Coach Battery Charging

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

shearhawk

Active member
Joined
Apr 4, 2006
Posts
39
I would like to install a charge line for the Coach batteries.  Since most RV do not have wiring for this, anybody have an idea how to keep seperate from the engine battery.  I tried installing a straight line from generator to the coach battery, by doing so I inadvertedly bypassed the c/off switch for the engine battery.

Thanks,
Randy
 

Karl

Moderator Emeritus
Joined
Mar 3, 2005
Posts
5,154
Location
Elkhart Lake, WI for the summer. Work at Road Amer
Randy,

I'm not entirely clear if you're trying to charge your batteries from the engine alternator or a genset in the coach. Unless both the coach batteries and the chassis battery are the same type, size, approximate age, and condition, it isn't advisable to try charging them all at once by paralleling them. It would be a compromise at best, with neither getting the proper charge. Many MH's have a seperate charge controller for the coach batteries, and let the engine voltage regulator take care of the chassis battery. A little more detail would be helpful.
 

shearhawk

Active member
Joined
Apr 4, 2006
Posts
39
I already have charging capabilities with the genset, but I would like to be able to charge the coach batteries with the engine alternator, as well.  We do a lot of boondocking, and this would be a great alternative.  Maybe a charge line with a manual sw?

 

blueblood

Well-known member
Joined
Mar 16, 2005
Posts
1,082
shearhawk said:
I already have charging capabilities with the genset, but I would like to be able to charge the coach batteries with the engine alternator, as well.? We do a lot of boondocking, and this would be a great alternative.? Maybe a charge line with a manual sw?

Many motorhomes come with that capability. Are you sure yours doesn't have it? What is year, make and model of your RV ?
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,628
Location
At our Silver Springs FL home
Late model coaches do that, but there is a relay and circuitry to engage the charge line only when the engine is running. The circuit is open whn the engine is off (no alternator output).  That controller also prevents both the converter/chargers and the alternator from trying to charge the coach batteries at the same time, for example if you run the genset while driving down the road.
 

Len and Jo

Well-known member
Joined
Apr 25, 2005
Posts
1,360
Here is a picture of a SIMPLE house battery isolator installation.  When the alternator is running both house and coach batteries are charged by the alternator.  When the ignition key is off batteries are isolated from each other.  I don't think it covers (protects wiring, batteries) under condition of havint gen set and alternator running at same time.  W/o special isolator and relays sounds like a toasted alternator.
 

Attachments

  • House Battery Isolator.JPG
    House Battery Isolator.JPG
    116.7 KB · Views: 38

King

Well-known member
Joined
Jan 30, 2006
Posts
354
Location
MA
Looks like a simple diode isolator (including a downside return to the alternator voltage regulator to make up for the diode drop for the chassis battery).  There is no way a higher voltage from a generator powered charger connected to the house batteries can damage the alternator.  On the other hand, it seems that a charger design that could not withstand the higher voltage from the alternator wouldn't be in production long before the warranty returns forced a redesign.
Art
 

Len and Jo

Well-known member
Joined
Apr 25, 2005
Posts
1,360
Yes, it is a simple diode isolator.  The attached shows how I have it wired in.  I used to have a Ford van (1979) and they use a relay to tie the two batteries together on startup.  The diode system works but the diodes seem to have a history of failing.  The one I show has been in service since July 2004 and about 28K miles.


[edit]Picture attached.
 

Attachments

  • ELECTRICAL WIRING.JPG
    ELECTRICAL WIRING.JPG
    172.5 KB · Views: 22

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,937
Len,

Go ahead and email the photo to me (click the 'envelope' icon beneath my avatar). I'll get the photo attached to your message.

Thanks.
 

Len and Jo

Well-known member
Joined
Apr 25, 2005
Posts
1,360
Thanks Tom,

Your envelope icon isn't there.  You can e-mail me your address or I ccan send the file to Gary and see if he can relay it.  His envelope icon does show.

Len S
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,937
Len,

I don't know why my envelope icon doesn't show. Meanwhile, I emailed you my email address.

Wouldn't help to email it to Gary as he'd run into the same size limitation.
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,937
Len,

I went ahead and attached the image to your earlier message. Apologies for delay - just as I was downloading your email we received a visitor.
 

Forum statistics

Threads
120,624
Posts
1,212,054
Members
125,720
Latest member
Jatozano
Top Bottom