On the Sprinter, you cannot leave the chassis battery hooked up for long periods of time, it will go dead. There is a huge amount of parasitic loads on a Sprinter. Most Sprinter owners use the MB provided disconnect under the dash to save the battery.
When you park it in storage or for more than a few days, allow about 10 to 15 minutes for all of the computers to reset and settle down, and then use the ground cable disconnect under the dash near the accelerator to disconnect the battery. The disconnect/reconnect procedure is described in your MB owners manual. That is what it is there for.
The disconnect is a quick disconnect that requires no tools and is relatively easy to do.
Charles
