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catjer 12-12-2019 08:51 PM

Sprinter engine battery failed and Fusion “confusion”
After three years our engine battery would no longer hold a charge. It was replaced in Pensacola at the Mercedes dealer who was very gracious and got us into their booked up schedule.
Mercedes did a battery diagnosis and determined the battery was pooched. It also diagnosed a 1.1 amp parasitic draw on the battery but the source wasn’t located due to time constraints. For now they recommended we use the battery disconnect by the gas pedal whenever we stop for an extended time until the load is determined. Mercedes suggested that it was not a Mercedes cause but an add on from Airstream.

Coincidently there has been an unusual thing happening with the Fusion System. When we are on shore power and the battery is disconnected, every time the transfer switch changes and the inverter goes into a charging cycle the Fusion turns on ??? even though we always shut the radio off and hit the power button twice. It happened three or four times last night. It seems that once a charge cycle starts it sequences the whole electrical system.
Has anyone experienced this or have suggestions.

StreamingAI 12-12-2019 10:31 PM

I've had nothing but battery trouble since I bought my 2017, about 3 months ago. It had 3600 miles on it and all battery's were in bad shape.
There are several old threads on this. First I put the Fusion on the
House power.
If you pull the radio out you will see the wire spared in the wiring nest. It is currently on a 10 amp fuse from the chassis battery. The drain is coming from the signal wires. I then replaced the airstream installed ACR with the Blue Sea ML ACR that comes with a remote switch. I replaced the Pushbutton start assist with the blue sea toggle switch.
If parked with shore power, I put the switch in "manual. Driving in "auto". Parked and no shore power "off". Working perfect. There is a pic on one of my posts of the switch.

BayouBiker 12-14-2019 08:05 AM

Sounds like a voltage spike occurs when the converter cycles into charge mode. Add in the parasitic load and I'd want to suspect the two issues are related. It is possible the rapid voltage change causes the Fusion to trigger its internal low/high voltage protection circuitry causing the thing to "reboot" in the on position. I have seen this many times in my line of work with industrial controls and instrumentation containing digital circuitry.

So on the assumption the two issues are related, I'd disconnect/isolate the converter first and then the fusion next to try to locate the source of the parasitic load.

Good luck!

StreamingAI 12-14-2019 12:07 PM

catjer Go to Battery Isolator- Replacement Help page 2 as it has a lot of info.
about the Blue Sea Isolator.
My pic is on page 3 on the post

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