2011 F-53 chassis battery help?

[Csupp11]

I have a 2011 Newmar Bay Star on a Ford chassis. I’ve spent numerous hours trying to figure this out! Coach is always plugged into 30A shore power. Chassis battery is a few months old. House batteries are just over a year old. Main switch is always “ON” with fridge and HVAC on auto. Ignition switch & dash radio/clock are totally dead. I have to hold the “battery boost“ button for about 10 seconds to start the engine & get the gauges to register. If I drive for 10 minutes, ignition switch starts the engine without the “boost” switch. I spoke with a tech @ Intellitec who helped me verify that my battery disconnect “BIRD module“ is working properly. While plugged into shore power, chassis & house batteries all test above 13.1V. What should I check next? I’m lost at this point!

 

[DonTom]

While plugged into shore power, chassis & house batteries all test above 13.1V. What should I check next? I’m lost at this point!

What does the engine battery voltage measure a few minutes after you remove the shore power?

Also, check the cables to the engine battery. They can corrode and drop most of your starter voltage. Negative cable to the engine can cause some rather weird problems when it gets corroded inside. Often with no evidence on the outside.

I once owned a car where the engine would die as soon as the A/C was turned on, but ran perfectly otherwise. Would even start up with no problem.

But the problem from the A/C shutting down the car was from the high resistance in the negative cable to the engine. Problem went away totally when I ran my own cable from the engine to battery negative.

-Don- Reno, NV

 

[Jeff in Ferndale Wa]

have you checked the fluid level in the engine battery?

 

[John From Detroit]

Generally Engine batteries are Maintenance free so no way to check fluid level
Possiblity since it's a 2011 if it still has the Original battery you are beyond design life.
Posibility though I doubt it the unit does NOT have a bi-direcitonal isolator
To test the first: Remove battery to auto-shop battery tester. Expect to come home with a new one.
To test the second.. With the RV unplugged, install the new battery, Hook up a digital voltmeter to said new battery once installed 12.6 or there about.. Good.. NOW plug in the RV wait 5 minutes, Still 12.6 or there about BAD now over 13 volts GOOD.
NOTE Some RV's the dash 12 volt is a chassis port (you can check while battery out) and some it's an accessory I forget if it's accessory or battery on fords (GM it's accessory Chrysler it's your choice) IF it's a chassis-battery then you can get plug in 12 volt "Line monitors" at most auto stores. Get one that shows tenths of a volt

But a 5 or 10 buck Harbor Freight digital multi-meter.. VERY HIGHLY USEFUL TOOL.

 

[Mark_K5LXP]

You're introducing too many variables at once - shore power, boost switch, running vs parked. Per above advice, using a separate meter - not relying on existing instruments - check the chassis battery at the same time your dash/ignition is dead. From there you'll either be troubleshooting a charging/battery problem, or a chassis electrical problem.

Mark B.
Albuquerque, NM

 

[Escaper1]

Most likely dead battery

 

[Kirk]

Chassis battery is a few months old. ... What should I check next?

You need to start by lifting the negative battery cable and then measure the voltage between the two posts. Clearly it isn't getting power to the starter and even a new battery could be defective. If the battery reads good you may want to take it to a battery dealer and ask them to load test it.

It could also be that the starter motor is failing and requires a much higher current than normal so needs 2 batteries to get enough. We had that happen in a previous coach.

 

[DonTom]

Most likely dead battery

"Chassis battery is a few months old."

-Don- Reno, NV

 

[Mark_K5LXP]

Clearly it isn't getting power to the starter

Or anything else: Ignition switch & dash radio/clock are totally dead.

It's implied that dash, ignition and starter work when being powered from the house batteries via boost switch.

Mark B.
Albuquerque, NM

 

[Kirk]

It's implied that dash, ignition and starter work when being powered from the house batteries via boost switch.

Reading his post again, it does seem that way.

I have to hold the “battery boost“ button for about 10 seconds to start the engine & get the gauges to register. If I drive for 10 minutes, ignition switch starts the engine without the “boost” switch.

Holding it down for only 10 seconds? I wonder if anything would change if he lifted a cable from the chassis battery?

If I drive for 10 minutes, ignition switch starts the engine without the “boost” switch.

So how long does the effect of driving for 10 minutes last before the boost switch is needed again?

 

[Csupp11]

After hours of online research & speaking with Intellitec’s tech support, I determined that the “Chassis Battery Disconnect Relay # 01-00055-000” was not working properly! I ordered a new one from Amazon. I disconnected my 30A shore power for a few days & gently slammed the engine compartment hood.

3 days later, I received the new relay. I didn’t have time to remove & replace it, but I needed to move my coach. After I moved it, I plugged it in to shore power. Then I turned the fridge on & the heat pump to auto on 78 degrees. The next day, I went inside to pull the engine compartment release & noticed the dash radio clock was on. So, I decided to try the ignition switch. Surprise me, the darn thing started up without the boost button. I tried it several times, with shore power unplugged, generator running & not running, everything 12V turned on, etc. The engine started every single time!

I’m hoping that when I slammed the engine compartment hood, it rattled a loose connection, fuse, or released the relay! I have spent hours checking every fuse, connection & ground wire in the engine compartment. At this point, I’m jokingly saying that the fix to my problem is just order a new relay on Amazon! You don’t even have to install it….

I hate 12V electrical gremlins! I will update this thread if I ever figure it out, but I’m going with it for now!

 

[Gary RV_Wizard]

Good luck finding it. Intermittent faults can drive you nuts!