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Re: Re: Ammeter Reading!
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Posted by Mike on January 20, 1999 at 12:42:06:
In Reply to: Re: Ammeter Reading! posted by John T on January 19, 1999 at 18:18:49:
If I understand what you indicated, you have the ammeter between the alternator/generator and battery. Ok so far, but which side of the ammeter are the accessories hooked to? If they are hooked to the battery side of the ammeter, then you're not making full use of the ammeter, you're only measuring the total output of the alternator/generator to the battery/accessories (you'll never get a minus reading on the ammeter unless the alternator/generator fries and shorts out)!
Example: let's say your alternator/generator is on the left and your battery and accessories are on the right of the ammeter. Let's also say that everything is normal and running OK. The lights are drawing 20 amps and the alternator is putting out full capacity (60 amps?), that means the other 40 amps are going into charging the battery. The problem is that the ammeter is showing the full output of 60 amps because it's all going in the same direction (as far as the ammeter is concerned). If the accessories are hooked to the alternator/generator side of the ammeter, the ammeter should read in the minus or discharge portion with the engine off and accessories on (power going out of the battery to the load and not being replaced). With the engine running and the battery fully charged, the ammeter should show very near neutral (not charging too much, and "not discharging too much at idle" - should not show as discharging at all when the engine is running above idle. If it does, your accessories are pulling too much power and you need to run fewer lights or get a bigger alternator/generator).
Example: The alternator/generator is on the left again and the battery is on the right again (like before, the ammeter is between them) BUT this time the accessories are hooked to the ammeter on the left side of the ammeter (the same side as the alternator/generator). This way when everything is working properly you'll get a real reading of what's going into or out of the battery. Lets figure that the alternator is again putting out the max (60 amps?) and your lights are drawing 20 amps. Your ammeter will show what's left as going into the battery (40 amps charge). If the alternator takes a dump and is only putting out 10 amps because of loose belts or some other problem, your ammeter will show a discharge of 10 amps (your lights are still pulling 20 amps, the alternator is making 10 amps and the rest are coming out of the battery! Yeah, you're right, you're going to have a dead battery with the tractor out in the middle of the planted field before morning and you have to carry a replacement to the tractor!). NOTE! The STARTER should never get it's power through the ammeter as it can draw several hundred amps while cranking a cold engine (unless you've got one like mine, I'm something of a "Techno-Slut" so I built my own digital amp meter that reads up to 1999 amps charge/discharge with a 100%duty cycle, and displays in one amp increments) Hope this helps, and sorry for gettin' windy!
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