IS THERE A DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH, SIMILAR TO THE PROGRESSIVE INDUSTRIES EMS DEVICES THAT MONITOR THE 120 VOLT SYSTEM?
I RECENTLY HAD THE VOLTAGE SPIKE TO OVER 19 VOLTS AS I WAS DRIVING. I WASN'T AWARE IF IT UNTIL I NOTICED SMOKE COMING OUT OF MY BLAUPUNKT STEREO AND TANK MONITOR DEVICE. AS SOON AS I COULD STOP, I DISCONNECTED NEGATIVE TERMINALS ON THE HOUSE BATTERIES. IT TURNED OUT TO BE THE ISOLATOR THAT FAILED. I HAVE REPLACED THAT, BUT I NOT ONLY LOST THE BLAUPUNKT, BUT ALSO HAD TO REPLACE THE HWH MOTHER BOARD( A PRICEY ITEM FOR SURE). I WOULD LIKE TO INSTALL A DEVICE THAT WILL MONITOR THE LOW VOLTAGE SYSTEM IN THE COACH AND PROTECT IT IF A SPIKE OCCURS.
THANKS TO ALL IN ADVANCE
EXCUSE MY ALL CAPS, I DO THAT BY DEFAULT AS I COMMUNICATE OFTEN WITH PERSON WITH A DEGENERATIVE EYE CONDITION AND IT HELPS HER TREMENDOUSLY.
Super simple monitoring device. LED lights, small enough to mount just about anywhere, and top LED indicates overvoltage of 15.5V
After seeing a picture of a poster here I went on the internet and bought one for "house" battery and one for the engine battery. Haven't failed yet.
Here is the web page, for what it is worth.
Google 12 volt surge suppression.
There are TVS diodes that you connect between the + and - of you battery to bleed off excessive voltage.
Different clip voltage diodes are aviable.
I was looking at one that clips the voltage st 14.5 volts but now I can't find it again. Think it was a $20 item.
Probably would be good to add to both battery banks.
I don't see how the "isolator failure" would cause 12V system to spike to 19 volts. Something else going on...
Chuck,
I agree, that voltage came from his alternator.
I wonder if a bad isolator started playing games with the voltage regulator on his alternator?
That was my thoughts also, how can an isolator multiply voltage. If the sense wire broke at the isolator would the alternator take off unregulated?
Yes, a bad isolator can send false voltage readings to the sense terminal of the alternator. As can dirty or loose sense wire connections.
That's one of the big reasons I have the twin voltmeters right in front of me while driving. Usually, it's not a sudden failure but can be seen as rapid voltage changes or abnormally high or low voltages. After driving a short time with the meters installed, it's easy to see an unusual change and then monitor it closely.
Pierce
A lot of us have added a Trimetric device to monitor the 12 V system. It gives you amps in, amps out, percent of charge and voltage on the coach bats and just voltage on the start batts.
jor
All the devices we are talking about give an indication of high voltage. That may not do any good as that high voltage had already gone through the 12volt system. We need a device to trim that voltage as it attempts to go through the system.
That's why we use 120 volt surge protection. To stop it before it goes through the system and do a lot of damage.
It's to late to close the gate after the cows are out.
It happened to me... isolator failed and alternator started putting out just over 17 volts. Obviously, the sense wire (which is actually hooked up to a relay near the isolator and must have been taken the chassis battery voltage from the failed side of the isolator) was telling the voltage regulator that the battery voltage was low or non-exisitant, so the alternator was putting out max. I relocated the center terminal to the chassis battery side and the alternator was working normally. As cascading series of failures which included the HWH control box, though it took a few days to die (new one cost me about a coach buck with trade in credit for the old one). Other trashed components included the SeeLevel 914 display was fried (new one about $400), and a few other things as well. It was an expensive experience! After changing the location of the the cable which had been connected to the center post of the isolator, the only issue was that the house bank was no longer getting charged by the alternator unless the boost switch was on. I ran it that way for quite a while until I installed a new set up which includes a zero voltage drop isolator and multi-stage alternator to battery charger, as well as some other components.
Don
John,
Understand what you are saying, but the failure rate of a well maintained electrical system may make such a device a less than good business decision.
Said another way, the failure rate causing this is pretty low and easily identifiable. OE on Foretravels is a dash gauge showing chassis battery and the dash monitor showing house bank. Yes, one could fit even more precise gauges, but quite frankly, the OE gauges are adequate to identify this kind of issue.
Had EXACTLY this scenario on a coach I inspected recently (the first I have observed in 19 years of working on Foretravels). While on test drive, chassis battery voltage just under 12 VDC. House at 17. Immediately hit battery boost, and both instantly changed to 14.0.
Brett,
Sorry but i can't agree with it being to costly. Well maintained is a good thought. Your are right, damage from voltage spikes is rare,but tell that to someone that just lost computer of some kind. And probably doesn't know that a voltage spike may have been responsible.
Transistors don't like voltage spikes, eventually they give up.
I think we're talking $40 here.
It's just another kind of insurance.
When you see high voltage, all the electronics have already been banged on. To late.
Something everyone has to decide for themselves.
I wonder if the new Fortravel's have any protection for all that electronic stuff. They certainly could benifit from it.
I'm not saying it can't happen, cuz obviously it DID happen to the OP and to Don and to others...but I still don't understand a failure mode in the isolator that would cause the alternator output to go crazy. If the sense wire from the alternator is connected (either directly or indirectly) to the chassis battery post on the isolator, then it would continue to see chassis battery voltage, regardless of the condition of the isolator. Why then would the alternator suddenly think the chassis battery bank voltage has gone to zero, triggering a spike in output?
If the voltage spike was caused by a broken sense wire, or a faulty voltage regulator, then that is not a isolator malfunction.
As Brett says, this is a very rare occurrence. As I have posted before, just purchasing a couple of plug in meters for your lighter receptacles will be adequate without breaking the piggy bank. I chose to install a couple of meters where the old audit CRT was as they are bright LEDs and right in my field of vision. The total investment is only $6 to $16 delivered for two different voltage readings. Either U.S. or China suppliers.
12V-24V Waterproof Car Boat Truck Motorcycle Dual LED Voltmeter Voltage... (http://www.ebay.com/itm/12V-24V-Waterproof-Car-Boat-Truck-Motorcycle-Dual-LED-Voltmeter-Voltage-Meter-/222571940352?hash=item33d2524a00:g:EXoAAOSwOMdZXaJZ)
12V Lead-acid Battery Indicator Intuitive Voltage Display LED Display Meter... (http://www.ebay.com/itm/12V-Lead-acid-Battery-Indicator-Intuitive-Voltage-Display-LED-Display-Meter-/272726253834?hash=item3f7fc0610a:g:NN0AAOSwCmZZSIK~)
Pierce
OK, here is how it happens:
Could this really be a voltage SPIKE? Yes, if the sense wire connection was loose, it could cause spikes as the alternator reads accurate, then very low voltage causing it to output correct, then very high voltage.
It could also be sustained very high voltage caused by the sense wire reading lower and lower voltage.
Example: diode in the isolator that feeds the chassis battery fails. So, chassis battery voltage falls. Let's say it goes to 11.5. Assuming that the sense wire is well-connected at each end (worse if it is not) that info is communicated to the alternator. Which tell the alternator to WORK HARDER-- VOLTAGE IS TOO LOW. BTW, this is exactly what happened on the coach I inspected recently. As soon as the battery boost/combine switch was on, the sense wire read correct voltage (through house battery side and from that through the boost solenoid to chassis battery and sense wire).
Pierce,
I see what you have but when you see high voltage so has everything powered by that system. What you can't see are the many small quick spikes that can occur, but all your electronics feel it
In time some of those components will finally fail and we just think it was old and time for a new one. Maybe.
I don't know if these diodes will do much if a 190 amp alternator goes wild but I think they will smooth out all the little spikes that will effect the longevity of these solid state devices.
For me spending $20 instead of replacing a radio in the dash is worth it.
John,
I run into the spike problem in aircraft radios all the time. It's estimated that three quarters of all the aircraft radio failures are the result of voltage spikes. That's why we don't turn on any radios/transponders/engine monitors until the engine is running and shut them down before stopping the engine.
My simple gauges won't catch the spikes but react fast enough to catch sudden abnormalities as well as seeing high voltage as well as low voltage so the cause can be investigated before it becomes a problem.
Two days ago, I discovered a slightly low voltage in the bank of engine batteries. The trickle charger had been keeping them at 13.1 volts for years but went down to 12.8 on my digital dash gauges. I pulled the cables off and sure enough, the center of three batteries had a bad cell. 8 years old so not too bad.
I just bought a set of three 31 series commercial batteries and will show how to build a rack and replace your U300 trio with the larger 31 series in a week or so. Also, how to get a discount from Autozone so they are $107.99/ea plus the $3 for conventional posts to screw down on the threaded posts the batteries come with. You do have to buy three to get the discount. They are very heavy at 59.9 lbs. but weight is an excellent indicator of battery quality. The next best was Sam's Club at 55 lbs. that I found in a quick search.
Pierce
Brett,
Not being argumentative here (well, perhaps a little...), but in your example, which would happen first:
A. The chassis battery bank voltage would get so
low that the transmission would not shift and other "low voltage" problems would appear.
B. The coach battery bank voltage would get so
high that "high voltage" damage would occur to sensitive equipment.
I guess the answer depends on how low the voltage in your
chassis batteries can go before you start having problems, and with what. Will the coach still run normally if the chassis battery voltage is low enough to make the alternator go to maximum voltage output?
I don't know. I do know that after reading this discussion, I will be even more diligent about scanning my gauges when driving!
Chuck,
Don't see this as any argument-- more a learning experience for all of us.
I can't answer whether ECU's/ECM's powered by the chassis battery would fail before or after house systems suffer damage from high voltage.
And, suspect I will never be able to answer that. Also suspect that you and most others here on the ForeForum pay more attention than to allow this to happen.
I know it only took me a matter of a few minutes in a coach I had never been in to identify the problem (under 12 VDC on chassis and over 17 VDC on the house bank) and implement a "work around" for the rest of our test drive. As I said in that coach, turning on the boost switch "fixed" the problem.
WHEN THIS VOLTAGE SPIKE OCCURED, I WAS DRIVING. WHEN I SAW THE SMOKE COMING UP THE BACK SIDE OF THE MONITOR ON THE BLAUPUNKT, I KNEW THERE WAS A PROBLEM. I LOOKED AT THE AMP METER ON THE DASH, IT HAD DROPPED FROM ITS NORMAL MID 13 VOLT RANGE, TO BELOW 12 VOLTS. I THOUGHT I MIGHT HAVE THROWN A BELT ON THE ALTERNATOR. WHEN I WAS ABLE TO PULL OVER, I WALKED TO THE XANTREX DISPLAY AND SAW THE HIGH VOLTAGE READING AND THE DISPLAY FLASHING EXCESS VOLTAGE. THAT WAS NOT CONSISTENT WITH THE DASH AMP METER. I SHUT THE ENGINE OFF. I WENT OUTSIDE TO THE HOUSE BATTERIES, THEY WERE BOILING HOT. I THEN DISCONNECTED THE NEGATIVE TERMINALS. I CHECKED THE BELT ON THE ALTERNATOR, IT WAS FINE. I STARTED THE COACH, AND THE AMP METER ON DASH WENT BACK TO NORMAL POSITION. I THEN CONTINUED DRIVING UNTIL I GOT TO CAMPGROUND AND SHUT DOWN COACH. ONCE SHUT DOWN I RECONNECTED THE HOUSE BATTERIES. THAT IS WHEN I REALIZED I HAD LOST THE HWH SYSTEM. WHEN I RESTARTED THE COACH , VOLTAGE WOULD IMMEDIATELY SPIKE. FROM THAT POINT ON I WOULD TRAVEL WITH HOUSE BATTERIES DISCONNECTED UNTIL I COULD GET TO AN ALTERNATOR SHOP. THAT IS WHEN ISOLATOR WAS DETERMINED TO HAVE FAILED. INSTALLED NEW ISOLATOR, VOLTAGE WAS BACK TO NORMAL ON ALL BATTERIES. PRIOR TO THIS EVENT, I HAD NEVER HEARD OF AN ISOLATOR. ONCE NEW ISOLATOR WAS IN, I TACKLED THE HWH PROBLEM AND IT WAS DETERMINED THE MOTHERBOARD NEEDED TO BE REPLACED. HWH SYSTEM HAD TO BE RECALIBRATED AFTER NEW MOTHER BOARD WAS INSTALLED. I HAVE NOT TACKLED REPLACING THE BLAUPUNKT, BUT HAVE LEARNED I CAN PLUG THE VIDEO WIRES THAT USED TO PLUG INTO THE BLAUPUNKT, INTO A 7"MONITOR I BOUGHT OFF AMAZON, AND I AM ABLE TO SEE THE REAR VIEW CAMERA AND THE TANK MONITORS. AS A FORETRAVEL ROOKIE, I LEARNED A LOT FROM THIS EXPERIENCE, NOT TO MENTION THE COST OF REPLACING THESE ITEMS.. THANKS TO EVERYONE FOR THEIR INPUT
If you want people to read your posts, stop using all caps. It's considered rude.
CM, I understand your using caps for your friend but for me it is hard to read a statement in CAPS as it looses something. I would think increasing the size of the font and maybe putting it into bold letters would be a better idea
JohnH
Agree, very hard to read!
Pierce
How hard is it to press the "CAPS LOCK" key "OFF" before posting here? Then press it "ON" again for notes to your friend. EASY!
X2
Cap locks on is considered shouting
I have tried to read this thread, but every time I start an all-caps paragraph, I get frustrated and give up after the second line.
I have been thinking about and rereading this post.
It looks like there are two things that can happen and damage the equipment on the 12 volt electrical system.
An over voltage problem which is what happened to OP here.
I don't see this as a spike. It was too high a continuous voltage from the alternator.
If we had a normaly closed relay between the alternator and the isolator that would be powered open at say 15 volts to disconnect the alternator from the system that would happen before you could even see it on a dash meter and prevent that high voltage surge from abusing the components on the bus.
Maybe it should include a timer to prevent resetting for maybe a minute or more even if the voltage corrected giving you time to pull over and shut down to investigate the problem. The other problem would be the very short duration voltage spikes that someone here stated the other day that an alternator with worn brushes can produce short voltage spikes that are hard on solid state devices.
A TVS diode connected between the + and - of the engine batteries would solve that.
This shouldn't be a big expense and would probably reduce operating expense as the years go by hopefully reducing component failures.
I'm not sure if a relay like this is available off the shelf. That could be a problem.
There are people on this forum from all walks of life that may be able to modify this idea into a working design.
Any ideas folks?
No, John, having the alternator B+ feeding an open line (relay open) will blow the diodes in the alternator.
In fact on marine manual switches, there is a warning label to NOT switch it off with the engine running for just this reason.
Cheapest way to to buy a vmspec and program the battery voltage to sound an alarm and a visual warning when voltage goes over a programmed point. This would give you time to pull over and shut engine off before major damage is done.
Jim C.
Brett,
Maybe you could put a dummy load on that side of the relay to keep some load on the alternator even during switching. I was not aware of that, that's why I asked for ideas in my post. If we think positive we can come up with something useful before someone else looses the kind of items the OP here did.
The problem is any high voltage can do damage before you can do anything about it. You may not see it now but it may show up later.
Some things are more tolerant to high voltage than others. A motor could take more than a transistor. And everything has transistors.
Saw this item on eBay, in case anyone is interested in a "period correct" battery monitor for their GV:
TAYTRONICS Battery Monitor for 2 Banks of 12 Volt Batteries Model BVM-100A 1990 (http://www.ebay.com/itm/TAYTRONICS-Battery-Monitor-for-2-Banks-of-12-Volt-Batteries-Model-BVM-100A-1990-/263086972581)
This discussion got me to searching online for a simple way to monitor both battery banks while sitting in the driver seat. Up to now, I have been relying on a cheap lighter plug digital gauge to watch the chassis batteries, and the OEM Audit voltage readout for the coach batteries. This is not ideal, because I have to turn the Audit CRT on to use it, and I am looking at two different places to see the readings. I learned from flying the B-52 (8 engines) that scanning individual engine gauges for anomalies is not as efficient as looking at a whole row of identical gauges and watching for the outlier. This prompted me to search for a small, simple, inexpensive and easy to install dual battery voltage readout of some type.
Voila! Found this one on eBay, and just put in my order. I think this will do nicely. Before starting, I can assess the relative status of house and chassis banks. I can check the function of the boost switch/solenoid by watching to see that the readings equalize when it is activated. When cranking, I can watch how low the chassis voltage dips. After starting, both banks should indicate the positive charging effect of the alternator. When I'm driving, a gross deviation by one of the numbers (high or low) might give me early warning of various mechanical problems.
Anyway, when it arrives, I'll give it a try, and report back.
MICTUNING DC10-60V Dual Voltmeter Voltage LED Digital For Pickup RV Dual Battery (http://www.ebay.com/itm/MICTUNING-DC10-60V-Dual-Voltmeter-Voltage-LED-Digital-For-Pickup-RV-Dual-Battery-/122559979267)
Chuck,
I thought mine was great but yours is perfect. Looks pretty easy to find a place to make it fit. A blue crimp splice off of the Audit wires is a good place to get both engine and battery voltages. They are labeled nicely in the coach schematic. Also, might consider a switch to shut off the display but the draw would be miniscule without a switch. The matching USB charging outlets also look good.
Pierce
Be aware that voltage tapped at the front of the coach is usually a few tenths of a volt lower than at batteries. So, once installed, make a "conversion chart".
The alternative is to run a dedicated wire from each battery bank positive. Lots of work for little gain IMO.
Problem of measuring battery voltage by connecting to an existing wire located far from battery, is the voltage drop when 'other' things on the wire are drawing power. Never a true reading of the battery. To remotely measure voltage, a dedicated long (shorter the better) wire of proper wire size, better twisted to reduce 'outside' interference, would be needed.
So, take a digital voltmeter reading at the dash location and compare it to the voltmeter reading at the engine and coach batteries with the engine running and typical accessories like headlights, heater in operation. Inverter in the on position for coach battery reading. Then, as Brett suggested, have a correction card for the difference if there is one.
P
If you don't want to go to the trouble of dedicated wires from battery, best place to connect:
For chassis battery: The battery side of the ignition solenoid.
For house battery: The positive wire "in" at the front fuse box.
Another source is the starter lug on the generator-- again, a large-gauge wire from the battery lead to the front of the coach.
All the above comments are true and acknowledged, BUT, I'm not really looking for precisely
correct voltage readings. I realize a $16 dollar gauge located 30' away from the battery banks is not going to show the
actual voltage. If I really want to know what my batteries are doing, I'll walk back to the bedroom and look at our Magnum and Blue Sky remote panels.
Totally agreeing with Pierce (reply #15), all I want
while driving is "quick and dirty" voltage values to allow comparison between the two battery banks, and to indicate a sudden change from "normal" operational conditions. Hopefully this little gauge will meet this requirement (and also be slightly easier to fit into my dash area than the two that Pierce mentioned).
And Brett, thanks for the tip, I will absolutely use those two points to connect the dash gauge.
I am not suggesting this as a cost effective way of monitoring the alternator output voltage and the state of charge of the Chassis battery, but I have installed a Victron BMV-702 battery monitor on the chassis battery. This does give me an accurate indication of the battery voltage because the voltage is taken directly from the shunt located at the chassis battery and transmitted digitally via a cat 5e cable to the BMV-702 display. It has a second input as well which can be either a second bank voltage (what I am currently using it for), battery temperature, or mid-point voltage monitoring (not applicable in my case as I have only a single 8D AGM starting battery). It also has a rogrammable visual and audible alarm as well as a programmable relay which may come in handy some day. The alarm will be set up for high voltage (say 15 volts) and could have saved me a couple of coach bucks if it had been installed when my isolator went south. I don't expect the Sterling battery to alternator charger to recreate that issue, since it has protections of its own, but still a "belt AND suspenders" approach won't hurt where my peace of mind is concerned... ::)
Besides, I think it looks cool 8)
Don
I guess the high voltage possibility is still on my mind.
High voltage is not acceptable. It will cause damage. The only thing you can do is shut it down, but what do you do if there isn't a place to pull over and shut down? The longer you have to drive the more damage you will do and smoke and even fire are possibilities.
If we don't have automatic high voltage protection then how about a switch to turn off the alternator? That should be doable.
As Brett mentioned in a previous post, "turning off" the alternator will damage the diodes in the unit. Only way to turn it off is to remove the belt. You could install a clutch on the alternator pulley [much like the ac compressor clutch] and run a wire to the dash with a switch to declutch if voltage rises.
Brett said disconnecting the output would hurt the diodes. There may be a way to switch off an alternator without damaging the alternator. Maybe someone here would know if that is possible. That would be an easy way to handle high voltage. Maybe turn off the field?
Alternator - Wikipedia (https://en.wikipedia.org/wiki/Alternator_)(automotive)
This will explain how an alternator works, if it is turning, it is producing current. Only way to stop that in our type of alternator, is to stop it turning.
Things have changed a lot I guess. On my 1966 Chevelle I had a switch going to the field that I could shut off the alternator as I went down the drag strip. The alternator would not draw horsepower with the field cut off. Never burned up anything in the alternator doing this.
In the old days alternators had separate voltage regulators that supplied field current to the alternator which regulated the voltage output of the alternator. You could adjust or cut it off which would reduce the voltage and load on the alternator. Many modern auto alternators have a built in voltage regulator. I suppose you could disassemble the alternator and attempt to find the field wire, but most are set in a potted self contained assembly.
Good info here: Alternator alternatives (http://www.foreforums.com/index.php?topic=15183.msg91342#msg91342)
I think we're overthinking this solution. Since the Alternator uses an "Ignition" from Key switch input to turn the excitation field "ON" simply having a Voltage Sensing Switch to "Break" the ignition signal will drop the output per Leece-Neville. You should be able to set the Switch to trip at a preset Over Voltage Condition say 15.5 Volts. This would immediately stop the output, protecting the system.
I have to run. So tell me what your think...
Plausible?
Dan
Low voltage is not a problem.
Start the generator!
AND turn on the boost switch.....
Maybe a fly in the ointment.
Alternator Wiring Diagrams and Information - BRIANESSER.COM (http://brianesser.com/technical-information/alternator-wiring-diagrams-and-information/)
Read the paragraph titled: Field Current Supply.
Now is the time for any Electrical Engineers to chime in...........
That is referencing the battery cable connection. If you had the headlights on, on some cars and unhooked the battery cable with the engine running the lights would pop like flash bulbs.
True, " After the engine is started, and the alternator is up to speed, the output of the diode trio is fed back to the regulator, and serves as a source of current for the field current. At this time, the alternator is self sustaining," The point I am trying to make is that just stopping the excite voltage from the ignition switch may not stop the alternator output after it is up to speed.
..... Like I said, time for an E.E.
Though I would check out the alternator situation this morning. Found that alternator excite voltage is fed from the ignition switch to a self resetting breaker under pass side dash [in my case #35] then back to alternator excite terminal. As soon a key is turned on, 12 volts is sent to this terminal. I put a jumper between breaker and wire and started engine, vmspc showed charging at 13.9 volts, about normal. removed jumper and voltage fell to 13.1 volts. The conclusion I draw is that when the alternator is turning, it self-excites to a certain extent, without the need of 12 volts to exciter terminal. Not sure of the long term effects on the alternator running like this, but if one wanted to install a overvoltage relay in this line to the alternator. Output voltage would fall enough to protect the coach electronics until you could find the problem.
Jim,
Good test.
I wonder what the voltage would do if you loaded up the system or even increased RPM?
Your brave. If you do something bad it would be $.
I did rev it up to about 1800 rpm, voltage stayed about 13. Did price alternator first, about $150 on ebay. :)) :))
Jim,
Would you please share your link? I have been looking for an alternator replacement, but never found one for that kind of money.
Thanks,
Trent
110-555JHO / 8LHA2070VF OEM Leece Neville Alternator Reman, 12V, 160A, CW | eBay (http://www.ebay.com/itm/110-555JHO-8LHA2070VF-OEM-Leece-Neville-Alternator-Reman-12V-160A-CW-/132236830742?hash=item1ec9ede816:g:4YkAAOSw4YdYz9gC&vxp=mtr)
Have seen them from $99 for new reman. Check ebay every day as the cheap ones go fast.
Just make sure frame size is the same and it is DUVAC. Anything from 110 to 200 amps will do our coaches fine.
Easy conversion to make alternator not DUVAC into DUVAC alternator. Link: Prestolite - Leece Neville (http://www.prestolite.com/pgs_support/duvac.php)
Pierce
Reading those instructions shows removing the diode trio for Duvac. That puts us back at the possibility of cutting power from the ignition to the field.
Back to Jim is yours Duvac?
Yup, three different alternator configurations.
The simplest is just a B+ with either separate ground, or ground to metal of the engine.
Next adds an external sense wire-- very important with a diode-based isolator.
Next adds an ignition hot/excite wire.
Yes, PO replaced with what coach came with. If it goes out, I would consider a standard alternator as I do use a battery combiner.
Our experience is finding and 'old fashioned' alternator / starter rebuilder to rebuild our alternators instead of buying reman or new, often lower quality alternator. The final outcome may be better and last longer.
Hi Barry,
I have a feeling the alternators for under $200 may be foreign and or reman models. Maybe I'm wrong and Ebay etc.is offering some really great prices.
Jim
2002 U320
Lot of American companies remanufacture alternators, starters, turbos, etc. Taking a good quality core and rebuilding it with good quality bearings, brushes etc., does not necessarily lower its quality, sometimes it increases it. I had a bmw, and a datsun, they both had foreign alternators and starters, and had over 200,000 miles on each one with no problems.
A lot of OEM american made parts in cars had problems, and when they fail, dealer replaces them with reman parts that have improved components.
There are a lot of lower quality starters for sale. Not sure about alternators. Just seems a shame to turn in an original unit that is probably high quality part for an unknown new or reman. Just seems like we can have our cake and... by starting with our worn and tired units and having them rebuilt by an 'old school' shop, especially if we can hang around and watch.
Lewco in Costa Mesa, ca charged me $300 to replace a bad diode and the $70 main bearings that were a pain to get out.
Plus they have the best Bakelite old Chicago made test unit with big knobs.
Thirty year shop. I am sure he does mail stuff.
An old timer, (means he was 10 years older than me!)told me in an emergency, say your chassis battery shorts out , on a diesel that turns off the fuel solinoid, engine dies, now no power steering, diesels steer quite hard with out power steering, he told me to use the combiner switch. Fast forward a few years, going down a bendy grade at 55 mph going into Sisters,OR, my engine quits, no steering, brakes didn't work, try to start engine, no such luck. I turned off stereo, wife said whats wrong, told her leave me alone for a moment please, she saw me strugling to make the turns. Combine switch pushed, dead short in chassis battery, 9 volts, yikes, engine still had not enough voltage to start, pushed gen switch to start gen, voltage goes up to 11, enough to start Cummins. Old timer saved my life. So why did my brakes not work?
If you are talking about the
air brakes on your
present coach, they should have worked as long as you had sufficient air pressure. Depending on the system pressure at the instant the engine quit, you might only have one or two full applications before brake tank pressure was depleted. At that point, the emergency spring brakes should activate, and you are just along for the ride.
Thank you Chuck, your post makes me feel so much better. This happened over ten years ago driving from Eugene, Or to the 2007 FMCA, Family Motor Coach Association Rally, in Redmond, near Bend, Oregon in my 1992 Monaco Signature. I saw the air gauges dropping when I touched the foot brake, I must admit panic set in since I was almost unable to make the turns, thinking I'd soon not have brakes, and I just remembered that "old timer" telling me about the story with his combiner switch. I knew better, I knew about the springs kicking in, I just didn't at that instant. Interesting is that the Monaco combiner had an automatic spring return, and so I had to hold the combiner switch all the way into Redmond, where I replaced the chassis battery. The chassis battery was quite warm when I got to Redmond, so I am also thankful it did not catch on fire. So what happened was the chassis battery shorted out while I was driving, just as I reached the summit the voltage got so low it kicked off the fuel solenoid, as I started down the hwy to Sisters, OR., which killed the engine. Had I been in the Foretravel with a combiner switch that is either on or off, it would have been much easier. I believe it is a good thing to remember this scenario of our 12V systems. Since then, in the sales environment, with no power post near by to plug in to, I have often encountered a battery with not enough "juice" to start the main engine. Thank goodness it did have enough to start the gen set which then in turn would start charging the 12V system.