2017 Interstate Completely Dead won't charge

[Sealfit59]

Helping my neighbor.He just bought a 2017,I have a 14.

Came back yesterday and did not plug in after 2 weeks. Everything dead, batt voltage down to 8.8. Shore power does not charge or even seem to get to the inverter. Chassis battery does nothing but tern on a few dash lights. Jump does nothing... All fuses on the inverter good but the the 20amp GFCI but I think that needs power to be reset.. Panel says NOCOMM w inverter.. trying to bet MB here to get it started today.. Somewhere is their a MAIN fuse causing it not to start on jump ? Why no 110... and just so stupid to have the main batteries hanging underneath? mine are in the back under seat and the chassis under the floor..what pain... any help would be great... has to be a fuse -- it was running great before parked... he knows it should be plugged in just goofed ...

[Hawk-ination]

You might need a smart battery charger to initiate the battery charge at that low of voltage, one that is labeled to be made for AGM batteries. May need a good 12 hours to put it on the charger. There’s a recent feed that talks about how MB electronics don’t like to be connected while charging a battery, it can throw a lot of codes and such, so you might consider disconnecting the battery cables while charging. I’m not sure if the pedal disconnect will do the job or not. I’m thinking possibly not.

I get argued with when I say AGM batteries can’t take a discharge past a certain percentage but we’ve had two sets go bad from miscommunication from not plugging our RV in (we throw the breaker to shut it off for disconnect and when we got back I thought he did it and he thought I did it). Oops. Your neighbor is not the only one.

We had to replace both batteries this year, both the engine battery and the one under your feet at the driver’s seat. They get a lot of use and charge/recharge. You wouldn’t think either would be bad after a few years, but might check it out after having it discharge that far. Ours were beyond saving after not plugging in last year. We had one sulfate this year and it’s not holding a charge properly. I just don’t think AGM batteries like to be discharged that much. I’m sure I’ll get commented on though but from our experience, they get touchy when discharged a lot and for more than a little bit of time. If at all.

Wish you luck.

[Boxster1971]

Hawk is correct you need to get an external battery charger on those batteries. Best done by unhooking them and charging individually. The inverter/charger will not work with voltage that low. There is Low Battery fault protection. This is what it says in the attached manual for the Magnum Inverter/Charger:

"Low Battery - Whenever the battery voltage falls to a low level (10
VDC, default setting) for more than one minute, the inverter will
shut down to protect the batteries from being over-discharged."

Hope this helps,

[Rocinante]

Yep, you're going to need a battery tender that can start pushing electrons into a dead system, or a battery charger that includes an option to "activate" a dead battery by initially pushing a charge into it despite the low voltage. Back in the day we had a plug-in battery charger that you clamped to the battery and a switch that said "activate / jump-start." The transformer in the unit would emit an audible hum as it shoved as much power into the battery as possible, to either knock the battery upside the head and activate it, or jump start the vehicle. Whether that's good for a battery, especially an AGM that's nearly stone dead, is another question, but at this point your batteries are likely already damaged, so that might be worth a try.

We have a pair of seriously damaged AGM coach batteries in our Interstate, ruined by the previous owners most likely by the same types of misadventures. They will take a charge, but they don't hold one long enough to do much good at all. Most likely one or more cells are dead in each of our batteries. We'll be replacing them with Lithium in December, so for now we're just limping along.

[coasttocoast]

Check out a Noco Genius.

[ArcherTC]

Not sure if this is a help but I had a similar problem and getting the engine started allowed the alternator to begin charging the house batteries. After a few minutes the charger/inverter must have reset as 110v A/C then worked to continue the charging. Much easier to get an external charger to the chassis battery using the lugs under the hood to recharge that battery first, then start the engine.

[Wazbro]

One comment often when a battery is really dead you need to use a DUMB charger to charge it as the smart ones have "smart" "safety features" that keep them from working.

[Boxster1971]

Originally Posted by Wazbro

One comment often when a battery is really dead you need to use a DUMB charger to charge it as the smart ones have "smart" "safety features" that keep them from working.

I agree with Wazbo - I have an old Sears “dumb” battery charger that was able to bring back a dead battery that my smart CTEK would not charge.

[Rocinante]

...and that's exactly what the "activate / jump start" switch on my old battery charger was. It turned the "smart" charger into a "dumb" charger that just shoved amps into the battery as hard as it could until you either gave up or woke the battery up again. Something you don't want to do for too long, but yeah, it could potentially wake up a truly dead battery and hopefully get it to the point where a smart charger could see it and then maybe get it back up to snuff.

You should face the fact, though, that in taking your batteries down to such a low level, some amount of permanent damage has likely been done. Doing so multiple times would damage the batteries enough that no amount of dumb and then smart charging would bring them back to an acceptable facsimile of being good dependable batteries for you, and you would likely have to replace them.

[Sealfit59]

Thanks for all the help we got it going... he put in new batts,got rid of his fusion and put in a kenwood and we are both headed from Chicago to Ashville NC next weekend at the biltmore... just finishing winterizing this week..

for those interested in a security system under $600.. just put in cellular base unit .. took 10 min. will text you if anyone gets in.. great if you are overnight at a hotel.. leaving a campsite or leaving somewhere while plugged in .. but also battery based.

www.tatteltale.com... get on amazon .. don't like it send back to amazon but works great for me

[FlaBucki]

I need to replace my 6 YO Lifelines as they no longer hold a charge. What lithiums are you looking at?

[Rocinante]

BattleBorn are a common drop-in Lithium replacement, so worth looking at. We are going another direction altogether with a pair of 200AH LifeBlue lithium batteries. This isn't exactly how our vendor is installing it, but this will give you an idea: https://amsolar.com/rv-lithium-batte.../40-lilbbmv200

[ROBBCO]

What was the age and health of the coach batteries when purchased ? The AGMs under normal to heavy use only seem to get about 3 maybe 4 years of "battery age" not necessarily coach age. You probably have a power drain somewhere - the TV booster is a common issue - make sure the monitor light is off as it will drasin the coach batteries after several days.