Mounting Ammeter

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Bill Allred

I have a Hunter 23 with an electric start (charging)motor. I would like to mount an ammeter in my battery system to monitor charge and discharge. Would you connect it just across the positive and negative battery terminals? Thanks for your consideration. BILL/Orlando
 
Sep 25, 2008
7,688
Alden 50 Sarasota, Florida
CAREFUL

you cannot mount an ammeter in parallel unless it is specifically designed to be done so. The shunt should be wired in parallel and the meter connected to it.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Bill, an amp meter must be connected in line

with the load. If you connect directly across the battery you will instantly burn the meter out. You can connect a volt meter across the battery but the amp meter measures the current through a load. I urge you to but a 12 volt handbook and study before you continue. Your intentions are good but you need more knowledge.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Connect it in the ground circuit

The preferred place is in the between the system ground buss and the wire that goes to the batteries ground terminals. A second option is to cut the ground returns from the panel and engine and place it there. I'd not put it in the battery box as there are lots of nasty things floating around in the air and a shunt does not hold up too well in that kind of environment. The hard thing here is that there are so many different set ups it is hard to address all the variables with out knowing more info. A place to start is How many wires do you have running to your battery negative terminals? Don't include the ones that just connect all the terminals together just the returns. The should all be passing through the battery box wall. NEVER EVER EVER EVER EVER connect a shunt in parallel. While the big spark show is purdy it does not do the shunt much good. You can get the same light show with a wrench BTW. VOLT meters----> parallel connections ammeters----> series connections and volts=amps times resistance V=IR You should memorize this! That last on has a practical application here; with 12 volt batteries and a shunt that has 0.000001 ohms resistance you get V=IR ---> I=V/R --> 12/0.000001=12 million amps when you treat a shunt like a load!!!! Aren't you glad you asked?
 
Aug 30, 2006
118
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Voltmeter

or hydrometer if you're really particular, if you are wanting to monitor the state of charge of your battery, the fuel guage of your battery so to speak. I may be off on a tangent here, but i took your question differently than above. And connect it across the leads of the battery.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
DanW

He is talking about an ammeter. You can monitor the charge and discharge much more accurately with an ammeter than with a volt meter. Factory made charge meters are just a fancy ammeter that keeps track of the amps every second or so and computes amp seconds. FTR, 60 amp seconds = 1 amp minuet and 60 amp minutes = 1 amp hour. So it just sums up the AH consumed/produced and that is truly the state of charge.
 
Aug 30, 2006
118
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Someday

when i grow up, i'm going to have a boat in a slip, with a diesel, and lots of batteries. For now i just have to measure how much charge is left in the battery i charge at home for my trailer sailer.
 
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