Alternator problems

[Ben Cut-wright]

The combined problems the OP expressed are quite often topics of forum posts.  Engine dying, dead batteries, poor performance of electrical accessories, all these I find interesting faults and try to keep up with whatever resolve they illicit. Others have added voltmeters and ammeters and suggest different alternator styles.  Why this model sawmill does NOT include a gauge or light to warn of no or low charging is a mystery to me. No matter how new or recently replaced a part or unit is it can have faults.  All this makes it difficult  to diagnose and to help others when a problem occurs. WoodMizer phone help is excellent. Their assistance in getting a machine back working properly is UN-excelled IMO.  There are but a few tests needed to ascertain a direction for further testing or repairs.  All these tests require an accurate test point and an understanding of each test result with the test tool used.  At any point in the diagnosis there comes opportunity for errors that have no or little meaning in the actual fault solution. Where to begin the diagnosis and what steps to take will be dictated by the health of the complete circuit and its components.  What is working is as important as what is NOT working.  How well something is working is often too subjective to be used by someone not present. Example, if the starter is able  to rotate the engine it does not mean the battery and starter are sound. 


Posts often state the engine dies when an electrical load is placed on the charging system.  Does this mean the electrical supply is diminished or the actual engine load on the charging device was too great?  Either way the engine dies.  Of course there are many, many other reasons an engine may cease to run not confined to charging or battery health.  This is what I mean by tests that can quickly confirm a direction for further testing. If the electrical supply tests sound when the dying occurs, something else is causing the engine to die. 


In this thread there are more possible faults.  Begin with the dead battery, or too low a battery to start the engine.  Was the battery merely jumped or was it charged to some extent. The OP says the battery operated the electrical accessories for a lengthy period after getting the engine started.  A battery may not charge even though the charging system is trying to recharge it.  That is easily tested. If the charging device is charging/not charging then you have direction for further testing. The manufacturer sent new components and the problem persists.  We have no test results indicating why the alternator and ignition switch were replaced or if any other testing of the circuits for these components proved good or faulty. It would be mostly guesswork or speculation past this point.


I do hope the OP has resolved his issue and presents us with the cause and results of what it took to get there.

[DixieReb31]

WM LT 35 HD. Less than a year old.  25 hp gas. 
Problem: Hydraulics are using battery juice faster than the alternator can recharge. OR the alternator isn't charging the battery quickly enough. I put a volt meter on to watch the charging.  I think the alternator (brand new alternator sent to me from WM along with a new key switch) isn't charging as fast as it should.  Cannot figure out why.  I can cut about 3 logs before the machine just shuts down from low amperage.  I replace the battery with another deep cycle marine battery and I can saw more while the first is on charge.  But swapping batteries every 2-4 logs gets old quick.

Question: can the hydraulic pump be converted to AC? That way I can bypass the alternator.

[Ianab]

I'd be looking at all the Earthing connections in the circuit. If you have a bad connection there it adds resistance to the charging loop, and that creates a voltage drop. What you might then find is the alternator produces it's 13.8 volts on it's terminals, and you have 13.8 (to ground) at the battery +. But you may only find 13.3 across the actual battery terminals (not enough to charge properly). The missing 0.5 volts is warming up an earth lug someplace. An accurate voltmeter directly across the battery terminals would give a clue here. Especially if it's different from the voltage being produced at the alternator. 

It does seem you have eliminated the obvious causes,. so it's now on to the less obvious ones. 

I imagine you could swap the pumps for electric ones off a stationary all electric mill, but that seem a bit excessive as they wont be cheap. 

[Magicman]

My alternator supplies 14.5+ volts and easily keeps my battery charged.  Voltage is what charges the battery.  As Ian suggested, read the voltage at the alternator and at the battery.  The reading should be virtually the same.  If they are not, then move the voltmeter leads to various check points within the circuit to identify the bad/loose connection.

[mike_belben]

Check for continuity from the alt case to the battery ground post. Should be almost zero ohms, and should beep a meter.

Check if the alt case itself has any voltage with a meter.  Black lead to battery negative post. red lead to alternator case.  It should read zero volts.  

Run the machine, record alternator charge post output.  It should be in the 13s.

Now briefly put a jumper wire from battery positive post to the alternator field terminal.  This will create full output. Should be into the 14 volt range with strong magnetism on the case. 

If there is a dummy light bulb it MUST work. Dead alt warning bulb means no field voltage. With key on engine off tge bulb should light then go out when running. 

[DixieReb31]

Thank you Mike, I will try it this evening when I get home.  I'll let you know what I find out.

Electrical issues seem to be my Achilles heel.  

[SawyerTed]

This is one of those overlooked but simple items that shows up as other problems.  It will cost 0 money to eliminate this as a possible problem.

If you haven't checked the contact shoe for the hydraulics that rides on the bottom of the rail, check it to make sure it is making contact.  It is held in contact with springs and can get bumped out of contact.  I experienced similar problems and I started with a battery replacement.  While replacing the battery, I saw the contact wasn't right.  I adjusted it, put the old battery back in and no more issues.

In the manual or on the website look at the drawings for the Hydraulic Power Supply Strip.  It will show parts 14-24 for the ground contact assembly.  

[mike_belben]

Good to know ted. 

Thats the kinda machine specific info that ya really need, which i cant be any help with having never had my hands on half the stuff we are on here trying to troubleshoot. 

Let us know what ya find. The more details the easier it makes it for others to help ya find the issue.

[Ianab]

Yeah, that's another connection in the charging loop that needs to be checked. And being a moving one, it's more likely to give problems. 

[Ben Cut-wright]

WM LT 35 HD. Less than a year old.  25 hp gas.
Problem: Hydraulics are using battery juice faster than the alternator can recharge. OR the alternator isn't charging the battery quickly enough. I put a volt meter on to watch the charging.  I think the alternator (brand new alternator sent to me from WM along with a new key switch) isn't charging as fast as it should.  Cannot figure out why.  I can cut about 3 logs before the machine just shuts down from low amperage.  I replace the battery with another deep cycle marine battery and I can saw more while the first is on charge.  But swapping batteries every 2-4 logs gets old quick.

Question: can the hydraulic pump be converted to AC? That way I can bypass the alternator.

Describing the results you see does not define the *problem.  You present TWO scenarios that could contribute to dead batteries and cause an engine to die.  "put a voltmeter on to watch the charging" has NO information we can use.  How many volts are you reading at the alternator and at the battery when the hydraulics are not in use?  What are the readings when the hydraulics are in operation?  Volts alone will NOT tell the entire story.  Volts are pressure but amps are volume.
 
The assumption the "battery isn't charging fast enough" encompasses to many variables to conclude anything.  Battery state of charge, alternator voltage and amperage, and electrical demands all have to be accounted for to conclude such a thing.  It is possible to eliminate many faults and test for proper operation to determine where the fault resides with simple tools and step by step testing methods.  A test light will clearly and accurately show voltage drops across poor connections. A voltmeter will certainly indicate healthy voltages and can be used to test more accurately for voltage drops. 


No idea how the hydraulic contacts could cause a dead battery or dying engine though.  An Achilles heel in electrical will make converting the hydraulics to AC very difficult.  The unit as designed will/should preform more than adequately for the task.    

[Jim_Rogers]

Many years ago, when I had an issue with the engine dying when I ran my hydraulics the tech guy at WM told me it was my battery.
So, I replaced it.
Another time when I had issues with the alternator not keeping the good battery up, he told me to check the voltage at the alternator and note the amount. Like write it down.
Next, he told me to go to the next connection in the circuit from the alternator to the battery and check the voltage there. He said if there was a voltage drop of more the point 2 volts then that connection had an issue. Clean it and or repair it so that there is no voltage drop. Continue this process until you reach the battery.
I believe it was mentioned above that the red light on your dash, if you have one, needs to be working in order for the alternator to charge the battery.
Good luck with your search and repairs.
Jim Rogers

[stavebuyer]

Bypassing the DC hydraulics was the best upgrade I ever did. The factory hydraulic system has a multitude of pitfalls and limitations. 

[stavebuyer]

Here are some links showing Bibbymans hydraulic upgrade project which I later copied and adapted for my LT70DCS. There is a really detailed thread from his original build some where but I haven't found it yet.

Any mods for faster hydraulics of portable woodmizer in Sawmills and Milling

Plumbing an LT-40 to a stationary hydrualic power pack. in Sawmills and Milling

[DixieReb31]

Test results

Test 1 - Continuity
Red lead to + on Alt. Black lead to - on battery - results = nothing happened. Meter screen made no movement and did not beep. Meter was set to continuity correctly. 

Test 2 - Voltage (engine not running)
Black lead to - on battery. Red lead to + on Alt. Results = 12.24 v

Test 3 - Voltage (engine running)
Same set up as prior test - 
Result = 12.11 v

Test 4 - jumper wire (not sure I did this correctly, not sure what you meant by "Alternator FIELD terminal). 
I assumed you meant the yellow wire that excites the alt.  This is what I did. Black lead to unplugged yellow wire.  Red to + on battery. Results = 12.03

I hope this helps. I do appreciate the input. 

[Magicman]

All of your voltage readings are too low.  A fully charged battery should read at least 12.7 volts and your alternator should be putting out close to or above 14 volts.

Neither the hydraulic contact strip nor the ground on the bottom of the rail have anything to do with your alternator charging the battery.

[DixieReb31]

I don't disagree.  Any idea as to why they are too low?  I have traced all the connections and they are clean and tight. 

[Magicman]

No, I can't personally help you without being there, but obviously your alternator is not supplying enough voltage and your attempted usage has drained the battery down. 

Your alternator has to put out first.

[doc henderson]

if the voltage does not go up when running, it must be the alternator, or voltage regulator if it has one.  

[Jim_Rogers]

Does the red light lite up when you turn the key on? and not start the engine. if not then it is burn out. and alternator will not produce juice.

Jim Rogers

[Ben Cut-wright]

Test results

Test 1 - Continuity
Red lead to + on Alt. Black lead to - on battery - results = nothing happened. Meter screen made no movement and did not beep. Meter was set to continuity correctly.

Test 2 - Voltage (engine not running)
Black lead to - on battery. Red lead to + on Alt. Results = 12.24 v

Test 3 - Voltage (engine running)
Same set up as prior test -
Result = 12.11 v

Test 4 - jumper wire (not sure I did this correctly, not sure what you meant by "Alternator FIELD terminal).
I assumed you meant the yellow wire that excites the alt.  This is what I did. Black lead to unplugged yellow wire.  Red to + on battery. Results = 12.03

I hope this helps. I do appreciate the input.

(Test 1) What, exactly.... did the meter *setting position have written beside that setting?   Your leads were placed to read VOLTAGE.  The test device might not be working now or accuracy may be shot.

 
IF, if...the meter is correct in (Test 2 and 3) you have NO battery charging.  Probably no alternator charging either but your tests cannot reveal that the way you had the leads connected.

 
(Test 4) has no useful information.

 
Continuity is a test using proper tools and methods to qualify the BASE integrity of a wire or circuit.  Think of continuity testing in that it proves ONE wire or connection or switch is capable (or not) carrying electricity.  It's NOT a load test, only that a circuit is available.  Normally a very low voltage is placed across the tester leads and then OHMS are read at the setting selected.  This test does NOT insure the circuit can operate properly.

 
It would be advisable for you to follow testing procedures precisely as advised using a simple test light and multimeter.  The test light can provide a quick indication of voltage and ground and is useful in testing voltage drops and opens at connections.  You need to test starting at the start, the beginning of the circuit, and confirm each connection and device is operating properly.

 
Step ONE should be to confirm the alternator is wired correctly,  voltage and grounds are sound and proper, and the signal to begin charging is present with key on.  Best I can tell, this has not been confirmed.  Pretty basic steps and pretty easy to explain, IF each step is followed exactly and each result is accurate and understood.   Lets say your Test 2 was correct.  That means the wire to and from the alternator and battery has continuity, but does not prove it is adequate to carry load.  Test 3 then, would indicate the alternator was NOT charging.  That dictates that the excitation circuit needs to be tested.  Plenty of members here who affirm there is NO charge light on these models, the LT25's.  A charge light indicator uses the resistance in the bulb  filament to place a small load on the excitation circuit and thereby create magnetism to begin the charging.  Some alternator systems, delco among them, utilize a voltage with no resistance to switch the regulator.  In either case the signal wire can be disconnected and the signal can be tested. Key off, no voltage. Key on, voltage present at the disconnected wire.


These are basic tests and as such might entail a variance during testing steps.  There is NO benefit in testing other points if the circuit isn't proven sound from the beginning.  You must use correct settings on your test device. You must have the clips affixed soundly to the test points.  The test points must be the correct ones for the tests to be taken.  Don't waste your time testing anything if you aren't sure what to expect and how to do it.  This isn't the place to experiment.  If expected results are not achieved, double check what you did before replacing or repairing.  Honest, this isn't that hard.

[Jim_Rogers]

Sorry, I didn't know this model didn't have a red light.
I'll back out now, and not offer any incorrect advice.
Jim Rogers

[mike_belben]

Test one you misplaced the positive lead We need to know that the alternator CASE has a path to ground, it should not have continuity the way you tested, from the charge lug to negative.  It should have continuity from charge lug to battery positive post. 



So far its sounding like a bad alt. I dont remember if youve replaced it or not.  No idea what alt you have or what wires go to what.  Any alternator needs voltage to excite the field windings and make magnetism.  Youve got none.  

[biggkidd]

This is probably to simple to be possible but have you made sure the alternator belt is tight and not slipping? My daughters truck kept having a dead battery because her belt was slipping enough to keep it from charging well. Amazingly not all slipping belts make noise. New mill new belt might have stretched a little during break-in.

[Ben Cut-wright]

@biggkidd:

Interesting thought, but it is hard to imagine a loose belt is the problem since he has replaced the alternator.  Surely he would have noticed a loose belt on the original unit and certainly must have know to tighten the belt when he installed the new one. 

[bannerd]

You'll need a multi-meter... you'll need to contact the positive post on the alternator and then ground it.  Typically found by itself off set to the housing.  The alternator needs to be reading around 14v.  Anything lower than that and you're out of load range and your battery will never fully charge or become retarded from the incorrect load.  If it's the IGN/IND switch you can test that fairly easy, a fault would degauss the magnetic current to the circuit.  A flat blade screw driver to the back of the alternator on the center cap/split ring location will stick to a working alternator because of the magnetic field.  

If it is not present or engaged cross the two wires where plug is and test the magnetic field again.  Sometimes this will not engage until an certain rpm is met which gives the rectifier a certain level of charging capacity to excite it.  If this is a self energizing alternator then you most likely will not have the above, just a single wire out feed.  Isolate the alternator by removing the positive wire and the ign/ind plug.  If that is outputting 14v AT the alternator then you know it's not that and move to the next problem.