Diesel Benz

OK, this should rule out the isolation relay.

novae500

Installed voltage regulator today. No luck got the car up and running and still have the red battery light. Front aux battery not charging, sitting at 12.6v while rear goes to 14.0...so probably the aux relay cable is bad. Taking it to get diagnosed at my indy shop. Before both batteries were being charged.

motorcaster57

I got that last week and my power steering was out as well... I drove aboute 1 mile and notice temp heating up rapidly... Pulled off and had her towed to shop... water pump out.... and belt destroyed....

phelicia

mine is '06 E350. replaced both batteries and alternator. after a few wks of aggravation and an outlay of +$1200, the damn red light is out. waiting for the other shoe to drop.if it does, I go back to Japanese.

Green E-300 DT

You failed to mention how many miles are on your E klass?
Your car is well over six years old. How long do you expect your alternator to last?

Do you think any Japanese machine will do better?
Do you think any Japanerse vehicle will drive and handle like your E-350?

For the money you spent, you shelled out far to much IMHO.
You should have spent only two hundred for both batteries and not too much more for an alernator.
Where did you go? To the dealer?

Good luck!



DHG

vettdvr

Bought my Corvette new in 99 now 13 yrs old, put 2000 miles on it this weekend still going strong. YES I would expect an alternator to last longer but reliablity data indicates some may fail at 1 sigma others (68.2%) 2 sigma (95.4%) , and 3Sigma (99.7%) So of course some will fail in the minus 3 sigma range.

However 2 of 3 should last the "average" life which is predicatble. What triggers MB buyers is the high price $125/hr for labor and labor on my airplane is only $75/hr AND the high number of failures of the total components.

Look at the cars from Japan and find a lower mean on failures? This is where the competion is, the mean and standard distribution in the failure rates.


On the topic of cars from Japan I changed my belt idler pulley on my bought new E500 and opened up the pulley. The bearing was clearly stamped made in CHINA. Given MB is buying parts now from low cost suppliers I can't help but wonder why a $50 pulley from the Dealer made in China is any better than an Autozone Part with the bearing stamped Made In China.?

Sort a makes ya wonder where did all my $$ go and did I really get reliability.

Remember quality is defined in the customer terms not the manufacturer. If a customer feels the car is bad quality then it is bad quality no matter what anyone else claims.

And of course your results may vary, you may be totally happy with your car and failure rates where others may not be happy. This gets to the freedom of choice to buy what each owner wants.

novae500

Well since my rear battery is getting charged by the alternator (12.6 to 14.0) once car is running. I've picked up a front aux battery relay and waiting for it to ship to me. Since the front aux battery is stuck at 12.6 when car is running and off, its not getting charged at all.

Green E-300 DT

Your rear battery is being charged and you think that the aux. battery is not, how is it maintaining 12.6 volts?
Every time I get into my CDI, I hear the motor for the SBC running to build up (?) or whatever it does.
Wouldn't you think the aux. battery would loose energy and its voltage would be dropping?



DHG

vettdvr

12.6 V on the front battery means engine off means it is charged.

Green E-300 DT

Since we both believe that the aux. battery is being charged and it is
maintaining a full charge, what good will a new aux battery relay do?



DHG

vettdvr

Not much but help the dealer.

Diesel Benz

How did you conclude the front battery is being charged?

Since the front battery is not loaded at normal conditions, it remains charged even if the car was not able to recharge the AUX battery. The fact that the front battery is fully charged, does not necessarily mean the car is able to charge it.

If the isolation relay is bad, the car detects that it cannot charge the front battery and gives a warning.

However I'm quite confused with the OP's case because I thought he had measured the front battery reaching the same voltage as the rear battery when engine was running. Now at a late post the front battery does not seem to reach 14+ volts. This again could be a measurement error because the isolation relay would not need to be closed all the time the engine is running.

I would remove the isolation relay and test it out of the car to find out if it really is working.

novae500

I replaced the front aux battery w a new one and at rest was 12.6. Before was getting charged but not any more. Now when car runs it's still 12.6 while the rear as before goes from 12.6 up to 14.0 And stays there while front sits at 12.6. So front not charging anymore. Isolation relay going haywire or bad. Will find out when I replace w new relay for the front.
I'm puzzled myself thinking the voltage reg would get rid of the red battery code.


I've pulled both neg terminal cables off so it's not getting any juice to drain either battery since the red cel and only put them on to test the car after working on it.

spkml320

I have just a word of caution to offer anyone trying to self diagnose a problem with the red battery visit workshop message. Do not continue to spend your money and time buying parts throughout the system expecting the red light to go out. It may not.

According to the mercedes dealer that I use, a hard fault will not self reset after the parts are replaced. And here's the best part. It is possible that no parts are bad at all. Mercedes has a computer fix for the software that delays the self check circuit fo a minute or so after starting the engine, rather than immediately as was normal. This happened to my 2004 e500. I bought two new batteries and when that did nothing to turn the warning light out, I went to the dealer and they reset the light for the one hour charge, which included the software update.

I did not have lots if time for battery shopping, but I would buy two new interstate batteries, especially if your car is still on the original batteries. You can buy less expensive batteries as some will suggest, and that might be ok as well. Then drive the car for 3 weeks. According to dealer, this may clear the fault. If not, only the star system will work. Just make sure that you let the dealership know that you are there for diagnosis and not repair and insist on speaking with the mechanic, not the service advisor, after the diagnosis.

The star diagnosis is money well spent. You'll also spare yourself the aggravation of chasing down a problem that might not even exist. Aren't modern cars fun?

konigstiger

novae500

Update: Followed the DIY for Heater regulator to remove the plastic shield cover under the wipers. Received the Battery Isolator relay and replaced the old battery relay with the one i got. Reinstalled both batteries and tested the batteries again. Off, 12.5v front and rear 12.8v. Started the car with a/c blasting, lights on, and still red battery and wasnt happy at all.

But could see the Volts go up on the dash from 12.5 up to 13.9. Got out to check the rear battery, 14.1, front 13.3 after running the car for 10 min. So rear still getting charged, and also the front battery is getting charged, unlike before. Went to check the dash for red battery message, GONE!!! No more messages at all. So it was my relay that went haywire/bad, and wasnt the voltage regulator. But i'm glad i replaced both now. Didnt get a chance to button up everything, still have to reinstall the wipers.

Will reinstall the wipers and take it for a nice long ride tomorrow to get it fully charged and running. Hate seeing the car sitting in the garage for past 2 wks. Thanks again MBworld

Green E-300 DT

Sounds like you've discovered that sometimes, it is not just the battery (s) but that relay that can be at fault!

Good information to know for all of us. I've learned something, and I thank you.



Derrel

S1CKE92

My car was started when i check voltage. Aux shows 7.6 lol which aftermarket battery is cheapest?

novae500

advance auto has the motorcycle bs14 battery for $93. Wally world/sams has it for $80 but you have to fill it with acid and charge it afterwards. I had mine leaking from the top cover and ended up returning it.

S1CKE92

Ok so i just go to my local autozone/o'reily and ask them for an bs14 motorcycly battery that dont need charging acid or whatever? Or is there a specific part number?

bernard farquar

Part number for an AGM battery at Oreilly auto is GTX14BSJ

looks like 89.99 exchange right now, at least in my area.

S1CKE92

Peps and oriellys have the one that you have to mix with the acid and autozone chick had no idea what i was talking bout lol.

novae500

Any of those stores will carry the BS14 battery. You will need to open the box and if there is a row of plastic tubes with acid, then you will need to fill, let sit for 30min , charge for a few hrs then install.

Go to sears if you dont want the hassle, but will pay a bit more. Advance Autoparts has the magna power ready to go battery , no acid to fill, charge..

ASHBURY04

Hi diezel benz. Is ther anyway to test the AUX battery relay to make sure that it is the culprit. my Aux. battery reads 12.78v with or without the car running but the main battery reads 12.43v with car not running and 14.15v running. Should I replace the Aux. battery relay? Are there any aditional tests to confirm this. thanks

Diesel Benz

The Star Diagnosis tool has a specific test for that relay. You could disconnect the relay and measure it pretty much like a normal relay. It would be a bit difficult to check from the car because the relay isn't always closed when engine is running.