Case 1845C 3rd alternator
Printed From: Unofficial Allis
Category: Other Topics
Forum Name: Shops, Barns, Varmints, and Trucks
Forum Description: anything you want to talk about except politics
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=171611
Printed Date: 27 Jul 2025 at 2:54pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Case 1845C 3rd alternator
Posted By: thendrix
Subject: Case 1845C 3rd alternator
Date Posted: 29 May 2020 at 6:08pm
|
I'm about to replace the third alternator since around Christmas on my 1845. It's a 1996 1845C with the Cummins 4B. I got the alternators at Napa and they're Wilson alternators. The guy at Napa was very surprised when I brought the first one back after about 2 months and now it's been about another 2 to 3 months it's not charging again according to a battery tester. I had to jump it off today and after running it for a few hours the battery shows on the weak side of the good range while the engine is running. According to the gage on the tester it's around 11 to 12 volts running and if I'm not mistaken it should show between 12.5 and 13.5. What do you guys think? Bad alternators or something else to look for? ------------- "Farming is a business that makes a Las Vegas craps table look like a regular paycheck" Ronald Reagan |
Replies:
Posted By: steve(ill)
Date Posted: 29 May 2020 at 6:27pm
|
Your right that the alternator needs to put out around 13.5 volts.... Also the charge depends on the wiring and the regulator... I assume you have an INTERNAL VOLTAGE REGULATOR in the alternator ? That would have been common in 1996.... Something is REGULATING the voltage and it does that by MONITORING the battery voltage and INCREASING charge out put when needed... Since it worked for 2 months, i assume when FIRST installed you had 13.5 volts out put ? NAPA should be able to test the alternator on the bench and verify that it has no or low output. If you get a new alternator, verify the OUTPUT from day one.. The alternator probably has 2-3 wires going to it.. ONE BIG is the output.. NOrmally there is a small wire or two that causes excitation and " turns the alternator on".... and monitors the battery voltage to determine alternator output..... A wiring diagram would heop. ------------- Like them all, but love the "B"s. |
Posted By: jaybmiller
Date Posted: 29 May 2020 at 6:40pm
|
Have you load tested the battery(s) ?? A bad battery( internally shorting cell) will kill an alternator by having it try to dump a LOT of current into it over a long period of time. This is where an ammeter is important, it'd SHOW you what's going on. If the battery(s) good, then probable wiring issues. simple test, if you disconnect the alternator from the wiring, it should give 13-14 volts output. If it doesn't alternator is bad. ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: thendrix
Date Posted: 29 May 2020 at 6:46pm
|
Yes it is an internal voltage regulator and the battery was replaced about 3 weeks or so ago. But now that you mention it this is the 2nd battery I've put in it in the past 2 to 3 months. I'll try the test you mentioned Jay and see what I get. ------------- "Farming is a business that makes a Las Vegas craps table look like a regular paycheck" Ronald Reagan |
Posted By: steve(ill)
Date Posted: 29 May 2020 at 6:48pm
|
Tyler, i could not find a 1845 skid steer.. this is a 1835. Note on the alternator there is a couple small wires in addition to the large charge wire.. The small wire with the resistor and diode is probably the "signal wire" to turn the alternator on and make it charge... If you alternator WORKED ONCE, then quit a month later that is one thing... IF if NEVER put out 13.5 volts, then you might have a WIRE problem and not an alternator problem. ............. i assume your battery is good since it worked for a month. if you have a volt meter, turn the key ON, but dont start.. Measure the voltage at the BIG wire on the alternator ( should be 12 volts)... Then measure the voltage at the SMALL wire on the alterntor ( should be less than 12).... the negative lead goes to the alternator case........... when you start up, the BIG should go to 13.5 and the SMALL wire should be LESS than that. ...... might be a good test to take the wires OFF the alternator when NOT RUNNING and check the voltage on each.  ------------- Like them all, but love the "B"s. |
Posted By: Boss Man
Date Posted: 29 May 2020 at 7:59pm
| Charging should be 13.5-14.5. I would start cleaning connections. Could be a bad ground or dirty power connection wiping them out. What shape is the starter? A starter that is drawing hard will over work the alternator and battery shortening their life. |
Posted By: thendrix
Date Posted: 29 May 2020 at 8:54pm
|
Steve, I've got an 1845 wiring diagram somewhere on this phone. I'll check it and see if it's the same then go checking. Boss man, as far as I know the starter is in good shape. With a good charge on the battery it cranks fine so I'm assuming it's ok. Never noticed it lagging. ------------- "Farming is a business that makes a Las Vegas craps table look like a regular paycheck" Ronald Reagan |
Posted By: HD6GTOM
Date Posted: 29 May 2020 at 8:55pm
| I have a Hydro Mac with a Motorcraft alternator. Just took it back to the rebuild shop. Had it done last fall. Guy said he put a heavier duty regulator on it this time. Last regulator he put on it starting charging 35 amps. My old loader sits out all the time. You might ask if they have a heavier duty unit. |
Posted By: wjohn
Date Posted: 29 May 2020 at 9:00pm
|
May not be the problem but it never hurts to replace the battery cables. My Dakota went through an alternator and did a bunch of funny stuff due to a bad positive battery cable that had intermittent connection. I would agree that you probably have a regulator or bad connection issue somewhere. ------------- 1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45 |
Posted By: encreed
Date Posted: 30 Nov 2021 at 3:11am
|
yup bro you are right some time the problem is with regulator or some where with the connection. so it is better to check to both and if they had problem than change them. ------------- https://shopsavvy.mobi" rel="nofollow - shopsavvy.mobi |
Posted By: DMiller
Date Posted: 30 Nov 2021 at 4:28am
| Hand over hand the wiring, I suspect gonna find a worn spot making intermittent short as well deep corrosion resistance causing the alternator to Hard Charge at times and cooked itself. Would also explain the battery being hard cycled as works both the same way. |
Posted By: thendrix
Date Posted: 30 Nov 2021 at 5:51am
|
I'll look it over again. Haven't had a chance to work on it yet. Between the farm and the kids it seems like there's ALWAYS something else to do ------------- "Farming is a business that makes a Las Vegas craps table look like a regular paycheck" Ronald Reagan |
Posted By: Steve in NJ
Date Posted: 30 Nov 2021 at 7:30pm
|
The first thing I tell customer's is to do a draw test on the Battery. New or not, if you have a Battery that's having an issue internally, that will almost always take out an Alternator. May take a little time, but it'll take em' out. Also, make sure the Alternator case is grounded correctly. If it isn't, the Alternator will be searching for a ground. This will show on a Voltmeter where the charging output rate is either low or bouncing around. BTW, speaking of output, on any 12V system, normal charging rate is 13.9-14.5 Volts. 14.2 being ideal. Anything above or below those normal charging rates is a problem, or a problem developing. I don't know how many customer's I've helped out just this year alone over the phone with charging and operating problems all leading back to the Battery. New ones as well as some that haven't been in service for to long. I don't know what it is, maybe stores not rotating stock, or whatever, but this year has been the year for the "Battery issue". The Battery may be new to you, but you don't know how long its been sitting around till it was sold to you. When Batteries sit, and they're not active, they start to sulfate. Once put into service, depending on how much of a "bridge" started between the cells, sometimes putting it into service activates that bridge even more and eventually you have a dead short internally..... Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |