WD45 12 volt question
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=22406
Printed Date: 13 Feb 2025 at 5:14am
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Topic: WD45 12 volt question
Posted By: RSponenberg
Subject: WD45 12 volt question
Date Posted: 16 Dec 2010 at 4:37pm
| I have a WD45 converted to 12 volt with an altenator,it also has a push button switch next to the key,you have to push the switch to get it too charge.Do I need this switch or not???? I have another WD45 thats converted and it doesn't have that switch.I'm confussed.... |
Replies:
Posted By: Gerald J.
Date Posted: 16 Dec 2010 at 5:00pm
|
That switch puts excitation on the alternator. It could be done with a diode or a resistor from the ignition circuit. Or the alternator excitation could come from the ignition circuit, but it would back feed and turning the key off wouldn't kill the engine without the series resistor or diode. Or you can run the engine speed up very fast and the alternator wiill start charging. Its a one wire alternator in an application that needs two or three wires. Gerald J. |
Posted By: RSponenberg
Date Posted: 16 Dec 2010 at 5:18pm
| Gerald, it is a 3 wire alternator just like the other WD45?? My problem with this one is I have to push the button multipial times to get it to charge??? Is it the switch or is it the alternator??? Can I bypass the switch?? Both WD45s had this done when I inhierited them..My guess is neither one is coverted to 12 volts the RIGHT way,lol,my grandfather would just fix it to get by,not for the long term.. |
Posted By: steve(ill)
Date Posted: 16 Dec 2010 at 5:27pm
|
the alternator has a big wiere on the back on a stud. that goes to the ampmeter - battery to charge... the two smaller wires are numbered 1 and 2 or R and F. I believe the #2 wire is always hot and you can run a jumper back to the big lug on the backside of the alternator.. THe #1 terminal is excitation. It only has 12 volts when the tractor is running. You can turn that on with a key, a toggle switch or a pressure switch. Im not sure why you are pushing a button. It should be an on- off switch. I acutally use a double throw double pole toggles switch. WHen i turn it "on", it puts 12 volts to #1 wire, and 12 volts to the coil for ignition. When you go to "off" i kills the power to both.. YOu can also use this on a magnito, except instead of putting 12 volts to the coil, you ground the mag and stop the 12 volts to the alternator #1 at the same time, or open the mag wire and also send 12 volts to the alternator... lets see if i can find a drawing of the alternator wire... you need a better switch. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 16 Dec 2010 at 5:30pm
 ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 16 Dec 2010 at 5:31pm
|
the wire feeding the #1 terminal needs "somehting" in the line to drop voltage slightly, or/ and stop feedback when you shut off. I prefer a 10 ohm 10 watt resistor from RAdio Shack for $2. You can also use a idiot liight bulb or a diode. ------------- Like them all, but love the "B"s. |
Posted By: LouSWPA
Date Posted: 16 Dec 2010 at 5:47pm
|
I think Steve is correct, however, the #1 terminal is the exciter terminal, and, as Steve points out requires a 12v applied to "excite" the alternator. But, I believe, with the #2 terminal tied to the alternator output lug once the alternator is producing power, the 12v can be removed from the #1 terminal, as excitation is now supplied at #2 terminal.
I think this is what the push button is for, to supply excitation to #1 terminal long enough for the alternator to come on line. Your problem may be you're not holding it long enough, push button switch is going funky, engine not running fast enough when you excite, etc. With this set up, I don't believe you need the diode or dropping resistor, but, I could be wrong ------------- I am still confident of this; I will see the goodness of the Lord in the land of the living. Wait for the Lord; be strong and take heart and wait for the Lord. Ps 27 |
Posted By: wfmurray
Date Posted: 16 Dec 2010 at 6:00pm
| I put extra switch on my B. Motor would not rev enough to excite . Put toggle on should have been pushbutton because if you leave it on when not running it runs battery down. |
Posted By: RSponenberg
Date Posted: 16 Dec 2010 at 6:02pm
| Lou and Gerald,I think you are both right,the button excite the alternator,I can not find any diode in the wiring or a lightbulb..I think the switch is shot I think holding it in for 5 minutes should be long enough... |
Posted By: Gerald J.
Date Posted: 16 Dec 2010 at 6:08pm
|
So short the terminals on the switch with a wire or screwdriver (being careful to not go to ground) and the alternator should start charging in less than a second. If so its the switch. If not, its the alternator. Gerald J. |
Posted By: RSponenberg
Date Posted: 16 Dec 2010 at 6:26pm
| Thanks Gerald its the switch I just jump it ang it charges!!! |
Posted By: bluebanshee
Date Posted: 16 Dec 2010 at 7:31pm
| I thought #2 was all that needed to be hooked up to the ignition switch? As long as the key is on the gauges, alternator and coil all have power. Is there anything wrong with doing it like that if you don't care about a dummy light? |
Posted By: Gerald J.
Date Posted: 16 Dec 2010 at 8:01pm
|
With no light, resistor, or diode, the alternator will back feed the ignition so turniing the key off won't stop the engine. Otherwise it works. Gerald J. |
Posted By: bluebanshee
Date Posted: 16 Dec 2010 at 8:26pm
Our wd45 is wired that way and shuts off fine as long as the battery is hooked up. |
Gerald J. wrote:Posted By: Steve in NJ
Date Posted: 17 Dec 2010 at 8:19pm
|
The jumper wire off #2 to the Batt output stud is the "sense" wire. This tells the VR when power is needed in the system. (load) #1 as mentioned is to turn the VR on when 12V is applied to that circuit. A 1 amp 50V diode in the number 1 wire will take care of any backfeed to the Ignition switch or circuit for engine run-on. A heavy key switch should be used with Alternator equipped systems to sever power on board the Tractor. Power should run from the Starter Motor to the Ignition Sw's BAT terminal. The key switch will then control all power on board the Tractor so there won't be a chance of a parasitic draw while the Tractor sits.... Steve@B&B |