Thread Tools Display Modes
Old 03-09-2018, 01:32 PM   #1
Almost There
Join Date: Jan 2018
Posts: 95
12v VERSUS 24v

So I am working on a 1978 MC8 Coach Bus....

It runs a 24v system on the coach side but I am not sure what all the other lights/headlights and the like run off of.

I am told there is a 24v to 12v converter in the bus but I haven't found it yet...

I am pulling out everything passenger bus related and starting fresh...only the bus running lights and such are going to stay,

How can I tell what voltage the device uses?

I am NOT an electrician...
PNWorBUST72 is offline   Reply With Quote
Old 03-09-2018, 02:16 PM   #2
Site Team
JDOnTheGo's Avatar
Join Date: Feb 2017
Location: The West
Posts: 1,188
Year: 1998
Coachwork: MCI
Chassis: 102 EL3
Engine: DD 60
In the absence of any documentation or markings, I would connect a voltmeter to the +/_ wires, turn the thing on, and see what the meter reads (set to the 'volts' option). A clip on meter might make it even easier.

I can tell you that my MCI (102-EL3 - so much different model) does in fact run the headlights, tail lights, marker lights, etc... from 12 VDC.
JD - Full timer out west
Missy - 1998 MCI 102-EL3 - 1.7kW Solar - 10kWh Lithium
My Adventures & Build
JDOnTheGo is offline   Reply With Quote
Old 03-09-2018, 04:09 PM   #3
Almost There
Join Date: Jan 2018
Posts: 95
suggestion on a decent entry level voltmeter? I am thinking I am going to have to track down alot of wiring here...
PNWorBUST72 is offline   Reply With Quote
Old 03-09-2018, 04:17 PM   #4
Bus Geek
brokedown's Avatar
Join Date: Dec 2016
Location: Weeki Wachee, FL
Posts: 3,028
Year: 1997
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: Cummins 5.9
Rated Cap: 72
You can get a free one (with purchase) at Harbor Freight.

Harbor Freight Tools Coupon Database - Free coupons, 25 percent off coupons, toolbox coupons - 7 FUNCTION DIGITAL MULTIMETER
Keep up with us and our build!
Follow us on Facebook, Instagram, YouTube, and Twitter
brokedown is offline   Reply With Quote
Old 03-09-2018, 04:45 PM   #5
Bus Geek
o1marc's Avatar
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 9,333
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
Originally Posted by PNWorBUST72 View Post
suggestion on a decent entry level voltmeter? I am thinking I am going to have to track down alot of wiring here...
Harbor Freight has weekend sales all the time. Some sales you can get a volt meter free with any purchase. They are only like $6 regularly, work as well a any.
go to their site and sign up for their catalogs and coupons. Every sale they have I pick up 4" angle grinders for $5, whether I need one or not.

Can you buy better, more expensive ones, sure. But I've never had a need for one that was "better".

Didn't see brokedowns post before posting mine.
o1marc is offline   Reply With Quote
Old 03-09-2018, 05:01 PM   #6
Bus Crazy
Jolly Roger bus 223's Avatar
Join Date: Sep 2017
Location: Swansboro,NC
Posts: 1,270
Year: 86
Coachwork: Thomas
Chassis: Ford B700
Engine: 8.2
Rated Cap: 60 bodies
A volt meter is a must have and learning the settings if not specifically marked AC/Dc is a must do. As well as the amps and ohms settings.
On a side note. Might help might not?
You can look at how your batteries are wired and tell if it's a 24v system or a 12v.
I can explain it but you can get diagrams and specific info from google about wiring batteries in series or in parallel.
series gives you 24v off of 2-12v batteries and parallel gives you a higher capacity 12v system.
When you replace your batteries pay attention.
That's the only help I can give right now?
Jolly Roger bus 223 is offline   Reply With Quote
Old 03-09-2018, 07:02 PM   #7
Bus Geek
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
I have been around a few MCI's of that vintage and older. I have NOT worked on them myself so I am simply repeating what I have heard. Take it for what its worth....

As best I understand it earlier MCI's had 24v coach batteries (12v in series) and ran most of the coach functions, starter, headlights etc on 24v.

Some time later they switched most of the functions, lights etc, to 12 v using a 24v-12v converter but the starter remained 24v.

Some time during the MC-8 production they went all 12v.

I do love the Skoolie board and the people here. However, you will find more MCI specific knowledge on BNO BBS - BNO's Bulletin Board System - Index or Bus Conversion Magazine Bulletin Board - Index I will warn you that folks there are not the easy going bunch that we enjoy here........

I will third (or fourth) the advice given above. Get a volt meter and start checking batteries and accessories to see what is 12v or 24v.

Where are you currently located? If you are anywhere close to me I would be happy to spend a day with you and see if we can get your questions answered.
PNW_Steve is offline   Reply With Quote
Old 03-09-2018, 07:09 PM   #8
Bus Nut
Join Date: Mar 2017
Location: Greenwood, Indiana
Posts: 669
Year: 1999
Coachwork: New Flyer
Chassis: D45HF "Viking"
Engine: 11.1L Detroit Diesel S60
Rated Cap: 51,600
My New Flyer has the 24-to-12 converter in the "engineering section" under the back cap but above the engine. Looks something like this:
MarkyDee is offline   Reply With Quote
Old 03-10-2018, 08:01 AM   #9
Almost There
Join Date: Jan 2018
Posts: 95
Thanks all!

I am on the other boards but this one gets alot more traffic it appears so on general conversion type topics I tend to come here first and for Coach specific things I lean on those boards.

Currently I live in Jacksonville but the idea is take the bus on tour to the PNW this Summer.
PNWorBUST72 is offline   Reply With Quote

Thread Tools
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

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 08:25 AM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.