My 1990 580K P3 has charging issues. It seems slow to crank, and as of recently needs a jump start to help it out. Using a multi-meter, the battery reads 13.16 Volts when not running, and 14.08 when running. So, I think the battery is fine. I use a gauge on the alternator that shows about 50 amps going to the battery when the machine is running. My battery cables are tight and clean, the negative cable is bolted to the exhaust manifold with a “woven” cable running from there to the frame. The manifold is rusty, and the woven cable is dirty and greasy. Is it possible that the rust and grease could be the problem? I’ve included a pic of the cable. Thanks. John.
Grease & oil ON the cable won't affect your current draw. However those connection points need to be undone cleaned with emery paper, dried & re tightened. There is another one of those cables connecting the battery to the chassis - those mounting points should also get the same treatment. **TIP - You also may want to consider fitting an extra ground cable from the battery directly to one of the starter motor mounting bolts. (after removing paint & rust at the bolt area)
Move the connection from the exhaust to the engine block. Was that original? Those numbers don't add up to me. I've never seen a battery with 13+ resting volts OR 50A charging. Does your multimeter read 13V on other 12 V batteries? Did you have any accessories on when getting that 50A reading?
This it the reading on my battery at rest. I’ve cleaned every cable end, bolt, stud, to and from the battery, starter, and alternator. It seems to crank better, but I don’t think it has the cranking power it should. Could the starter be creating a lot of resistance? The starter seems fine ( no dead spots,) and I’ve never had a starter or alternator issue in the past. The are the original ones since I bought the machine in 1998.
The exhaust manifold has a gasket between it and the block IRRC. So, your connection is dependent primarily on the condition of the bolt threads. As Alrman and Delmer suggested before, put a ground cable directly from the battery to one of the starting motor mounting bolts. Did you check the connections on the starter relay ? Does it get hot when the starter is engaged ? There are meters that will measure the amp draw while the starting motor is rotating. Perhaps you have a starting motor problem. After 20 years of service on that starter, it really should be rebuilt. Regardless of the battery voltage, have you had a load test done on it ? 50 amps charging ??? If that is accurate you have a serious battery or alternator problem.
I just had this same problem with my diesel pickup. It cranked so slow it was affecting the starting. Once I cranked on it so long I saw a wisp of smoke come out from under the hood. So that clued me in that I had a connection problem somewhere. Also the batteries seem to hold power and check out fine. I looked all the connections over at the batteries, no signs of overheating. I then pulled the starter. Everything looked fine there except the nut and the short connection to the actual starter motor looked very clean and rusty, like they had gotten hot. Everything else on the starter was covered in grease and oil except that spot. So it looked like there was something wrong with the solenoid on the starter. I swapped the solenoid out on the starter and all is good, it cranks over very fast now. So looks yours over very good, look for any signs of overheating on the connections. Very clean with no oil is a sign it's getting hot and that is caused by resistance at that connection.
Go out to any vehicle, lawn mower, mobility scooter, and see what the multimeter says for resting voltage. IF your battery is producing 13V+ resting, then the acid is overconcentrated because it's boiled off and doesn't have the amp capacity that it needs to start. 50A charging current will do that...
I checked the voltage of my pickup, and it read 12.6 at rest. The battery in the backhoe is a little over 5 years old. 11/13. As far as 50 amps charging, I just assumed that because the battery took suck a beating trying to start the backhoe, that’s what it was drawing from the alternator to recharge itself once the backhoe was running. Also, I’m going to test the starter amp draw. Does anyone know what a 3.9 non turbo Cummins draws? Thanks.
now I'm worried about your pickup not starting 12.6 is more like a battery voltage. Check the water level in your backhoe battery, while it's out, swap in the pickup battery and see if it starts better. Or check the amps with the old battery, then again with jumper cables run so that the amps all go through the meter, and see how much the added amps improves the starter speed. I'd expect around 200 amps cranking, but I'd bet that's a wide range depending on temp, engine accessories, etc. the 50 amps at 14V is odd, that means the battery is in great condition if I'm understanding correctly, we'll see how this turns out.
Check voltage drop across the battery terminals when cranking (not on the clamps of the cables). Then check the voltage drop across your starter at the starter post and starter ground (again not on the battery cable itself). If for example you have 10 V at both locations and it cranks slow you have a starter issue. If you have 9 V at both locations and it cranks slow then you have a battery issue. if you have 10 V at the battery posts and 8 V at the starter posts with slow cranking then you have a cable issue (Positive or Ground). Easiest way to eliminate starter/battery/cable issues with just a volt meter.
Sorry I haven’t replied back, but I have to find a multimeter that measures DC current, so I can check the current draw of the starter.
I doubt you will find one that will do it accurately that you can afford. The starter draws a lot of current. The voltage drop method described in a previous post is a very accurate way to check the starter circuit, though sometimes it requires two people or a remote starter button. If the voltage reading you are getting at the battery terminals during cranking is the same reading you are getting at the starter itself during cranking, it's safe to say you have a starter problem. That is, if that voltage reading is adequate from a good battery.
Ok, following mg2361’s instructions, I checked voltage across the battery terminals, and the meter showed 10.20V. Measuring across the starter showed 9.75V.
That is not too bad. Battery cables have about 0.1 V drop per foot. So a 1/2 volt drop would be acceptable. Sounds like a starter issue or something in the hydraulics is on/partially on causing a parasitic load while cranking.
Clean battery terminals.
We had a similar issue on our Super L. I took starter off and took it to our local starter/ alternator rebuilder. He checked it out and worked it over for about $150. Cranked like new after that. They are made to be able to rebuild. New one is double that or more from what I remember.
Take the starter off and take it to a competent rebuilder. He will do a load test on it. If the starter checks out OK then there is most likely a parasitic load like mg2361 stated.
We've had problems like this. Starter wouldn't crank with the battery, but add a jumper and off it goes. We cleaned every connection point and terminal there were several times. Turned out inside the starter there are copper connect points that provides current flow. Once these get pitted and sooted up, it requires more amps to spin. The answer was getting the starter rebuilt. Haven't had any issues since. There's a guy in our area that's honest and reasonable who stands behind his work, so we're lucky!