idk i read somewhere your comment about switch it ON few times per week/month it might be beneficial but i can't find where or you meant something else?

 

The end goal is to regain STABILITY against chaos.
Prefer ALT-LIN over ECO.
ECO helps cook the CPS for "oil in harness"

 

Guys, I plugged my alt back in today. I did so because I got Aux Battery Malfunction warning this morning. To be clear, the problem was with my aux battery being below 9 volts. I replaced it with a freshly charged and maintained aux battery and that fixed the problem. My question is “why” did the battery drain down. My only suspicion is that disconnecting the alt-lin line caused the problem. But I have no proof. We shall see if the new battery also fails.

The other thing that happened was that I got a couple of additional DTCs in the Front SAM and stability control. I could clear all the codes with my LAUNCH and iCarsoft except the code for communication failure with the alternator. (I will post my report later.) I had to use XENTRY to clear that one.

 

That's interesting, are you doing the Reboot procedure which were mentioned in the thread, me on my w205 can't since i don't have battery in the trunk

Also any other difference you noticed after plug in back again apart of the swing voltage?

 

I had to replace my aux battery. In my car it is the small 12V battery behind the passenger's seat. I have it on my CTEK charger now to try to recondition it. It wasn't but a couple of years old.

I have not noticed any difference in the car since plugging the alt-lin line back in. At idle, I show a steady 14V ± 0.1V.

 

These are the errors (C073300 and B1E211B) that caused me to replace my aux battery.






And this is the error (U012087) everyone gets when disconnecting the alt-lin wire. This is the error I could not erase with either my LAUNCH scanner or my iCarsoft scanner and had to break out XENTRY to clear it.

 

@JettaRed Disconnecting ALT-Lin disables eco start/stop related stuff and thats tied to the aux battery as far as charging goes. @S-Prihadi has a thread on this somewhere. you can keep it topped off or plug in the ALT-LIN cable to resolve that.

The SAM stuff I dont know of. Mine has been disconnected for abot for a year now and I only top off the aux during every other oil change.

 

Good to know. I've never topped off my Aux Battery. I did put it on my CTEK charger for about the last 7 hours and it is fully restored now. I checked it with my battery checker and it looks like the battery is healthy, but just discharged. Wish I had printed a report right after removing it.

It seems that the SAM fault is tied to the battery health.

 

Thanks for the update. I wonder what about those vehicles equipped with a super capacitor/voltage converter type aux "battery" as well.

 

The R-SAM calls bad AUX when the internal resistance is too high or voltage too low.

The old AUX charged up battery test shows near new capacity.

I believe this is evidence ALT-LIN does not hurt AUX yes?

> How can AUX get drained ?
AUX Bart. circuitry shadows after MAIN Batt...

It's either drained by driving, that's disabled by ALT-LIN)
or drained by parking... we're getting there!

-- Was your chassis given a chance to drain MAIN AGM while parked ??

-- Use your IC Display to monitor voltage while driving.

-- Use DVM on AUX to measure resting voltage (above 12.5V) and after driving voltage near 13.5V.


> WITH OR WITHOUT ...
-- the voltage yo-yo positively expedites aging both batteries with high currents
-- ALT-LIN stable voltage preserves both batteries with low currents

meaning stable voltage did not trigger this event, low voltage did but we knew that to begin with...

The only way to get AUX AGM to contribute power is with a low MAIN AGM battery (AUX shadows MAIN to supply its VIP circuits).

Let us know your test results.

 

@JettaRed My scenario is a bit more wacky as I have to rev to 1,000 rpm on any startup before it starts to charge (This diesel never jumps above 1k rpm)

I ordered another alternator used on an equivalent sprinter. Not much hope on resolving that 1,000 rpm issue but It does have a clutched pulley to help with some of the harshness that a fixed pulley causes when rpms move (since ALT-LIN is unplugged, the ecu no longer turns on/off the alternator to elimate drag)

If that fails I may experiement just hardwiring a ctek cable, plug in the ALT-LIN and just commit to topping off the main battery every week. Maybe I can still achieve some smoothness without much sacrifice.

@S-Prihadi have you experimented using deep cycle Marine batteries? curious of your thoughts as I know you love your boats 😉

I can confidently say that my bluetooth Audio no longer skips with this ALT-LIN unplugged. Maybe its just me but has anybody else experienced this?

 

> BATTS...
For the record both my lead-acid AGM batteries passed 10Yrs age before MAIN lost enough capacity from cranking currents.

My AUX still near original. I don't expect AUX to make it to 20th anniversary... 15th perhaps.

> REBOOT + FLOAT....
Chassis still responds very well to combined "reboot + floats" regardless of "ALT-LIN" already stable 14V running voltage.

There's a reason why that is... but until we find out "CTEK float" is an effective workaround.

 

01. ALT-LIN soft DTC , that lost COM with ALT or STARTER is inevitable when ALT-LIN is disconnected. It can not be removed even with Xentry. It will always come back.
It is a soft reminder that indeed Alt-Lin got disconnected. So accept it.

02A. Eco start-stop defeat has nothing to do with ALT-LIN unplugged/disconnected.
When I first used Autel MS906 many years ago to code out ECO start-stop, it was still the brute force dumb-azz method, it was not elegant at all.
The result was, the rear SAM from then on does not charge the baby AUX 12Ah trunk battery anymore, dont ask me why.
However, the basic sensing of resistance and voltage of baby AUX 12Ah battery is still being conducted.
So after like 3 years thereabout, of ECO Start Stop defeat, the baby AUX 12Ah battery went kapoot and I get AUX battery warning on Instrument Cluster.
On my car, if AUX battery deemed bad, the BRAKE-HOLD feature get disabled. I need the brake-hold , a must for Jakarta sickening traffic jam.
So, I DELETED by AUX baby battery completely with some needed modification to fool the sensing algo, which always wants to see AUX battery voltage and resistance.
DONE, all well till now.


02B. There is a more elegant method of defeating ECO start-stop after I done my crude dumb-azz version.
The new method supposedly can have last memory recall to what you last choose for ECO start stop before engine kill, and it will maintain that memory everytime
you start your engine. So no need manual hand operation of pushing ECO button to disable it at every engine start.
This method I think will retain all ECO start stop charging protocol for the 12Ah baby AUX battery at the trunk (w212).
I never bother to try this more elegant method with baby Launch which seems to be able to do it, as I have removed my AUX 12Ah battery already and done that mod I mentioned.


03. ALT-LIN when disconnected.
Whatever charging performance we get, it all depends on the alternator voltage controller design, as there is no more assist or command over-ride from ECM.
The Valeo on my car been beautiful.
The one on 2010 W204 C200 , I forgot what brand and amperage, this alternator needed first to see 1,000 RPM-engine for alternator to start charging.
Every alternator has minimum kick-in (cut-in) RPM for it to start operation. You can find it in their datasheet, which is not easy to get if Valeo.
Example here Bosch for motorsport alternator cut-in speed at 1,700 rpm alternator RPM, not engine : https://www.bosch-motorsport.com/med...ator_150_a.pdf
Remember, alternator RPM is not engine RPM, calculate the pulley ratio please.

That's all.........

 

This is good to re-awaken this thread and refresh the information. I must have missed the part previously about needing to charge up the Aux battery every now and then. I had the alt-lin disconnected for quite some time -- I wish I had made note of the date and mileage! I acquired the Aux battery that just faulted on me in March 2022, so about 3½ years ago. Since then, the price has gone from $130 to $176. Glad it wasn't damaged. I have it on my CTEK to recondition and float it until needed. The other good thing is that my C350 uses the same Aux battery as my SL400.

Here's the thing I will need to keep in mind: My 2014 C350 also has the alt-lin disconnected, which was done at the same time. So, it will be interesting to see when I get the error message for that car, if ever.

 

AUX is unfortunately charged at the same time as MAIN while driving - There is normally zero special need to recharge AUX (with or without ALT-LIN: same!)

EXCEPT IF BATTS WERE DRAINED down!
In that case then AUX was drained as a result of MAIN getting wasted by CAN-B restless modules AUX then will absorb an high current punch of energy just like MAIN because ALT (LIN plugged in or not) ARE *NEVER* GOOD CHARGERS of flat batteries they abuse with unlimited Max current regardless of ALT-LIN in use or not... 30 years ago already that way.

ALT never limits battery current, it is a fixed voltage power supply.

> two ways to preserve UNUSED batteries:

1. CTEK/NOCO MAIN only or
2. disconnect both GND!

(sharing personal views not based on mechanical aptitudes... you know yadi yada ...)

 

> Meaning of "BOTH GND's"...
Means both BATT GND, not simply MAIN Batt ONLY, AUX as well also... ie. Both MAIN+AUX GND's.

For storage when you expect your chassis may drain your batteries **,
If you decide to disconnect your "MAIN Batt GND" great, then you must also disconnect "AUX Batt GND" as well. Without that step AUX will be drained flat quickly in short order.

**: batteries "drained while parked" is caused by restless CAN-B security background work.
Healthy Batts can go flat from 3 days to 3 weeks or more according to your chassis condition.

There are many ways to deal with that condition:

1. Repair string of faulty CAN-B Modules (KG + DCU,...)
2. Sanitize chassis temporarily by Rebooting
3. Disconnect both batteries!
4. Buy a "jump pack" for rainy days!!
5. .... any other ??

Enjoy good ownership

 

Re-visiting this topic for those who has a super capacitor or votage converter in lieu of a Regular aux battery. So the consensus is to leave it during the reboot procedure? Does disconnecting just the main 12V starter battery for like 30 minutes do anything or should I not go through the reboot process at all? I am also wondering how do I charge this super capacitor or voltage converter without ALT charging it. Eventually it will be depleted? From this video, it seems simple enough and I mean, he didn't even disconnect the 12V battery. Thoughts? youtube.com/watch?v=qiLLqjqyNoM

I am still out of the country but considering rebooting the car when returning back the end of the year or early next year. I am not even sure the car can still start up when I get back so that is another thing, it is off the charger and not driven since June.

 

From June to January without a trickle charger... That's 2x flat units: MAIN + (Aux/)CAP.

This is gonna get you to find out how to power up a flap "capacitor".
The answer is not with a 1000.Amp spark !!

There's got to be a procedure to limit the charging current to non destructive levels.

A capacitor of multiple Farads value has charging current similar to an unlimited short-circuit. It packs a lunch both ways: charging & discharging.
It very similar to a big AGM battery but more fragile.

Handle cap according to manufacturer instructions - We'd like to see them...

I still don't know exactly what makes these cars voltage sensitive (resistive cable drop-voltage?).
As far as reboot this is the organized assault on CGW.
Reboot + Float works a treat!

FYI: from what Ive seen, CAPS module become BBQ'ed from over currents, likely after being flat ($$$).

 

Thank you Cali : )

It is fair to say I should not unplug it with the reboot, is there still a point of rebooting by simply unplugging the 12V starter battery then if I need to leave AUX plugged in?

 

That video linked shows FCPEuro tech unplugging aux battery and installing a new with all limbs intact

 

I think this question needs answers about what's the differences between AUX-Batt vs. AUX-CAP??

> An Auxiliary AGM Battery is based on a stack of 6x lead-acid cells that store energy as 12Volts.

> An Auxiliary Farad Capacitor bank has no chemistry voltage. It gets charged and discharged by a variable current under a fixed voltage.
The current must be control because Capacitors can act as a short-circuit with unlimited current. This is known to be destructive with charcoaled PCB internals: RIP!

-- I know how to charge an AUX-Batt using a trickle charger...
-- I don't know how to charge an AUX-CAP. because battery chargers require a set voltage Caps don't have.

CAUTION:
Experimental rebooting of AUX-CAP chassis...
Find the factory WIS PROCEDURE related to a replacement of AUX-CAP... these CAPS units do not survive high currents.
This will help you understand how to charge up AUX-CAP so you don't experience frying your own unit.


After 6 Month of non use, you are nearly assured both MAIN + AUX-CAP are dead flat.
You will need the specific instructions to service this without frying your car fuse-links connected to AUX-CAP.
I don't know how.... let us know: share instructions.

 

Much appreciated Cali, will need to return and see. Not to jinx my battery but it is the original battery that came with the vehicle and has been fine surviving many winters, I even started it up successfully after leaving 5 months just last year when the car was left in a not climate controlled garage in the winter that hits negative temperatures. Given this time it is mostly summer when the car is stored, there is still a chance car will be able to be started when back depending on what month I return to Canada, we will have to see : ) Thanks so much Cali for the detailed analysis on this.

 

Alternator has been swapped. Driveability improved with the clutched vs fixed ALT pulley.

Unfortunately I still needed to rev above 1,000 RPM at startup. Decided to plug the ALT-LIN back in.

With that after starting the vehicle I noticed something...




I have stable voltages! Headlights are off

Now, I have left an element out of this discovery. I did get a tune recently which also included removing the ECO related parameters (I dont even have a functional button)

I dont know if thats tied to this but now the only time I get unstable voltages is the following after each startup:

Going into reverse (R) once
Going into drive (D) once

When that happens I see volts quickly drop to 11v-12v and immediately after switch to 14v+ (14.2-14.6) IB amps start going down during the entire drive cycle. Incredible. Transmission still feels great. Will continue to observe and report.

 

Spoke too soon. Stoplight idle. My guess was recharging the dormant AUX the past 1.5 hrs of driving.
Like clockwork the Bluetooth started skipping again

EDIT 1HR later, Stable volts again on the next drive cycle. Nothing on, no accesories. Very interesting

 

> GOOD + BAD MIXED...
That's interesting, you can see ALT voltage going down to 11V, 12V including normal 14V. - This is evidence of "yoyo chaos".

Normal ALT control range by ECU is between 12.6V and 14.9V . The voltage management is based on
-- either "Batt state of charge"
-- or "active consumers" (AirCon, headLights, Defrost, Engine cooling,...).

Overall this fancy ECU management current into battery is
-- only positively charging Batt (12.6 /14.9V)
-- never draining Batt power out (below 12.5V)

12.6V to 14V range is sort of typical lead-acid charge control. When batt is well charged based on the Batt Hyundai sensor module the ECU simply supply chassis with 12.6V.
Target may be near 80% or 100% charge... ok!

What should never happen is crazy ECU gone wild forcing low chassis voltage below 12.5V
such as 12.3, 12.1, 11.7, 11.3... for extended periods or until engine restart.
That is followed by 90.Amps (1300.Watts) "charge" into roasting batt regardless of Hyundai Temp measure at Neg(-) pole.

Once you witness that abuse then decide to experiment the self-managed regulator (aka. ALT-LIN:Out)


> SUPER SIMPLE...
So many MB chassis use distinct Bosch firmware at various stage of development. The distributed voltage control using the float-charge by Rear-SAM at 12.6V on my chassis evidence that it benefits user scrutiny to preserve battery integrity.
Perhaps yours does too...??

smart display $10 phone charger combo

The dashboard "IC Display" can be set to monitor voltage under shop-mode menu options.

Normal Bartery charge current is less than 15Amps... not 40A to 90.Amps!!

Slow cranks after longer drives are obvious signs of low battery.

Chassis with an appetite for dead batteries should seek a root cause fix.


Experiment + troubleshoot + decide based on your opinion. It's a basic voltage management going quietly rogue.
Drive with both hands on the wheel.