$15 Ammeter/Voltmeter Retrofit write-up

[Kenall]

Originally posted by steven79:
Also on your wireing of the volt meter, if you do it the way you say won't it read even with the key off? as it will come from the battery?

well what you can do is to connect the 2 OE wires from the back of the ammeter together away from the new voltmeter, and then cover with shrink tube. then connect the + of the voltmeter to a switched source.

but tedz way is simpler

[Joe Guilbeau]

This is not a bad idea, however as mentioned on other posts on this subject matter, it is not nearly critical as some might have you believe.

The reason that this is so is because the Alternator's output is generally sent to the Ammeters Positive post AND to the big splice (generally Wire #12) which also feeds the following:

1. The Fuse Box
2. The Ignition Switch
3. Light Switch/Dome Light
4. Horn

So, this means that the Ammeter is only passing the current that the Battery needs in order to be charged, which is controlled by the Alternator's Regulator.

What IS true, is that if there is a short to ground in the Ammeter circuit then there will be a major problem.

In reality, if the regulator circuit is in good shape and you simply run an ANL fuse inline on the Alternator Output and the return charge line going to the Positive Terminal of the Solenoid you will be perfectly safe.

The ammeter only displays the charge rate of the battery, this is why in normal good running jeeps the alternator reads almost "Zeo" amps.

This is because under normal operating conditions, the battery is recieving just a trickle charge, as the alternator is supplying most of what the vehicle needs in order to run thru the splice and not thru the Ammeter.

When the vehicle just starts up, the ammeter reads a negative charge rate because the battery is supplying amps to the starter (like 200 - 400 amps).

This is why the ammeter initially goes negative, because of the Positive/Negative terminal hook-up of the ammeter in the circuit, The battery is giving up amps, and this dep;etion flow rate is indicated on the ammeter, after the vehicle starts the alternator sez... "...Gee let's give that ole battery some juice...", cause it appears to be somewhat low.

So now the ammeter shows a positive charge for a few moments so the battery can take up the charge that the starter has just depleted.

With a good battery and alternator combo, and a good starter, the charge rate to replenish the alternator should not take but a minute... any longer than this indicates that the battery does not have enough reserve capacity to supply the starting current and voltage that the starter needs, and puts too much of its capacity into the starting process.

Then the ammeter shows a large current transfer to the battery as the alternator attempts to replace the depleted charge.

[ November 25, 2005, 05:23 PM: Message edited by: Joe Guilbeau ]

[DAHoyle]

I am completely at a loss for words in the quality of the work you did, and if copying someones work is really a form of flattery, then consider yourself flattered. I'm in the area, so if you can point me to a source for the Voltmeter, and save me a little legwork, I'd really appreciate it.

[Ted_Z]

I picked the volt meter up at my local Autozone.

You could also get it online from them. Just do a part number search on www.autozone.com for CP7985.

[DAHoyle]

Ted_Z,

Thanks for the follow up reply, and sorry for missing it in the original writeup. I was too busy looking at the pictures. Anyways, it's an awsome mod, and so well done it's pretty much invisible to anyone who doesn't know better.

[J10-401]

Not to be a spoil-sport or anything but.... That's the same instrument cluster and gauge types used in maybe a million total Hornets, Gremlins, Javelins etc. How come I never heard of this fire hazard issue in the cars?

Don't get me wrong, it still looks really nice and if I were to completly rewire my Jeep I'd likely go to a voltmeter if only to simplify things.

[ November 28, 2005, 07:49 PM: Message edited by: J10-401 ]

[Retro93]

Originally posted by J10-401:
Not to be a spoil-sport or anything but.... That's the same instrument cluster and gauge types used in maybe a million total Hornets, Gremlins, Javelins etc. How come I never heard of this fire hazard issue in the cars?

Don't get me wrong, it still looks really nice and if I were to completly rewire my Jeep I'd likely go to a voltmeter if only to simplify things.

Have you taken a REAL close look at the wiring in your Jeep? To put it mildly, it's junk from the factory. Maybe the true AMC cars had better quality components installed.

[J10-401]

Any wiring is junk after 15-years. Especially if people make modifications with no understanding of what's required. There is no difference from car to Jeep in the wiring harnesses. Same connectors, wire gauges and wrappings. Maybe some lengths are different and some extra functions - but essentially the same.

A new engine harmess is in my future plans for the same reasoning. It gets the most heat and flexing. So the copper gets work-hardened and the plastic connector shells and wire insulation become cracked and brittle too.

[ November 28, 2005, 09:06 PM: Message edited by: J10-401 ]

[Retro93]

Originally posted by J10-401:
Any wiring is junk after 15-years. Especially if people make modifications with no understanding of what's required. There is no difference from car to Jeep in the wiring harnesses. Same connectors, wire gauges and wrappings. Maybe some lengths are different and some extra functions - but essentially the same.

So I take it..you haven't looked closely at your rigs wiring harness??

[ November 28, 2005, 09:06 PM: Message edited by: Retro93 ]

[Kenall]

Well I just got done with my retro fit, works great.

Instead of using part of the lable from the voltmeters face, I just used the gauge 'faces' from a later wag with the icon (instead of words) of a bat instead of the word AMP

[J10-401]

"So I take it..you haven't looked closely at your rigs wiring harness?? "

Ya got me thinkin'. I started looking at all the places where wiring could rub on sharp edges and things like that. Maybe they did overlook what can happen in real offroad shake and vibration. So I made a lot of changes with liberal re-routing and tiewraps.

[Magnum CJ]

what an awesome idea. just so happens my ammeter crapped out on me last saturday. I spent 3 hours tracing down why my ignition switch and accessories had no battery power. don't know about the fire hazard, but mine burned open altogether. I already did the jumpering part, but the voltmeter substitution is a great idea. Good Job! thanks.

[Sitting Bull]

My compliments...

[Allen78J20]

Wow great job!!! If I do this I'll need a new place to put my tach, it currently blocks the amp gauge(not used due to the ammeter bypass/upgrade) Excellent job!

[Heimeken]

Excellent, best tech post I've seen in long time. Thanks.