MB Sprinter, battery drained, can't even turn ignition

[magicbus]

You didn’t by chance bump the shifter out of Park while working on the battery did you?

[markopolo]

Originally Posted by Teja

Thanks George.
All the standard warning lights come on (PARKING, BRAKE, Lane Assist, etc.) and quickly disappear except the icon that looks like an engine - that remains on.
You say you cleared your codes, how to do that? (just in case it is necessary pre-starting.)
Under the dash near the fusebox, there is a cable ending in a pushable button (see photo.) Don't know what that is, but the red indicator light at the tip is flashing. Pushing the center button makes it stop, trying restart makes it flash again.

[IMG]file:///Users/Rhythm/Desktop/Flashing%20button%20under%20dash.JPG[/IMG]

Try to add the photo again. Use the paperclip icon/button in the message window & make sure to click on Upload.

[rj-rv]

Not a Mercedes owner but red flashing light could be related to an Alarm/Anti Theft/Immobilization System which may not let vehicle start if activated.

[Teja]

Boy do I feel STOOOOPID

It was an "extra" engine lock.
When we first bought our Sprinter (A Pleasure Way from an RV dealer,) they presented us with 2 extra key fobs (see photo below) that had buttons to "lock the engine." Since the Sprinter already has its own built-in anti-theft lock at the ignition, they concurred that the extra engine lock was not a 'necessity,' just a second-line extra security measure. I remember looking at the fobs and thinking, "These are trouble!"

We have never consciously pushed any of the buttons on these fobs, but I picked them up a few weeks ago to move them, and must have inadvertently depressed the 'lock' button. This AM, I thought to grab one and depress the 'unlock' button, and damn if the engine didn't turn right over.

Thanks to all who tried to diagnose this with me, I learned a lot (especially about the battery disconnect dongle next to the accelerator,) and my total expense was the $230 new Interstate battery, which I needed anyway. This forum is full of very kind, responsive people.

Engine Lock Fob.jpg

[DUTCH in Atlanta]

Don't feel stupid. Stupid is the dealer who put something like that on a vehicle that already has good security. Far too many nannies on vehicles now days.

[rowiebowie]

Glad you had success. Persistence pays off and congrats to you and forum members for trying every trick and tip they/you could think of.

[GeorgeRa]

Originally Posted by DUTCH in Atlanta

Don't feel stupid. Stupid is the dealer who put something like that on a vehicle that already has good security. Far too many nannies on vehicles now days.

.....why indeed.

[Taysmine]

To be honest, I don't know how, I've never had such a thing

[Churcael]

Get your car checked in your local store.

[Jon in AZ]

Originally Posted by DUTCH in Atlanta

Don't feel stupid. Stupid is the dealer who put something like that on a vehicle that already has good security. Far too many nannies on vehicles now days.

Years ago a Honda dealer had sold my now-wife a CRV with an aftermarket security system. We never used it and over time it started alarming randomly. Ended up paying good money to have it removed. Several vehicles later we were purchasing a used Pilot on which the dealer had added another aftermarket security system. I refused point blank and made them remove it before I would sign the contract. They left the sticker on the door. It must have worked because the vehicle was never stolen.

Aftermarket security systems are right up there with paint and upholstery protection. Useless profit padding. Just say no!

Rant over.

[avanti]

This thread appears to be conflating alarms with engine immobilizers and aftermarket security systems in general.

I agree that attaching an immobilizer to a modern vehicle represents a potentially-dangerous case of belt-and-suspenders.

However, there is nothing wrong with a properly-designed and installed aftermarket security system, and it can be very useful. I self-installed one shortly after acquiring my rig. My motivation was that this particular system has 2-way direct communication with its fob (no cell-service required) for distances up to a mile. I adjudged that this was quite valuable around campgrounds and on short hikes.

This system is in no way redundant with the OEM alarm and has been totally trouble-free for eight years now. I would install such a system again. I would never connect an aftermarket immobilizer or remote engine start. They ARE asking for trouble.

It is true that the alarm industry is rife with incompetent installers. But, there is danger of painting with too broad a stroke. Many of the alarms themselves are perfectly fine products.

[Lawrence L.]

My 2022 Tellaro was dead after the winter. I have an Emergency Start switch. Worked perfectly. I drove about 20 miles, and the battery still wouldn't turn the engine. After another 30 minutes, the starting battery was able to start.

[Hollander79]

Ok, so I have been chasing this bastard for about 3 weeks (after hours), have rewired the entire electrical area, traced circuits, checked diagrams, spent HOURS killing myself on this stupid thing.... and what did it end up being? A cheap shortcut by the manufacturer!! If you have a sprinter converted to an RV 90% chance this is also your issue. The Mercedes Serenity is considered a luxury unit (apparently), so to find such a cheap short cut move was disgusting. Most of you probably have the factory installed auxiliary battery under the hood right? Pretty sure RV manufacturers order them that way on purpose. Anyway, when the sprinter has the factory installed auxiliary battery under the hood, the manufacturer installs a heavy duty solonoid under the driver's seat to disconnect this battery from the battery under the driver's seat when the ignition is turned off (separating the two). Instead of buying their own $60 solonoid to create the ignition disconnect from the alternator/front battery to the back end of the rv, the rv manufacturers are simply stealing the factory installed solonoid for their purposes. They are cutting the factory installed battery cable that runs from under the driver's chair to the auxiliary battery under the hood, then running a new $20 battery cable from the auxiliary battery directly down to the starter (where the internal battery is hooked up to). This links the two batteries permanently... and if one goes/is going, you won't know because the second battery helps to maintain the voltage/charge. Creating a parasitic draw that can't be isolated/identified because the good battery makes the bad battery check out at 12v. This starts as a slow draw, and becomes worse (after it's too late) as the battery breaks down further.

A $60 solonoid, and an extra 6 inches of wire is all they needed to avoid this. They could've maintained the original integrity of the system by installing a second solonoid under the seat, and connecting their solonoid to the existing cut off solonoid with a short wire as the power source. The cable coming from the hood area is at least zero gauge, and would easily handle the small draw for the charging of the house batteries.

I am new here, but will attempt to attach pictures.

I have devised a simple/cost effective solution that you can also do (of your own choice/risk) to re-establish the disconnect of the front hood battery.

It involves simply cutting the new battery cable of the front hood battery, putting a set of $4 cable ends on, installing a heavy duty solonoid (similar to something from an old ford truck where they had standalone solonoids for the starter), and wiring the solonoid to an ignition activated power connection (with an inline fuse). I used the factory ignition power connection under the driver's seat.

When the ignition is turned on, it then links the batteries for the added cranking amperage/ensured backup charge for starting. When the ignitinnis turned off, it disconnects the front battery making it stand alone, so one cannot drain the other, and the one under the hood retains it's charge because it is completely separated from anything in the vehicle. This is what the manufacturer intended for the system to do. The factory installed solonoid uses the same connection.

Be sure to double check wiring diagrams for your unit to ensure itnis the same, it should be, but always double check.

This was performed on a 2010 mercedes sprinter, and they have remained failrly standard since.

We were fighting with the parasitic drain for 3 years, lost 3 good batteries over the winters, so this year I set out to solve the issue.

I hope this comment can help at least 1 of you.

Two separate batteries will create a parasitic drain. What lead me to the discovery was removing the positive cable from the hood battery, and testing the voltage of the hood battery disconnected, and also finding voltage still showing up on the disconnected battery cable. I was checking to see if the parasitic draw of front battery was somehow related to the back end rv connection... but the voltage of my house batteries was different than the front battery, and different again from the cable voltage. That eliminated a connection to the back end, but lead me to check the voltage of the driver's feet battery, which matched the cable voltage (so direct connection full time), and the driver's feet battery voltage was lower than the front battery, thus establishing the parasitic drain I was looking for. Because the 2 batteries are 2 separate systems with 2 different environments, chemistry etc, they will try to equalize when hooked together... if one battery develops a bad cell, it drains the other battery trying to rqualize the charge.

[GeorgeRa]

Originally Posted by Hollander79

..................... The Mercedes Serenity is considered a luxury unit (apparently), so to find such a cheap short cut move was disgusting. ........................

What is this cheap short cut? sorry I didn’t get it. I used MB wiring for auxiliary battery on my 2013 Sprinter and found nothing cheap there.

[Hollander79]

Originally Posted by GeorgeRa

What is this cheap short cut? sorry I didn’t get it. I used MB wiring for auxiliary battery on my 2013 Sprinter and found nothing cheap there.

I get that my comment is a bit long, but that is what the whole comment is about... the short cut causes a parasitic drain. They use the factory installed solonoid that is designed for the auxiliary battery, as the solonoid to disconnect the back RV conversion instead. Then link the starting battery to the auxiliary battery under the hood permanently. One battery will create a parasitic drain on the other.

[GeorgeRa]

Originally Posted by Hollander79

I get that my comment is a bit long, but that is what the whole comment is about... the short cut causes a parasitic drain. They use the factory installed solonoid that is designed for the auxiliary battery, as the solonoid to disconnect the back RV conversion instead. Then link the starting battery to the auxiliary battery under the hood permanently. One battery will create a parasitic drain on the other.

I really think MB design is correct, I found no cheap short cut. MB relay is on with engine on to charge MB auxiliary battery. With excess power parasitic relay lost is meaningless. Work by anyone misusing this system is not fault of MB folks.
I wired this relay using a 3 ways switch and Magnum SBC:

1. alternator to house
2. house to engine battery
3. and off

[avanti]

Originally Posted by Hollander79

One battery will create a parasitic drain on the other.

If I understand you correctly, I don't think that that is completely true. Two batteries in parallel will self-balance until their voltages are equal, but after that, they will be stable. I don't believe that there would be any ongoing parasitic drain, and (except for some inefficiency in the transfer of amps) there is no power lost, even during the balancing itself.

I may be wrong, but I am not seeing it.

[GeorgeRa]

I must have been not patient enough reading OP’s essay; I thought the issue was with MB relay induced losses. By MB design auxiliary and engine batteries are never connected via MB relay except with engine on when power loss for relay activation is insignificant.

[Hatteras Jim]

Hi There:

Thanks for all your information and troubleshooting over the past 3 years and for sharing the information with us. I will agree that having two batteries permanently connected is not ideal; but, I don't think you solved your parasitic draw problem. I say that, because I have a 2013 Sprinter that needs charged or disconnected when not being used to prevent discharge, and I only have a single battery under the floor. See what happens this winter. Hope your problem is solved, mine goes on. Cheers.

[Hollander79]

Originally Posted by avanti

If I understand you correctly, I don't think that that is completely true. Two batteries in parallel will self-balance until their voltages are equal, but after that, they will be stable. I don't believe that there would be any ongoing parasitic drain, and (except for some inefficiency in the transfer of amps) there is no power lost, even during the balancing itself.

I may be wrong, but I am not seeing it.

I apologize my answers are a bit long winded.

If one battey develops a bad cell, that bad cell will continually draw down the entire battery trying to equalize the voltage across all cells attached. If that bad cell has a short, that draw will be larger and continuous and essentially becomes a draw that will drain the batteries to nothing or almost nothing. I Have seen it happen many times on things like electric golf carts that have multiple batteries linked. One bad apple spoils the whole damn bunch.... same with the auto batteries.

All it takes is one damaged/bad/under-performing cell in one battery to drain all of the batteries. It's just not as noticeable until that drain is significant enough to be obvious. I worked on cars for 10 solid years. Too many times 1 bad cell or dead cell was the issue causing everything.

On your house batteries, sure, you need them linked for the volume of power required, but people are more mindfull of these, understand they they are linked, and there are systems that maintain the charge on these when not in use, there is a 12v disconnect for them and people are shown to use that switch.

Batteries have a natural disharge rate, but that increases when something isn't right... even something as simple as the water/acid levels being low in one cell can cause a drain. Off gassing while charging or alternator charging going down the road can be enough to cause low levels in the batteries.

There are so many reasons why batteries cause their own parasitic draw. It is because of this fact that MB put the solonoid in, to sepaprate the batteries when not in use. The RV manufacturers are the ones who disrupted this system to build their add on, rather than putting in their own independant solonoid and leaving the MB solonoid and system left as factory.

In a perfect world where 2 batteries are hooked up together, they will simply equalize and that would be the end of it. But there are many other determining factors. Like one cell under performing. It takes more effort trying to equalize that cell, that equals loss... and it will keep trying to equalize that cell, because usually an under perfomring cell will also not hold it's charge.

Think about batteries you have put in a remote or something that hasn't been used. Those batteries while sitting in the box have very little natural discharge, and last for years without issue. Those batteries linked in the remote, even though no power is used unless you are pushing buttons, can sit there and die within a couple months, or end up leaking out battery acid... becaise with more than one battery there is a constant push/pull for equalization. That constant push pull from 2 sepaprate equilibriums causes continual discharge.

Just for clarification, I didn't say that MB made the shortcut, they did not, MB did their due diligence in adding the solonoid to account for battery equalization loss and for someone running the one battery down using interal lights/power while the motor/ignition is off etc. It's quite clear in their literature.

The RV manufacturer and MB are two separate bodies.

The RV manufacturer commandeered MB's solonoid so they wouldn't have to put in their own. The RV manufacturer could have simply added their own solonoid under the seat with a short piece of wire, and left the existing battery disconnect in place. This would have eliminated likely many of the parasitic draw problems people are having due to battery equalization.

The driver's feet battery in our rv had 4 volts. It was never found by the many different mechanics who tested it. Because who bothers to disconnect a battery when checking voltage? The linked battery made the bad battery show up at 12 v. And thinking that there was a factory installed disconnect in place to separate those 2 batteries when the ignition was off, was even less reason to check batteries with the cable off. (House batteries we know are linked and have to be tested individually)

The RV manufacturer removing that factory disconnect caused everyone to miss it for years.

So if you have a sprinter, remove the positive battery cable and check for voltage... if you have voltage, you have an additinal parasitic draw from the added battery. Maybe it solves your problem, maybe it brings you one step closer.