Alternator replacement question

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Alternator replacement question

December 03, 2016, 06:49:03 pm

My coach alternator had gone out a few months ago. I had bought a replacement alternator with the same numbers but the wire install is different. Mine has 4 areas and the new one is 3. See the picture.

It looks to be positive on one side and negative on the other. Can I use the lower screws for the 4th wire or is this a problem ?

attach the positive or little wire that was on the positive side to the screw below the black wire and to the right? Hope I am making sense.. will it work that way or just get the old one rebuilt next week?

Re: Alternator replacement question

Reply #1 – December 03, 2016, 07:40:49 pm

Did you get wiring instructions?

Re: Alternator replacement question

Reply #2 – December 03, 2016, 08:24:04 pm

Sticker on the top of the new one says "ELVAC E102200". A Google search turns up exactly one hit: a similar one for sale on eBay.

Not exactly a well known brand...good luck finding any tech documents or wiring diagrams.

Re: Alternator replacement question

Reply #3 – December 03, 2016, 08:24:25 pm

No. I did not. It had the same part number on it so figured it would be good to go.

Re: Alternator replacement question

Reply #4 – December 03, 2016, 08:26:13 pm

Quote from: Chuck & Jeannie – December 03, 2016, 08:24:04 pm

Sticker on the top of the new one says "ELVAC E102200". A Google search turns up exactly one hit: a similar one for sale on eBay.

Not exactly a well known brand...good luck finding any tech documents or wiring diagrams.

Yes it matches the one I pulled out part number wise. but it is definitley not the same on the backside

Re: Alternator replacement question

Reply #5 – December 03, 2016, 08:31:32 pm

You are missing the post for the sensing wire.

Re: Alternator replacement question

Reply #6 – December 03, 2016, 08:35:16 pm

Quote from: oldguy – December 03, 2016, 08:31:32 pm

You are missing the post for the sensing wire.

Is it possible to attach it to the lug to the bottom right of the black ground wire in the pic? Get the same result? Ill run this over to the alternator guy monday am and see what he thinks

Re: Alternator replacement question

Reply #7 – December 03, 2016, 08:36:44 pm

Further Google search indicates that "ELVAC" is the brand of the voltage regulator. Does the alternator have any other identifying marks or labels?

Did the old alternator have 4 wires connected - 2 big ones and two small ones?

Re: Alternator replacement question

Reply #8 – December 03, 2016, 08:43:01 pm

We need a sensing wire when the is an isolator as the alternator doesn't know how much voltage to put out. If a solenoid is used
to isolate the battery you would be fine.

Re: Alternator replacement question

Reply #9 – December 03, 2016, 08:45:08 pm

I mean to isolate the house battery from the coach battery. My class C coaches used a solenoid

Re: Alternator replacement question

Reply #10 – December 03, 2016, 08:57:43 pm

Quote from: Chuck & Jeannie – December 03, 2016, 08:36:44 pm

Further Google search indicates that "ELVAC" is the brand of the voltage regulator. Does the alternator have any other identifying marks or labels?

Did the old alternator have 4 wires connected - 2 big ones and two small ones?

yes the old is 2 large and 2 small.. seems to be 2 negative and 2 positive (each being 1 large and 1 small)

Re: Alternator replacement question

Reply #11 – December 03, 2016, 09:16:29 pm

Your old alternator was set up to require "external excitation" and "external sensing". As you have already deduced, the new alternator is missing one of the small terminals. The question is "which one?". It is possible that the black jumper wire coming out of the voltage regulator will allow the new alternator to function in a "self excited" mode. IF that is the case, then it will still need a "sense" wire connected...but where? Since you have no installation instructions, perhaps your "alternator guy" can answer that question.

See the link below for explanation of 4-wire alternators.

Foretravel Alternators and Isolated Battery Charging

Re: Alternator replacement question

Reply #12 – December 03, 2016, 10:00:08 pm

BINGO! The Google Guru finds the answer, but you are not going to like it. It appears the new alternator, in it's present condition, may not be used in a "external sense" application. There is no provision on the back of the alternator (voltage regulator) for connecting a "sense" wire.

See link below for wiring diagram:

http://www.prestolite.com/literature/tech/alts/TSB-1029_wiring_diagram_JC-LC.pdf

Re: Alternator replacement question

Reply #13 – December 03, 2016, 10:14:58 pm

These look like your old alternator, or at least have the same type voltage regulator. As you can see, they are set up for a 4 wire connection. This style voltage regulator is what you need to connect to your existing wiring arrangement. It is possible your alternator guy could convert your new unit to DUVAC by simply replacing the voltage regulator.

Prestolite - Leece Neville

Prestolite - Leece Neville

Re: Alternator replacement question

Reply #14 – December 03, 2016, 10:27:40 pm

Here's a couple on Amazon - can't tell if they are genuine Leece-Neville, or a clone:

Amazon.com: New 160 Amp Leece Neville 'DUVAC" Alternator for applications...

Amazon.com: NEW 160A ALTERNATOR FITS DUVAC RV MOTOR FITSHOME 2824LC 90772...

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Alternator replacement question

Reply #15 – December 04, 2016, 12:47:16 am

The two small wire connections have specific functions & alternators with them are commonly called Duvac. I think to convert your new alternator to Duvac, it only takes an experienced shop to add a bolt for the missing connection and to make a simple modification to the existing voltage regulator, which is the separate part with the ELVAC name. Keep what you have and the best outcome will be to find an old time alternator, generator, starter shop and have them make the change. If you have storage space, keep the original alternator and someday consider rebuilding it. You will probably need the pulley from the old unit put on the new one.

Re: Alternator replacement question

Reply #16 – December 04, 2016, 09:09:25 am

A common issue today. Many parts are described as "replaces ......." That does NOT mean it IS that part and may be a cheap Chinese knock-off. And, as you have discovered, the term "replaces" can be used very loosely.

Same for air dryers and many other parts. My suggestion is to specify ONLY the OE part brand, not a "replaces .....".

Re: Alternator replacement question

Reply #17 – December 04, 2016, 11:03:37 am

Many thanks to all.. I will take it to the rebuild guy tomorrow and see if he can make the new one work and get the old rebuilt at the same time.. Cant believe what a hassle this has been

Re: Alternator replacement question

Reply #18 – December 04, 2016, 11:33:33 am

I think the best way to repair/replace an older alternator is to get it rebuilt at a shop that knows what they are doing.

Re: Alternator replacement question

Reply #19 – December 04, 2016, 08:28:34 pm

Your alternator problem may be as simple as a stuck brush. You can take off the voltage regulator and pull the brushes out and see if they are badly worn or sticking and then polish the slip rings and put back together and probably will work of course the alt rebuild shop can also repair your old one like new again.

Re: Alternator replacement question

Reply #20 – December 05, 2016, 11:16:50 am

Quote from: Chuck & Jeannie – December 03, 2016, 10:14:58 pm

It is possible your alternator guy could convert your new unit to DUVAC by simply replacing the voltage regulator.

Here is how to convert to a DUVAC on a L/N alternator:

Prestolite - Leece Neville

We have used this procedure several times to fix this problem on various coaches.

Pamela & Mike

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