Sprinter Chassis Battery

[Dja06422]

I'm looking for advice here. My 2019 3500xd chassis battery only lasts about 2 days before it requires charging. I assume this is due to using the electric door opener. What is troubling is that you don't know the state of charge until you open the drivers door which we rarely do when on or off grid camping. How long should i run the engine at idle to get a reasonable charge back? Can you recommend a trickle charger when I'm at a campground? I did receive an email from Mercedes Me that mg battety level wss critical this morning and ran the motor for about 30 min.

[avanti]

Originally Posted by Dja06422

Can you recommend a trickle charger when I'm at a campground?

The Trik-L-Start line of products are probably the best choice for your situation.

That said, what you describe doesn't sound normal. Consider having the battery tested at an auto parts store.

[mkguitar]

if your battery does not have the capacity to retain a charge, replace it as it is a drain on your alternator whenever your motor is running.
a $150 problem becomes a $700 repair


get a load test at any autozone etc.


I buy my batteries at costco for the generous and a nationwide warranty service


if your battery is "good" , something is "on" and draining your battery. you can find this with a trouble light and pulling out fuses one by one- check youtube.


maybe the "thing that is on draining the battery" is the communication with mercedes!

[Dja06422]

I had the chasis battery load tested and the results were nominal. I then measured 3amps draw with the motor off. Next step is to test which circuits are causing the draw. I suspect this is normal Mercedes system monitoring including coms to Mercedes.

[mkguitar]

3 amps is alot something is pulling 36 watts


that means in a 24 hour period something is using 72 amp-hours of your battery capacity

[Davydd]

I have an electric door opener and I also have Trik-L-Start. You didn't say what house battery you have but I think the trickle charge comes off your house battery. So, unless you are plugged into shore power I would think you would be robbing Peter to pay Paul unless you have a house battery significantly more capacity than you chassis battery. I have a 532ah house battery bank so don't have a problem either way shore power or not and with autostart which I've never needed. I store my Sprinter plugged into shore power.

[avanti]

Trik-l-starts only operate when shore power is present. At least that’s the idea.

[Snowy]

Have you through/posted your question at a sprinter-specific forum? People there might be able to tell you what is normal or what common problems lead to this result.

[GeorgeRa]

Originally Posted by Dja06422

I had the chasis battery load tested and the results were nominal. I then measured 3amps draw with the motor off. Next step is to test which circuits are causing the draw. I suspect this is normal Mercedes system monitoring including coms to Mercedes.

Was just the motor off or ignition off. Parasitic drain with ignition off should be in milliamps not amps. My battery is barely making 3 months so I always disconnect it if longer parking (weeks) is expected.

[mkguitar]

another check would be to record the current draw ( many flukes have a record function which at least give a max/min or you could monitor manually). It is possible your 3 amp draw is during the period where the van is first turned off , there may be diagnostics, security or other systems which continue for a short period then "go to sleep".


my chev electronics can be fairly active in such a way and then settle down after an hour or so.


remember to deactivate any underhood lights


On the chev I was able to decrease issues by removing and cleaning the legs of each fuse with a scotchbrite as i did a current draw test, some had oxidisation which increases resistance.


In the end my issues were tracked to the "speedometer head unit" which others have had trouble with. I have a draw of about 380mA parked.
I use a trickle charger when stored at home & carry it on long trips, I may also disconnect negative if at a camp for a week or so off grid.

[Davydd]

Originally Posted by avanti

Trik-l-starts only operate when shore power is present. At least that’s the idea.

Did you wire Trik-L-Start yourself? I don't understand. Shore Power goes to the house battery and I thought that was the only path. You then have to have an electrical source and that can only be the house battery same as everything else. I didn't install mine. The upfitter did so I will have to ask. I just can't imagine a separate little wire going from the back of the van plug-in to my Trik-L-Start that is located under the driver's seat when there is a bundle of wires fed from the house battery bank supplying everything else upfront on my van. Whether shore power is present or not, the house battery bank can thus supply electricity and of course, say if in long-time storage or several day camping, plugged into shore power, that electrical supply is constant no matter what the house battery size.

Edit: I found this...

[avanti]

Originally Posted by Davydd

Did you wire Trik-L-Start yourself? I don't understand. Shore Power goes to the house battery and I thought that was the only path. You then have to have an electrical source and that can only be the house battery same as everything else. I didn't install mine. The upfitter did so I will have to ask. I just can't imagine a separate little wire going from the back of the van plug-in to my Trik-L-Start that is located under the driver's seat when there is a bundle of wires fed from the house battery bank supplying everything else upfront on my van. Whether shore power is present or not, the house battery bank can thus supply electricity and of course, say if in long-time storage or several day camping, plugged into shore power, that electrical supply is constant no matter what the house battery size.

Yes, I installed it myself.

From their FAQ:

I STORE MY MOTOR HOME WITHOUT ANY AC HOOKUPS. CAN TRIK-L-START™ BE USED TO DRAW POWER FROM MY HOUSE BATTERIES TO KEEP MY STARTING BATTERIES CHARGED? No, TRIK-L-START™ only works when there is a house battery charging source (i.e., DC power converter, inverter/charger or solar panels) present. In the absence of this charging source, TRIK-L-START™ is effectively disconnected, and doesn't supply any charge to your starting battery(s).

The way this works is that the Trik-L-Start monitors the voltage it sees at the house battery terminal. It has a cutoff threshold somewhere between the normal "resting" voltage of the battery and the "charging" voltage that is only present when the battery is being charged. Unless it sees a charging voltage, it isolates the chassis battery and does not use power from your house battery to charge the chassis battery (or vice versa).

This is why you need to use an Amp-L-Start rather than a Trik-L-Start if you have lithium house batteries -- the appropriate "charge" threshed is different for lithium, which is why both products exist.

[Arlo]

Originally Posted by avanti

The way this works is that the Trik-L-Start monitors the voltage it sees at the house battery terminal. It has a cutoff threshold somewhere between the normal "resting" voltage of the battery and the "charging" voltage that is only present when the battery is being charged. Unless it sees a charging voltage, it isolates the chassis battery and does not use power from your house battery to charge the chassis battery (or vice versa).

I’ve been told (by ARV) that my 2020 build has the Trik-L-Start, so the lithium house batteries charge the chassis battery when the house battery bank is at or above 13.2 volts. The lower cutoff is 12.8 volts, which I’ve never observed. When connected to shore power the lithium bank is maintained at 14.2 volts and the Trik-L Start maintains the chassis battery at 14 volts. Seems a little high, but so far so good. It might be set up this way because of the power sliding door potentially drawing down the chassis battery while camping. That’s speculation - I have never asked that question.

[mangomike]

We uae rhis
Schumacher SP-400 Solar Battery Charger it's a almost a 5 watt charher,,, so we use a controler with it.We use it both while stored and camping without hooks. . We putit inside the windshield for safty. It's not as efficient that way ,but it dosen't go missing either.
Safe travles
Michael

[Dja06422]

More research indicates that there's a 12amp draw when opening of closing the side door. I also noticed that for a period a 3 minutes after unlocking, MBUX is active and drawing approx. 3 amps. The main display will stay active until I "Tell Merceds" to turn off display, the current drops to about 1.4 amps. I suspect that this residual current is related to MBUX monitoring cellular for a remote LTE command from my cell.

[Buford Wilson]

Originally Posted by avanti

Trik-l-starts only operate when shore power is present. At least that’s the idea.

On my Roadtrek, the house battery keeps the starter battery charged via Echo Charge (similar to Trik-l-Start). House battery connected to shore power or charged by solar panels.

[GeorgeKG]

I don't have anything to add regarding the OP's battery question, but the issue of parasitic drain on the coach battery is a great justification for solar.

Our van has 300 W of solar on the roof and a Zamp controller. The controller is programmed to send 75% of the solar output to the house battery and 25% to the coach battery. This seems to be enough to overcome the parasitic load in the 2019+ sprinter vans. The coach battery is always at 100% charge even if the van is sitting for several weeks and disconnected from shore power.