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Topic: Prestolite alternator-no output??? (Read 1789 times) previous topic - next topic

Prestolite alternator-no output???

Hi, All,
I just purchased a 1989 Grand villa UNIhome U280 ORED with a 250HP Caterpillar engine about three months ago.  I use it as a domicile for when I'm at work in Crockett, TX... (hence the handle," Crockett man").  My plans are to get this coach restored into a roadworthy state so when I retire, I can have some fun traveling with my better half for the rest of my life.  This is going to be a large project and I expect it to take time to get things right and roadworthy!  Right now, I am delving into an electrical issue with my alternator not charging.  Below is a synopsis...
1.)   The dash voltmeter reads 12 volts.  It should be at least 13-14 volts for charging.
2.)   With the engine running, there is no voltage output from the alternators terminal so the voltmeter is probably only reading from the battery.
3.)   The alternator that is installed is a Prestolite (Leese-Neville) model # 8LHC2010Z - High Output Alternator.  According to the specs, it is a self-excited type alternator similar to the one pictured below except mine does not have the terminal shown on the top right as pictured.

http://www.prestolite.com/productinfo/alternators/8LHC2010Z/8LHC2010Z_r.jpg

 
4.)   It looks original but I could be wrong.  The Left terminal has an R embossed on the housing next to it with no wires attached.  The middle is alternator output (+) with two cables attached...one going to the Battery Isolator, and the other into the wire harness. The right terminal is Ground. 
So my question ... is there supposed to be a wire attached to the R terminal?  All the research I have done on this forum points me to a DUVAC style alternator which is NOT what I have. 
The Coach is old but it does have low miles (65 k) and I don't think that the alternator is toast yet.  I am not excluding the possibility though.  I'm hoping that someone out there who owns one of these can point me in the right direction as far as troubleshooting this problem. 

Steve, the Crockett Man

Re: Prestolite alternator-no output???

Reply #1 –
Steve,

Does alternator B+ output go to a diode-based isolator? If not, how is it tied to the battery banks.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Prestolite alternator-no output???

Reply #2 –
Steve,

The 8LHC2010Z alternator presently on your coach does not have "remote sense" capability.  It is self-excited, which is fine - that will not be a problem.  But because it does not have a "remote sense" terminal, it is not suitable for use with the diode-based battery isolator found on your coach.  The only way you can use that alternator with your present setup is to hook the POS (+) output wire to either the "Start" battery post on the isolator, or directly to the POS (+) post on a start battery.  If you do that, the "Start" battery (or batteries) will get a proper charge.  However, the "Coach" batteries will NOT be charged by the alternator unless the "Boost" switch is activated (assuming you have a "Boost" switch).

DO NOT try to run a "Sense" wire off the "R" terminal.  According to the tech sheet linked below, that is the "AC Tap", which is sometimes used to power a tachometer.

8lhc2010z - Alternator Product Details | Prestolite / Leece-Neville
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Prestolite alternator-no output???

Reply #3 –
Brett,

OP states two wires coming off the (+) terminal on alternator - one goes to isolator (he does not say which post), and the other goes "into the wiring harness".  I would like to know where the 2nd wire goes.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Prestolite alternator-no output???

Reply #4 –
Several "work arounds" for an alternator without sense terminal that still leave the ability to separate the house from chassis battery banks when the engine is not running.

Simplest is a marine ON-OFF switch.  Can be mounted at foot of bed where it is easily switched from inside, wires to the back of it in the "electric area".  Alternator B+ and wire to chassis battery to one lug.  House to other.  With engine running, chassis battery is always charged at full/correct voltage.  With switch ON, both banks charged.  With switch OFF, house bank does not receive a charge. And with switch off, battery banks are separated.

That is far less $$ then replacing the alternator and still having what I suspect is a 25+ year old diode-based isolator.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Prestolite alternator-no output???

Reply #5 –
I installed a Cole hersee smart isolator recently which does not use diodes, so far so good. Brains are separate from the mechanical solenoid, should the continuous duty rated solenoid wear out, that part can be replaced. About $100 for a 200 amp Isolater. It is bi-directional based on battery bank voltage, once chassis battery is charged.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Prestolite alternator-no output???

Reply #6 –
Quote from: Old phart phred –
I installed a Cole hersee smart isolator recently which does not use diodes, so far so good. Brains are separate from the mechanical solenoid, should the continuous duty rated solenoid wear out, that part can be replaced. About $100 for a 200 amp Isolater. It is bi-directional based on battery bank voltage, once chassis battery is charged.

Another reasonable alternative.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Prestolite alternator-no output???

Reply #7 –
Take the alternator to a shop that can test it.
96 U270 BUILD 4810
85 380SL
Drummonds TN.
 

Re: Prestolite alternator-no output???

Reply #8 –
Wow, Thanks for all the fast replies...you guys are fantastic! 

Brett, the + cable from the alternator goes to a four post Battery Isolator.  I'm pretty sure its the Diode type (red) original to the coach.  I  am going to bench check the isolator as the next step in my anayisis but even still, the Alt should have output. I might disconnect the second wire attached to the + Lug on the alt to identify its function.  I really don't think I need to pull the alternator (ugh) at this time!  Some electrical things I've done are... replaced the converter and an 80 amp CB, removed and cleaned all cables from relays, batteries, and isolator and most importantly, the grounding lug to chassis. This got the batteries to charge from the shore power nicely.  By the way, this coach only has three batteries...1 chassis, 2 coach...weird huh!