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Ammeter Gauge


adept99

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I gave the Resource Guide a guick once-over but didn't see what I needed. Has anyone added/installed an ammeter gauge in the DIP? We have a 2001 770 with a very basic Driver's Info Panel. It does not include an ammeter. There are several spare spaces in the panel, just wondering how involved installing the Volvo meter would be. Or, would I be better off to say to heck with that and just add an aftermarket analog version. After my last adventure with a dead battery, It occurred to me that a gauge would be kinda handy.

 

By the way, Coach Net did a fine job coming out to jump the rig even though it was just sitting in our driveway. No charge. No arguments about "That's a semi". Cool...

 

Paul

 

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Paul,

Amp meters have basically been replaced by volt meters in most all vehicles. The reason being a volt meter does not require an in-line shunt. Amp meters with a shunt operate in the milivolt range and do not rob enough power through a voltage drop to cause concern - but it is extra hardware that needs to be protected from weather and an accidental short. Back "in the day" when 30 amps from a generator was all we expected an amp meter was OK since the shunts were physically located on the back of the meter (or inside the meter). Now we are looking at 200 amp shunts for our vehicles. That said, you can find amp meters that use a current transformer slipped over the line between the generator and the battery. DC amp meters with CT's need additional circuitry in the meter to collapse the magnetic field in the CT on a timed interval so they can operate similar to an AC amp meter. Most of the CT type in the 12 - 24 VDC range I have seen on eBay are LED (digital) and come directly from vendors in China. I would say without hesitation that a man of your talents could easily figure out a way to slip such a meter behind the DID. Still, IMHO, a digital voltmeter would give you the needed battery/alternator info and be much easier to install.

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How much is Volvo going to charge for the ammeter parts versus what will it cost you to buy non-branded bits. Appearance comes into play too, maybe just buy the branded and matching meter head and buy the shunt and associated bits somewhere cheaper?

 

How much of your high-amp wiring are you going to want or need to rearrange? Do you want the starter motor pulling amps through the shunt for an example.

 

Another thing to think on is that you need a big enough range on the meter to show maximum currents but that leaves a very tiny needle movement from normal operation to the alternator not charging and no big current draws.

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Ok, Ok, this is me looking foolish. Back in the day (as you say) I learned/was taught to call them an ammeter. Never changed. And you folks are correct, what I want is a voltmeter. Specifically, one from Volvo that fits in the DID and plugs into the existing wiring. Anybody have any experience with that? And thank you all for the gentle responses so far...this 'lectric stuff is hard for a ol' ironworker once you get beyond batteries and light bulbs.

 

Paul

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Ammeter and voltmeter are truly two different things. Voltmeter should read 12V when running on pure battery (if they're well charged AND you're not drawing high current), and should read higher (13.8-14.4V depending on the system) while the engine is running. That voltage while the engine is running can be a distant indicator of charge status (higher voltage translates to fuller charge state), but by no means accurate. An ammeter will show you when the batteries have reached a charged state, as it'll read 0 amps heading to the batteries (it'd read positive during charging, and would read negative during discharging).

 

Back when I drove fire trucks, I remember one that had an ammeter and a voltmeter. If you've seen the classic "Q" (Federal Signal Q2B) siren, that gorgeous bulb of chrome sitting on the bumper, you've seen an object that draws 100A at 12V when the button is pressed (i.e. it's spinning up to peak pitch) and 0A when the button is released. If I'd hit the Q, the voltmeter would dip a tiny bit, but the ammeter would swing from charge into discharge. (Meanwhile, my lips would swing from straight&level to ear-to-ear-grin-like-I-just-stole-something...) Sadly they've come up with an electronic Q that just isn't the same - it sounds similar, but doesn't project nearly as well as the classic.

 

Think of voltmeter as blood pressure and ammeter as blood flow.

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For a quick cheap option just pick a 12 volt connector, run a short wire up to the dash area and hook up a multimeter, that will show you your system voltage.

 

If your voltage looks good from where you hooked the meter you may want to start looking for a corrosion issue, the meter can help there too.

-- Is the positive battery post (not clamp) showing the charging voltage?

-- Is the negative post showing no voltage when measured against the frame or block?

 

Pick different spots to hook the meter hot and ground leads in the battery wiring and see if you can spot where the voltage goes wrong. A lot of folks have become very frustrated looking for a charging issue that turned out to be the frame end of the negative battery cable not making good contact.

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Back when I drove fire trucks, I remember one that had an ammeter and a voltmeter. If you've seen the classic "Q" (Federal Signal Q2B) siren, that gorgeous bulb of chrome sitting on the bumper, you've seen an object that draws 100A at 12V when the button is pressed (i.e. it's spinning up to peak pitch) and 0A when the button is released. If I'd hit the Q, the voltmeter would dip a tiny bit, but the ammeter would swing from charge into discharge. (Meanwhile, my lips would swing from straight&level to ear-to-ear-grin-like-I-just-stole-something...)

We had the same sirens and I would get the same grin - except when I moved my left foot to the floorboard switch for the siren and kicked it in the headlights would dim (at night - of course.)

 

Paul - my "V" is an '04. I know zilch about gen 1 displays but I do get to choose what is on my "favorite display". I go with oil temp, outside temp and volts. Time and mileage are always there. I have the up/down buttons on the end of the stalk, a center button on the stalk with a return arrow and an esc button. Using those buttons I can set or clear several dozen different display parameters. some only with the key off, others only with the key on. My Volvo owner's manual describes the steps. When a password is requested I enter the default 1234. Are you sure your gen 1 does not have similar capabilities?

 

Now for the dead batteries. Have you checked to see what might be drawing them down? You can get a "free" DVM at Harbor Freight (coupon) that will measure up to 10 amps DC and, of course the low DC voltage. With the engine and key off slip the DVM in-line in the amps position at the batteries. With the key off start looking for the current draw by pulling plugs in the fuse panel to identify the branch circuit to study closer. If you need more specifics you have my number and I can put on the "crew shirt" so this old wire jigglier is official :) . BTW - I once had a phantom battery drain issue that turned out to be one of the outside compartment lights left on. Like many of us I had defeated that low voltage sleeper shut down nuisance circuit that would have prevented that from happening :( .

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I have been through the "stalk" settings looking for more/better/different information quite a bit in the past. With the book open in my lap. Just never really found much. As I say, the display is really basic. However, with your encouragement, I'll go look again when I get the ol' beast fired up again,

 

In the mean time, I'll check the alternator output, then for parasitic draw, then for battery condition. When I purchased the truck there was a spare alternator of unknown status in it. I'm guessing the alternator has been repaired or replaced already. The batteries were about 3 years old. Add my nearly 2 years and I can see a case for bad 5 year old batteries. Never had any issue with parasitic draw since I've owned the truck.

 

I'll keep ya'll posted (Jeez....what a pun)

 

Paul

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Ok, time to put this foolishness to bed.

 

Big 5er & Hero Maker - You are correct, if you look in the far back corner in the third basement down, there is sho' nuff a digital voltmeter. Thank You

 

DW says no more Hi-Zoot 'lectric gadgets til we pay the steer tires off, so no to the ScanGage D (but it sounds pretty cool)

 

Got the beast running, checked the alternator myself (pat pat), seemed ok, alternator shop said the same thing, so off to the battery shop. We have a battery recycler and manufacturer here locally. Offered 4 new replacements for $150 each. I whined, moaned, rolled around on the ground, etc, etc, and convinced them to sell me the cosmetic seconds. New guts, outside of the case is not perfect, i.e. scratch marks or grinder marks from removing a name, that kink of stuff. Price is now $75 each. Bit over 1000 cca per battery. Seemed like a deal to me. Been buying batteries there for 15 years and have had as good of luck with them as anything else.

 

Now just gotta get 'em in the Toy Draggin.

 

Again, thanks to everyone for the advice.

 

Paul

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