Cat 305.5e not charging

[Tj345]

Hey guys, having some trouble with my 305.5
Seemed like the alternator wasn’t charging
Took it off, got it tested and it tested good on one of those table testers.
Was told it could be the exciter wire.
Got a mechanic to check it out he said the wires were working how they were supposed to.
I put a brand new alternator on, exciter is getting 12v and still not charging.
Any ideas?

 

[007]

Please explain how you are testing for charging.
Are you measuring the output voltage of the alternator at the alternator or the battery.
What voltages are you reading.
What are the engine rpms when you are testing.
What do you mean seems like not charging, did the battery go flat or starting issues?

 

[Delmer]

How did the mechanic explain the excite working but the alternator not working after it was tested? the wires have to be hooked up in the right spot also.

 

[Tj345]

Getting 12v from the battery and from the charging wire. My understanding is it’s supposed to be 13-14v?
Don’t recall the rpm’s but it was about idle for sure.
Had trouble starting one day, put a brand new battery in.With the old alternator my brother was operating all day with the ac running and the battery did go flat. Charged battery machine cranks up no problem. Take off battery wire shuts down right away.(not sure if that trick works on this machine)

 

[Tj345]

How did the mechanic explain the excite working but the alternator not working after it was tested? the wires have to be hooked up in the right spot also.

Took the alternator off and got it tested at a shop on one of those table testers, guy said it tested good. Put it back in and changed the belt because the belt was pretty slack tried it and no change.
The mechanic came and tested the wires while it was back in the machine said the exciter was doing its job but it wasn’t charging. Took it back off and took it to his shop he hooked it up to a battery, multimeter and a drill to test if it was charging and it wasn’t.
Tried that trick on a brand new alternator and it was charging. Which ended up to be a slightly different alternator and i ended up ordering one and now I’m here.

 

[007]

It is extremely unwise to disconnect battery on any machine while still running.
Yes the voltage should be higher.
Be aware that the voltage should be checked in both places during your testing.
Even though the machine charges at idle you should bump the rpm up a little for testing.
Drill test is very pour test of device.
If it is a new alternator clearly the excitation wire is not working or is connected to wrong terminal.
Can you take a pic of back of alternator?
Can you explain how he tested and said exciter wire was good on the machine please.

 

[Tj345]

Noted.
Best picture I have on hand.
Not sure exactly how he tested it because I wasn’t there my brother was.
There’s only one wire in that plug so not sure how it could be connected wrong.
When I turned the key on and tested the plug I got 12v.

 

[007]

The picture does not show the detail i wanted.
Not having the wiring diagram for your machine i am only guessing at this point.
I notice you have not mentioned the alternator warning light, is it coming on and going out when started?
There are generally two types of systems used these days and one is where the small current from the alternator warning globe or resister in the dash cluster is used to excite the alternator.
The other is a fixed 12V from the ignition circuit to the alternator.
In both cases the tests need to be done with the plug in on the alternator.
So you need to probe the plug from the back.
So with the warning light system you will have a couple of volts with respect to ground at the terminal when you turn the key on and that will go to 12-14V when the engine starts.
The other system is not really exciting the alternator, but the 12V is powering the field circuit of the alternator and should be 12V with the key on and go higher when the engine starts.

 

[Tj345]

The picture does not show the detail i wanted.
Not having the wiring diagram for your machine i am only guessing at this point.
I notice you have not mentioned the alternator warning light, is it coming on and going out when started?
There are generally two types of systems used these days and one is where the small current from the alternator warning globe or resister in the dash cluster is used to excite the alternator.
The other is a fixed 12V from the ignition circuit to the alternator.
In both cases the tests need to be done with the plug in on the alternator.
So you need to probe the plug from the back.
So with the warning light system you will have a couple of volts with respect to ground at the terminal when you turn the key on and that will go to 12-14V when the engine starts.
The other system is not really exciting the alternator, but the 12V is powering the field circuit of the alternator and should be 12V with the key on and go higher when the engine starts.

Unfortunately I don’t have a wiring diagram.
Tbh with you didn’t even check for a warning light. I’ll be sure to check it tomorrow and probe the plug like you said.
Here’s a better picture with the old alternator.

 

[Nige]

Unfortunately I don’t have a wiring diagram.

Providing a machine Serial Number will get you one.

Not having the wiring diagram for your machine i am only guessing at this point.

See my answer above.......

 

[Tj345]

FKY02196. Thanks in advance.

 

[Nige]

Check your messages. You have mail.

 

[Delmer]

I can only see one wire in that old alternator plug, is that correct? are there more wires that broke off possibly? One wire there and one big wire on on the threaded terminal are all that are needed, but not common anymore.

It's not unusual for an alternator to work cold and then quit when it warms up, then work again when it cools off. That's what happened when it ran all day with the ac, it would have died in a couple hours with no charging.

 

[Tj345]

Providing a machine Serial Number will get you one.

See my answer above.......

I can only see one wire in that old alternator plug, is that correct? are there more wires that broke off possibly? One wire there and one big wire on on the threaded terminal are all that are needed, but not common anymore.

It's not unusual for an alternator to work cold and then quit when it warms up, then work again when it cools off. That's what happened when it ran all day with the ac, it would have died in a couple hours with no charging.

Possibly
Still doesn’t make sense to me.
It ran the battery all the way down until the screen went black and the machine couldn’t move. Turned it off and Wouldn’t start back until i put another battery in.

 

[007]

Thats very interesting problem you have there.
The diagram was not very helpful but did answer a few questions.
The one wire you have there should have 12V on it when the ignition is turned on.
Your old alternator is so covered in dirt that often the brushes get stuck in the holder which will make them charge intermittently.
The diagram suggests that wire should be on 2 in the middle on terminal marked L but is on three which is nothing according to diagram.
So how could it be possible it has been working, well the excitation wire on an alternator is only there to make it reliably start every time the engine starts.
Depending on the brand and internal tolerances an alternator will start every time without external help.
So your new alternator might just need that wire in the correct place to get it up and away each time.
Can you take a look at the markings on the terminal block on the alt as there should be a R and a L marked.

 

[Tj345]

At this point that sounds like the best solution.
Not by the machine at this time so not sure about the markings, at least the old alternator doesn’t have any markings. Found this on the website I ordered the alternator from. I think you’re spot on with the terminals. Correct me if I’m wrong.

 

[007]

Yeah if the specs you have are listing those terminals in order then its blank N/C then ignition then Light terminal.
I have seen it many times where they excite themself s so your old one was one of them?
The reasons this is so would fill a couple of pages so not worth getting into just take it on faith.
One thing i would do is not just put 12V on that middle terminal without being cautious.
I would get a small bulb and some wires and with one wire on battery positive and the other in your hand I would flash the wire on the middle terminal when it was running and just confirm the alternator gets away ok.
You could also try the light terminal if number 2 failed to fix.
If still no success i would place 12V without bulb on term2 with your wire but just touch it on and off quickly.
You should hear the note of the alternator change when it starts and the voltage at the output terminal will jump up as well.
If it does fix then bingo move the wire.
If it turns out to fix it i would thank Nige if i was you as his diagram sped things up big time.

 

[Tj345]

Yeah if the specs you have are listing those terminals in order then its blank N/C then ignition then Light terminal.
I have seen it many times where they excite themself s so your old one was one of them?
The reasons this is so would fill a couple of pages so not worth getting into just take it on faith.
One thing i would do is not just put 12V on that middle terminal without being cautious.
I would get a small bulb and some wires and with one wire on battery positive and the other in your hand I would flash the wire on the middle terminal when it was running and just confirm the alternator gets away ok.
You could also try the light terminal if number 2 failed to fix.
If still no success i would place 12V without bulb on term2 with your wire but just touch it on and off quickly.
You should hear the note of the alternator change when it starts and the voltage at the output terminal will jump up as well.
If it does fix then bingo move the wire.
If it turns out to fix it i would thank Nige if i was you as his diagram sped things up big time.

Shout out to all you guys for the help I really appreciate it.
Feel like I’m actually getting somewhere now. Was getting really discouraged.
I’ll try it out tomorrow as it’s 9:30pm where I am (Cayman Islands).
I’ll keep y’all updated

 

[Tj345]

Shout out to all you guys for the help I really appreciate it.
Feel like I’m actually getting somewhere now. Was getting really discouraged.
I’ll try it out tomorrow as it’s 9:30pm where I am (Cayman Islands).
I’ll keep y’all updated

I got the machine sorted today and it’s now charging.
The exciter wire was in the wrong place, moved the pin over to the middle of the plug and that did the trick.
Thank you all for all the help!!
Really appreciate it!