current flow & found your problem circuit. We know it has to be a circuit that is powered up all the time with the key off, so get a test lamp & write the numbers of the fuses that are "hot all the time", these are the ones that you are concerned with for now. Remember the only way to get to the bottom of this kind of problem is "Repairs through testing ", You have to fix it with " SMARTS NOT PARTS ". Please post your findings so all can benefit. Good Luck,----Ray

zafarhayatkhan · #3 10-18-2005, 07:44 AM

Last night checked the codes, DM Code 1, Pin 8 Code 1, but the check engine light is not turning off. Removed the key, check engine light stayed on.

Disconnected battery, after reconnection, the check engine light did not come on at all. Even with the key in the on position.

Went to DM, got code 1 again. Check engine light came on, won't go off.

Checked in the morning, check engine light was still on, with no key in the ignition.

87tdwagen · #4 10-18-2005, 04:42 PM

Quote:

Originally Posted by zafarhayatkhan

Car: 94 E320

A few days back, ASR/Check Engine lights started coming on intermitently. Then the car failed to start, clicking noise. Replace battery. Everything was good for a few days.

Then the car failed to start again. Jump started, had the battery and alternater check at Advance Auto Parts: both good. Drove around, came back, started fine. In the morning, the car failed to start again.

Ordered a voltage regulater from Phil Today.

What is the most likely source for drain?

This morning heard the AC blower with the key on, PBU was in the off position. The sound was very faint, so not sure.

Luckily you have a voltage regulator coming, unfortunately this is also the likely problem. If your output voltage is 0 or very small, likely caused by a worn Volt reg, you are draining the car as you drive/use it. If the Volt regulator has gone bad, they are usually on/off, and you should not see any alternator charging with a spent reg.

All the electrical irregularities will probalbly go away, once the charge system is fixed and working normally.

In my experience, my volt reg went while driving during the afternoon, so I didn't notice it at first, no factory Volt meter in my 87300TD. So anyhow it starts getting dark and I flip on the headlights. Within about a minute, my abs light, check engine...all dash lights, come on the radio starts turning on and off, I mean it was wierd. Checked the output voltage and zero, pulled the volt reg and found the problem. replaced with new and she's back to normal in every respect. Now I have one less ashtray and a Volt, Boost and EGT gauges in its place.

zafarhayatkhan · #5 10-19-2005, 08:21 AM

Quote:

If the Volt regulator has gone bad, they are usually on/off, and you should not see any alternator charging with a spent reg.

Voltage at Battery with the engine off is 12.4 and with the engine running it is 13.4.

I thought it should be around 14.5 V.

So looks like the alternater is working. The Advance Auto Parts testing equipment passed the alternater.

I believe I may have a combination of weak charging, along with a battery drain.

Should have the voltage regulater in a day or so. Hopefully that will resolve the issue.

Moneypit SEL · #6 10-19-2005, 08:35 AM

Quote:

Originally Posted by zafarhayatkhan

Voltage at Battery with the engine off is 12.4 and with the engine running it is 13.4.

I thought it should be around 14.5 V.

So looks like the alternater is working. The Advance Auto Parts testing equipment passed the alternater.

I believe I may have a combination of weak charging, along with a battery drain.

Should have the voltage regulater in a day or so. Hopefully that will resolve the issue.

The charging voltage will drop from ideal due to temperature and/or load. 13.4 volts would only be too low with a cold alternator, no electrical loads, and a fully charged battery.

MrCjames · #7 10-19-2005, 12:15 PM

Quote:

Originally Posted by zafarhayatkhan

Last night checked the codes, DM Code 1, Pin 8 Code 1, but the check engine light is not turning off. Removed the key, check engine light stayed on.

Disconnected battery, after reconnection, the check engine light did not come on at all. Even with the key in the on position.

Went to DM, got code 1 again. Check engine light came on, won't go off.

Checked in the morning, check engine light was still on, with no key in the ignition.

If your check engine light is staying illuminated with the ignition key removed then I would suspect the steering lock and ignition switch as a cause to your "current" problem. There is a pin between the lock mechanism and the electrical switch, when it is broken the electrical switch may not turn on or off correctly.

zafarhayatkhan · #8 10-19-2005, 12:47 PM

All the other lights turn on and off correctly with the key.

I rememberd one other thing. After replacing the battery, I checked the codes from pin 8 using the led/sw.

I did not insert the pins into the right sockets the first try.

Is it possible to damage the ECU by doing that?

I have misplaced Arther Dalton's schematic for the led/sw, so not sure what effect that would have.

MrCjames · #9 10-19-2005, 01:03 PM

Another thought-the OVP relay might be sticking but I believe the ABS light would come on as well. Not cetain how you connected your blink tester, can it damage the ecu..........not sure about that, I suppose it's possible.

With the key removed test voltage at fuse 7.......if voltage is present I might suspect a broken ignition switch. I like to approach electrical matters one step at a time, in my eyes the switch needs to be confirmed or eliminated as a/the cause.

zafarhayatkhan · #10 10-19-2005, 01:51 PM

Will check fuse #7 this evening.

zafarhayatkhan · #11 01-03-2006, 05:27 PM

Fuse C has 1.94 ma
Fuse 9 has 2.1 ma

All other fuses were 0. Between battery and negative terminal, 3.56 with all fuses in place, about 2.0 ma with fuses C & 9 out.

Please check how many milli amps you are getting at these 2 fuses with the key removed.

Fuse C (rear roof light, turnk light, rear door locking system, safery belt handover arm, seat back arrester, central locking system, door lights, reading lamps, aut. antenna)

Fuse 9 (diagnostic term 6, hazard warning system, clock, front roof light, radio, vanity mirror light, relay comfort circuitry term 86)

Intermitently, my fuel door fails to open, could that cause the drain?

The above testing was done by removing each fuse and placeing the multi meter in its place.

mpolli · #12 01-03-2006, 08:26 PM

Looks like you got a new regulator a couple of months ago. I assume that did not fix the problem? I can tell you that 3.5 mA will not drain a battery. Even a weak battery should not be drained by 3.5 mA. What eveidence do you have that the battery is actually draining at all? It appears you have eveidence that the battery is NOT draining at all. So you have some other problem not related to the battery. Is the symptom still car won't start and check engine light on?

Mike

zafarhayatkhan · #13 01-04-2006, 08:02 AM

I did not drive the car for the last few months. Have not installed the voltage regulator either yet.

So yesterday I bought a new battery, it showed 12 volts. After driving the car for about 70 miles and 2 starts, checked the voltage again with engine running 13.9 volts, with the engine off 13 volts. So my conclusion is that the voltage regulator/alternater is working fine.

As far as what was happening a few months ago, the car would click and not start, but at that time, my wife was using the car for short multiple in town trips. At that time, the new battery lasted about 10 days before the car failed to start. At that point, we stopped driving the car to avoid getting stranded until the problem had been diagnosed.

I disconnected the battery last night, I will leave it connected and drive the car for a few days and see what happens.

zafarhayatkhan · #14 01-04-2006, 08:04 AM

Quote:

Originally Posted by MrCjames

Another thought-the OVP relay might be sticking but I believe the ABS light would come on as well. Not cetain how you connected your blink tester, can it damage the ecu..........not sure about that, I suppose it's possible.

With the key removed test voltage at fuse 7.......if voltage is present I might suspect a broken ignition switch. I like to approach electrical matters one step at a time, in my eyes the switch needs to be confirmed or eliminated as a/the cause.

The ABS light is not on, but I noticed that the ASR light stayed on the first time I started the car after installing the new battery. How can I check for sticking OVP?

zafarhayatkhan · #15 01-25-2006, 08:23 AM

Installed a new Voltage Regulator, along witn a new battery. Installed a product called "battery brain", as well. It shuts the battery down if the voltage gets to 12 volt. Has a remote control to turn on/off the battery manually.

I also found that my reading of 3.56 mA drain was not correct. I turned the headlights on, and then tried to complete the circuit, the headlights did not turn on.

Please advise on the proper procedure, this is what I have been doing:

Disconnect negative battery terminal. Turn the dial on the multimeter to mA. Place 1 probe on the battery terminal and the other on the disconnected cable.

Also tried going directly from the battery terminal to ground, still get only 2 mA.