Just spent a couple of weeks at the Wa. Coast and Mount Adams. While at Mt. Adams. We were hooked up to 50 amp, I of course had the inverters charger going as well as a 3 amp trickle charger to the chassis batteries. I did a maint clean of the start batteries posts and clamps. Upon starting the coach for the drive home. The engine spun over nice and quickly.
Two hours down the road we stop for lunch and shut the engine off. Upon a restart 30-45 minutes latter. The start battery voltage at the VMSPC shows 12V a little bit down the road it shows 11.8 YIKES! WTH!
So I start the genset and have the wife make sure the inverter was off and then press the charge button and I activated the boost switch. The voltage came up to 12.4V but then dropped back to 11.8-12 the remainder of the trip (about 100 miles)
After getting home. I go to the electrical panel and see that the charger is in float mode even though the start battery reads 11.5V. So I turned the charger off then back on. It went from charge to accept in a few seconds. I walk up front and the start batteries are reading 12.8V on the VMSPC. No low voltage fault on the VMSPC either.
Any clues?
Tonight I'm getting out the old dumb charger and charge each start battery that way and then check each batteries voltage.
Don't rely on the VMSPC as the last word for voltage. Go to the batteries and check with a digital meter with the engine stopped and then running. A battery just taken off the charger won't show a stable voltage for six hours. If low, follow Brett's earlier about the isolator. Naturally, check to make sure the batteries terminals are clean and have a good connection.
Pierce
VMSpc does not measure voltage or anything else. It simply reports the data reported on the data bus from the engine and transmission computers. I agree with Pierce, check voltage at the batteries or the isolator or the alternator.
Use the VMSpc Diagnostics Menu to see reported events. Be sure to look at History.
These kind of voltage changes point to an issue that you need to chase down. Alternator, isolator, connections,
Yes on the VMSPC just being the messenger. Just cleaned those battery connections a couple of days ago.
As soon as it cools off a bit. I'm going to do some measurements at the isolator and check both banks and then again with the coach running at high idle. I take it to measure the alternator output at the isolator, You use the center terminal and ground. Never have dealt with an isolator and two battery banks.
Took some measurements at the isolator. There are three terminal lugs. Both outside lugs measure 12.67 volts.
With engine running at high idle of 1150 RPM. The center lug measures a bit over 10 volts. But was bouncing around a lot between 7-10 Volts.
Maybe I have an alternator issue?
There were two faults logged.
1, 251-80 Power supply = Low voltage
2, 251-52 Power supply = Low voltage
The 251 SID code shows as real time clock power interrupted.
Both of these were on July 12th When I started the coach at the coast. It had sat all week and only the coach batteries got charged while running the genset. It turned a bit slow and I released the key before it started and that's when that code showed up. The code did not reoccur on today's trip.
Alternator post should be about 0.8v more than the house and start battery posts. Make sure your excite wire is in good shape. It should read what the start battery does. The excite wire is hot when ignition is on. Same with the sense wire, it is connected to start battery so same voltage.
Measure voltage (carefully) at the alternator to rule out a bad cable.
Before condemning the alternator, make sure the sense wire and if present, the ign wire are OK.
The ignition wire at the alternator has battery voltage when the key is on. When I started the engine and put it on high idle (1100 RPM) I checked the alternator output. 4.6Volts. Oh Oh.
I couldn't figure out how and where the other wire went. On the alternator it says "from #1 post of the duvac" HMMM!
Is your volt meter on the right scale? Maybe 14.6
Yep. Minimum setting on my meter is 0-20 VDC
Besides possible bad alternator you could have a boost solenoide that may be coming and going. With boost switch on all batteries should read the same voltage.
BigD,
Your sense wire goes to a breaker on the same panel as the isolator is mounted on. It then goes to the same terminal as the A.C compressor gets it power. (unless someone has relocated it).
With your alternator putting out some power it is most likely that either a brush is stuck in the holder, the voltage regulator is failing or possibly you have a diode inside the alternator gone bad. Any of the 3 are not an expensive fix. If you have a bad stator or rotor (both a high $ repair) you wouldn't be producing any power.
Mike
Here is the exact alternator for our coach. New, no core for $254 delivered. Sure cheap if you have one fail and the coach has to be towed or someone has to work on it. LEECE NEVILLE 160 AMP DUVAC ALTERNATOR MOTORHOMES RV'S 2824LC 2825LC EL-039... (https://www.ebay.com/itm/LEECE-NEVILLE-160-AMP-DUVAC-ALTERNATOR-MOTORHOMES-RV-S-2824LC-2825LC-EL-039-/262856475635)
How about just installing it where the AC compressor is/was? We don't use ours so the space goes to waste. One alternator could go to the engine batteries, one to the house. Get rid of the isolator then.
Pierce
Good one. Bought a spare. Mine was recently rebuilt and works fine. Cheaper than my rebuild by $50. May swap the new for the rebuilt and store the rebuilt one. One diode was bad on mine which means the other 5 are 22 years old....,
I have two. The second is a one wire Delco wired to house bats. Did nothing to my isolator. Not sure if it bothers it or not .
BigDog,
I have had good luck getting my alternator rebuilt at Texas Alternator Starter Service in Austin. Came back looking like new with new bearings, internal wiring, and regulator for about $60 in 2011. More now of course. I know you are on the west coast, but if you can find a good shop to rebuild yours, might save you some $$, assuming you have an alternator problem which is what it sounds like. If you are up to removing and replacing the alternator, more $$ saved. Disconnect the start batteries first and label all the wires on the alternator. Good luck.
Going to the NAPA store in the AM to run an alternator test to verify if the diodes have gone south. Seems that is likely the case as the alt still energizes but only manages 6.4 V @ 1100RPM.
The engine bay in the unicoaches are quite roomy and the alt looks easy to r&r. So I'll go the DIY route. NAPA has the Wilson exact replacement for the LN. Although thinking about the Delco SI28 and the zero loss isolator.
I'll shot this question out there. With the Wilson being a direct LN replacement. What does that mean for a change to a zero loss isolator?
By "zero loss isolator" do you mean something like the Victron Energy Argo FET isolator, or a similar device? If so, it will not require any change in the alternator wiring,
as long as the alternator sense wire is reading start battery voltage.
With the common diode based isolator, in order to fully charge the start battery, the alternator must increase its output voltage to make up for the voltage lost across the diode between the alternator post and the start battery post.
If the new isolator has zero voltage loss (or close to it) between the alternator post and the start battery post, then the alternator will simply supply the voltage required to fully charge the start battery. To the alternator, it will seem exactly like being connected directly to the start battery.
I am running the Victron Argo FET isolator, and it works just fine with my remote sense alternator.
'93 U280 Isolator Panel Upgrade (https://www.foreforums.com/index.php?topic=34743)
Jerry, consider a Delco Remy 40si series alternator. Brushless, more efficient, no excite wire needed, just a sense wire.
Victron makes a nice series of zero voltage drop isolators, ArgoFET as Chuck mentioned. Sterling makes a smart zero voltage drop isolator, the ProSplitR. They also make an Alternator to Battery charger, smart, faster recharge. Lots of options out there.
You will pardon me for mentioning again that the entire rv biz has changed to a auto combiner. No one uses a isolater. Too much power loss. That's why they have fins on it! Dead engine batteries. Customers unhappy.
Straight install where the isolator was. The boost switch is replaced by a off/auto/combine switch. No new wiring.
Run a wire to the starter relay and the house batteries are locked out during the starter relay being used unless you manually combine them or choose not to add the starter relay sense wire.
I give up. You can all replace your 20 year old tech with the same parts and kill batteries regularly.
Not right if you might REALLY need the coach to work.
So the sense wire tells the alt to increase voltage automatically to compensate for a diode loss and the opposite for a no loss isolator. I think I got that. Seeing all the posts about amps & voltage requirements had me scratching my melon.
That sounds good. I'm open to anything.
The 40SI would be nice. But she who must not be disobeyed and comptroller of the Big Dog family budget nixed that as to expensive given the cost of that alt and the new run of very big cables from stem to stern needed to go from 160 to 240 amps.
The batteries will only take so much input. Regardless of the alternator size. The LN has an adjustable voltage regulator on the unit.
See the eBay link on the deal on new ones. Look at the users. Gillig. Transit busses.
Std Delco puts our 14.15 volts to the battery as far a I have read, if the batteries are physically hot you are massively overcharging them. More than a volt. Ballooned cases.
As Brett has posted many times here you need 13,6 at the batteries to lessen the overcharge.
Unless you have 5 house 8d's to be able to charge at 1/5th C no use for the extra amps.
Especially at too high of a voltage.
Does the delco have adjustable voltage?
It's not a car. Long drives.
Like I said look at the eBay link for the LN where it mentions the adjustable voltage.
If we had lost power in flooded cells long ago we(I) used to turn up the built in voltage regulator to equalize batteries to restore capacity.
We did not have chargers that could do that. That's why the LN has adjustable voltage to tailor it to the use.
My 160 alt and 125 charger normally max out at 110-115 amps into three 8g8d mk gels.
Ah if you have Lifelines they may be able to take more amps? 20% faster charging than any other AGM as far as I have seen.
I bought another LN on purpose. 20 years life. 10-12 year house and engine batteries life reported here many times.
And you want to change it?
Cabling is fine. The batteries cannot take that many amps period
For a 160 amp alternator look at a Delco Remy 28si.
Bob,
All alternators will put around 14.4 volts (or a little more) or so when you start the car/coach tapering off as the battery voltage rises. The further the battery has been depleted during the night, the longer the alternator will produce the higher voltage. If you have voltmeters in front of on the dash, you can watch this happen. Batteries can take a very high charging rate until the temperature reaches 125 degrees. Our solar controller like many battery chargers, has a sensor glued to the side of the battery so if the battery temperature reaches 125 degrees, the voltage (like water pressure) will be reduced so the battery will not be damaged.
Radios, ECUs, etc are usually designed to operate at 13.8 volts.
Alternators will have an idle output and a 6000 RPM (alternator) output. The alternator fan is not that efficient at idle RPM and having to output it's max output for idle RPM on a hot day in a hot engine compartment can shorten it's life. In hot SoCal days and heavy traffic, the alternator earns it's keep plus car manufactures keep the pulley size small so the RPM is high to offset the heavy load the AC, etc put on it.
If you drive with the inverter on, heater fan on, lights, etc., don't expect to see voltages down in the low 13V range.
Yes, the voltage on a LN is adjustable but only with fully charged batteries and nothing else drawing current, should it be checked
with the thought of adjusting it.
Now, with automatic tensioners, the correct tension is kept on the belt. With no auto tensioner, the highest rate of alternator failure is with conventional belts being too tight and shortening the life of the bearings. The belt should just be able to be turned 90 degrees with your fingers half way between pulleys. Too loose, the belt slips, overheats and has a short life.
Pierce
Well, That trip to NAPA bore no fruit at all. In fact I was kind of miffed that they told me over the phone that YES their fancy hand held could check diodes while alt was on the engine. Which of course turned out to not be the case. They simply hooked up to my battery cable and said. 12.4V your OK. Brought out multi-meter and read 4.V at the iso center post. NOT OK.
I'm convince now that it is my alt. As the strong aroma of toasted electrical equipment was emanating from the alternator.
So now, Next question. Can I remove the belt from the alt. and run the genset on charge mode with boost on to get to my storage location? Walla Walla has a 24 hr limit for parking RV's, Boats and any sort of trailer at the curb.
The short answer, Yes.
Mike
I like short answers. I thought that was the case. But feel better with a verification. Thanks Mike
Those are remote sense capable. If hooked up the alternator will adjust its voltage output higher until the voltage at the battery is 14 volts.
Here's the LN
Applications
Popular RV Motorhome Alternator
CUSTOM CHASSIS INC EL-039
DAIMLER TRUCKS NORTH AMERICA LN 2824LC
GILLIG CORP 51-00179-008
INTERNATIONAL TRUCK & ENGINE ZLN2824LC
LEECE NEVILLE 2824LC, 90772, A001090772, A0012824LC, A0012825LC, 2825LC
MACK TRUCKS INC 2742 5034-2824LC,
Monaco A001090772, A0012824LC, A0012825LC
Newmar 2824LC 2825LC 2828LC
OSHKOSH CORPORATION 6HA518
PRINOTH 110954522
SPARTAN MOTORS INC 0499-GG1
VOLVO NORTH AMERICAN CORP. LN 2824LC
Series number: 2500JB, 2600JB, 2700JB, and 2800JB.
MODELS: 2524JB, 2624JB, 2724JB 2824JB AND 2829JB
NOTE: INCLUDES STANDARD 8 GROOVE PULLEY
OEM(s): Leece Neville
System voltage: 12
Output: 160 AMPS
Rectifier location: Internal
Excitation type: Ignition Excite
Regulator Location: Internal
Mounting style: J-180
Fan Location: External
Rotation: BI-DIRECTIONAL
Mounting bolt size: 1/2-13 UNC
Positive stud: 5/16-18 UNC
Negative stud: 5/16-18 UNC
For Duvac or Dual Battery Systems
Industrial, Recreational & Medium & Heavy Duty Truck Applications
Weight: 24 lbs. / 10.91 kg
Includes Simple Hook-up Instructions
*PLEASE VERIFY YOU HAVE DUVAC TYPE SYSTEM BEFORE PURCHASE*
On my u-240, running the genset gets you 110vac and onboard 75 Amp battery charger. Now you can run anything that uses 110vac like A/C's to stay cool on the way and still run the 75 amp battery charger. Turn off all 12vdc items like Headlights, radio, cb. Boost switch must be ON for charging starting/chassis batteries from house/onboard charger. Why remove any belt that is running good? Go far it I think you will run as long as genset is running.
Once you make sure a start battery is not internally shorted, the generator besides supplying the battery charger for the start batteries will not only run the main engine forever, but also both ACs, inverter, microwave, headlights, etc. until it runs out of fuel. How much juice do you think it takes to run the ECU, etc? Not much. You don't even need the boost solenoid.
Pierce
MAYBE. But not if wiring is OE. From the factory, the inverter/charger or converter ONLY charge the house bank, not the chassis battery.
So, boost switch needed. OR as an alternative that takes 5 minutes to do, hard wire the battery banks together-- easiest at the battery isolator. Just remove the cable from one outer lug (goes to one battery bank) and ADD IT to the other outer lug (goes to the other battery bank. Basically makes one large bank. Make sure you do not have any weak batteries that could affect all the other ones. If one is weak, remove or replace it.
No problem with driving as far as you want like this-- just mind "total bank" voltage if drycamping!!!
because after arriving at napa for an alt test. I could smell burning electronics coming from the alternator. So I thought it best not to push it into catching fire driving on the highway to my storage location. The coach is now at it's storage location.
Your incident brought up maybe another advantage to a auto combiner.
If the alternator was to fail our house battery side which in daylight is being charged while driving as it's hooked up thru the refer wires then to the combiner then to the house system would have combined the batteries and charged the engine batteries from the solar.
Not unusual except for the automatic part if the driver did not notice the failure.
I keep dual 12.00 volt gauges in the dash while driving and under discharge they show warning lights.
Versus a 3amp consuming 12v boost switch that manually needs to be energized and no power loss auto system would seem a better way?
In my case if the systems load exceeded my solars output or at night then the auto combiner would disconnect the banks and the engine battery dash display would show lower volts right away and it's warning lights display
I have decided to order up a new Delco-Remy 28si 180amp alt, Sterling zero loss isolator. And a new AC belt tensioner that broke in half.
Found the alt. at find it parts for $315.25 ^.^d and the Sterling Iso at Bay Marine. And always helpful MoT had the AC pulley and bracket in stock.
Good info pierce.
On startup I see around 13.85 volts max. Probably because the auto combiner has both banks together as soon as the alternator is energized by exceeding normal idle.
I notice the new LN has a updated solid state internal voltage regulator that supposedly energizes the alternator to start at lower levels.
A sensing alternator that adjusts it output to always be 14 at the engines battery bank would seem to need optima red tops which were made to handle the high battery heat and higher voltage.
If the no loss isolator and the Delco end up putting out 14 volts always to both banks the house side at minimum in summer is being at least .75 volts overcharged.
In a non sense system you could add load to reduce the volts. In a sense system if hooked up the alternator turns itself up.
The LN has large heat sinks and a large external fan to cool it at high under hood temps and low rpms as far as I know.
Hence the use by Gillig as they built the Gillig Phantom intracity transit busses for many years.
I would test this and after the batteries are fully charged the Delco is still putting out 14volts I would disconnect the sense wire.
Their Delco site shows 13.5 without the sense. As 13.6 was the voltage for long drives that would slow the overcharging damage.
Factory used the LN and mk gels and redtops as this combo lasted longer. Lots of 10-12 lives reported here for this exact setup.
House side charging on inverter for the last 20 years has been temp controlled.
But not the alternator unless you had a link 2000R panel on a old freedom 25 for the engine side.
Too much work and parts when redtops handle the overcharge and heat when they moved the batteries into the engine bay when the unicoach was built in 95.
Temp controlled engine battery charging had the alternator down to almost 13 volts. Buddy had to disconnect the engine batteries temp sensor