Aesthetics Electronics Interior

Add or Upgrade Ambient Lighting to 205 C-Class

Whether your car has or does not have ambient lighting from the factory you can add it or upgrade it to 64 Colors.  The processes are slightly different.


Be warned though this is not a quick job.  This YouTuber, Life of Emi, says it takes 2 days.  If your car has 3 colors and you would like it to be 64 colors follow the instructions on changing out the harnesses here:


If your car does not have ambient lighting from the factory but you would like to install it follow these instructions here:

Check out DMP Car Design for the Lighting Kit that works for you.

Electronics Stereo

Subwoofer Cable Management in Trunk

Last time I took signals off the subwoofer amp and test fitted 2 10" JL W0v3 woofers, and mounted the amp.

Subwoofers in a Mercedes
I painted the board with black enamel

Running the wires thru MB cable management

From the top of the trunk to get the signals and remote on, or from the trunk to bring power up, no matter how where you mount your amp you'll want to take advantage of MB cable management.

From the spare tire area into the ceiling in the forward right there is space for either a 4 gauge wire.  There also seems to be some provisioning for running potentially other wires into the cabin and perhaps forward.  In this case we will just unhook all the black pusher pins on the starboard side.  We will also need to unhook the two black pusher pins for the carpet.

At this point there should be three luggage tie downs to take off.  They pop off from the front using a plastic trim tool on each side.  Then are undone with a pretty big torq.  Please note it is very easy to cross thread these if you take the bolts all the way out please ensure they thread straight ahead when returning them into place or they may not seat completely and provide resistance.  Please note the general direction of all the luggage tie down tabs, as they stay the same in case you forget.

In my case I ran my negative to a ground on the right side, but in retrospect may have done it to the trunk as there seems to be an extra ground there.  I however decide to run it down the front right area and then taped it down then grounded to the areas on the starboard abaft area.

I ran up through this making sure not to hit anything that moves or articulates, like the trunk arms.

Was going to hit the wood with some black but maybe the red and moving some of the tape would be better. I taped the signal wire and the remote on from the subwoofer amp to the aftermarket subwoofer amp. I left the stock amp unplugged and taped it to the top.  I later painted the board and am considering adding a fuse further by the battery as well.

Electronics Stereo

Mount an Amplifier in a Mercedes Benz CLS C218, W212

In the second part of my sub install in a Mercedes CLS or E class I mounted the amplifier.  I wish I had never done it this way but take this post as learning from some of my mistakes and use the benefit of my retrospect for your install. If you want to skip this part and read about cable management check out part 3.

I need a garage...

I mounted the amp to the ceiling of the trunk, before the trunk lid, on a black mount made out of some ridiculously hard material. Something so hard you can't really thread into it.  So if you are going to mount on this, which in retrospect I wouldn't, it is best to drill a hole and have either a metal fastener at the end, or maybe a slick bolt setup?

There is some room further "in" (fore) the trunk.  If you really want to mount on the ceiling I would do something here carefully with like 1/2" sheetmetal screws and perhaps some spaces depending on depth.  My amp was too big to mount here.

What I should have done in retrospect was mount the amp to a side fairing to the side of my subwoofer.  I would likely attach an amp fairing piece with the up to 2x10" subwoofers (2x10") with some sort of dampening between, like padded rubber washers, and another fairing for the other side of the subwoofer.  Both can be attached to load space loops near the back seats with strap ties.

Overall I wouldn't mount to the black thing again, or the ceiling as mentioned.  However I did and it was painful.  I used a 3/4" piece of MDF mounted to 4 screws with metal fasteners and 1/4" rubberized plastic spacers.  I mounted the amp to this and in retrospect i would have set the threaded inserts.  I thought the dude on youtube suggesting it was adding complexity but it would have been useful as holding the amp and drilling holes and then hand screwing the screws in so you don't strip them.

Started to pour.

The wiring I still have to work out. It started to pour so I didn't really even get a chance to clean up, not just ruining my prior car wash.


Electronics Stereo

Add a Subwoofer: install a subwoofer on CLS C218 E W212

Adding a subwoofer can add to new sensation of frequencies factory drivers don't hit.  I went with 2 - ten inch jl audio 10w0v3.  While back in the 1990s the W0 I didn't pay much attention to, running a JL 18w6.  I enjoy the new w0v3 series.  The new 10w6 is what I would go with if money were of no issue.

I like 10" woofers a lot.  8" woofers are great for mid-bass. 12" subwoofers are loud.  15" and 18" subs hit hard low and lower.  While 10" subs to me sound pretty good for their size and they are easier to blend and smaller than 12" woofers.  I also like their tonality more than 12" woofers, and would likely choose only a much larger subwoofer if 10" wasn't useful (e.g. PA). In those cases I like sealed 18" woofers. They hit low and deep while retaining accuracy. Anyway back to the 10" woofers, they sound great in the car, and I could potentially see pairing them with 8" woofers too.  But I would go with dual 10" woofers and I did.

 While the CLS C218, similar to W212 stereo isn't bad for a starting base, I added dynamat and upgraded the once I upgraded the front drivers things really got going, later I installed crossovers, all of this of course was car audio foreplay, art.

There are a few things to note. One if you have harman kardon with the subwoofer amp n40/9, I tap that socket and leave it unplugged.  I opted to use two different tap styles to test both.  The first are long traditional ones,  you fit two uncut wires and the newer taps into just one wire and uses a spade connector for the second.  This spade connector style is shorter and the connection seems sturdier as the spade presents a structural resistance, so I would use this one.

I found two blacks.  One of which was wired into remote power on of the new amp.  The second two wires are for the RCA style signals.  White is positive and and I believe brown is negative but please reference the pictures.

I then ran a small run of wire from the small battery in the back, for the power on.  I installed two speaker cables out for a run to two 10w0v3 which are rated for approximately 330 watts.  I used my old hifonics hercules amp to provide 2 ohm outs for each sub a total of 750watts RMS.  I found in this setup about 9pm on the dial worked well in 2 channel mode to provide a smooth listening experience, and in 4 channel and logic mode to produce a party like experience with the woofer being fed both the 60 hz low pass and the 80 hz rear low pass signal.

At 11pm I found two channel in flat mode to provide a great but slightly overpowering experience. Maybe 10pm is a happy medium? Moving foward and summing up this original post, yes the old forum posts work.

Thanks a lot to all the mbworld members who helped make this work, posts like:

Read how I mounted the amp and routed the wires using MB Cable management.


DIY Electronics Maintenance Performance

Laser Jammer Install on E class w212

Check out this install thread on for AL Priority Laser on a w212.

Very clean and detailed with some help from other members with CAD information on the mounts.

I am not advocating the use of this, but I do love clean installs and have to link to it for that reason.

Electronics Stereo

Adding Capacitors and Crossovers to Enhance Factory Speakers’ Sound

One of the ways manufactures can save on the total cost of an audio system is by cutting the costs of the crossovers.  As digital processing has evolved one might assume that factory wiring and amps would put out tightly controlled audio signals to each and every speaker independently.  However, that is not true for the vast majority of cars.  To see how I crafted the crossovers for the front door mid-woofers check out the mid-woofer upgrade post.

The drivers that are used in luxury cars are often numerous and of various non-standard sizes.  While upgrading the main playing drivers makes a lot of sense, the difficulty increases and return decreases greatly when we are discussing the rear surround for example.

Using this capacitor will make the factory center speaker sound cleaner. It should be mounted on the grey side.

In these cases, it makes a lot of sense to control the frequencies theses small drivers are getting fed.  So that when you turn up the volume, the sound remains clear and undistorted for longer. On the center channel I added two capacitors but upon reflection of the wiring diagram the center channel is not a summation of two speakers but one connector seems to be for SOS and Mercedes calling, and the other, it seems like right side is for the music.  I'll try to remove the left capacitor in the future to come back and check to see if that is the case.

To remove the front grid, you use a straight plastic pry tool. releasing 4 tabs near the you.  The windshield side is attached by lifting up and out.  Remove the front two connectors carefully. Once at the speaker pry gently on the center speaker and splice inline a 68mF capacitor on the right connector solid color.

Remember to always insulate any metal

For now I can say that with the volume all the way up, the front stock does not distort when paired with a 68mF capacitor.  It does sound a bit bright for my tastes, but I like bass, and with a subwoofer I'm sure it will sound good if I ever decide to go into logic 7 mode.

In the rear it looks like the easiest way to add cross overs is from the trunk amp.  I would look at the stock wiring diagram and find the surround left and right + output and inline splice a 68mF capacitor.  These 68mF capacitors should pass frequencies of ~600hz and above.  Protecting these small woofers from trying to play frequencies they cannot.  Which I guess would be some where close to 400hz but have not tested.

Electronics Stereo

Upgrade Mid-Woofers in a Mercedes CLS 2011-2018 (likely others too)

After I upgraded the front woofers, added dynamat, upgraded the tweeters, it was time to tackle the mid-woofers.  I wanted something that would fit, match the sensitivity, and that was well controlled.

I choose the Memphis audio 2.75" mid-woofer which left a small gap (that should be remedied with some mounting options), but more importantly the depth fit.  The original have a depth of just less than 2" so the upgraded option must also have a depth of no more than 2" because of how it mounts against the 6.5" inner door card.

To control the frequency I used a capacitor of 68 microfarad (mF) paired wit an inductor of .1 mH.  The capacitor blocks bass frequencies that would overwhelm the small driver.  The inductor blocks the hi-frequencies which are handled by the tweeter.  The mid-woofer and tweeter share a common take off.  Whereas in the rear it seems the audio is routed to the mid-woofer then then to the tweeter.  I think that is for a different post though.

I bought more of the 68 mF capacitors to block bass or hi-pass frequencies the small factory center and rear surrounds cannot play.  While I am not going to upgrade these speakers I am going to add capacitors to them.

Later I am going to add .85 mH inductors on the front and rear woofers which will block high-frequencies from being played by the woofers.  This should help clean up the sound when the volume is turned up.  After all this next are the subwoofers!

Android Screen Electronics

Install Android Screen in Mercedes CLS C218

Original Screen on the CLS 2011-2014
Original Screen on the 2014 CLS

So there's been things I've needed to do, and I haven't done for too long.  There is a specific category that is at or near the bottom of the list on my life to do, but  high in terms of what I should post or write about.  I think perhaps every car guy knows what I am talking about, that point where the house could be on fire and you wonder if you should change something on the car.

I know I need to do a video about USB Sound

This aftermarket android screen install is just one of videos I needed to do.  Prior to upgrading the android screen I mulled the decision for a while. The three phases of my decision was awareness but uncertainty in terms of keeping a stock look, research into previous experiences on forums and FB, and finally the install.

IWC Clock Upgrade for Mercedes-Benz to AMG
Aftermarket Android Screen in CLS

The first year I ran my new to me with less than 5k miles on the odo 2014 MB CLS 550 completely stock.  And loved it. Coming from a Range Rover it was nice to have the leather (or MBUX?) on the dash and most surfaces, like an Autobiography.  There were terrible rattles over rough road or with music loud.  I felt the power delivery could be weird.

EuroMotorcars Bethesda did hook up a map update which was really useful in terms of actually finding things.  I love Aki and the used manager over there.

But... I did miss CarPlay. There was a way to hook in car play into the factory screen, but that screen wasn't really worth writing about too much.  Although the way it was integrated means the aftermarket screen could be install salubriously.  Talking to Aki about the mods on my car thinking about stepping up to a 2018 CLS 63s, he didn't even catch it wasn't OEM.

Android 10 Split Screen Capability Waze and Youtube

Actually installing the screen

Ok so on the Facebook group there were some great informational write-ups about installing the units.  I'll see if it is ok to post some of the downloaded ones I have here.

In summary though the screen works by piggybacking the existing unit and interfacing with it by capturing the video, and outputting audio to the Aux in port on the COMMAND unit.

Step by Step

  • Remove dash*
  • Remove OEM brackets
  • Remove OEM screen
  • Loosen lower COMMAND unit
  • Unplug some wires
    • Carefully unhook the fiberoptic in/out connector and plug it into the screen provided connector
    • Plug the existing unit plug into the female end of the screen provided connector
  • Route Aux and USB Wires Down
    • USBs toward footwell or mid section
    • AUX toward mid section in CLS but some models have the AUX in near the glovebox
  • GPS and Cell antenna toward a pillar wings adjacent to glove box
  • Run aftermarket (not included) 3.5mm mic to screen exit (can mount on back of screen or steering wheel for optimal pickup to USB area
  • Test function with audio set to aux if it works proceed
  • Remount COMMAND unit
  • Mount aftermarket bracket
  • Remount dashboard piece
  • Remount side piece
  • Hook in USB Carlinkit adapter
    • Take note of linked page to find the app to download for the Screen
  • Hook in USB Soundcard
  • Hook 3.5MM mic into the mic input and hook a male to male (or as needed) 6-10 foot 3.5mm cord from USB sound card aux out to the AUX in of the MB (remove the screen's provided 3.5mm)
  • Test the sound.
  • Begin to remove center mid console pieces
  • Loosen cup holder
  • Remove the console opener
  • Remove console lock trim piece
  • Unscrew several torx screws
  • Pry up surround near center console buttons unhook electronic connectors
  • Remove ~ 4 torx lift up the center COMMAND wheel but do not remove or put much stress on it
  • remove trim by lifting upward from forward trim two tabs left and right then pull up and forward on rear
  • Route the 3.5mm to the AUX port (from MMI connector)
  • Join facebook and discord group
  • Remove volume limiter (android will pick up the usb card but resets it each time)
    • With some code from github (sections of the below code are copied or edited from the previous link)
    • More to come
      • In general set up ADB
        • Some info here
        • and more from google here
      • Connect the device with ADB to the same WIFI as the powered on android screen
      • pull the build.prop
        • adb connect SCREEN_IP_ADDRESS:5555 
          adb root
          adb disable-verity
          adb reboot
          adb connect SCREEN_IP_ADDRESS:5555
          adb root
          adb remount
          adb pull /system/build.prop
      • edit the build prop by inserting  the  following  code
        • # Safe Media Bypass for External USB Sound Cards
      • push the build.prop back
        • adb push build.prop /storage/emulated/0/
          adb shell
          mv /storage/emulated/0/build.prop /system/build.prop
          chmod 644 /system/build.prop
  • Note the position for the AUX in on the COMMAND screen and configure that into the AUX position
DIY Stereo

Upgrade Mercedes Tweeters in CLS

Previously, I purchased a set of speakers to fit into the front.  I was only able to ft the woofers at the time but it made a huge difference.  The dynaudio tweeters and mid did not fit.  The screen I previously upgraded but haven't yet done a video on.

Later I upgraded the MB CLS rear woofers and then added inductors to them but honestly it didn't make as big of a difference. The rear woofers cut over at 80hz, the front at 60hz.

With the upgraded front woofers, I decided it was time to take on the tweeters as they became muddy and distorted at higher volumes now that I've tamed some of the front & rear rattles.

Upgrade front tweeters in a Mercedes with Harmon Kardon

Upgrading the front tweeter is not difficult at all. You do not need to remove the door card, but you will need to add a capacitor inline to protect it.  I choose to use the capacitor from the JL C2 crossover which reduced the crossover frequency allowing the front tweeter to play approximately 2000hz deeper than the oem MB HK front tweeter.  Approximately 6500hz with 6 MFD mylar aftermarket cap acting as a 1st order crossover, so some sound down to 3250hz would be audible at -6db, vs  ~8500hz with 4.7MFD stock 1st over crossover, which could be heard again at 4250 at -6db.

Tweeter Upgrade in Mercedes CLS c218 w218

This actually helped staging quite a bit more than I thought it would.

I have a set of mids ordered for the front doors and the install is written up: upgrade mercedes mid woofers

DIY Stereo

Reduce Bass Rattle from Rear of Mercedes CLS or E-Class

I really enjoy driving my CLS.  I do remember though the speakers would rattle, the doors would rattle; I drove over a rough patch of road and I thought to myself, "why did I trade in my avalon."  That is how bad the speakers and rattle were.

Slowly, piece by piece, door by door, I began to dynamat everything that rattled.  Dynamatting the front doors (and adding new woofers) paid out huge and completely stopped rattling that used to occur by the front arm rest.

I got to a point though when I didn't know what to do next.  I turned to the mbworld for suggestions.  I sound treated the rear grill, and later the area where the back up indicator lights are.  Both suggestions of mbworld.

This article deals with the area in the rear where the indicator lights are.  It is detached from the roof by pulling down by the glass, popping a clip on each side with straight downward force.  No pry tool is needed. Then this slides forward to release the part from the ceiling.

Inside you'll find a plastic part that is prone to resonate rattling, by this I mean if you tap it, it sounds hallow and perhaps a bit shaky.  There is a soft noise deadener applied,  carefully remove this part, apply the dynamat beneath it, and reattach the soft noise deadener with the dynamat backing to use as glue against the soft deadener.

I applied dynamat to this plastic part and to the areas that hold the clips in place.  Be careful not to plug the holes though. as their are fingers which slide through these holes.  I added a bit of dynamat above this plastic piece to the bare metal areas.  I tapped on each to see which "rang" or were hallow sounding and applied to those pieces.

Electronics Performance

Dragy Review: A GPS Performance Tracker and Social Network

I recently picked up a Dragy which is a 10hz GPS sensor that can track your performance data.  This is pretty cool. BUT the really great part is that you can see the leaderboards by make, comment on other's times (and receive replies).  Which can really demystify tuning.

Leaderboard by Makes

One example of this for me was regarding AMG fuel pumps on non-AMG m278.  Madness Motorsports posted that when he went to bigger turbos he had to go with AMG fuel pumps, this caused many to take similar routes.  Well the top CLS 550 on the leaderboards ran M157 turbos without the AMG fuel pumps.  I was able to ask him and get a reply.

Correspondence with a top of the leaderboard CLS550 tuner

To me that saved a bunch of effort in terms of trying to upgrade my fuel pumps.

There are videos to browse, and it an link to your phone with a mount to take a video.  Unfortunately it can also remind you that real life driving isn't always fun.  I tracked a 4 minute mile...

The dragy is great as a social tool, a performance metric tool, and in general a highly reccomended purchase at under $150, which is far less than existing popular boxes.  These other boxes often do not have the validation feature and the ability to share and track performance with other people.


While I'm not likely going to hard launch my car at this point, the direction it has shown me is invaluable.  No AMG fuel pumps, combined with upgraded billet AMG turbos should make the CLS 550 a compelling performance car that can keep up with some of the tuned AMGs.

I would highly recommend downloading the dragy app for free.  I also think the box works really well.

Recommended Modification :  Put tape over the LED.  Way too bright and distracting when driving.  Perhaps a few layers of scotch if you want to see it a bit, or electrical tape I'd recommend if you don't need to see the LED.

I've read several places 60-130mph is the new quarter mile.  As an owner I feel more comfortable running something running versus launching.

DIY Stereo

Eliminate Some Rattling from Rear Deck

Many Mercedes in the USA have a built in subwoofer in the rear deck. There is unfortunately a certain amount of rattle that occurs when the bass or volume is turned up.

I find this unpleasant, and go to great lengths to eliminate rattles. I've researched this a bit, and it seems some are caused by loose nuts in the trunk, some are from areas where the rear shade retracts. I found though a lot comes from the grill that goes over the subwoofer.

It's very easy to take out. Just a few tabs. It's a long piece of plastic with not much holding the tabs in place. I used dynamat on the back of all the tabs and along some of the longer areas without any musical output and along some of the sides.

It's a really nice DIY project that pays big dividends! I would also doubt they would even attempt to fix this at most MB dealerships.

DIY Electronics Maintenance Performance

Change Mercedes Spark Plugs: Tuning? Go for Newer, Colder Spark Plugs

Spark plugs actually have a temperature range that they are designed to operate in.  A colder spark plug doesn't fire colder, but it does help evacuate heat from the cylinder head faster.  Pressures with emissions and finding the right balance between a spark plug that will burn fuel completely even during short trips and one that can handle long hard driving is difficult.

Merecedes over time has revised spark plugs to one step colder on M278 and M157 according to Jason at OE Tuning.  Who recommends the current Mercedes spark plugs with oem gapping for the M278 and M157 even when tuned. NGK and Weistec do offer spark plugs which are colder I believe and some tuners may recommend changing the gap on either setup.

When tuners started with these engines they almost all suggested one step colder plugs.  Over time revisions occurred, and even official power output numbers revised.  This is an important step in your pre-tune checklist.

Changing Mercedes spark plugs are a DIY job but harder than normal.  With a DIY scale of 5-6.  It takes time, you have to go slowly and may not finish in one go.   After changing sparks you'll notice the ECU recalibrating and after this recalibration you may want to consider flashing to a tune if you have had previous trouble.

How to Change Mercedes Spark Plugs

  1. Get the instructions from Mercedes Star
    1. Ask, Search on FB, MBworld as needed
  2. Note the torque and special tools suggested
    1. Buy generic versions of the special tools
  3. Undo electrics with tool
  4. Unscrew two bolts per coil
    1. Unclip any electrical from fuel rod
    2. Unscrew wire harness between cylinder banks
  5. Remove coil with special tool
  6. Remove Spark Plug with special tool
  7. Add antiseize to threads optionally
  8. Add dielectric boot grease to end of boot and spark plug boot area
  9. Put spark plug in spark plug socket, tigheten to specifications, in the case of m278 17 pound feet, approximately tight plus a quarter turn.
  10. Insert boot back on
  11. Plug in coil
  12. Repeat

Fuel injectors have also been revised overtime as I understand for the M278 application.  Some I believe some upgrade these as well.  I'll do more research on the fuel injectors.

Android Screen Electronics

Eliminate Rattling from Aftermarket Android Screen

While the electronics in the aftermarket android setups are fairly good although I would use a usb dac or sound card and usb external dongle for wireless apple car play or android auto.  Both of those usb dongles are superior than the stock implementation.  Although, I feel that the internal sound could be good potentially, it just isn't out of the box.

There are some issues.  For me the biggest is the screen would rattle on rough roads or across bumps.  I took off the screen which is held into place above by two screws.  You may need to pry open the screw covers with a knife. The screen pulls upward after the screws are undone.

The screen has a few cables in it. 2 Coax type for the GPS and Wifi, a USB, 2 multi connectors.  I would remove them all but I guess it is possible to do it without it.  If you do please have blankets or towels protecting the dash, the radio, everything.  It is really easy to scratch stuff.

After the screen is off you often remove two more screws often holding the mount to another mount.  It is often this plastic outer mount that rattles. 

IWC Clock Upgrade for Mercedes-Benz to AMG
The area between the plastic display mount bracket and the factory dash is prone to rattle

Apply black silicone to the outer edges of the plastic mount and let it dry

or Use small amounts of butyl rubber on the interior. If you use butyl rubber, a small amount to the inner most parts of contact is often sufficient. The silicone is a cleaner install, but the rubber butyl (like the backing of dynamat), does provide some adhesion and actually makes the whole install a bit tighter.

I also added some dynamat to the metal retaining bracket that the plastic mount attaches to.  The plan of attack being two fold, stop the plastic on wood or plastic plastic rattles with the silicone and actually use the dynamat to slightly provide more rigidity more resistance to harmonics.

The install is the reverse, mount the plastic into the metal.  Plug in the connectors to the screen.  Slot the screen in downward.  Ensure it is slotted then use screw the screws and replace covers.

DIY Electronics Maintenance Performance

When, Why & How to Replace Mercedes Auxiliary Battery

As the push for ever increasing fuel economy has pushed engines to be more efficient and use innovative technology we may not otherwise see, there are some configurations of Mercedes that run a dual battery set-up with one battery primarily, to my knowledge, to power start the engine and power most things, and another for start stop system reserve and to regulate voltage.  To see how to change the main battery check out this post.

Modern Mercedes use so much computing in the delivery of torque to the wheels, and in almost every sensor, computer, etc.  I figured taking a lesson from Range Rover Ownership that these cars may be sensitive to voltage and I could not be more right. Right out of the gate previously my brakes felt more powerful and confident with the big H8 battery.  With this smaller Aux battery in my car, a 200 CCA Duralast Platinum replacing a 7 year old OEM battery, I wondered what the impact would be.

If you are on a factory battery in years 5-7 you may want to preemptively change your battery without even testing it.  It drives that much better.

In a empty stretch of road I gently hit the gas to a known level.  And wow, she took off.  There was such a big difference I changed the plans for the rest of my day.  Literally, not just taking the long way home, but hey let's drive that beautiful back road to the UPS Store to send the cable equipment back.  Then let's return the core even though this new one isn't even an exact fit.

Wow, completely different.  So different the transmission really had to remap itself in eco pro or whatever, e mode stands for. A CLA 250 was driving very hard stop light to stop light and in eco with almost no effort I outpaced it but she was a bit jerky as the transmission learned.  Perhaps the transmission control unit (TCU) itself was operating differently with the additional torque.  Either way she put down power very nicely.

This drive was so nice. It really made ,e reflect on the fact that with ESP mode on there is a giant barrier of computer between the go pedal and the drivetrain.  I would not recommend running an ECU tune with ESP off.

When to Replace Your Auxiliary Battery

  • It says to
    • There can be a dash warning "Replace Aux Battery". It is ok to drive for a bit but not too long.
  • Your car is a certain age
    • I love the 2014-2016 Mercedes but if you are running original OEM AUX battery you may want to switch it.
  • It doesn't test to rated power
  • Start/Stop Stops Stopping the Engine
    • If your eco is always yellow, and your car isn't staying off as long or as often as it used to, it is a good sign your AUX battery is worn
  • Park Assist Stops Assisting
    • When you pull next to an open spot to parallel park, your car may have previously asked if you want to engage Park assist or something similar
      • If this stops working as often you may want to consider replacing your AUX battery

Why Replace Your Aux Battery

  • You're about to tune your car and the batteries are more than 5 years old
    • For me my car runs better tuned with the batteries updated
      • I would guess it has to do with voltage droop under load while trying to deal with aging batteries as part of the load
  • You want your park assist to assist, and your eco mode to stop your car
  • Overall you like your cars in top operating condition
    • Changing a worn AUX battery does make a palpable difference in my case, and for many reported on MBforums.
Tubing setup aftermarket AUX battery replacement
Here you can see my use of a cut down jura milk frothing adapter and the milk container adapter to connect to the factory tubing.  Using this Upgrade Provides an additional 10% capacity over factory, also using the part compatible AMG battery will yield similar gains. 

How to Replace Your Aux Battery

  • These batteries are often located in the trunk of your car or under the dashboard
    • For ones in the dash I cannot advise further but to point you to MBworld and suggest you ask there, which is not a bad choice when posed with a Mercedes question
  • For the ones located in the boot
    • Fairly easy, a 10mm wrench unhook the terminals
      • I loosely taped positive out of an abundance of caution
      • A 10mm bolt that secures a swinging holder in the case of the C218 likely W212 and similar
      • Unhook the vent
      • Install new battery
        • If you are using an aftermarket battery you will likely need to hold the aftermarket bolt loosely with your hand
        • If you are using aftermarket consider the venting solution if it doesn't fit stock
          • I ended up using two tips from a JURA Espresso Machine Milk hook up
            • I cut the black frothing tip down and used the tubing to connect while using the clear tip to connect to the factory tubing

Upgrade Mercedes Battery

  • AUX 14, and various 14 size batteries will work
    • Some car audio batteries may fit, these are hybrid batteries designed with large capacitors to capture and deliver power faster
    • You will likely need to modify the vent system or holding system in some cases.
  • AUX 14 Platinum
    • Will likely need to utilize vent adapter as above, and hold the bolts in
  • AMG Batteries are often bigger than non-AMG but will direct fit
    • CLS 63 battery almost surely fits perfectly into the CLS550 and provides ~12% increase in CCA from 170 to 200.

Ease of DIY: 1 for MB Battery 4 for non-MB battery

You will need a 10mm wrench or socket.  No extenders are needed.   If you are going to a different battery other than MB, may need to fabricate a vent adapter as above out of a cut down Jura milk adapter.