I JUST PUT A NEW ALTERNATOR ON MY BACKHOE....(NOT A MECHANIC BY FAR ) BUT AFTER REPLACING IT IT STILL ONLY SHOWES 12.46 VOLTS AT THE BATTERY....REMOVED IT AND HAD IT CHECKED...............PUT OUT 14.5 VOLTS.....BUT ONCE HOOKED UP ONLY SHOWING 12.4....WHEN RPM IS UP IY RISES TO 12.7....THIS CANT BE RIGHT....WHAT AM I DOING WRONG??????????WIRING??????????HELP ME PLEASE :usa
Welcome to the forum rntvin. :usa Just so ya know, the moderators frown on using all caps on a post. As for your alternator, you probably have a simple wiring problem, but it's hard for us to say without knowing what alternator you have on the machine. Can you post a pic of the alternator on the machine?
Does it have the same size pulley as the original alternator ?
The pulley is the same....and the alternator was rebuilt so its the same alternator:usa
is the bat. fully charged and tested when you are checking alt.? check amp output at alt. bat. ter.
Battery is brand new, took it off and had it tested, it's ok.
Bad earth??
If batt, is fully charged - I would dis connect one batt. cable and check for draw with amp meter - both key on and OFF- I would than disconnect heavy wire from alt, ( batt) and check output with amp meter
Thats assuming you have checked connections for good contact - also when you changed batt, make sure that the little wires ( if any ) did not get broken at clamp
In rereading your post you have checked for output I would have to agree with ATCOE
I have noticed alot of the new trucks will only put out 12.7 - 12.9 volts when the batteries are at 98 - 100% charged and will increase when the batteries are low. A rebuilder told me that alot of the replacement regulators have been upgraded to this as well. I don't know if this applies to your cat but I have seen it on the Freightliners.
all connections seem to be good.......before the alternator was rebuilt i had a friend over and were testing things and removed the battery cable a few different times.....but i have noted that the one time i removed the bat cable the machine died............if anything can go wrong it will with me.....i am pulling out what hair i have left.......:beatsme :usa
but i have seen it on a test machine putting out 14.5 volts................ what can it be???does anyone have a wiring diagram of this machine ?????????????remember i didnt have the tach or excite wire attached when i bought it
Pulling cable off with engine running not best practice
Yes sir...I do know that......a friend working on it pulled it right before i shut it down..................and the person who runs my water and sewer traetment plants was pulling it off alot before i had it rebuilt.....so those are the times it was pulles off Can anyone help me out with a wiring diagram............yall dont know how happy i would be :usa
Why ? is there elec, draw that should not be there? This is why I suggested amp meter test - if you do not have one shut EVERYTHING off and see if you get a spark removing bat. cable from bat
I'm not familiar with that alternator, not much I can say for it. But, I'm assuming that big cable going to the large terminal is battery positive cable. I say that because you did say the voltage goes up ever so slightly when you rev engine. If that cable is hot, then I would guess the alternator isn't being excited by a switched wire, but I have no idea what the terminals are on that unit. I'm wondering why two small wires are going to one terminal on the back of the unit? Don't see that very often. And what's up with that ground connection at the bolt on the engine block? Looks like a wire that's stripped and wrapped around a bolt!
:yup:yup:yup
Atcoe after you mention the ground I magnified pic. and both of the lg connections look corroded , but that could be me magnifying it . Would i be right in a assuming this is a Perkins motor (4.236 ? with turbo ) if it is , and a Perkins supplied alt. I can check the welders tomorrow to see how the alt is wired on them.
Not certain myself. If it's a 416B it's a Perkins, not sure about the other models, but I'm thinking Perkins as well. He said it would put out max regulated voltage on the test stand, but ain't on the machine. That's what's making me think it's not being excited. If nothing else, he can take the alternator back to the service guy and say "help me out please...which wire's should connect to which terminal?"
I will look tomorrow - they may not have same alt. any way -- I agree about alt not being excited- but also wonder why they kept disconnecting bat.
Beats me bro! I'm ALWAYS a little uneasy disconnecting batteries with a load on them, as in with engine running. I don't like making sparks around batteries. It doesn't happen often, but a spark "can" explode a battery by igniting the gases present around batteries. I read your post about checking a load on the battery when everything is (supposedly) off. To check for phantom current draw on a battery, you can disconnect the negative cable, then connect a 12v test light in-line of the neg cable and neg battery terminal. If there is any current draw, you will see the lamp in the test light glow. If your working on a 12v system, this works best with a 6v bulb in the tester, on a 24v system use a 12v bulb.
Hi ATCO: thank you that is a neat trick I will have to try it out. rntvin: when you turn on the ign switch do you have 12v at the center lug (the yellow and gray wire) this should be the exciter signal. If not you can check it while running and with the engine off you can remove these wires and check voltage with key on. if only one wire has power try it with just the one wire. you can also run 12V from bat to there with the other two off or even better with a power probe and see what your voltage is. I don't know alot about CAT but Duetz has a charge light and when the bulb burns out it will not excite the alt the bulb completes the circuit.
Maybe the accuracy of the volt meter being used for the checking is faulty. Try another voltmeter.
It's wired up wrong my friend. The terminal with the yellow and grey wire should only have the grey wire attached. That's the exiter terminal and the grey wire provides +ve feed from the ignition switch (via a resistor and diode). The black earth wire should be on the stud below it, for alternator case ground. The yellow wire then goes on the terminal vacated by the black wire. This is your tachometer feed. The orange wire is OK. Hope this helps.
Good thing cmark told you how mine are a different Alt
Don’t know if this will help but 416b prior to 1993 had Perkins engines. 1993 to 1996 had Caterpillar engines. Alternator has to be excited for it to operate properly. On most alternators this only has to be done once when removed or replaced.