jbeech

Hmmm, there's seemingly nothing I can do to bring the bus voltage up. Anyway, thanks for the uber fast thought of using another display page.

wjcandee

It didn't work because it's the wrong instructions for a W211.

On your car, when you first turn the key to the first click, the temperature normally appears as the main information. If it doesn't, page until it does. Then, with the temp in front of you, push the little knob 3 times. It will beep and give you something like 12.8UB in the display. That's your voltage at the battery. If you then start the car, that information will stay in the display and you can see the voltage at the battery with the alternator going. Once you turn off the ignition, that clears and you have to repeat the procedure if you want to see it again.

jbeech

Not the instructions for the W211, eh? OK, now I'm not feeling quite so dumb . . . but it's still not working. My car, an '05 E320 wagon, 'is' a W211, right?

Here's what I'm doing. Insert key, turn to first click. I then get "No Messages" in the display. Then I page down, first to "NAV OFF", then "AUD OFF", and then to the temeprature, in my case +84 degrees. Now I then press the stud three times . . . and nothing. No beep, no change in the display. Nothing at all happens.

Anyway, I appreciate your trying to help guide me and look forward to figuring it out so I can get a display of the bus voltage. Many thanks.

Last thing, to preclude hijacking this valuable thread, I'm starting a separate thread about the various noises I hear when I turn the key to the second position, which I tried when none of the above worked at the first key position.

bbirdwell

I literally just walked back from my garage after checking this on my 2005 W211.


Scroll the menu to the page with:
-speed (mph, kph), outside air temperature, miles remaining until next service due interval, oil level
-I set mine to the road speed (0 mph), note: I typed mileage, not mph in my earlier post.
-press button on lower left dash three times


UB 12.6 volts came up on my display.


That is all.

jbeech

Here's what works for me . . .

Insert key, turn to first position.
With temp showing, three presses.
Results = UB11.9

Hmmm, looked again and the auxiliary battery was replaced in December. A 200CCM battery was charged at $179 plus 1/2 hour labor, or $45 (independent shop for the last three years). Since I don't know where the aux battery is located, maybe that's fair but it seems pricey. Meanwhile, I've looked more closely at the records on hand and don't find a record of a main battery being replaced like I thought (saw that $179 and assumed, oops). BTW, is that how much those Aux batteries go for?!?! I wonder because I saw a line on an invoice in 2010 that the aux battery failed on Midtronics test - but no record (at the dealer that time) of the battery being changed. Hmmmm.

Anyway, buying a new main battery 'may' resolve this but I don't want to throw parts at this when it may also be the voltage regulator isn't doing its thing properly, or perhaps the alternator has a dead field and thus, isn't fully charging. Also, my C320 (W203) wagon's battery was, I believe, beneath the rear seat on the right side. Where is it for this W211 wagon?

I guess I'll call around tomorrow to see who has the right device (Midtronics - is there a compatible device?) to check this car for me but I have Advance, AutoZone, CarQuest, and NAPA readily available, plus two near-ish MB dealers. Post #9 said Advance has the Midtronics tester so I'll call to ask them first. Will the Midtronic tester confirm whether the alternator and voltage regulator are doing their thing?

Last thing . . . thanks for the guidance!

wjcandee

The best aftermarket AUX battery is the YUASA YtX-14BS, which is available on Amazon for about $70. There is a good video on how to replace it. Takes about ten minutes with the only tools required being a single ratchet. Easily accessible and you're not likely even to get your hands dirty. In the Amazon reviews there is a set of instructions on how to use it in a Mercedes.

The YUASA is an AGM battery which doesn't vent fumes in ordinary operation, unlike some of the cheapo online non-AGM batteries that some recommend for this application. Walmart has an AGM battery that will do the trick, as does Sears, NAPA, etc. Advance only sells a non-AGM battery as a replacement, which really isn't the best idea.

wjcandee

Yeah, Advance has the Midtronics tester. No. It tests the battery, not the alternator. Advance will test your alternator, but you have to pull it out first. If you have the ability to pull up that UB reading, just start the car and see whether the voltage goes up or down when you push on the accelerator. I had an alternator go bad and the way I determined it was that when I stepped on the accelerator, the voltage went DOWN on the readout rather than UP. Of course, the car is USING power rather than generating it when the alternator is dead. So I'm betting on a battery issue given the info you've given us. If you're going to Advance, and you need a battery, I can swear by the AutoCraft Platinum H8 AGM battery, which they have for about $188. There is a 20 percent off coupon on their web site which you will have to order online to use, but that will cut the price to about $150 for a high-quality AGM battery, which is a good deal, and they will put it in free.

jbeech

I read the manual about removing and replacing the main battery (the one in the cargo compartment) and it seems like I will have to resynchronize the ESP, windows, sunroof, and of course reset the clock.

I had sort of hoped the Aux battery would have kept everything 'alive' while the main battery was exchanged for a new one. Guess I am mistaken, eh? Doesn't sound like too much trouble, otherwise.

However, before doing that I am desulphating the battery with a BatteryMinder, which is a smart charger (also discharges and desulphates). No, I don't really have great hopes for this procedure because the battery is an OEM unit and has no date information. Moreover, since the car is 10 years old I rather doubt it's the original unit. However, I don't have a record of it being replaced so maybe it's a miracle battery. Anyway, I'm going to let this puppy run its cycle overnight before spending money on a new battery because I have nothing to loose.

wjcandee

Good plan. No the AUX doesn't work that way. You can use a settings preserver cable to the ODBII port, but it takes like a minute to "resynchonize" everything, so why spend the money on one. I have one and it's great, but how often do I change a battery? They might have one to use at Advance if you have them install it for free. I know Pep Boys uses one, but they charge for installation on the W211, although you can probably talk them out of the charge by indicating that Advance would install it for free. Lots of ways to skin this cat, and all of them are affordable (except going to the dealer -- one of our contributors had a $1200 charge at the dealer for changing both batteries, which is about $1000 more than it cost me to do it myself, including top-of-the-line parts).

jbeech

While the overnight on the battery runs, I'm playing what-if.

First, I called Advance and he has the battery in stock. Moreover, he confirmed a) if I buy online there's a discount (always good) and then I just go to the store for pick up and b) they'll do the installation for free, and c) he has the cable that goes in the ODBII port to preclude losing the settings on ESP, windows, rood, and clock 'and' that he uses it all the time.

Second, that he has the Midtronics tester and can do a battery and charging system check, and it's free as well.

Now for the what-if. If I read it correctly, post #5, states the voltage regulator is at the alternator and is a removable part and goes for about 80 bucks. The fellow at Advanced looked it up but said, in effect, 'that thing goes inside the alternator' so you're going to be removing the alternator anyway. Anyway, a remanufactured alternator through them is $160-ish (I haven't shopped around), which seems fair enough and in line with prices mentioned in previous posts within this thread.

So . . . is the voltage regulator really a replaceable unit as I seem to read in post #5, or not? I'm wondering because someone mentioned these are a maintenance item - I would have though by 2005 it would electronic instead of a type with points inside, but what the heck do I know?

Also, someone else mentioned removing a cover and accessing this thing from beneath the car. I have a floor jack and jack stands but wouldn't be averse to borrowing ramps from a pal or, gasp, buying some if this would be easier than jacking it up, which I suspect. Fortunately, loosening an alternator to ease the belt off to R&R the unit is within my mechanical wheelhouse but I've never done one from below.

Also, someone mentioned the Battery Control Module, presumably a MB dealer part? Any idea on cost? Aftermarket availability? Just curious right now because I have zero indication any of this issue is other than an old battery in need of replacing. Like I said, I'm playing what-if while I await the results of the desulphating experiment.

Thanks in advance!

wjcandee

The voltage regulator is a little thingy that sits inside the alternator. Yep. Points. Because of that, it is always a question of whether to replace just the regulator or the whole alternator, because you have to remove the alternator and take the cover off it in order to get to the regulator. If one is using a mechanic to do the job, the labor costs quickly out strip the difference in price between the regulator and the alternator. Me, I just bought the ProStart Remanufactured Alternator, which is remanufactured by Bosch of the Bosch alternator, at Pep Boys for like a hundred and forty dollars with a lifetime warranty, and they put it in, and that was that. Since you have to take the alternator off to test it and/or to get to the voltage regulator, you might as well just get the new thing because the extra labor may vitiate the price differential between the two. Removing the alternator in the car isn't complex, but it's a PITA, because it's heavy and awkwardly-positioned, so that it's hard to hold in place to bolt and unbolt, and sits amidst some hoses and such that you can't squeeze it through; you have to disconnect some hoses to get it out, and you'd prefer that the ones you choose to move don't have fluid in them.

It's not going to be the BCM. You have a 10 year old battery, and it's probably finally dead. Everybody on these forums likes to talk about this control module and that control module, and that is rarely the cause of issues, particularly when you have an obvious wear part in hand. Logistically, I would just take the thing to Advance, have them test it with the mid Tronics tester, if it's dead, pull out your smart phone and order the new battery online with the discount, then pick it up while you're standing there and have them put it in for free. That is overnall the absolutely best deal you can get. As I mentioned, you can do your own kind of charging system test by just seeing whether the voltage goes up or down on the dash when you step on the accelerator. If it goes down a bunch, its the alternator. If it stays steady, its the battery. Very over simplified, but probably 90 percent accurate. Keep coming with questions. They are good ones, & I appreciate the thought you were putting into this.

jbeech

I was unaware Pep Boys offered mechanic-service as well as parts, my impression was they were an Advance-type parts store. Interesting. So they did the alternator R&R for you? Do you recall their approximate labor charge? Wondering because doing it myself is within my wheelhouse but doesn't obviate the exacta, e.g. I'm usually busy and sometimes lazy! So if the price is right I'll spectate.

cetialpha5

Advance always seems to have a $50 off $125 coupon code floating around which is better than the 20% off code. Current code is WD519, but if that doesn't work, try increasing the number by one, or just check retailmenot for the most current code. I had them put a battery in another car, the guy did the positive first so the quality of the guy doing the job may vary. You're always supposed to disconnect the negative terminal first. If you disconnect the positive first and touch the body of the car, you'll get a big short, if you do the negative first, nothing will happen. And once you disconnect the negative even if you touch the positive to the body nothing will happen.

jbeech

Thanks for the code possibility, and especially thanks for the reminder on the battery disconnect sequence with the nice explanation for why.

wjcandee

Pep Boys charged me $200 to remove and reinstall the alternator. That was the price here in NYC. Maybe less elsewhere. I actually got a better deal than that because I complained about their practice at this shop of marking up the alternator (and all parts from their parts department) 50%, and I complained about my particular experience where the guys on duty after 5pm couldn't manage to do the job, and just timed me out until closing at 9, whereupon I had to leave the car for the morning crew, where the master mechanic spent maybe 20 minutes to do the whole job and handed me my keys. They honored their non-marked-up online price for the alternator and then gave me a free serpentine belt, for which they sent out for a good one, and put it in for free. for which they would charge anyone else $94, and they took 20 percent off. They are actually very attuned to customer satisfaction, because they survey the crap out of their customer base, and they have a "we'll beat anyone's written price by 5%" guarantee for parts AND for labor, so they are actually very, very flexible on price and their managers are incentivized to make sure you leave happy. Here in NY, everyone complains about everything constantly, so they have to set some limits, but they know me by now over there and know that I will pay a fair price for good parts and good service, so they actually go out of their way any time I haven't been happy, which is frankly-rarely. This shop, at least, does decent work at a fair-enough price. I still try to bring the thing to my super-talented, super-honest Independent guy on Long Island for anything that I can plan (brakes, maintenance, etc.), but Pep Boys is so freakin' convenient for me here in Manhattan (right over the bridge from my apartment), that sometimes I just take it there just to get the stuff done. (There's a newer dealer almost next-door to them that does very good service at less-than-total-ripoff prices, but it's still an order of magnitude more expensive on parts and labor than my current routine, so I only use them when I really only want the dealer to touch it.)

jbeech

The overnight brought the battery up from 11.9 to 12.1V, which is too low so it's toast. Also, with the car running, the bus voltage goes to 13.8V, which is normal. This confirms what you suggested re: it's not likely the alternator (when you hear hooves, think horse not zebras). So my plan is to just get a new battery because absent records proving a battery in the car's past, 10 years is a remarkable run in my experience.

Meanwhile, there are a host of things I am investigating with this car. FWIW, this is my third MB, a used 230TE when we lived outside the US, a W124), a new C320 (C203), and now this E320 (W211), also used, and all three were wagons. But I'll bring these queries/issues up in other threads, or start my own to preclude hijacking this very nice one about the low battery warning, which incidentally I never received.

To recap for the next guy . . . my records indicate the original owner (the guy I bought this car from) had the Aux battery replaced in December 2014 because of a "Replace Battery" warning (which as I've learned in this thread, is what tells you the Aux battery is history). When I first got in the car (before I bought it) there was a "Convenience Functions Temporarily unavailable" message, which the owner said went away and only appeared sporadically. After making the deal, I subsequently drove the car home 300+ miles (from Charleston, SC to Orlando, FL) and never saw the message again because the alternator juiced it up sufficiently. However, I had it in my phone (because I took a picture) for later research, which is how I arrived in this thread. As I've learned in this thread, the convenience functions message is what you get when the main battery is on its last legs (interestingly, nobody has mentioned what message we get when it's actually toast, but I suspect what happens is the car simply won't start one day). Anyway, it seems there should be some message before this (and I bet there actually is one).

In closing, good job, folks . . . . aren't forums great for sharing community knowledge?

btv94

Using BA-9 battery tester on my car this morning and the result Shows.


Battery test:


BAT = 12.34v
CCA = 768 (it said Recharge)
SOH = 90%
SOC = 67% (4.12m ohm)


Alternator test:


Cranking = 11.11
ALT = 14.19V
RIPPLE = 0.12V


The question I have is that when CCA is too low to start the car or battery needs to be replace. Still have the original battery with 850CCA.


Thanks,

turbo97se

Well I am going through this ordeal now.

When it gets hot and driving for a long time, I get battery low convenience features message and then after a while, it is fine again. I took the car to O'Reillys and they said the alternator is bad. Refurb Bosch is more than $400. That is nuts compared to a few years ago where you could but from dealer for $280. Mine is E320 CDI.

1. I bought a remanufactured alternator (AC Delco) from Rockauto. It was reasonable price $230 including core charge of $60. I really wanted the 200A version not the standard 150A as my car had the 200A version in it. So that is one thing to look out for. I am not saying the 150A version will not work but there are 2 models. The other thing is that the E320 CDI uses a high power 650W (new version has 850W) radiator fan that draws more juice than most other E Class vehicles (including my E55). I am not quite sure I understand why because Diesels are supposed to be more efficient and not generate so much heat .. . or so I thought.

2. A tip during replacement. When putting the new alternator in, plug in the 2 pin connector and also the main power (thick) line. Then use DAS to make sure it can communicate. Rockauto sent me a bad unit and it could not communicate with the alternator at all. I had to pull everything apart again and put the old one back in .. I am pretty unhappy about this. If I did this step, I would have saved myself an additional hour of work.

3. I am now going to try a genuine Bosch 200A voltage regulator. I think the alternator itself is OK just probably the contacts or bad regulator. They are about $60 ... worth a shot. The whole process took me over 2 hours the first time and less than an hour the second time. Just be careful with the radiator when pulling the alternator out not to damage the fins. Will post back what I find .. hope it is just the regulator. I think it is because it reads over 14V when cold but when it gets hotter, I get the error message for a while and then it goes away again.

Proctor750

Welp My 05 CDI is doing the same. Car starts fine and even temporarily AC kicks on but then the warning appears and convenience features are disabled for ~3-5 min of run time. Then everything kicks on as normal. It has been upper 90s since this started.

My guess is either contacts on the regulator or bad main battery. I tried the dash voltage reading and it was at about 12.3 before starting BUT I think this is misleading.

When you turn the car to ACC position to see the voltage readout, you are activating several things in the car that use up battery, so wouldn't the 12.3 be normal considering it's being drawn on as you are looking at the readout?

kajtek1

Dash voltage shows often 0.5V less than battery voltage, so good idea is to confirm that with other meter.
Measuring static battery voltage is not telling much.
For proper testing you should use load tester, or turn on all the headlights and rear defroster and then observe the voltage drop.

Proctor750

I think I just need to disconnect the leads at advanced auto and have them test it with the merc style tester.

I will say that when revving the engine the volts go up not down which is promising for the alternator.

I'm curious if it's neither the main battery nor the alternator, what's left? Control module?

kajtek1

My MB alternators keep the voltage at the same level (+- 0.1V)regardless engine speed
The car system is extremely sensitive. I had the "convenience items" message coming to me during week-long vacation and careful inspection back home found ... battery clamp not torqued properly. You'd think poor starter cranking would be the first symptom.

Proctor750

Something interesting happened.

I once again checked dash and it was 12.3 before starting and it jumps up to ~14.2 can dip to 13 with accessories.
I drove to Advance Auto and had them test the battery and it tested fine! Not only fine but he asked if it was new because it was almost overcharged...
Now if the battery is charging fine that would eliminate alternator/regulator.
The tester would rule out the battery...

So what's left? Maybe a faulty SAM unit from the heat giving false warnings?

What is strange is that the next time the warning came up I was ready with the dash volt readout and it forced the volts down to 12.00!!! As soon as the warning disappeared it shot back up to 14...

Perhaps the battery control unit was doing this? Strange..

kajtek1

Typical symptoms for something having bad connections.
Like short brushes.
How many miles?

Proctor750

17x,xxx

this seems too consistent for that.
When you first start the car it will recover from the starter draw, got to 14v then about 5 sec later light comes on and volts drop to 12.0.
RPM must reach over 1500 for x amount of time and the system is restored.