Amp Gauge / Volt Gauge

[rangerscott275]

Hello,

I have been working on trying to get all systems operational on my boat...one dilemma was that many gauges either weren't hooked up or weren't working correctly. Instead of hooking back up my Amp Gauges, i installed 2 new volt gauges...b/c my system is 32V, I figured I could more easily understand problems with a Volt gauge (close to or away from 32).

what does an AMp gauge tell me.....should I hook these up as well? For someone who is impaired when it comes to understanding electricity, what else will my volt gauges tell me beside voltage system is currrenlty putting out. Thanks@!

 

[(Nobody You Know)]

In my simplest explaination, consider volts just like water pressure, and consider amps just like the water flow volumn. Therefore, the 4 ga. (?) wire to the starter on my Ford Explorer is adequate. However my '49 ford pick up with a 6 volt system requires a much larger "O" guage battery wire - less voltage but more amperage to do the same job.

While (Nobody You Know) doesen't have one (ok I have a portable clip on type) they can say tell you if say your starter motor is getting proper amperage should you have problems cranking an engine. Not sure how they are applied as a dash instrument.

No doubt others know more about this than I, hope someone else will jump in - before they rush off to the boat.

Capt'n Bill

 

[Wild Bill]

As an old Navy Chief once told me, if you mess with electricity and don't know what you're doing, you could make an ASH of yourself.

AMP meters read amperage or current flow. Voltmeters read voltage or pressure. An AMP meter is connected differrently than a Volt meter. Make sure that you don't use the same connections for your volt meter that you had for the AMP meter.

 

[rangerscott275]

I didn't! but I still don't undestand what that amp gauge would tell me if I hooked it up....what is good or bad reading? what trouble is it warning me of?

 

[yachtsmanbill]

First of all an ammeter is wired in series through a shunt--that carries the load while the meter just reads it.( parallel to the shunt ) Without the shunt you would burn up the meter. A voltmeter is in parallel and just reads the voltage. I sh12'd the ammeters on the ROAMER and replaced with a good voltmeter. If youve got volts the amps are there too. I.E. if your alternators are only giving 10volts due to a bad diode the amps dont matter do they? Amps ( only ) are an indication of load on the system. Look at your A.C. panel and it may make sense. Look at the volts and then turn on the water heater. Volts will momentarily drop and amps skyrocket.Volts will pick back up and amps will settle down to the wattage rating. Amps X volts = watts.
A lot of cranking will load the system. Maybe 50 amps to re-charge and then taper off as batts charge. A lot of these numbers depends on the system --12V vs 32V. If you are charging 12volts amps dont really matter.
15 volts will tell you you are over charging. An ammeter will however tell you if there is a drain on the system. I guess its more of a diagnostic tool.
Dont feel bad. I understand OHMs and continuity but dont comprehend resistance ( in ohms ) sometimes more is better ( sic ).I must be electrically dyslexic. ws

 

[chris piazza]

I would think a surge in amps or a high amp reading could indicate a 32v motor going bad. Good way to detect if you have a problem around the corner.

 

[yachtsmanbill]

Thats true too. Maybe a HARPOON string stuck in the macerator. To me meters are like apples and oranges. ws

 

[yachtsmanbill]

Whats wierd is that old Chryslers used to use ammeters scaled in VOLTS so John Q Public read "volts" and was satisfied that he was good to go. The needle never moved much tho-- 9 or 10 volts was actually showing a discharge. Hmm ws

 

[Will]

As previously stated, Voltmeters and Ammeters provide different information. Both can be helpful.

Voltmeters as you would guess, provide you with the available voltage (water pressure). Essentially, if you have a 12 V system and your voltmeter reads 12 Volts, you are probably not charging your batteries. (In order to charge batteries, you must supply voltage higher than that which the batteries have without being charged). 13.5 – 14 volts would indicate that your batteries are being charged. If you have less than 12 volts, your batteries are not being charged and in fact, are probably quite low. Most automotive type voltmeters have colors to assist you in determining the state of your system. The key thing to remember is that you are unlikely to get a low voltage reading until your batteries are very low. On the other hand, if you get a high reading like 16 Volts on a 12 volt system, something is wrong with your charging system and your batteries are boiling over. Voltmeters are easy to wire into a system because the wires only need to be large enough to supply electricity to the meter itself. The Boat’s electrical load does not pass through the voltmeter.

Ammeters display information related to current (water) flow. Automotive type ammeters show the amount of electricity flowing to or from the batteries as a rate of charge and discharge. Other ammeters show the electrical load only, regardless of alternator output. In either case all of the electrical load must flow by the ammeter. With the latter, if you had a 50 amp alternator and your ammeter showed 60 amps, you batteries are being discharged. On the other hand if your ammeter showed 30 amps and you had a 50 amp alternator your batteries would be charging as long as the alternator was working properly. But how would you know without a voltmeter or another ammeter just for alternator output. Because of heavy electrical loads and the size of cable required, it is often difficult to install low voltage ammeters on larger sized boats. Therefore many larger boats have voltmeters for their low voltage systems rather than ammeters.

I hope this helps to clear things up a bit for you. I sure got confused writing it.

Will

 

[spartonboat1]

FWIW, I was looking at a used Jaguar, around 1996-7 vintage XJ6...beautiful car. I noticed the voltmeter didn't move at all, after it jumped to straight vertical, after starting the car; dropped back to zero when car turned off. When I asked the salesman, he said that because Jaguar (the engineers at the factory) had had so much trouble with them, that they just wired the meters as an on/off indicator and that the voltage no longer registered. But they still retained the voltmeter gauge face. Go figure...