Can I test the amps from my alternator like this?

[Soundguy]

good diagram.

and if one segment of the full wave rectification is out, you can imagine thaqt same diagram with every other positive wave form missing, making the ripple huge.. or average charge voltage less.

depending on the way the regulator works ( much different if perm magnet dynamo ) vs a variable field alternator.. etc.. could even be seeing a dead regulator with a shorted rectifier, and some negative wave form on the battery.. since current output of charge circuit is low compaired to battery, you don't see the negative wave.. just a drop in the positive voltage of the bat.

soundguy

 

[rsmith02184]

you guys lost me at "hello". way beyond my understanding or capabilities.

i just know i have invested over $400 in VR and I would like to solve this myself. It hasn't rained in my parts in months so I haven't had to use my tractor much.

the thing that confuses me is that the VR tests that it is putting out 14.5 VDC. the tech manual says that if it goes over 14.8 then, the VR is shot. The 14.8VDC are going into the first fusible link, then they go somewhere that I can't trace but it seems like they are going back to the starter switch and/or the starter solenoid and then they go to the battery. By the time they get to the battery, they are around 13.5 or so.

what do you think about those numbers?

 

[Soundguy]

I'm not sure I'd go along with this. It could be done with a hefty Zener, but then you'd need some resistance to absorb the extra wattage. Then you get into current limitations of the system and a lot of heat to dissipate. A linear regulator would also work. The few that I've been into use an SCR or Triac with a pulse width system, no full wave bridge needed.

eh.. there are umpteen dozen ways to regulate that power... series pass.. etc... I for one would use a shunt regulator as a LAST resort.....too many possibilities to guess. and since we don't have the schematic.. guessing is pointless.

also.. since we are all online.. the key diagnostic step, IE, observation is denied us, since we can't reach thru the monitor with a clamp on ammeter, a good lab grade dvom, and an o-scope probe...

soundguy

 

[jinman]

the thing that confuses me is that the VR tests that it is putting out 14.5 VDC. . .

. . . By the time they get to the battery, they are around 13.5 or so.

what do you think about those numbers?

I've said this before, but I think that a 1 volt drop between the VR and the battery indicates a heavy load is being drawn. The fact that your VR and output wire are hot would seem to also indicate that is true. The additional fact that your tractor dies when the + battery terminal is removed and that you measured a high ripple AC on the output of the VR says something is also very strange. The problem with doing anymore disconnecting is that your tractor won't run if you disconnect power to the operator safety circuits or fuel solenoid. We've come to the point where we need a diagram to know where/what to check.

EDIT: If you check the current on the output of the VR and found it to be 25 amps, what would you do? We can't go into the regulator. It's a "magic box" as far as we are concerned. Unfortunately, it's a magic box that is burning up. We can disconnect the input (alternator) or the output (red wire). That's about all we can do with an encapsulated regulator inside a metal heatsink case. We're very limited. It's frustrating.

 

[rsmith02184]

ok...i hear you loud and clear: you need a schematic.

question: do you want a schematic of the charging circuit or all the electrical systems? making a copy of the charging circuit will be easy,,,the other is harder to do because it is bigger.

thanks again for all your help

 

[Soundguy]

to the OP.. do you have a clamp on ammeter? if so, test alt.dyn input to the vreg and output to the bat.

soundguy

 

[jinman]

question: do you want a schematic of the charging circuit or all the electrical systems?

Smitty, let's start with the charging circuit. If it's not enough, we'll go to the rest as needed.

Soundguy: I would like to know what the currents are in the circuit, but cheap clamp-on meters don't read DC current, only AC. So he could read the output of the Alternator and check the output of the VR for AC current as well since he has both DC and AC superimposed. However, knowing what the AC current is coming out of the alternator would tell us a lot because the VR can't put it out as DC if the alternator doesn't make it as AC. What do you think? I think an old Ford ammeter with a built-in shunt would be ideal to use on the output side of the VR to measure current.

 

[Soundguy]

cheap clamp-on meters don't read DC current, only AC. .

I guess it depends on your definition of cheap.

There are always the SNAP-ON P/N MT1009 sets that go for about 40$.. they are inductive low and hig amp dc inductive meters.. not clamp on.. but slip on..

for clamp ons, sears has the 82369 clamp on... is about 60$ give or take.. there are compies of it out there to for less $

http://www.sears.com/shc/s/p_10153_...3d&srccode=cii_13736960&cpncode=21-77174516-2

I kinda consider any meter sub 100$ to be consumer grade.. and from there to a few hundred industrial, and from there up lab grade.

I try to not mess with anything under about 30$.. and NO autorangers.. they are practically useless for anything with brushes or points..

In regular practice I use an industrial meter with graphing and freq count capabilities.. temp probe, transistor gain and cap check.. good basic meter.

soundguy

 

[Transit]

I've made a simple diagram of an alternator charging system that may help to see what is going on. The last time I tied to upload the file it would not go. The diagram was created in Visio and printed as a PDF file using PDF995. The file should upload; I do it all the time at work for those who do not have access to Visio to open the file.
Here goes again.

The PDF file is uploaded, but when you try to open it, a window opens to my desk top. I'll have to remove the PDF file till this is cleared up.

Another try with an older pdf file.

Nope! same results.

OK, it works!! Open the file as a Word Doc.

 

[jinman]

I guess it depends on your definition of cheap.

There are always the SNAP-ON P/N MT1009 sets that go for about 40$.. they are inductive low and hig amp dc inductive meters.. not clamp on.. but slip on..

for clamp ons, sears has the 82369 clamp on... is about 60$ give or take.. there are compies of it out there to for less $

http://www.sears.com/shc/s/p_10153_...3d&srccode=cii_13736960&cpncode=21-77174516-2

Well, I first thought that was the case, but I looked at my meter and it only does AC current. When I did a google search, I only found $400 Flukes with both AC and DC current. I'm glad you debunked my theory. I'll have to change my statement to "a lot of cheap meters only read AC." Thanks for the correction and link Soundguy.