Battery jumping

[Fcranger]

Thanks for the info Lou
I didn't know that the coach batteries were charged from the alternator also, I thought you had to be plugged into shore power or run the gen. to charge the house batteries. I always keep the rv plugged in when it is home and when I go camping im always someplace that has electric.
Next month were going to Phoenix International raceway for a  couple of Nascar races and I know there is no eletric hookups there so we'll be about 3 days boondocking
I have a jumper pack that I can take with me to start the motor if the chassis battery gets low, so if the batteries go low all I have to do is get the motor started and the altenator will charge the house batteries too. hmmm didn't know that. In this forum you learn something new every day.

 

[John From Detroit]

I'm just toying with JID about how he started his generator from his chassis battery.  If he doesn't figure out how that really happened, I'll tell him

Well, it could be it don't take all that much to engage the battery,  but I"d like to know how it happened,, (Will save me a lot of work testing)

 

[Just Lou]

so if the batteries go low all I have to do is get the motor started and the altenator will charge the house batteries too. hmmm didn't know that. In this forum you learn something new every day.

Frank, that's the way it's supposed to work.  Check it out before you make your trip to be sure it does.  One set of faulty contacts can muck up the works.

Tell us the make and model of your coach and we can tell you what should charge when.  It always helps to know these things.

Good luck at the races

 

[Fcranger]

Its a 2007 Winnebago Aspect  24ft.

 

[DonTom]

Thanks for the info Lou
I didn't know that the coach batteries were charged from the alternator also,

In RV's , the vehicle alternator output goes to an "isolator". It has two outputs. One goes to the chassis battery and the other output goes to your house batteries so both will charge as you drive (or run the engine).

-Don- San Francisco​

 

[Gary RV_Wizard]

The little diodes we were discussing are used to power the disconnect switches...

I was responding to John's question about why they did NOT use diodes on the Aux start circuit.

 

[Just Lou]

Well, it could be it don't take all that much to engage the battery,  but I"d like to know how it happened,, (Will save me a lot of work testing)

John (JID),

First, as we discussed earlier, your battery connect/disconnect switches, and associated solenoids, will operate as long as you have 12v in either set of batteries so that is no mystery.

if your coach batteries were as dead as you say..."and I mean dead"  your words..., there are only two ways the chassis battery could be utilized to help start the generator.  (Short of using jumper cables)

One - If you were connected to shore power at the time, (with batteries connected as you said) the converter would automatically provide voltage through the disconnect solenoid to power the Aux Start Switch and allow activation of the boost relay even though the coach batteries were dead.  The chassis battery would then be connected through to the generator start cable.

Two - If you were in the boondocks at the time you would have had to start the engine to allow the alternator, through the Bi-directional charge control circuits, (not the Aux start switch) to close the boost relay and provide a path from the chassis battery to start the generator.  It would actually be trying to charge the coach batteries as well, which is normal.

Long story short... with your setup, you need to either run the engine or have shore power available to get chassis battery power to start the generator.

This whole scenario assumes NO user mods or electrical malfunctions exist in your BCC.

 

[Just Lou]

Its a 2007 Winnebago Aspect  24ft.

Frank, the Winnebago is kind of a breed apart.  As DonTom and others have stated, it is standard for the alternator to charge both chassis and coach batteries in all modern motorhomes.

Other aspects of battery and charge control discussed here, may or may-not apply to the winnebago since they do not utilize the Intellitec or RV-CP battery control center boxes being kicked around.

I am glad that you got your original question answered before I so unceremoniously hijacked your thread.  I do apologize. lou