Amp meter wiring

[riotwarrior]

I've searched and all I can see is an Amp meter wired with the Alternator in system and when I start winching and running more than 60 amp draw with a winch I'll be damned if I'm going to smoke my wiring by having the alternator in this setup.

Does anyone know of a way around wring an amp meter in your rig with an alternator and not having it run through the amp meter, maybe some kind of shunt?

If not...then I'm SOL and off to find a Volt meter.

[wfo]

you just don't run the load through the amp meter, run you load straight to the battery.
it will still charge but won't read through the meter. only run small loads through the meter that way you know its charging or discharging

[Tomo]

hi
Leave the factory amp meter installed . Winch should be wired straight to the battery posts . That makes both these circuits independent .

tomo

[rodp]

The amp meter should only show the current the alternator is supplying, regardless of the current the battery is discharging. So long as the amp meter is rated to a higher amperage than the alternator puts out you'll be fine.
As you can see from the diagram (?) below the winch current doesn't pass through the meter. (I use the term diagram loosely)

Alt + .....meter......... bat+ ................. winch

[riotwarrior]

NO Factory Amp meter in this machine it's an install by me and is 60 amp with 90 amp alternator going in! Hence my concern.

Guess need 100 amp alternator now DOH!

[rodp]

The ammeter needs to read more than the alternator puts out, IE. 100 amp alternator and 120amp ammeter. Although it's highly unlikely the battery would accept that sort of charge you don't want a meltdown.

[Tomo]

HI
Remember at high charging amps ""voltage drop"" will occur using an amp guage =will not charge battery well . Amp meter are wired in line /series
Typically that is why a volt meter is used , If the voltage is under 13.5 volts minimum the battery is not charging
With a 100 plus amp alternator running out of amps will not be an issue .

The ideal is to only loose under heavy current .10 volt measured between alternator output and then measure at battery posts . If u r increase the wire size 3/8 to 1/2 OD should be ok

tomo

[Rudy_Magnum]

Available current has nothing to do with how a battery charges, well, in the majority of cases (small vehicles like our machines are included in this). You want a constant voltage between 13.8 and 14.4 to charge a "12 volt" lead acid battery. You can have 120 amps available, but the battery will only accept so much charge at the voltage put in. As the battery "fills" with charge, the charging current will go down as the exchange of electrons slows down. It's a common misconception that available current dictates how much current will flow. It's the load that dictates current draw from the source, and you always want a source (and conductors) big enough to handle the load(s) you will be putting on it.

To give an example: You have an 800 watt amplifier for your car stereo. You have 2 speakers rated at 100 watts each. You can draw, under normal circumstances, 200 watts with both of them running. Not more. I won't get into "why" or "how it works", nobody wants to read that book right now.

Now, say you have a 200 watt amp, and 2 speakers at 400 watts each. If you crank it up, your amp will trip, blow a fuse (if fused correctly), or blow up, as it will try to put out the 800 watts demanded by the load, until it can't.

Current is dictated by voltage divided by resistance. Voltage should be a relative constant in the equation, so should resistance. As a by product, so is current. It's all math, and it's all pretty easy.

Batteries have current ratings. Alternators have current ratings. Even winch motors have current ratings. Unless you work with the stuff every day and can design in your head, draw out a schematic, figure out your size of loads and sources, wire for max current plus a bit of "safety" factor, and you'll be happy with a system that works the way it was designed to.

For instrumentation, get stuff that is rated for what you're putting through it. This is where your schematic comes in handy. If you're putting in an ammeter to monitor your loads, but not including the winch, put it on the line from the battery to the main post on the key switch. If you want to watch what your alternator is putting out, put it in the + wire from the alternator.

Ammeters do not give a very accurate picture of charging status. Voltage is a better indicator of problems. If your battery is bad, it won't hold a charge, and voltage will drop. If your alternator isn't putting out power, voltage will drop. Current flows until the source or load goes away, so, you could be out on the trail, watching your ammeter, and think everything is fine running at 2 amps. If you notice the current climbing, either your voltage is dropping, or your load is developing problems. An ammeter on the alternator output will only tell you that the alternator has stopped working, or that there is no load on it.

That said, monitoring both current and voltage is the best way to know exactly what's going on. But I'd rather see voltage than current, if I had a choice between one or the other. My machine will have both meters, and my alternator has an output for a "charge" indicator. Handy.

[chris davison]

I could not have said it better. charging a battery is like filling an air tank. one holds electrons under pressure 12vdc and the tank holds air say under 100psi. Electromotive force is volts it is just electrical pressure that pushes electrons thru the wire the same as psi pushes air thru hoses. Currant or amps is just like gallons per minute. Its just a measurement of flow. Now that being said you could not put 100 gallons of water at 500 psi thru your garden hose. its not large enough to handle the flow rate and its walls are not strong enough to handle the pressure. Its the same thing you can't put 100 amps at 1000 volts thru a 16 gauge wire like thhn stranded. Its only good for about 11 amps at 600 volts ac. So I think I can give you some ballpark amp ratings for some wire sizes. I don't think I would go below 14 gauge for anything in your vehices just for physical strength. 12 gauge stranded gives you about 23 amps, 10 gauge will do about 35 amps and 8 gauge will do about 55 amps. now you can understand why starter cables are so big a 2 hp 12v starter can draw 125 amps from a battery that can deliver 450 cold start amps. But it all depends on the load a worn out v8 with 400,000 miles on it may only take 3/4 hp to turn over and a racing motor with 11 to 1 compression all 2 hp.

[chris davison]

p.s. if you don't have an oil pressure gauge and your oil pressure goes in the toilet volts and amps don't mean a thing

[Tomo]

HI
So people are not confused
CCA or cold cranking amps is NOT THE SAME as normal amp/current draw .
CCA was invented by the battery industry

Normal current draw for a eg briggs 23hp vanguard twin starter mtr approx. 250 amps
most automotive starters 250-350 amps

tomo