IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Topic: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH? (Read 2739 times) previous topic - next topic

IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

July 13, 2017, 09:11:36 am

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #1 – July 13, 2017, 09:20:47 am

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #2 – July 13, 2017, 09:30:00 am

Here is the web page, for what it is worth.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #3 – July 13, 2017, 09:50:08 am

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #4 – July 13, 2017, 10:31:54 am

I don't see how the "isolator failure" would cause 12V system to spike to 19 volts. Something else going on...

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #5 – July 13, 2017, 10:36:20 am

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?

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #6 – July 13, 2017, 10:38:23 am

Quote from: Chuck & Jeannie – July 13, 2017, 10:31:54 am

I don't see how the "isolator failure" would cause 12V system to spike to 19 volts. Something else going on...

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?

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #7 – July 13, 2017, 10:41:08 am

Yes, a bad isolator can send false voltage readings to the sense terminal of the alternator. As can dirty or loose sense wire connections.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #8 – July 13, 2017, 10:56:07 am

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #9 – July 13, 2017, 11:29:52 am

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #10 – July 13, 2017, 11:56:08 am

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #11 – July 13, 2017, 11:59:26 am

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #12 – July 13, 2017, 12:16:57 pm

Quote from: John Duld – July 13, 2017, 11:56:08 am

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.

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #13 – July 13, 2017, 01:49:17 pm

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #14 – July 13, 2017, 02:01:14 pm

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #15 – July 13, 2017, 02:04:15 pm

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...

12V Lead-acid Battery Indicator Intuitive Voltage Display LED Display Meter...

Pierce

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #16 – July 13, 2017, 02:32:40 pm

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).

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #17 – July 13, 2017, 02:41:54 pm

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #18 – July 13, 2017, 03:03:02 pm

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #19 – July 13, 2017, 03:33:30 pm

Quote from: wolfe10 – July 13, 2017, 02:32:40 pm

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.

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!

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #20 – July 13, 2017, 03:44:32 pm

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.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #21 – July 13, 2017, 09:40:26 pm

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #22 – July 13, 2017, 10:35:07 pm

If you want people to read your posts, stop using all caps. It's considered rude.

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #23 – July 13, 2017, 11:48:37 pm

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

Re: IS THERE DEVICE THAT WILL MONITOR THE 12 VOLT SYSTEM IN A COACH?

Reply #24 – July 13, 2017, 11:49:41 pm

Agree, very hard to read!

Pierce

Affiliate Notice