How to read an am meter
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=3765
Printed Date: November-23-2024 at 2:19pm
Topic: How to read an am meter
Posted By: Tribal150
Subject: How to read an am meter
Date Posted: June-02-2006 at 11:42pm
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I think my boat is having charging issues, what should my ammeter be reading when I am at open throttle, to verify that the alternator is charging, or what test can I do to check that it is working.
Rob ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=796&sort=Year&pagenum=2&yrstart=1976&yrend=1976 - 1976 Ski Nautique |
Replies:
Posted By: surroundsound64
Date Posted: June-03-2006 at 12:13am
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You should get a positive reading. A negative reading would indicate your battery is doing all the work. ------------- 1981 Ski Nautique 2000 SAN Looking for a 2000-2006 SAN |
Posted By: 62 wood
Date Posted: June-03-2006 at 12:19am
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Rob,
If any questions about its condition,take it the alt. to a rebuilder....they should be able to test it under a load to see how many amps its actually putting out. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1117&sort=&pagenum=6" rel="nofollow - 64 American Skier 62 Classic.. 73 Ski Nautique |
Posted By: nuttyskier2002
Date Posted: June-03-2006 at 2:22am
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Reading the ammeter can be a bit tricky. What you have to remember is that the more amps your alternator is putting out the higher the ammeter will read in the positive direction. This means that if your battery is discharged, it will pull more current from the alternator making the ammeter read higher (in the + direction). Likewise, a fully charged battery will draw little from the alternator and the ammeter will not read much above the neutral position. Volt meters are best for telling a true indication of your overall charging system. They also require a much shorter charger circuit meaning less voltage loss between the alternator and the battery. Converting is very easy and in my opinion very worthwhile. ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: 77stang
Date Posted: June-03-2006 at 7:13am
| i made the switch from ammeter to a volt meter a few years ago. it was a very wothwhile change for me. i always felt like i was chasing my tail trying to figure out other circuit issues with the ammeter. |
Posted By: Kevin's '79
Date Posted: June-03-2006 at 8:58am
| I was thinking aobut putting a volt meter in my '79. If the conversion is easy, then could someone detail out the steps. |
Posted By: 79nautique
Date Posted: June-03-2006 at 6:58pm
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amp meters are a better indicator of the electrical systems status or state. When you first start the engine it will read on the plus side to indicate it is charging the bat. after it is charged it goes back to zero or slightly to the plus side, meaning the elctrical system is operating correctly. If it goes to the neg side then you are drawing from the battery and you have a problem with the alternator or regulartor.
Now when you turn on the lights it should jump to the plus side or you turn on the radio it is drawing from the battery and the alternator need to charge it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 77stang
Date Posted: June-04-2006 at 2:16pm
Its not so much steps as much as it is a difference in wire configuration. The following pic has the wiring for PCM engines and provides volt meter and ammeter options http://www.skiboathelp.com/tech/colorcode.html ------------- http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17 |
Kevin's '79 wrote:Posted By: Kevin's '79
Date Posted: June-05-2006 at 9:20am
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77stang,
Thanks for the link and the info. |
Posted By: David F
Date Posted: June-05-2006 at 3:56pm
Wow, I agree with 79!
Anyway, to me, the ammeter is the better of the two gauges just for the reasons 79 mentioned. To me, the voltmeter is only useful in telling me that my battery has 12 or more volts. The big problem with the ammeter is the heavy electrical current flowing from the alternator through the gauge and back to the battery thus requiring a heavy gauge wire and very good connections. The volt meter only requires a light gauge wire with minimal current. I view the volt meter as useless because when a real problem is evident by the gauge, you are SOL. ------------- |
Posted By: 79nautique
Date Posted: June-05-2006 at 4:04pm
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that's basicly my take on volt meters all it's going to tell you is that the alternator is producing X amount of voltage and does not indicate where it's going. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 77stang
Date Posted: June-05-2006 at 4:32pm
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Page 20 of the PCM service manual referenced on this website states a preference for the volt meter as follows:
1. By simply turning on the ignition key for a moment, it is possible to tell the charge condition of your battery. 2. By enabling the alternator output to shunt directly to the battery, rather than all the way to the instrument panel and back, there is virtually no current loss or line drop. In installations requiring an unusually long harness, such as houseboats, this is especially desirable. 3. Any overcharging tendency can be readily detected as an abnormally high voltage reading on the voltmeter, and corrections can be made before battery damage occurs. I dont know which is better. I guess its simply what your comfortable with  ------------- http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17 |
Posted By: 79nautique
Date Posted: June-05-2006 at 4:46pm
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There shouldn't be a line lose or drop unless the gauge is bad, and if you see a high current or neg current then you know the charging system isn't working correctly and all I have to do to tell the state of the battery is turn the key and engage the starter. The only advantage is with long lead applications. If it already has a volt meter keep it, if it has a amp meter keep, there more to it than changing gauges and to do it right you need replace the wiring harness. And you have to change the wiring routing on the engine as it is related to the solenoid and regulator, beside all of the under dash stuff. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: Jim_In_Houston
Date Posted: June-05-2006 at 9:18pm
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You say say "tomatoes" I say "tomahtoes". Both ammeters and volt meters are valuable. It seems to me that people with an understanding of the electrical system prefer an ammeter - others a volt meter - I guess because the volt meter indicates a level of "good" vs "bad"? My girlfriend prefers an idiot light and for her I do too.
I suggest you keep what ever comes in the boat and learn how to understand what it is indicating. BTW, for anyone who cares, I prefer an ammeter if I have to choose one over the other. I feel warm and fuzzy when I see my alternator throwing out all kinds of amps when needed. ("All kinds" is as accurate as my ammeter is capabile of indicating). It's easy to throw a volt meter on the battery at any time. It's a little difficult to "throw on" an ammeter. Is the subject of this thread drifting? Typically right after starting the engine the ammeter should read to the positive (+) side. After a few minutes and the battery recieves a charge, the needle should come down almost, I say "ALMOST" to zero. Sometimes you have to look really really close to see that the needle is not quite right straight up on zero. It should never point to the left negative (-) while running. If, right after starting, your ammeter is still on zero or slightly negative you have a problem - don't leave the dock without a paddle. Or, if you have a lot of riders take along a lot of paddles. They'll be impressed that you planned ahead and they'll think that you know what you are doing - even if your boat doesn't run. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JEFF KOSTIS
Date Posted: June-05-2006 at 9:33pm
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JIH we agree!!! It is a whole bunch easier to add a voltmeter than a ammeter. If I had the time, I would have both as the voltmeter will tell me whats going on with the regulator. Everything could be fine looking ammeter wise, but yiu could be at 12.8v instead of 13.8v. Had that happen with the old 302 in the 76. All was fine, but my cellphone plugged into the lighter kept beeping low batt, what the heck?? Sure enough, 12.9v all the time, yet it still charged to that point making everything appear normal.
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: Jim_In_Houston
Date Posted: June-05-2006 at 10:20pm
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Your boat has a lighter?
Man, they just put all kinds of frills on these new boats. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JEFF KOSTIS
Date Posted: June-05-2006 at 10:28pm
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LOL!!! Jim, you are a riot!! I guess new compared to ???? I would assume it was more intended for lighting up a butt as opposed to a phone or electronic device. Today, its just obviously the opposite. CC didnt mess around back then!! Wonder what the new boats have for a 30yr future electrical connector???
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: Jim_In_Houston
Date Posted: June-05-2006 at 10:35pm
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As a follow up, and on a slightly differnet note, I notice that 79, above, has 1197 posts and still has only 3 stars. What does it take to get 4 stars? And, what is the classification above "Senior Member"?
"Should be dead and buried member"? "Senile Member"? "Old as ShxT member"? (Notice I circumvented the *) In case your wondering, I just popped the cork on a new bottle fo cold white wine and it got me to thinking.... being primariy a red wine drinker I may have to reconsider my whole life. What I do know is right now, it is just too dark to untie the '68. But, I think I may just go sit in the boat, fire it up, and listen to the 40 year old 289 rumble while I consider the ups and downs of piston travel - at least until the wine runs out... nighty nite all. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JEFF KOSTIS
Date Posted: June-05-2006 at 10:47pm
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Jim, Jim, Jim....Always keepin us thinkin!!! You know theres a problem (too old and too many posts) when you prefer to be on ccfan than to spend it with the wife!!!
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |