Ammeter and protection

[Joe Guilbeau]

To the Collective:

I have decided once and for all to put to rest all of the threads on ammeter bypasses and alternator protection circuits. I prefer to keep that ammeter insturment in the dash, to upgrade it, to upgrade the wiring to and from and then to protect said investments for a lifetime of no longer thinking about said upgrade...priceless!

Most of you know that it is a simple matter to replace the stock alternators with a CS-130 or CS-144 higher amp range alternator.

These alternators come in 100-amp to 150-amp variations, and even higher amp versions.

I LIKE the ammeter option in my Jeep, it shows me how much charge/discharge the battery is recieving/sending.

If the ammeter shows a 30 amp or better reading for any length of time (10 minutes or longer) it tells me that something has drained my battery quite a bit. A voltmeter will only show that the battery is being charged...not much help, as this voltmeter will read the same when the battery is almost depleted (battery is almost drained or dead) as with a perfectly good battery.

Remember that ammeter only shows what current is being drawn or added FROM/TO THE BATTERY, it is NOT the ALTERNATOR OUTPUT, unless your battery is essentially a basic short circuit.

In any case, just buy 25-feet of #4 welding cable from these guys. The cost will be $30 dollars plus shipping.

http://store.solar-electric.com/wc--4.html

You will need 6 of these terminals (two to terminate welding cable run from the alternator BATT output to the studs on the Ammeter shunt, then the second two teminals on the welding cable from that same Ammeter shunt to the solenoid. The final two terminals on the welding cable from the solenoid to the positive battery terminal. Most automotive stores will sell you a terminal to hook on to the battery post mounting bolt to allow hookups of ring terminals.







Wire the shunt below in accordance with directions, this shunt has a resistor (shown in the below image) that developes a voltage across it when current is passed through the resistor. So, when the battery is accepting current from the alternator, the current flows from the Alternator BATT terminal to this shunt, thru the shunt and then to the solenoid post where the positive battery cable is terminated to. In this way the ammeter shows the current (as displayed as a voltage drop across the shunt resistor) that the battery is accepting from the alternator. That voltage that is developed across that shunt resistor is proportional to the current being drawn, that is the more current that the battery is accepting from the alternator the larger the voltage developed across the shunt resistor. In reality the "Ammeter" is really a voltmeter and the "Voltage displayed" is simply shown as amperage. Most ammeters operate this way, a few of the more expensive units actually have the current running thru them.

This is a good idea because it allows monitoring on a daily basis the health of the vehicle such as the starter, the alternator, the battery's capability to take and hold a charge, the headlights current draw and any potential connectors that are starting to die of old age and have an excessive current draw condition such as those same headlight circuits. The ammeter will show a very few amps of draw that the battery is telling you is being drawn off and must be replaced, this is normal. When the vehicle is started, there will be a negative draw on the battery and the ammeter will reveal this, as the alternator charges up the battery that ammeter reading will steadly decline indicating that the battery is accepting a charge.

On our standard amp gauges, this would have been displayed as a negative current as the starter was engaged, and then an immediate positive ammeter reading that show the amount of amps that the battery is accepting to replace the energy just delivered to the starter. It allows simple daily monitoring of the electrical health of the system.






Both the ammeter and the shunt can be purchased at this location for about $70 dollars
http://www.evparts.com/webcart11/zoo...WCSOID=1441916&

For those of you who like to approximate the original style of amp meters (actually these and the above are in reality millivoltmeter that display the voltage drop across a shunt resistance and send the millivolt on to a meter which is calibrated and the display is shown as amperage). The Westach gauge below also comes in a 150 amp version, but I have not been able to find an image of it, it will look the same as the below gauge with 150 amp readings.

Quota cops are limiting my bandwidth on this thread...

http://www.westach.com/gauge_images/2C6-3.jpg

So, for about 100 dollars you have a pretty bulletproof system.

AND since...

Guilbeau's my NAME...
Electronics MY game

To protect the whole shebang you put an inline circuit breaker that opens under overcurrent conditions. This one is from Waytek and is a 150 amp circuit breaker that is weather proof and that yellow hinged paddle will rotate60 degrees to click and reset the unit once tripped. $40 dollars...

http://order.waytekwire.com/productdetail2/M37/46894/MARINE%20CIRCUIT%20BREAKER%20150A/

[Jayrodoh]

I've always wondered when someone would do this.

The only problem is see with that gauge, is you'll only be able to show charge or discharge amount depending on how it's wired, not both.

[Joe Guilbeau]

I've always wondered when someone would do this.

The only problem is see with that gauge, is you'll only be able to show charge or discharge amount depending on how it's wired, not both.

A quote as in "Lonesome Dove" as Robert Duvall said...


"..."Just once I'd like to shoot at an educated man...." ~ Robert Duvall as Augustus 'Gus' McCrae , Lonesome Dove

You sir, are correct, and I am curretly seeking an ammeter to do just that. The this is cost, as the Jeep Collective are by an large a bunch of cheap bastards... ME TOO!!!

[smearig]

Would 6 gauge submersible-rated wire work? I have about 600' of that in my garage that I have leftover from getting my well re-wired.

[Joe Guilbeau]

Would 6 gauge submersible-rated wire work? I have about 600' of that in my garage that I have leftover from getting my well re-wired.

The simple answer is that 6 awg will carry about 2/3rds of the 4 awg load.

My suggestions were centered on 150 amp alternator so that gives a 100 amp alternator for your 6 awg wire as a good top limit if you go this route.

Just spend the $30 dollars....


See I told ya'll the collective was a bunch of cheap bastards...

[Joe Guilbeau]

I've always wondered when someone would do this.

The only problem is see with that gauge, is you'll only be able to show charge or discharge amount depending on how it's wired, not both.

Here you go...see the edited post.

[jsinajeep]

That all fine and dandy, but for a $100.00 + I will stick with the volt meter. If it show more than 12+ volts them I know the alt. is working and I don't have all those extra parts and wires causing me more headache than I need. And the volt meter fit in the dash where the amp. meter was and looks good.

[Jayrodoh]

Nice work!

[Joe Guilbeau]

That all fine and dandy, but for a $100.00 + I will stick with the volt meter. If it show more than 12+ volts them I know the alt. is working and I don't have all those extra parts and wires causing me more headache than I need. And the volt meter fit in the dash where the amp. meter was and looks good.

This was mainly for those of us with original amp meters who have upgraded the alternator to 100-150 amp varieties (CS-130D's & CS-144's)

Voltmeters are nice, they give you the voltage, but do not (for instance) tell you how much of a strain on the battery that starter is pulling, or when you flip on the headlights, if the amps drawn from the battery show more than usual, then you better get under the hood and check those connectors. The voltmeter will not show this, it will only tell you that the voltage from the alternator is (a pressure reading if you will) is good. You could very well have a bad battery and the voltmeter will tell you that the alternator is putting out a voltage, while the amp meter will tell you that the battery is being sucked dry by the over amperage that the alternator is pumping into it.

The amp meter also allows you to check individual loads on the battery by switching them on and off, all a voltmeter will tell you is that a drain on the pressure (voltage reading) is happening.

Best of both worlds is both meters.

Ever had a battery drain overnight due to something intermittent shorted or a bad diode in an alternator, simple thing to troubleshoot with an amp meter, a voltmeter can trooubleshoot almost as well but since I have been in electronics for 35 years, I pick up on things that jump out at me. Amps drawn from a battery are a fine indicator of the health of wiring and components.

It is not for everyone, nor would I suggest that everyone do this, much like any other option... some might like Dana 80's front and rear, others are happy with the AMC20 behind them.

Different strokes, eh?

As long as I am on the subject, that famous AMP meter bypass, really does nothing to protect your jeep, you are still sending the same currents and voltages through the firewall with the same wiring that you did before.

The ONLY thing that you are really doing is bypassing the shunt resistor that the milli-volt voltmeter (our "Amp Meter") is reading. It really only reads the voltage developed across the shunt resistor and this voltage is what moves the meter movement.

As I mentioned earlier, when the batter is discharging the current is flowing out of the battery, so our "Amp Meters" show a discharge or negative amps. All that is really happening is that the current is going one way when the battery discharges and the opposite direction when the battery is charging, therefore the voltage reading are kinda like taking your portable voltmeter leads and reversing them. Your ground reference is no longer chassis ground, but at the higher potential voltage and thus the meter will read negative volts.

It all depends on how you look at it.

One can always remote mount the shunt resistor and not even have the charging/discharging current from the battery go thru the firewall at all, just send the alternator output to the solenoid...but power needs to get inside the cab somehow...thats a whole 'nuther discussion altogether.

By the way, a good solid battery will show up good on the voltmeter for a while even with an alternator that has just failed, that amp meter will peg in the negative direction immediately, letting you know to shut her down ASAP and check it out....

Yet another instance that a amp meter will help, when something in your harness (perhaps a connector or connection or device) is not keeping its connection (intermittently making contact and then opening up for an instance and with the next bump or rattle making good contact again, you will see that amp gauge twitch towards positive amps. A real good indications that something is amiss in the wiring harness. The alternator will just keep putting out pressure (voltmeter readings will not vary much at all) while the current that the alternator is pumping into the battery is spiking due to the intermittent not making contact and then making contact.

It is just another tool in the tool box that can assist a knowledable individual at time. I always carry a portable Fluke Mulitmeter with me anyway, and can read thru the cigarette lighter adapter with meter pigtail leads that I can plug into the meter. Pretty simple and effective.

I just want everyone to understand that when you bypass the amp meter, all you are doing is bypassing that shunt resistor... you do nothing else to protect your jeep. And since the only current flowing in that circuit is what the battery is taking from the alternator or what the battery is delivering to the system, you seldom see anything near 40-50 amps running thru the Yellow and Red 10AWG wires (on most of our Jeeps).

Tune in next week, when (for a small donation) I will register a Star in your name and send you a nifty certificate to boot!

[Joe Guilbeau]

That all fine and dandy, but for a $100.00 + I will stick with the volt meter. If it show more than 12+ volts them I know the alt. is working and I don't have all those extra parts and wires causing me more headache than I need. And the volt meter fit in the dash where the amp. meter was and looks good.

This was mainly for those of us with original amp meters who have upgraded the alternator to 100-150 amp varieties (CS-130D's & CS-144's)

Voltmeters are nice, they give you the voltage, but do not (for instance) tell you how much of a strain on the battery that starter is pulling, or when you flip on the headlights, if the amps drawn from the battery show more than usual, then you better get under the hood and check those connectors. The voltmeter will not show this, it will only tell you that the voltage from the alternator is (a pressure reading if you will) is good. You could very well have a bad battery and the voltmeter will tell you that the alternator is putting out a voltage, while the amp meter will tell you that the battery is being sucked dry by the over amperage that the alternator is pumping into it.

The amp meter also allows you to check individual loads on the battery by switching them on and off, all a voltmeter will tell you is that a drain on the pressure (voltage reading) is happening.

Best of both worlds is both meters.

Ever had a battery drain overnight due to something intermittent shorted or a bad diode in an alternator, simple thing to troubleshoot with an amp meter, a voltmeter can trooubleshoot almost as well but since I have been in electronics for 35 years, I pick up on things that jump out at me. Amps drawn from a battery are a fine indicator of the health of wiring and components.

It is not for everyone, nor would I suggest that everyone do this, much like any other option... some might like Dana 80's front and rear, others are happy with the AMC20 behind them.

Different strokes, eh?

As long as I am on the subject, that famous AMP meter bypass, really does nothing to protect your jeep, you are still sending the same currents and voltages through the firewall with the same wiring that you did before.

The ONLY thing that you are really doing is bypassing the shunt resistor that the milli-volt voltmeter (our "Amp Meter") is reading. It really only reads the voltage developed across the shunt resistor and this voltage is what moves the meter movement.

As I mentioned earlier, when the batter is discharging the current is flowing out of the battery, so our "Amp Meters" show a discharge or negative amps. All that is really happening is that the current is going one way when the battery discharges and the opposite direction when the battery is charging, therefore the voltage reading are kinda like taking your portable voltmeter leads and reversing them. Your ground reference is no longer chassis ground, but at the higher potential voltage and thus the meter will read negative volts.

It all depends on how you look at it.

One can always remote mount the shunt resistor and not even have the charging/discharging current from the battery go thru the firewall at all, just send the alternator output to the solenoid...but power needs to get inside the cab somehow...thats a whole 'nuther discussion altogether.

By the way, a good solid battery will show up good on the voltmeter for a while even with an alternator that has just failed, that amp meter will peg in the negative direction immediately, letting you know to shut her down ASAP and check it out....

Yet another instance that a amp meter will help, when something in your harness (perhaps a connector or connection or device) is not keeping its connection (intermittently making contact and then opening up for an instance and with the next bump or rattle making good contact again, you will see that amp gauge twitch towards positive amps. A real good indications that something is amiss in the wiring harness. The alternator will just keep putting out pressure (voltmeter readings will not vary much at all) while the current that the alternator is pumping into the battery is spiking due to the intermittent not making contact and then making contact.

It is just another tool in the tool box that can assist a knowledable individual at time. I always carry a portable Fluke Mulitmeter with me anyway, and can read thru the cigarette lighter adapter with meter pigtail leads that I can plug into the meter. Pretty simple and effective.

I just want everyone to understand that when you bypass the amp meter, all you are doing is bypassing that shunt resistor... you do nothing else to protect your jeep. And since the only current flowing in that circuit is what the battery is taking from the alternator or what the battery is delivering to the system, you seldom see anything near 40-50 amps running thru the Yellow and Red 10AWG wires (on most of our Jeeps).

Tune in next week, when (for a small donation) I will register a Star in your name and send you a nifty certificate to boot!

[Chris P.]

On our standard amp gauges, this would have been displayed as a negative current as the starter was engaged

You made some very good points above, but the ammeter will not read the current draw of the starter when cranking.

[Joe Guilbeau]

You made some very good points above, but the ammeter will not read the current draw of the starter when cranking.

No ****...

[smearig]

See I told ya'll the collective was a bunch of cheap bastards...

I won't deny that. I'm just trying to think of a good use for that wire.

[sungoesdown]

I have an amp meter with the shunt like that in my Honda. It provides good info when my 1000 watt class D amplifier is maxed out.

When I lived in Orlando, there was an aircraft surplus store that had tons of old used ammeters and shunts that were very cheap.

[RubiconMike]

Was that the place across the street from Sound Advice's Audio Garage that had the bombs out front? I think it was on W. Fairbanks.