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Open Roads Forum  >  Class C Motorhomes  >  Class C

 > Is it a battery and what I think is for?

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pnichols

The Other California

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Posted: 11/18/20 03:33pm Link  |  Quote  |  Print  |  Notify Moderator

There's something that I don't understand about this discussion. [emoticon]

Is it that Class C motorhomes built on the Chevy 4500 cutaway van chassis don't have the usual coach battery storage areas included by the coach builder that hold one, two, or three or more batteries to power the coach when camping?

I doubt it, hence .... why the need for some kind of "extra" battery hung off the Chevy van's frame?

My Ford E450 cutaway van chassis based Class C just has the usual engine battery under the hood, and a battery compartment built into the coach structure that can hold two large batteries for the coach.

However, on the dash is a rocker switch that switches the power for the cab radio between either the engine battery or the coach batteries. This allows the cab radio to be used when camping for listening to radio stations or CD music - since the cab radio output can be routed to speakers in the coach.

The cab 12V outlets on the dash are always-hot and powered by the engine battery. The 12V outlets in the coach are of course always fed by the coach batteries.

BTW, since the the 12V outlets on the dash are directly connected (through fuses) to the engine battery, when on hookups or in storage one can plug a solar or other kind of battery charger into one of these dash 12V receptacles so as to keep the engine battery charged.


Phil, 2005 E450 Itasca Spirit 24V

BruceMc

Oregon - Willamette Valley

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Posted: 11/18/20 03:41pm Link  |  Quote  |  Print  |  Notify Moderator

Depending on the coach manufacturer, the house batteries may be behind an access door along either side of the coach, or in the step well just inside. Our Sunseeker has two group 27 12V batteries in the step well.

The extra battery is a GM option, and as Newbiecampers stated:

"Without the engine running, when you turn the ignition key to the very first accessory position, this frame-mounted battery will be powering the accessories instead of the battery in the engine compartment used for starting. "

Thus, this battery may or may not be in motorhomes based on the 4500 GM chassis.

It is this conversation that I've learned of the possible existence of an auxiliary battery on the GM 4500 chassis.


'16 Forest River Sunseeker 2250SLEC Chevrolet 6.0L
Previously:
'00 Four Winds 26Q Class C (Ford E350 V10)
'96 Kit Sportsmaster 212f Fifth Wheel/'93 GMC Sierra K2500
'91 SunLite poptop truck camper
and the first: a Wildernest flip-top canopy.


specware2020

Pacific

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Posted: 11/18/20 09:05pm Link  |  Quote  |  Print  |  Notify Moderator

Newbiecampers wrote:

My 2018 Coachmen Freelander 21qb has the same frame-mounted battery (on a 2017 chevy 4500 express chassis). I spent a bunch of time in '18 trying to find out what it was. Like you, since it was near the generator, I thought it was a starting battery for said generator. However:

It is called the "Isolated 2nd battery" option. Isolated 2nd Battery — allows 2nd battery to be used when the vehicle is not running without affecting ability to start the vehicle ....


That’s it, Man!

I feel like I was drilling and drilling, and hit the oil reserve!! How did I make it prior to the time of World-Wide-Web and on-line forums is beyond me…

Kudos to @Newbiecampers for providing this much sought after information.

Now it all makes sense; Chassis manufacturers usually don’t like RV makers to mess around with their chassis lest it voids their warranties, so this hidden battery has got to be part of the vehicle features/functions.

This explains the other peculiar Chevy truck/chassis behaviors I observed and was puzzled by. For example, the two DC power ports (i.e. cigarette lighter) on the dashboard are always present whether the key being in or not. The first time I realized it was when I reviewed the dash cam recordings caught me to and from the restroom at a gas station. The 115VAC socket next to them, however, is on the engine switch, prompting me to think that the inverter is hooked up to the engine battery.

Well, mystery solved and my curious mind can rest. Thank you all.

carringb

Corvallis, OR

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Posted: 11/18/20 09:27pm Link  |  Quote  |  Print  |  Notify Moderator

The location of the battery is most likely a result of the limited FAWR.

Ford offered this option too but it went below the passenger door. It took me a long time to discover it, and even longer to discover it dead. And yet even longer to discover it was never even hooked up because the original dealer never removed the removed the shipping jumper that isolates the aux battery. But it works great now! Only took 200,000 miles to figure it all out!


Bryan

2000 Ford E450 V10 VAN! 450,000+ miles
2014 ORV really big trailer
2015 Ford Focus ST


pnichols

The Other California

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Posted: 11/19/20 01:30am Link  |  Quote  |  Print  |  Notify Moderator

Why would this additional battery be needed in a motorhome that already had a boost switch on the dash?

paulrichter

Berlin

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Posted: 11/19/20 02:47am Link  |  Quote  |  Print  |  Notify Moderator

Das ist wirklich cool!

pnichols

The Other California

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Posted: 11/19/20 09:51am Link  |  Quote  |  Print  |  Notify Moderator

carringb wrote:

The location of the battery is most likely a result of the limited FAWR.

Ford offered this option too but it went below the passenger door. It took me a long time to discover it, and even longer to discover it dead. And yet even longer to discover it was never even hooked up because the original dealer never removed the removed the shipping jumper that isolates the aux battery. But it works great now! Only took 200,000 miles to figure it all out!


I'll bet that Ford option's wiring is present on the E350/E450 cutaway van chassis that Class C coach builders actually use to switch the solenoid ON that hooks the coach batteries to the engine alternator (so they will be charged when driving) whenever the ignition switch is turned to start the V10 engine. [emoticon]

ron.dittmer

North-East Illinois

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Posted: 11/28/20 07:03am Link  |  Quote  |  Print  |  Notify Moderator

So...as I understand this, the purpose of this 2nd chassis battery is to power your chassis-related accessories like your in-dash stereo when the ignition key is in the accessory position, installed to avoid draining the engine-start battery?


2007 Phoenix Cruiser model 2350, with 2006 Jeep Liberty in-tow


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