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

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

Reply #25 – July 14, 2017, 07:43:44 am

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!

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

Reply #26 – July 14, 2017, 09:46:01 am

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

Reply #27 – July 14, 2017, 12:43:41 pm

Cap locks on is considered shouting

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

Reply #28 – July 14, 2017, 03:26:37 pm

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.

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

Reply #29 – July 15, 2017, 06:13:09 pm

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?

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

Reply #30 – July 15, 2017, 10:42:34 pm

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.

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

Reply #31 – July 15, 2017, 11:08:09 pm

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.

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

Reply #32 – July 16, 2017, 08:56:50 am

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.

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

Reply #33 – July 16, 2017, 09:23:58 am

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

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

Reply #34 – July 16, 2017, 11:18:28 am

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

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

Reply #35 – July 16, 2017, 01:07:28 pm

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

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

Reply #36 – July 16, 2017, 01:23:31 pm

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.

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

Reply #37 – July 16, 2017, 01:47:58 pm

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.

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

Reply #38 – July 16, 2017, 01:59:43 pm

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

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

Reply #39 – July 16, 2017, 02:28:06 pm

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.

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

Reply #40 – July 16, 2017, 02:38:21 pm

Quote from: wolfe10 – July 16, 2017, 02:28:06 pm

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.

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.

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

Reply #41 – July 16, 2017, 04:04:08 pm

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

Don

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

Reply #42 – July 17, 2017, 02:53:01 pm

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.

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

Reply #43 – July 17, 2017, 03:21:13 pm

Quote from: John Duld – July 17, 2017, 02:53:01 pm

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.

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

Reply #44 – July 17, 2017, 03:25:35 pm

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?

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

Reply #45 – July 17, 2017, 03:42:17 pm

Alternator - Wikipedia(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.

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

Reply #46 – July 17, 2017, 05:51:09 pm

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.

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

Reply #47 – July 17, 2017, 06:37:04 pm

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

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

Reply #48 – July 17, 2017, 06:43:47 pm

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

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

Reply #49 – July 17, 2017, 07:02:37 pm

Quote from: TexasPop – July 17, 2017, 06:43:47 pm

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?

I don't see why not. If you have the old 4 wire alternator it might work. Voltage sensing device would have to be close to alternator because power from ignition switch should feed fuel solenoid and engine ecm. Bear in mind that if running with a big load, [lights, ac etc.] and your batteries are not the best, the drop in voltage from the lack of the alternator could cause other problems.

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