Model/techtype: 675E-699031700 Serial Number: 031026107 Alternator not charging the battery until the throttle is pushed. Once the engine is revved, everything works as it should until the unit is turned off. When restarted the issue reappears until the throttle is pressed again. It only requires a quick tap. The throttle does not need to be held. I replaced the battery a few weeks ago. Here is what I'm seeing. Battery voltage 12.65, loader started without issue. Immediately after starting the battery icon light is illuminated on the instrument cluster and RPM gauge needle is at zero even though the machine is idling. When the light is on and RPM gauge at zero, the voltage at the battery terminals is 12.06, voltage between the posts on the back of the alternator is 11.44, and there is what appears to be an additional ground wire (see photo) running from the block to the bolt on the alternator support bracket that gives a reading of 12.07. Giving it some gas to rev the engine causes the RPM gauge to kick in. This causes the battery light on the dash to go out. The RPM continues to function until the unit is turned off and reads between 5 – 10 while idling. When the battery light is out and RPM gauge functioning, the voltage at the battery reads 14.12. The posts on the alternator read 7.19 but the red wire on the alternator to the extra ground wire shows 14.26. I first thought it was the alternator because of the voltage readings I got at first. I replaced it but the new one gave the same results. This is when I noticed the relationship between the voltage and RPM gauge. I’m not sure what would cause it to behave like this. My next course of action will be to check the grounding points for continuity but that’s kind of a shot in the dark for me at this point. I figured I would put this up here to see if anyone had any experience or ideas about what may be going on. Thanks for in advance.
The tach gets it's signal from the alternator. Check the belt tension first. Engine idle may just be set to low. Idle speed should be 680 to 850.
I'm a little curious of the voltages between the posts on the back of the alternator. I'd need to know the id of each post and then look up a wiring diagram for that alternator brand if not model, to know what's up. It sounds like it's not getting voltage to the excite terminal? as the voltage "between posts" is almost full battery voltage. Typically, I'd measure all alternator voltages to the case of the alternator. To check alternator function, find the excite terminal, and jump between the B+ big terminal and the excite for a second and see if that raises the voltage to 14. On the other hand, it's charging and the tach is working once the alternator works, so there's not much of a problem, unless this really bothers you.
My 555E does the same exact thing when I have the throttle lever in the lowest position. I don’t have the technical answer that the book will probably give you, but I would assume it’s supposed to work like this. I highly doubt two different models of machine have the same issue without it supposed to be like that by factory.
My alternator light sometimes flickers at idle but I never start my machine without giving it some throttle. If I don't warm it up a few seconds at high idle it won't move.
Here are the frequency outputs for the alternator to tachometer if you want to check for that.
Just fired my machine up to pull some unwanted pines and I intentionally didn't give it any throttle. It does the same as you describe for yours. Alternator light remains on and tach doesn't register until I give it some throttle. Just never paid it any attention since I always throttle up some as soon as I start it. I'm gonna say it's normal. Thought I would let you know.
As NH575E said , Check if idle rpm is too low as I have seen this a few times before. A good check to check quality of diodes is to set meter on AC volts and measure from Positive output of Alternator to positive of Battery with both test leads on the positive cable. A good alternator is usually 200millivolts or less of AC current slipping past the diodes. I believe at full output it is 500 millivolts AC current according to Fluke. Simon C
That is an odd place for that ground cable to be terminated. I have never seen one go to the belt tension adjustment bracket. If the no charge at idle is a problem with no apparent solution, you could replace the Magnet Marell alternator with a Delco one wire alternator. But, it has to have a self-exciting regulator in it or it will not charge at idle. They are less than $50.00. The self exciting regulator for it is about $15.00
A one wire alternator would not provide a tachometer signal.
There are ones that do, or you could take the cover off and tap into one of the lead before the rectifier. It's not rocket science, but probably easier to fix what's there, or live with it.
My 555e does the exact same thing. I figured it was something to do with an excitor or something. Since it charges as soon as I back it out of the tractor port it doesn't bother me so I leave it alone.
Ditto for me too. I changed the belt on mine as it was suspect anyway, but no change. I'm gonna live with it.
Does it require an increase of very many RPM"s ? A smaller diameter pulley on the alternator may get it to charge at idle speed. A new regulator may be worth trying. It could be a cheap fix if you can do it yourself. Although the alternator in the video is a different model than yours it is quite similar. Here is real good video on Marten Marelli alternators.