Need electrical advice.

[Soundguy]

14.49v is charging. I wonder if the diode trio is breaking down and letting the battery discharge when sitting?

Has it been doing this regularly?

Soundguy

 

[Keoke]

Soundguy's quote: Besides, if the charge wire from the alt to the battery is of sufficient gauge size to not drop any voltage over it's length, then electrically, the battery positive will be the same potential as the alternator output stud anyway.
Soundguy, how do you do the blue font thing on quotes?

Soundguy, Never mind what the wire size, the voltage at battery is never as high as at alt output post. If it was, then the current would never move from alt to bat since the pressure (EMF) would be the same at both ends of circuit. Every fixed circuit has a voltage drop that is proportional to current flow flowing through it.
The max allowed voltage drop for alt to bat automotive charging circuits is .3volt for every 10 amps flowing in circuit, (e.g. 20amps=.6volt). These NOT a desireable numbers but are considered the max voltage drop to be allowed. Properly wired and gauged circuits should run at about half of the above numbers.
However, I agree that if one is looking to make it easy to install a 10si alt on a low electrical load vehicle then it is ok to simply tie regulator sensor input to the alt stud and save a bit of work and wire.
On Graybeards unit, if that alternator has a diode trio??, it could not be responsible for draining the battery since the trio would be wired to the ignition switch which is in the off (open) position and thus not tied to battery while tractor is not running.
Also, since his static battery voltage is 12.6 it doesn't look like he has a drain problem.
If I read Graybeard's post correctly, most likely not, his problem is:

1. That when he first turns on ignition he gets no chg lamp.
2. After he starts tractor lamps comes on, but alt seems to be charging at 14+ volts, however, lamp on says otherwise.
3. If he turns engine off and does a second start he then gets lamp on that goes off when tractor starts. A normal sequence.

I'm not sure I got the above striaght, if it is, then Graybeard needs to do TWO output voltage checks.

1. On first start, with no lamp on ignition, check alt output voltage with engine running and chg lamp now ON to see if you are still getting your 14+ volts. If not then the lamp is working correctly since the alt is not charging.
2. Do the same on the second start try. This is the check that you seemed to have already done.

Graybeard, how many wires do you have going to alt? Is there a brand name on alt?

Guys, this post went longer then expected, sorry:

cheers

 

[Soundguy]

</font><font color="blue" class="small">( how do you do the blue font thing on quotes )</font>

By using the quote function, and then copy/past the text into it.

</font><font color="blue" class="small">( Soundguy, Never mind what the wire size, the voltage at battery is never as high as at alt output post. If it was, then the current would never move from alt to bat since the pressure (EMF) would be the same at both ends of circuit. Every fixed circuit has a voltage drop that is proportional to current flow flowing through it.
)</font>

Voltage drop across the battery is the full voltage of the alternator. The voltage potential on the copper wire running from the alternator output stud to the battery is going to be virtually the same. The 'common' 4.99 to 9.99 vom that the auto store sells is about 1v accurate.. no way is a shade tree mechanic going to be looking for 1-3 tenths of a volt drop on that wire.. Like I said.. it's a technicality / practical issue. And current does flow due to the difference between the batteries static voltage compaired tot he alt's output.. 12.x to 14.x . As soon as the al is disconnected, the battery quickly drops to alower than charge voltage.

</font><font color="blue" class="small">( On Graybeards unit, if that alternator has a diode trio??, it could not be responsible for draining the battery since the trio would be wired to the ignition switch which is in the off (open) position and thus not tied to battery while tractor is not running )</font>

I think the trio might be wired to the battery... not the ignition switch. The field excite p1 might be going to the ignition switch. Then again.. if it is a 1 wire job, the p2 sense will be internall connected tot he output in the vr for 1 wire regulation/charging... hard to say just what is hooked to where with more info on the alt and the way it is wired up in the circuit.. too many possibilities to speculate about.


Soundguy

 

[Keoke]

Soundguy's quote, And current does flow due to the difference between the batteries static voltage compaired tot he alt's output.. 12.x to 14.x . As soon as the al is disconnected, the battery quickly drops to alower than charge voltage.

Soundguy, Static battery voltage, when alternator is charging, RISES to the voltage level at alt output terminal minus the voltage loss it takes in going thru wiring from alt to bat.
EG. if alt is at 14.0 and wiring voltage loss is 1.0 volts then voltage at battery will be 13.0 volts. All loads running on tractor should operate from alt, none should run on battery current or voltage when tractor is running.
However, if load demand (in amps) exceeds alt output (amps) then battery will move in to make up the difference. This is not desireable but is ok for short durations and sometimes happens at slow idle and high loads.
The reason vehicles have large alternators (75A plus) is not that they will ever use 75A but it is because they would like to get, say 30 to 40 amps at idle speeds to cover all elec loads.
Also, amps meters are a poor judge of alt output amps. Contrary to what most think, what you see on a series wired amp meter is NOT a value of total alt output.
The meter instead shows only amperage going to and from battery AFTER all vehicle loads have been satisfied.
EG. below
If meters shows 5 amps and vehicle load is 10 amps then actual alt ouput is really 15 amps and not 5 amps shown on gauge.

If meter said 0 amps and load is still 10 amps, then actual alt output is 10 amps. In this case load is being taken care of but current taken from battery for starting is not being replaced by alt. Seeing "0" on meter, some may conclude alt is not charging. Short term ok, long term bad news.

If meter says minus 5 amps then half of the 10 amp vehicle load is being furnised by alt and the other half by battery.
This is because system (alt) voltage has fallen BELOW the 12.6 static battery voltage allowing electrons to leave battery and move on to the loads.
Very short term ok, long term very bad news.

Soundguy, still can't the quote blue highlight to work on this (daughters) PC. This computer wont allow pop up's.

cheers,

 

[Soundguy]

</font><font color="blue" class="small">( Soundguy, Static battery voltage, when alternator is charging, RISES to the voltage level at alt output terminal minus the voltage loss it takes in going thru wiring from alt to bat.
EG. if alt is at 14.0 and wiring voltage loss is 1.0 volts then voltage at battery will be 13.0 volts. All loads running on tractor should operate from alt, none should run on battery current or voltage when tractor is running.
)</font>

Correct. The alternator will be suppling the power for the loads in the system unless it can't keep up with the demand.

</font><font color="blue" class="small">( Also, amps meters are a poor judge of alt output amps. Contrary to what most think, what you see on a series wired amp meter is NOT a value of total alt output.
The meter instead shows only amperage going to and from battery AFTER all vehicle loads have been satisfied.
EG. below
If meters shows 5 amps and vehicle load is 10 amps then actual alt ouput is really 15 amps and not 5 amps shown on gauge.
)</font>

An amp meter is not a poor judge of alt output.. it isn't intended to be a judge of alt output.. it is used as a 'snapshot' of total system use.. and lets you know the NET charge / discharge occouring in the system. If the needle is deflected positive, then all load demands are being met, and there is a net charge occouring to the battery.. a negative deflection on the the needle indicates the storage battery is in a state of discharge supplying power to loads in excess of the charging systems capability. As far back as the wire diagrams from 1939 on ford tractors, this type of net charge / discharge system has been used. Thats the primary difference betwen a center 0 'ammeter' and a 0-60 'amperage' gauge. The amperage gauge is designed to show gross urrent flow in a line.. such as gross alternator output, or gross current consumption of a downline device.. etc.

You know.. we're both saying the same thing here...

</font><font color="blue" class="small">( Soundguy, still can't the quote blue highlight to work on this (daughters) PC. This computer wont allow pop up's.
)</font>

Under the dialog area in the reply box, don't you get the list of emoticons and the instant markup options.. like quote, email, url, etc.

If so.. hit quote.. then go down to the message and copy/paste text into the quote section.. has nothing to do with pop-ups.. just markup language..

Soundguy

 

[GrayBeard]

Sorry about the late response, I've been out for a few days.
I'll get out to the tractor today and check on the wiring to the alt. and name brand.
Just to clear things up about the "second" start; after the light has been on while running , on the second attempt the light stays on with the key in the on position and glow plugs warming and then "cancels "out before "cranking".
Thanks again.
GrayBeard

 

[Keoke]

Graybeard & Soundguy, sorry but I ended up posting the same reply twice so I removed this entry.
If I live to be a hundred I will never be able to use a PC they way they are meant to be used.

cheers,

 

[Keoke]

Graybeard, let's take one step at a time.

1. On the first startup, where chg lamp comes on but won't go off. Go ahead start and run motor while chg light is still on, put a volt meter across bat and check voltage.
If voltage is above 12.6 (13.8 to 14.8v is average here) then even though lamp is saying no chg, alt is in effect charging. This kind of voltage numbers can only come from a working alt. Now what you need to do is find out why the chg lamp is not going off even though you have a working chg system.

2. If the above test, (engine running @ fast idle) gives a voltage reading of 12.6 or less then alt is not working on your first start up and lamp is doing as it should. Now, if all you have to do is turn engine off and re-start (2nd start) and now the light comes on with key on and goes off during run, this is kind of weird, but not unheard of. Obviously something that is not going right on the first start is fixing it's self on the second start.
The most likely, but not definite, cause of this weirdness is that the alt field is not being excited on the first key turn on but some how manages to excite on the second turn on.

Let't do the above test 1 & 2 and get some info and then proceed from there. These two tests will qualify the alternator output one way or the other.

Soundguy, I hear what you saying on the automotive type of amp meters. However, unless one know's for sure what the vehicle load amp draw is, (for this value needs to be added to gauge reading) then using the value shown on gauge as an indicator of alternator output is not wise.
For a rough guess on vehicle load one could put all loads on with engine off and write negative gauge amps down. Start vehicle and note positve chg amps and to this number add the earlier negative reading. The total of both readings is then total alt output.
However, the downside of this approach is that all loads will use more amps with motor running due to higher source voltage (alt) then with motor off (bat) voltage.
Futhermore, there are some loads (elec fuel pumps, injectors, etc.) that simply won't go on unless the motor is running.
Also, on vehicles with large alternators it is impossible to get load value up to anywhere near what is needed to push alt even with everthing on that con go on. On these systems a carbon pile (variable artifical load) is needed to push alt to it's rated output.
Bottom line, as Soundguy says, if needle is on plus side of zero with every possible load on, your alt is ok for present amp running load only. However, in no way does this guarantee that your alternator is preforming up to it's factory rated output.

cheers,

 

[Soundguy]

</font><font color="blue" class="small">( However, the downside of this approach is that all loads will use more amps with motor running due to higher source voltage (alt) then with motor off (bat) voltage. )</font>

True.. but a quick ohm law calculation should easilly ballpark the 'running' load due tot he higher voltage. Use the current observed in the static check, use the voltage observed in the static check, calculate dc resistance.. then plug that dc resistance number back into a new calculation using the higher observed running voltage, and then re-calc amps.

This is of course will have a margin of error, as the esitimated dc resistance that we are using via calculation, then plugging into the new equation will not be 100% correct... but it will give you a ballpark idea.

If this was a genny.. you could full field it and get a much better idea of rated output and observed output.. but that is a moot point.

</font><font color="blue" class="small">( as Soundguy says, if needle is on plus side of zero with every possible load on, your alt is ok for present amp running load only. However, in no way does this guarantee that your alternator is preforming up to it's factory rated output.
)</font>

I agree.. without a sufficient load device it would be hard to tell if the alt is outputting factory specs.. however as long as it is treading water or better.. he doesn't need to be looking for a problem there untill he is getting insufficient charging.

Soundguy

 

[GrayBeard]

koeke,
Per my previous post on batt. voltage :
12.67 volts prior to start
14.49 while running with the light on or off.
There are 2 wires on the alt. ; one large one to the batt. and a small one that appears to go to the "dash area ". ( I lose track of the small one at the the harness)
Could'nt find the make of the alternator.
GrayBeard