Does the aternator charge the house batteries?

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John Mo

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Here come all the newbie technical questions... well, sort of. I know my way around motorhomes reasonably well, but I need to get to know my Winnebago. :)

During our dealer walk-through I asked if the alternator charged the house batteries and the technician said it didn't. But I noticed tonight that my house lights got a lot brighter when I started the engine, so I think there must be some connection there. What's the scoop on the 12-volt electrical interactions between the chassis battery, alternator, and coach batteries and systems?

Thanks,
John
 
I would be extremely surprised if your alternator did not charge the house batteries.  That's been standard for many many years.
 
Right, the engine likely does charge the house batteries.  Although the opposite may not be true, with shore power charging the chassis (engine) battery.  Some rigs do, mine does not... I manually hook up a trickle charger to the chassis battery when camping.

If you look under your hood (for lack of a better term), follow the positive cable from the chassis battery and you will likely find it connected to a splitter that sends the juice off several different directions.  My splitter is right at eye level and easy to see.  One of those directions is to the house batteries.
 
Thank you gents. My batteries are under the entry step, so it's tough to trace the wiring. I'm familiar with Fleetwood's battery control system as I had a '96 Bounder before. In that one the chassis would get charged on shore power if the house batteries were fully charged. I don't know if Winnebago uses a similar system. I think there's more there than meets the eye on the Winnie. I'm still studying the manuals, but I've already found mistakes in manuals too. ::)
 
It most likely does.  My alternator will charge the house batteries, but only after the chassis batteries are charged.  I have a built in switch that I can sometimes hear clicking back and forth.  When plugged into shore power or running the generator, your house batteries will be charged first, then if you have a trick-L-start wired in your rig, it will take a small amount of power from your house batteries and feed it to the chassis batteries.  Winnie started adding trick-L-start on thier rigs in 2006.

Sarge
 
John Mo said:
Here come all the newbie technical questions... well, sort of. I know my way around motorhomes reasonably well, but I need to get to know my Winnebago. :)

During our dealer walk-through I asked if the alternator charged the house batteries and the technician said it didn't. But I noticed tonight that my house lights got a lot brighter when I started the engine, so I think there must be some connection there. What's the scoop on the 12-volt electrical interactions between the chassis battery, alternator, and coach batteries and systems?
Thanks,
John
Click to expand...

I never heard of a motorhome that didn't unless something was broken, such as the diode isolator.  But IMO, it's a good idea to have a couple of these.

Plug one in at your real cigarette lighter to see if your engine starting battery is charging and plug another in a 12 volt house outlet to see if your house battery is charging. You should notice at least a 1.0 volt difference between charging and not charging. 

I don't understand how a "technician" could not know if your house battery charges from your alternator.


-Don- San Francisco, CA​
 
DonTom said:
I don't understand how a "technician" could not know if your house battery charges from your alternator.
Click to expand...

He told me I couldn't run both air conditioners on shore power too (ours is a 30-amp unit). I knew that was flat-out wrong already, but I didn't debate the point. He was a nice fellow and I didn't want to be a jerk.

He wasn't a salesman in training either. He's one of the guys that works in the shop and seemed to be one of the veteran members of the crew there.

Ultimately I was a little disappointed that I knew more about some things than he did and didn't ask any of the tough questions I wanted to ask. I figured I'd prevail upon the collective wisdom in the forums for those questions.

Thanks,
John
 
Starting about the 2006 model year, Winnebago began installing a Trik-L-Charge which takes some charging current from the house batteries and feeds to chassis batteries while on shore power.

With the engine running, there is a solenoid that energizes and bridges the house and chassis banks together (also it is switch operated - "Battery Boost" on the dash if you have that feature.)
 
John Mo,
You can have both a/c's on, but they may not actually run simultaneously.  The second compressor's start-up load may cause you to exceed 30A and you probably have a built-in load management system that would shut off the compressor if that happens. The fans would continue to run, so you might not notice.

I've been told, though, that Winnie's basement air system will indeed run both airs on a 30A circuit if nothing else significant is using 120vac power.
 
RV Roamer said:
You can have both a/c's on, but they may not actually run simultaneously.  The second compressor's start-up load may cause you to exceed 30A and you probably have a built-in load management system that would shut off the compressor if that happens. The fans would continue to run, so you might not notice.
Click to expand...

Is this a feature on all  newer 30-amp rigs, or just newer Winnie's?  When I'm on shore power, I can only run 1 A/C at a time and there's a selector switch for which one I want to run.  Common on MH's of my era I believe, and I'm sure that's where the salesman was getting his assumption.  I can understand how newer rigs would probably be set up to run both A/C's simultaneously by alternating the compressor load.
 
We're drifting a little here...

Winnie's basement air will indeed start and run on 30 amps with both compressors and the blower on high speed - running load is about 21-22 amps (compressor starts are sequenced so they both don't come on-line at the same time.)  The Energy Management System will shed loads while on 30 amp shore power - if I remember correctly in this order:  water heater, compressor #2, high blower speed, and finally the fridge.

I'm on the verge of buying a roof air to augment the basement (for various reasons which I will get into with a project post after the fact) and discovered there is a wide variety of roof units - some are very energy efficient (10-12 amps for 13,500 BTU), and some aren't efficient (~15+ amps.)  If you have two roof airs and can't run both from 30 shore power, I'm not a bit surprised, especially with older units that are not high efficiency.
 
Our 2002 Itasca Sunrise has two roof ACs.  They work the way John explained, allowing both to run at the same time.
 
It's the compressor start up load that is the problem on 30A. Even with a compressor that runs at 11-12 amps, the second one starting can easily exceed 20A for a few seconds and that is often enough to trip a 30A supply breaker. The Energy Mgmt Systems are intended to avoid that by shedding load if needed to keep the breaker from popping.

The newer compressors for RV air are designed to minimize the starting loads as well as to run more efficiently. This makes it possible in some rigs to run two a/cs on 30A and actually get both compressors running at the same time. Since the fans continue to run in either case, many people think both a/c are running when they are not, so it is difficult to judge from anecdotal evidence in public forums.
 
John Canfield said:
Starting about the 2006 model year, Winnebago began installing a Trik-L-Charge which takes some charging current from the house batteries and feeds to chassis batteries while on shore power.

With the engine running, there is a solenoid that energizes and bridges the house and chassis banks together (also it is switch operated - "Battery Boost" on the dash if you have that feature.)
Click to expand...

Hey John -

Does that apply to Views and Navions too?  I've been all through my manuals and original paperwork (in the black Winnebago pouch) - I see no mention of the Trik-L-Charge anywhere.  I do, however have that Battery Boost switch. 
 
davemittan said:
Hey John -

Does that apply to Views and Navions too?  I've been all through my manuals and original paperwork (in the black Winnebago pouch) - I see no mention of the Trik-L-Charge anywhere.  I do, however have that Battery Boost switch. 
Click to expand...

In a short answer, NO.

Clarification, starting in 2006, Winnebago started including the Trick-L-Charger in all the Diesel powered Class A motorhomes.

 
John Mo said:
Here come all the newbie technical questions... well, sort of. I know my way around motorhomes reasonably well, but I need to get to know my Winnebago. :)

During our dealer walk-through I asked if the alternator charged the house batteries and the technician said it didn't. But I noticed tonight that my house lights got a lot brighter when I started the engine, so I think there must be some connection there. What's the scoop on the 12-volt electrical interactions between the chassis battery, alternator, and coach batteries and systems?

Thanks,
John
Click to expand...

John, YES, your alternator will charge the house batteries.  The technician is wrong on this.
 
Thanks Mark -

I'll stop looking for it.  I just went and looked at the converter (Parallax) - I couldn't see any evidence of it.
 
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