|
Author
|
Topic: Alternator wiring
|
jharville
True Blue Posts: 33
From: Augusta, GA, USA
Registered: Feb 2006
|
posted September 17, 2007 23:28
  
I have a Dexta that already had an alternator hooked up on it. It wasn't working when I first got it so I tinkered with the wires some and got it to start putting out good voltage. The next morning
I came out and something had caused my battery to drain completely. Even worse, the alternator doesn't appear to be charging. i'm guessing I got some sort of current backflow to the alternator overnight that fried something in it. Anyway, I'm going to grab another alternator soon and I need to know the easiest way to hook it up. My dexta has no Key switch or indicator light and the alternator has an internal regulator. I read some of the forum posts about this and my biggest question is whether or not I'll need the diode to keep the current from going both directions. Any suggestions?IP: Logged |
Dunggatherer
True Blue Posts: 142
From: Breezand,Netherlands
Registered: Jun 2004
|
posted September 18, 2007 08:39
Hello Jharville.Well it sounds like you did a good job.
And i'm not joking here. What probably happened is this: You connected the alternator correctly since it was working.
There's probably two wires?
Anyway,the alternator needs a little bit of current to activate it.
It takes that from the battery,and once the engine is running,it starts charging the battery,and not drawing anymore. Now what happened tonight was: The engine was off,but the alternator was still trying to get activated,thus drawing current from the battery.
Nothing prevented it from doing that. So your next job will be to reinstall a keyswitch,to which you connect the little wire to the alternator.
Switch off the "ignition key" and no current will be flowing anymore,so the battery stays full. Now i hope that all that current all night did indeed not fry your alternator. Anyway good luck,and i would also install one of those warning lights in the dash.
That way you'd know immediately if anything went wrong. IP: Logged |
Tubal Cain
True Blue Posts: 126
From: Pembrokeshire, West Wales, UK
Registered: Sep 2006
|
posted September 18, 2007 10:24
jharville,The feed to the small connector on the alternator should be through an indicator (charging) lamp, usually about 2.2 watts 12 volts. This lamp limits the amount of current flowing to the alternator field windings on start up and once the alternator is generating sufficient voltage the lamp will go out. In order to prevent the battery draining through this wire when the engine is stopped you should fit a switch in this circuit. This switch can also feed the switch on top of the starter motor and can be wired to the oil pressure switch via the oil pressure warning lamp. As a final precaution I would disconnect any wiring on the tractor which is no longer in use, in fact I usually remove all the original wiring and rewire the switches and lamps detailed above. This removes the possibility of loose or damaged wires causing problems. One final thought, is the original voltage regulator still fitted? As it is possible for the battery to drain through the regualtor if the contacts have welded together. Regards. Gerald. [This message has been edited by Tubal Cain (edited September 18, 2007).] [This message has been edited by Tubal Cain (edited September 18, 2007).] IP: Logged |
jharville
True Blue Posts: 33
From: Augusta, GA, USA
Registered: Feb 2006
|
posted September 18, 2007 15:27
ok, this is making sense now. I didn't think about the indicator light limiting the amount of battery drain but it makes sense now. I guess the diode is a good alternative to that if I don't want to bother with wiring in a light or a key switch.
The biggest problem with the switch is I'm very forgetful. My dexta has the manual starter thingy and a pull cable that shuts off the flow of diesel.(I guess all of them do,huh?) Anyway, there is nothing to remind me to turn the switch off if its not required to shut off the engine....and trust me if it can be forgotten I'm the one to forget it!! 
To answer your question, there is not external regulator and the only other wiring is to the lights....which could be another problem...the switch is old and sometimes doesn't work properly.
Think I'll take the alternator to the shop and have them test it and then proceed. Thanks for the info!IP: Logged |
Tubal Cain
True Blue Posts: 126
From: Pembrokeshire, West Wales, UK
Registered: Sep 2006
|
posted September 18, 2007 17:13
jarville,Fitting a diode in the wire to the alternator will not solve the problem. A diode is an electrical one way valve, which only allows current to flow one way! If you fit it so as to allow current to feed the alternator it will not prevent the battery from discharging through the alternator. If you fit it the other way round it will prevent the battery discharging and the alternator will fail to excite. If you fit an indicator lamp, when you stop the engine the lamp should light and remind you to switch the power off. If you wire the feed to the alternator and starter switch from a key switch, you will not be able to start the engine unless the switch is in the on position which in turn will supply current to the alternator and hence charge the battery. Regards. Gerald. [This message has been edited by Tubal Cain (edited September 18, 2007).] IP: Logged |
JC
True Blue Posts: 160
From: Montague, CA, USA
Registered: Mar 2005
|
posted September 18, 2007 23:36
jharville,
I know what you mean about forgetting to turn the switch off. We have a forklift at work that has a pull cable to shut it off, and it always has a dead battery because I or someone else forgot to turn the switch off. One of these days, when I have a little spare time, I'm going to put an oil pressure switch between the battery and the alternator. That way, when the engine isn't running, the battery isn't discharging, no matter what postion the key is in.IP: Logged |
jharville
True Blue Posts: 33
From: Augusta, GA, USA
Registered: Feb 2006
|
posted September 19, 2007 15:11
Good point on the diode. Guess it boils down to me remembering. I have gotten much better at remembering to unhook the battery cable when I leave the tractor . guess a key switch would be alot more convenient. Heck, as it stands I have a whole checklist of things to do before I start her up. 1)Inflate a random tire 2)Charge the battery 3)Fill up the radiator(waterpump leak). Its actually kinda funny b/c the waterpump only leaks when the engine is off. Gotta get a repair kit for that. Anyway, she's a good tractor...just needs some perripheral work.IP: Logged | |
Fordson Bulletin Board
UBBFriend: Email This Page to Someone! 
