No Power to Multiplex

[RachelZ3]

So... I got the Roadtrek back to work, they have a reset procedure for dead Ecotek AGM batteries. (Run the engine, turn on one battery at a time the batteries have to be ON to start charing, hit the reset button up to 50 times and then it starts charging).

And the nice folks at Mercedes/Sprinter said that it looks like there was a loose connector on the new starter battery, so that's fixed... I don't know if they gave me a new starter battery.

So what remains is getting the Interstate coach batteries to take a charge.

How would one normally charge the Interstate coach batteries? Do the Interstate batteries have to be ON to charge? How do I turn them on? I have familiarity with the Roadtrek, but the Interstate was set up by my RV mechanic in Florida, all I know how to do is use the display screeen and it is just black.

I have more courage now to start poking around the Interstate.

I'll look in the manuals and hunt the forum, if anyone has a link to a good thread about checking and charging the batteries please post it? I may start a new thread.

And any info on determining if the coach batteries are just dead dead and need to be replaced would be great.

Thanks for any help.

[Boxster1971]

I'm not sure which Interstate you have? I've re-read your posts and you said you have a 2018 Interstate 19. Best I can tell Airstream didn't make the Interstate 19 until 2019, built on a 2018 Sprinter.

I posted a photo of the coach battery boxes under the Interstate 19 on the iRV2 forum for your Florida RV tech. I'll add it to this post.

You have totally dead coach batteries so they will need to be recharged directly by attaching a separate battery charger to the batteries. The inverter/charger will not charge them as they are below the cutoff voltage. Here is a link to old thread on this forum that might help.
https://www.airforums.com/forums/f24...ck-210497.html

I think you can get access to direct charge the coach batteries by the terminals in the passenger seat base. That is where the inverter/charger is located.

Good luck!

[RachelZ3]

Continuing adventures...
LSS... the Mercedes Sprinter shop found and tested the battery boxes exactly where you showed them under the van, they said there is no way to charge them directly, and they were kind enough to connect up my battery tender to the terminals you posted are under the passenger seat (I didn't understand that we should look for the terminals under the passenger seat INSIDE the van, we didn't have to get under it ).
I took a photo of that terminal access under the passenger seat... fcol I coulda done that first... well anyway...

I used the same battery tender I use for my car/pick up, this one brand new out of the box.

It was on steady red light (connected propery, charging, should turn off when it completes the charging stage) when we hooked it up on Friday, its Sunday morning and I have a flashing red light on the battery charger, the battery tender manual says "The RED light flashing indicates that the battery charger has AC power available and that the microprocessor is functioning properly. If the RED light continues to flash then either the battery voltage is too low (less than 3 volts) or the output alligator clips or ring terminals are not connected correctly. The fuse in the output alligator clips or ring terminals may also be blown."

Ah so... this is what they are talking about in the post you linked...
https://www.airforums.com/forums/f24...ml#post2578886

Originally Posted by Vacayourway1

You can recharge AGM batteries if there completely dead I’ve done it several times, a friend of mine that’s own golf cart shop showed me years ago how they take supposedly dead batteries and recharge them. First you need to take a known good 12v battery and hook the battery charger to it and jumper cables from the good battery to the bad AGM battery, the charger will keep charging because it see’s a good battery. Another way is to have a old charger that doesn’t have all the smart sensor installed.

If that's correct, here's a couple questions before I try it...

Why wouldn't I just connect the terminals under the passenger seat with jumper cables to the battery in the Roadtrek with the Roadtrek engine running, like I did when I jumped the battery in the Airstream terminals in the engine compartment? Why would I connect the battery tender to the Roadtrek and then to the Airstream? Do they expect that the "good" battery is not installed in a vehicle?

Should I use a "good" battery that is not in a vehicle to try this method?

Many mucho mucho thanks

Oh and the battery tender manual says: "If you try to charge a dead battery having a voltage below 3 volts the Battery Tender charger will not start. An internal safety circuit prevents the charger from generating any output voltage unless it senses at least 3 volts at the charger output. In this situation the AMBER light will continue to clash, indicating that a charge has not been initiated."

That sounds like the post above except my battery tender is flashing Red, not Amber.
????

[RachelZ3]

Found a YT video that shows the whole deal from a MB tech!

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

Gonna order a battery...

[RachelZ3]

Just an update to say I fixed it and it was so easy.

I didn't need to buy a battery. I have a NOCO Boost Plus

I hooked that up to the connections under the seat (again, so easy, except the way its bolted in place you have to do the black before the red and need small hands to get in there)

It has a "boost" button to get a little power in to the battery.

Then I hooked it up to my battery tender and it started charging.

I charged it for 2 days I think.

Now everything is fine!

THANK YOU SO MUCH!

[Boxster1971]

Originally Posted by RachelZ3

Just an update to say I fixed it and it was so easy.

I didn't need to buy a battery. I have a NOCO Boost Plus

I hooked that up to the connections under the seat (again, so easy, except the way its bolted in place you have to do the black before the red and need small hands to get in there)

It has a "boost" button to get a little power in to the battery.

Then I hooked it up to my battery tender and it started charging.

I charged it for 2 days I think.

Now everything is fine!

THANK YOU SO MUCH!

Great - thanks for the follow-up.

Safe travels,