Atlas Chassis battery draining too fast

[Esfin]

Does anyone else have a problem with their chassis battery draining too fast when sitting idle? 2019 Atlas. Bought from original owner at 8K miles. They replaced battery just before turning over to me. Coach sat idle for 3 weeks and when I tried to start, battery was dead (11.5 V). I replaced battery again with an AGM thinking it would be more stable. But I am seeing an unusually high drain rate. Drops from 12.5 V to 12.1 V in only 40 hours with everything turned off. At this rate the battery has to be in near constant use or be recharged every 3 days! I have tried to hunt for parasitic draws, but am having a very tough time finding it.

Has anyone else run into this and figured out what was going on?

Thank you

[ITSNO60]

The Sprinter chassis does have a fair amount of parasitic loads when parked, there is a battery disconnect down by your skinny pedal that they recommend you use when storing the vehicle, it's just a big wire that pulls off of a connection point. I wired in a battery maintainer instead so I wouldn't have to use the disconnect and re program the radio, I just plug into the wall outlet whenever I park. My Sprinter chassis is older than yours but I don't think the newer ones are any better on parasitic draw and probably worse.

In order to see if anything is abnormal did you connect a meter in line? If you do this you must close all the doors and wait for all the modules to go to sleep before taking a reading, usually 20-30 min on most vehicles.

[ITSNO60]

Here is a good video showing how to do the test. You can do it right at the battery disconnect by the accelerator pedal.

https://www.youtube.com/watch?v=KF1gijj03_0

[Esfin]

Thank you so much for posting the suggestion Brian. Yes, I'm aware of the disconnect under the dash on driver side. My problem is that the draw is large enough to drain the battery over 3 days. This essentially means I have to disconnect every time I park! I have used a multimeter to test for parasitic draws. I may need to keep the meter plugged in for long periods to see what's going on because the meter shows I do not have any unusual draw.

I am actually considering getting a solar dual change controller which can automatically charge both the house and the chassis batteries at the same time, but can't help but think something is not right when the battery discharges over 3 days. So I'd rather find and fix before going there.

[RGJZ06]

Originally Posted by Esfin

Thank you so much for posting the suggestion Brian. Yes, I'm aware of the disconnect under the dash on driver side. My problem is that the draw is large enough to drain the battery over 3 days. This essentially means I have to disconnect every time I park! I have used a multimeter to test for parasitic draws. I may need to keep the meter plugged in for long periods to see what's going on because the meter shows I do not have any unusual draw.

I am actually considering getting a solar dual change controller which can automatically charge both the house and the chassis batteries at the same time, but can't help but think something is not right when the battery discharges over 3 days. So I'd rather find and fix before going there.

I was having the same problem until I found out the radio was still active even with the key off. Now I know how the shut it off and the problem went away. I do, however keep an Optima battery charger connected when it's in the storage lot.

[Esfin]

Battery drain problem solved for good! I replaced my solar charge controller (which on the stock 2019 Atlas is pretty useless (Atkinson Electronics 25A PWM controller) with a GoPower 30A MPPT controller (GP72RR and a Bluetooth enabled display) which can charge both the house batteries and the chassis battery at the same time. I can also monitor the state of charge for both batteries remotely, a huge improvement. Now I don't worry about it as the solar panels keep both batteries fully charged all the time. If you're handy, I strongly recommend this upgrade. p.s. I also threw on some additional panels on the top for a maximum of 506W of solar. Good investments!

[Bkujp91]

ITSNO60, I want to hard wire a battery trickle charger as you suggested in an earlier post. A few questions.

1. I keep the shore power connected to the coach when not in use. Is this a problem if the trickle charger is connected when on shore power?

2. I want to hardwire the trickle charger. Where should my connection points be? I was thinking about going inside the battery compartment under the drivers feet, but I don’t want to back feed to the coach batteries. Where did you make your connections. If possible, a photo would be helpful. Thanks

[ITSNO60]

Originally Posted by Bkujp91

ITSNO60, I want to hard wire a battery trickle charger as you suggested in an earlier post. A few questions.

1. I keep the shore power connected to the coach when not in use. Is this a problem if the trickle charger is connected when on shore power?

2. I want to hardwire the trickle charger. Where should my connection points be? I was thinking about going inside the battery compartment under the drivers feet, but I don’t want to back feed to the coach batteries. Where did you make your connections. If possible, a photo would be helpful. Thanks

With the key off the chassis battery is isolated from the coach batteries so keeping the coach plugged in won't be an issue, nor will back feeding. I opened up the battery cover on the floor and drilled a small hole in the plastic battery box from underneath, then I ran the charge cable under the chassis to the front bumper where I zip tied it in place. I can tuck it up out of view when not in use, then I reach up and pull it out to plug in the charger while in storage.
Most battery maintainers will use the standard SAE charge cable but I chose Victron which uses a different cable which I ordered from a Victron dealer. I'll post a pic or 2 later of the cable.
There are 2 models of Victron maintainers, one stays on the vehicle and you plug in the 120 volt cord to use it, the other, like mine, stays home and connects to the 12 volt wire on the vehicle.

[Mary Van]

Originally Posted by RGJZ06

I was having the same problem until I found out the radio was still active even with the key off. Now I know how the shut it off and the problem went away. I do, however keep an Optima battery charger connected when it's in the storage lot.

In your post, you mentioned you shut off the radio. Can you please explain the steps to shut off the radio? I have a power draw on the chassis battery and it might be a solution.