|
10-29-2021, 07:41 AM
|
#1
|
Senior Member
Winnebago Owners Club
Join Date: Dec 2008
Posts: 1,309
|
Voltage drops when Under load - Alternator?
Voltage seems to drop when ISM engine is under load, e.g. going uphill. Until recently voltage showed around 13.5-13.6. Last trip it was around 13.2 to 13.3, dropping to a little below 12 under load. Dash gauge and VMSpc show pretty much the same. Engine batteries are 1.5 yrs old and the BigBoy was replaced about the same time. The alternator is a Leece Neville, probably original.
So I'm not sure if it's the alternator losing output, the BigBoy somehow going bad so soon or something else.
__________________
... Rick P.
(Currently searching for early 2000s Monaco).
|
|
|
|
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!
|
10-29-2021, 08:59 AM
|
#2
|
Senior Member
Join Date: Mar 2019
Location: Braidwood Il.
Posts: 8,300
|
The big boy only combines to charge secondary battery if bidirectional. If your always running the genny driving I could see loss of it boosting the chassis battery due to low alt. output.
Higher rpms could make a bad brushes chatter more or belt flap if tensioner dampening is bad. Serpentine belts don't slip much. Alternator pulley is small and gets a lot of grooved side contact ,not really suggesting its the issue.
__________________
95 Monaco Crown Royale
M11 400hp, 4060 trans.
Aquahot, Generac Guardian7.5k
|
|
|
10-29-2021, 10:28 AM
|
#3
|
Senior Member
Join Date: Jan 2018
Location: Capistrano Beach, California
Posts: 4,465
|
Anytime the alternator output drops below 12v would be a red flag for me (not an expert!) I cannot remember ever seeing fluctuations on the voltage gauge once the initial start up and running has occurred, but I don't watch the gauge constantly. Regardless, I would not trust the reliability of the alternator dropping to that level, even under load (load being the engine effort, not electrical demand.)
If this was my situation, I would have the alternator/regulator tested at the first opportunity.
__________________
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.
|
|
|
10-29-2021, 10:40 AM
|
#4
|
Senior Member
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 31,311
|
I had my L/N alternator rebuilt over the summer ; noisy bearings ; during the bench testing the regulator proved faulty , wouldn't allow full output , so new regulator installed .
In 11 years with the coach I'd never seen the volt meter go to 14 volts; I'd assumed that was because the coach is always plugged in and batteries fully charged ; voltmeter now goes to 14 volts after start up ; so the regulator had been acting up for a long time.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
|
|
|
10-29-2021, 12:45 PM
|
#5
|
Senior Member
Winnebago Owners Club
Join Date: Dec 2008
Posts: 1,309
|
OOPS! Typo
I should have said "dropping to a little below 13 under load"
Called an Alternator place, I'm bringing it in to them to load test. The tech there also suggested that cables could be corroded inside after 15+ years.
__________________
... Rick P.
(Currently searching for early 2000s Monaco).
|
|
|
10-29-2021, 02:19 PM
|
#6
|
Senior Member
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 31,311
|
Quote:
Originally Posted by rpasetto
The tech there also suggested that cables could be corroded inside after 15+ years.
|
Amen to that ; in a pusher motor home , the air flow through the alternator is opposite to the way they were designed ( heat from exhaust going into the back of the alternator, instead of being blown away as in a front engine configuration ) it's actually a wonder they last as long as they do.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
|
|
|
10-29-2021, 03:06 PM
|
#7
|
Senior Member
Join Date: Oct 2016
Posts: 1,801
|
Hi Rick P.; If you want to test the alternator get a multi meter and hook the leads to the +&- terminals on the back of the alternator. Use your cruise control to bring the RPM's up to al least 800. Get a voltage reading. Should be above 13.8 volts plus. Now add loads like dash heater blower, headlights and fog lights. If voltage drops more than .2 volts I am going to guess your alternator is not putting out voltage and needs to be rebuilt.
Read Not2bars posts here and you can see what he had to deal with in his alternator woes. Hope this info helps and good luck!
|
|
|
10-30-2021, 09:42 AM
|
#8
|
Senior Member
Monaco Owners Club
Join Date: Jun 2014
Posts: 14,494
|
My coach was ~12 years old when my alternator crapped out, Alt Fail light came on. Didn't bother doing any diagnostics, just pulled it and had it rebuilt cost ~$185 ~7 years ago.
If I were you I'd just have them go through and rebuild your alternator. The hard part is done >>> pulling it and putting it back in is the hard part.
My alternator puts out 14.2 on the Silverleaf VPMSpc display. Dash gauge lower.
__________________
Jim J
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi
|
|
|
10-30-2021, 02:44 PM
|
#9
|
Senior Member
National RV Owners Club Freightliner Owners Club
Join Date: Dec 2008
Posts: 117
|
It sounds like your voltage regulator is not working correctly. When that happened to me, I replaced the regulator (it is attached to the top of the LN alternator and is a bit of a challenge to change). However, within a few months the diodes failed in the alternator and I had to remove the alternator in a campground and take it in to be rebuilt (the failing diodes may have been what caused the regulator to fail originally). So, my suggestion is to have the alternator rebuilt before it fails on the road somewhere. DO NOT let a rebuild shop exchange yours for one of their off-the-shelf rebuilt units. Have your original unit rebuilt. A little research will yield many horror stories of resulting problems when a supposedly correct substitute does NOT work correctly. Keep your original and rebuild it if at all possible. Just my opinion. Good luck.
Richard
|
|
|
11-02-2021, 07:45 PM
|
#10
|
Senior Member
Join Date: Feb 2020
Location: San Benito, Tx
Posts: 385
|
We have Leece Neville 200 amp alternator on our MH. Started out this trip showing 14+ volts on the dash gauge. Started fluctuating a week or so ago, pretty much the same symptoms as yours. Crapped out on us and resulted in a tow. (Thank you Passport America) Took the alternator to a rebuilder in Columbus, Ohio. Hite Parts Rebuilders, had it ready in under an hour. Now shows a steady 14+ at the gauge. Voltmeter at the isolator showing 14.2 volts on both legs. Might save yourself some trouble and get it rebuilt. God Bless and good luck, Ed & Sylvia
__________________
God is good, the rest doesn't matter!
2000 Monaco Dynasty 350 Cummins, 07 FJ Cruiser 4x4 Toad. Rescue - Sage
|
|
|
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
|