Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 11-07-2014, 06:33 PM   #1
Senior Member
High Ball's Avatar
Join Date: Nov 2014
Location: Ottawa, Ontario, Canada
Posts: 114
Battery Charging

Hi everyone.
Newbie here and am puzzled already. I just picked up a new to me 2006 Mandalay 40F. Had it for 3 days now. My problem is before I pick it up the "house" batteries were changed. I have 4 6 volts for the house and 2 12 volts for chassis. After a demonstration from dealer and driving about 2 hours to get to my parking spot we looked at all that we mist while looking to buy. I noticed that the "house" batteries are at 12 volts. I started the engine and had 14.2 on chassis batteries and still 12v on others.
Is there a isolator somewhere, where is it located, are there fuses for this, where. did they maybe forgot to install a wire, I'm sure the engine is suppose to charge these on the run.
Any help to solve the problem would be greatly appreciated.
Thanks so much

High Ball is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 11-07-2014, 09:37 PM   #2
Community Moderator
Scarab0088's Avatar

Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2012
Location: SoCal
Posts: 15,241

We don't have a Mandalay, so can offer no advice. But most Class A's do charge the house batteries from the engine. An issue could be as simple as a blown fuse or lose wire on the charge control unit.

Hope someone can offer some advice here.

Best luck

Kim and Steve, Mustang LCDR (USCG Ret), Outlaw #1193
"I have seen gross intolerance shown in support of tolerance", S.Coleridge 1797
Scarab0088 is offline   Reply With Quote
Old 11-07-2014, 09:39 PM   #3
Junior Member
fivejackie's Avatar
Thor Owners Club
Join Date: Nov 2012
Location: Lake Elsinore, CA
Posts: 25
Running the engine the alternator will read 14.2 charging. Your house batteries are deep cycle and if they are fully charge they will show 12 Volts. You should get a good battery hydrometer to check your house batteries once and a while. A bad cell can drain the others. New batteries should be check more often because of maybe bad construction. If they are good for 6 months they should be good for years.
2016 Hurricane 27K
2012 Redhawk
1988 Pace Arrow
fivejackie is offline   Reply With Quote
Old 11-08-2014, 04:45 AM   #4
Community Moderator
"007"'s Avatar

Nor'easters Club
Workhorse Chassis Owner
iRV2 No Limits Club
Join Date: Oct 2004
Posts: 27,793
Welcome to irv2.
Here is info on batteries and every thing else that may be of interest to you.
Enjoy the forums.
98KSCA, 99MACA, 03 KSCA-3740- 8.1 Chev-- ALLISON Trans, now in good hands
"007" is online now   Reply With Quote
Old 11-08-2014, 08:16 AM   #5
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,629
Your house batteries are deep cycle and if they are fully charge they will show 12 Volts.
Sorry, but I have to strongly disagree with that. House deep cycle batteries will normally show 13.3-13.6 volts when fully charged. 12v represents only about 50% state-of-charge.
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Old 11-08-2014, 09:00 AM   #6
Senior Member
Join Date: Feb 2010
Posts: 4,510
Call your dealer as something is broken and he needs to fix it...period.

Also note that this is an indication of possible lack of attention to detail.

So other things may be in need of attention.

Search here for checklists and inspection tips and give your unit the "once-over"...twice! Taking notes then have the dealer fix them.

And with the 12 volts have them show you what they found and how it was fixed.

Loose wire or blown fuse are symptoms of other things like no support for wire or possible short.

It is a used unit with a very short warranty and long unknown history...best to find silly things while under the short warranty...
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is online now   Reply With Quote
Old 11-08-2014, 09:26 AM   #7
Senior Member
tompen's Avatar
Join Date: Dec 2012
Posts: 500
While not familiar with your coach, I believe most class A motorhomes should charge the house batteries while running. If your house batteries are 12V with the engine running for a while they are not being charged. They should show charging voltage regardless of state of charge. From there you have to know which system it uses. I agree that if you just got it from a dealer it needs to go back. There is so much information on this site for you to read. Search BIRD or battery or isolator. As to the full charge voltage, moving target, rule of thumb is 2.1V per cell.
Attached Thumbnails
Click image for larger version

Name:	battery-state-of-charge.jpg
Views:	43
Size:	56.9 KB
ID:	78464  
2016 Wildwood 28RLDS
2014 Tundra 1794 Platnum,"23" T-Bucket
2011 Harley Softail, 2010 Spyder RTS
tompen is offline   Reply With Quote
Old 11-08-2014, 09:35 AM   #8
Senior Member
Country Coach Owners Club
Join Date: Jan 2006
Location: Redding
Posts: 3,516
I believe testing the battery voltage depends on two things.

1. What type of meter/gauge are you reading the voltage on.

2. At what stage of the charging process are you reading the voltage.

12.6 dcv is a full battery. Anything higher is measuring the float charge. Does your meter/gauge read in digital decimals?

12.0 is discharged to 50% of the useable charge.

14.2 dcv on the chassis batteries indicates that the battery charging process was just shut down and the "float" charge is still present. Turn on your headlights for 5 minutes and then test the volts in the chassis battery. A full charge will be @ 12.6 dvc.

BTW on my rig 14.2dcv is the highest charge rate that my alternator should produce. That usually only happens when the battery was low after startup of the engine and still is not fully charged. Normally my alternator charges at 13.6 dcv.

Depending on the answers to the meter and time of measurement, you may not have any problem with your batteries and charging system.
1995 CC Magna #5280
C8.3L 300hp Cummins, 31,000lbs
deandec is offline   Reply With Quote
Old 11-08-2014, 09:43 AM   #9
Senior Member
Join Date: Sep 2014
Location: Newcastle West, Ireland
Posts: 392
This is a very informative site and well worth the read.
Battery Maintenance | Trojan Battery Company
'98 Southwind 34L, too many cameras, old hat, young heart.
May the light be with you.
Mentor is offline   Reply With Quote
Old 11-08-2014, 09:00 PM   #10
Senior Member
Join Date: Mar 2014
Location: Fremont, CA
Posts: 168
welcome, and now the fun begins. Any rv that has independent batteries have an isolator. Mine is in the engine compartment. It usually has 4 wires going to it. 1 to the alternator, 1 to coach bat, 1 to starting bat and 1 excite wire. This is used on newer alternators. You can check with a voltmeter. Engine running, blk to ground, and red to each of terminals, should be 14v for alt, and 12.65 for full charge 12v bat. And I think 6.75v for 6 volts. I have 12v deep cycles for my coach.
crockwood is offline   Reply With Quote
Old 11-09-2014, 02:25 AM   #11
Senior Member
High Ball's Avatar
Join Date: Nov 2014
Location: Ottawa, Ontario, Canada
Posts: 114
battery charging

Thanks you all for the great info, suggestions and tips.
Yesterday had time to look at all and with tips for this site, I found the "Bird" and started testing all. Found that the purple wire on the "Big Boy" was not making good contact and after this was rectified house battery are charging with Alternator.
The thing I noticed is that soon after starting engine, the solenoid terminals, I have 14.4 volts on one side (chassis post) and the after the bird activates the solenoid I get 13 volts on house side. Guess the "penny" inside the solenoid has corrosion inside and contact is not as should be. Looks like maybe it can be dismantled with the 4 screws at bottom but not sure. Has anyone opened this up to clean the contacts ????
Many thanks again
High Ball is offline   Reply With Quote
Old 11-09-2014, 10:04 AM   #12
Senior Member
Join Date: Feb 2010
Posts: 4,510
Measure voltage across it.

One lead on each side to see actual voltage drop.

It could be cruddy and may be servicable but others will need to comment there.
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is online now   Reply With Quote
Old 11-09-2014, 10:47 AM   #13
Senior Member
wa8yxm's Avatar
Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 23,843
Motorhome 12 volt 1.001.

On most all (if not all) motor homes there is an isolator device, these come in two or 3 flavors.

One kind is controlled by the ignition switch, When you start your engine, it engages, it may take a few seconds to engage (Time delay) or it may engage right away.

The next is voltage controlled. It will not engage till the engine battery comes up to around 13 volts, NOTE: your dash voltmeter may show a higher voltage than the engine voltage. (Line loss in the wires) so it may take like 10-20 minutes for this one to engage if the engine battery is low enough.

The thired is the BIRD (Bidirectional Isolator Relay Device) IF EITHER house OR chassis goes over 13 volts, it engages (This one is best of course)

I suspect, in your case, the isolator may not be closing, this could be due to a blown/missing fuse, or a bad isolator relay or a control system problem, Step one is locating the solenoid. (Relay).
Home is where I park it!
wa8yxm is offline   Reply With Quote
Old 11-09-2014, 11:42 AM   #14
Join Date: Aug 2012
Posts: 49
Welcome, to the forum and good luck with your Mandalay. All the previous post's have pretty much said it all.


2005 Mandalay 40B, Cat 350 C7, Freightliner Chassis. 2014 GMC Terrain, toad w/ Blue Ox Base Plate and Aventa tow bar. Full-Timers
sleggio is offline   Reply With Quote

battery, charging

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Boondocking battery charging don8ch Newmar Owner's Forum 37 02-06-2015 09:07 AM
Battery not charging during run Robar RV Systems & Appliances 8 10-03-2014 11:46 AM
how can you tell if the house battery is charging Indiajo58 Vintage RV's 2 09-22-2014 10:49 PM
Battery charging mystery Kenneth Neal RV Systems & Appliances 12 02-25-2014 05:34 PM
Dimensions 2000 Watt inverter, no battery charging, need help ASAP! FIRE UP Winnebago Industries Owner's Forum 29 02-23-2014 11:36 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:45 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.