Ammeter is pegged

[Seattle Scott]

on the charge side at 200 amps. Analog meter (with needle) just goes to the plus side needle stop when engine started, with no electrical load and charged battaries. Adding and removing load has no effect. Getting 13-14 volts at batt terminal. The voltage regulator ("Next Step")indicates everything is fine, meaing the "error indicator" lamp is not lit. Just wondering how do I check for the amps flowing past the pegged meter. Pulled out my Calder book but couldn't figure it out. Need to determine whether I am getting a false reading from the meter and then work from there.Everything was fine, always getting 3 to 20 amp reading on the meter with little bump ups when loads are added then yesterday started engine and meter pegged.

 

[Jeff M21319]

Hard to troubleshoot from a distance, but....

my first guess would be that the ammeter has gone bad. If you have access to a high current D.C. amprobe, you could use that to determine the actual amp flow, but those types of meters are relatively expensive and therefore not too common. Because you're showing no fault indication on the regulator and have nominal voltage at the batteries (to get 200 amps to flow through a charged battery, you'd need a lot more than 14 volts, unless it was a REALLY big battery bank!) I'd bet it was the meter that has gone bad. Try feeling the alternator output wire with your hand while the engine is running. Is it hot to the touch? If it's outputting 200 amps it will probably be quite warm. If it turns out that the meter isn't fried, it may be time to call an electrician out to have a look at it!Jeff

 

[NewportVic]

Somewhere there is a fuse ... and that fuse is not

letting 200 amps through anything. And for sure it is going to be hard to get 200 amps out of a normal 75 amp alternator.Vic "Seven"

 

[MArk7608]

Bad meter shunt?

Hey Scott,Most ammeter movements have very low current ratings. The reason they can measure higher currents is because a large percentage of the current is shunted around the movement by resistors. In your case, the resistor is probably a pretty hefty copper or brass looking bar. If connection to that bar is corroded or broken, the meter will peg.(see link below)Happy sails _/),MArk

 

[Patrick]

Is there anything smoking?

200 amps will cause something to get real hot real quick.Probably, you have a bad connection between the meter and the shunt.You can check it by measuring the voltage across the terminals of the shunt with a good digital volt meter.The shunt should have a rating stamped on it. It will say something like 50mv which means that it will measure 50 millivolts ( 0.05 volts ) when the current through it is 200 amps (assuming a 200 amp shunt). It will read a proportional value for other current values - ie 25 mv for 100 amps. The meter terminals will read the same voltage if the connections are ok.

 

[Seattle Scott]

Thanks guys. I priced a replacement

at $75 -$100 so I will investigate rahter than just start with a swap out. Assuming I am correct that I have a 200 amp alt (Balmar). Isn't the amps out dedendnat on the RPMs as of the alt? Its not going to put out 200 amp when the engine is idling is it?I will dig out my multimeter and instructions and pop the ammeter and look for the shunt. Nothing is smoking, otherwise I would just get out the checkbook.

 

[Derek Rowell]

Alterrnator current...

Assuming your regulator is working, the alternator current is more dependent on the state of the battery than the engine rpm. In other words if the batteries are ok and charged you would expect very little current - certainly not 200 amps. It's the job of the regulator to limit the current.

 

[Stu Jackson]

Alternator Operation with Full Batteries

ScottIt may be helpful to read the link, and other search-able info on the C34 message board.With a full bank, the alternator will NOT put out much of anything, because the batteries don't need it. Even a quality shorepower charger won't, because the batteries don't need a charge.Calder does cover this in the first section of the book, look for battery acceptance, and under charging methods, i.e., charging systems including alternators and shorepower chargers. Enjoy the reference,Stu

 

[Seattle Scott]

Well it was gravity

that caused the meter needle to "peg" or actually "flop" to max amps. Pulled the meter out left connected and started engine. As I turned the meter in my hand the needle flopped between 100 and 200 amps and did the same with the engine off.I made a stab with diagnosis with the multi meter, all I could determine with certainty was that there was power to the terminals of the meter. Tried to hunt down the shunt, but it was not in the area of the panel, and when I found a likley suspect om the cockpit locker bulkhead it wasn't marked with any rating.Anyway the meter was stamped "Transportation Safety Devices, Inc. Indianapolis, Ind." got a phone number from the web and gave them a call. Turns out my meter was made in 1995 and after talking to the tech guy and assuring him I was not making a warranty claim they asked if I wanted a replacement with a chrome or black bezel and with a lamp or not. $100 minimum charge so I ordered the shunt to come up to $100. Nice to know some businesses stay around making the same things they always have. As an aside, I has determined that I don't know what my alternator rating is. There are no markings on the front and I can't see the back even with a mirror. Yanmar says standard alternator on my enine is 55 amps. I have white housing with blue fan blade. I can't get to the back of it to stick some probes on even if I knew where to stick them. I just assumed with a 200 amp meter scale I had a 200 amp alternator. So if I run the battaries down to 12 to 12.5 volts and turn on reffer and everything else will the output shown on the ammeter give me a ballpark for the alterntor output capacity?

 

[Rick D]

Scott, You Have A Non-Stock Alternator

What you are describing is a Balmar. If it is on a Yanmar, and if it has a single belt, it's somewhere between a 75 and 105 amp. Do you have a three-step external regulator? Rick D.

 

[Seattle Scott]

Rick, single belt

and external regulator made by Ample Power called a "Next Step". I guess its a 3 step. I really should read the owners manual. Can I measure amps at the regulator which is easy to access?

 

[Ed Allen]

Ok scott, ive been listening,

any electrician has a amp probe, this device clams arround the wire and will tell you now many amps is being drawn. find the electrical maintance man, rent one from an electrical shop, but scrounge one up for a nights look. wont take 15 miniutes. If your system has say 2 100 amp batteries and you start the engine with them, and run it for say 2 hours, the batteries would be cooked. I mean boiling and smelling and too hot to touch. and probably way sooner than that. Try this start it up, and immediatly check the voltage with a meeter, wait about ten min, and check the volage again, then again in ten more. it the voltage regulator is working then the voltage should drop down a bit say from 14+ to 13.5 or 13.2, that will tell you the regulator is working and regulating the volatage the engine is producing, I agree with others if the shunt or the meeter is probably bad or your batteries would be toast. 200 amps is a BUNCH. you may have a balmar but most of them will not do 200 amps.take a picture of it and put it on the net maybe someone can give you some hints on what it is or contact the previous owner.good luck

 

[Gord May]

Alternator

The typical clamp-on ammeter (‘Amprobe’ http://www.amprobe.com ) will only measure AC - not the DC alternator output. For DC measurements you need a (much more expensive) “Hall Effect” DC Ammeter.It sounds like you have a Balmar Alternator

 

[Stu Jackson]

Ample Power Primer

Gord's right. Given your questions, you should also download, print out and read the Ample Power Primer.It is a great discussion of how batteries should be charged.Everyone who hasn't already, should read it.It'd save a lot of unneccessary questions about charging.Stu

 

[Seattle Scott]

OK guys, I'll go do my homework.

and for now I will swap out the ammeter with an exact replacement, so I dont have to figure out what is the max amps the alternator is putting out or whether a different meter will work, such as digital. A general question, though, what is everybody else running in terms of alternator output and ammeter scale/capacity? If you have a 55 amp alternator do you install a 100 amp ammeter or a 75 amp ammeter? Sort of looks like from the suppliers that there are various meters from 100 amps and lower, but once you go over 100 amps, the next meter is a 200 ammeter.

 

[patrick]

I would go 200 amps and

get a digital readout so you can check up on various loads with more precision. Besides that the digits will not fall out. If your budget will allow, think about an amp-hour meter which will monitor a few other important values.

 

[George S]

Simple DC Ammeter add on

Here's a DC Ammeter from JC Whitney Automotive that you don't have to connect in circuit. You just hold it against the wire you want to measure the current in. It senses the magnetic field and tells you the current. Zero center, so it tells you current in either direction. Best of all it's only $10 plus s/h. Dual ranges 100/400 amps (I think). I got one for my Yanmar 2GMF and used some nylon wire ties to hold it against the big heavy red cable from the battery switch. It reads the starter current and the alternator charge current. before I installed it, I verified it's calibration in the lab, and it's amazingly accurate. Pretty cool meter to have. Part Number is ZX179446X. or goto:http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/storeId-10101/p-469/c-10101/catalogId-10101

 

[Seattle Scott]

Hey Gord, any comment on George's

$10 meter?

 

[Gord May]

Current Indicators

Current Indicators:George S. indicates that he “verified it's calibration in the lab, and it's amazingly accurate”. I don’t think he expected much.For $10 you’ll get an “indication” of charge or discharge, lots of current or not lots. It won’t provide a numerically significant amperage reading. Gord

 

[George S]

The meter IS accurate!

Hey Gord - I was skeptical about the accuracy when I ordered and received the meter - that's why I tested it in the calibration lab (with Fluke 5500A calibrator w/high current coil)at Brookhaven National Lab where I worked and it's accuracy came in at 2% of full scale (on both ranges)and regardless of it's inexpensive price that's more than accurate enough for any alternator or starter testing. It does provide a numerically significant amperage reading without using a Hall effect device. So, don't trash it without testing one for yourself.