I have a cat 322cl Hek00405 3126 engine. The screen is displaying “battery voltage irregular” . I checked everything and I am at 25.8 volts during operation. I was told the air inlet heater may not be turning on and causing this message. I checked the air inlet heater solenoid. It had rusty nuts on everything under the rubber caps. I have ordered a replacement solenoid. My issue is as I was trying to get the nuts off, my wrench touched the positive post of the solenoid and I think I may have shorted the relay signal upon start up. The key was on and I didnt realize it. Is there a fuse that goes to the air inlet heater signal? I will know more when I get my new solenoid in. Thanks guys.
That sounds a bit on the low side. Usually a nominal 24v system will charge at around 27v.
It looks very much like an alternator failure.
Alternator failure? I completely disagree. @cor21e , where are you checking voltage at?
I checked at the batteries. There are 4 batteries. On a google search I have heard if the air inlet heater cant turn on, it sends a code of irregular voltage.
Interesting. If you go to the performance menu on the monitor, it should display voltage. I wonder what that says?
It might pay you to check at the alternator output terminal.
Once the irregular voltage mesage comes up, the monitor will not allow you to use any functions or buttons.
A friends Honda Civic with 550,000 km on original alternator was acting up. I tested his alternator and yes there was amps but also there was more than the allowable AC leakage voltage coming out of the positive output post. A month later he had a code on dash for irregular voltage. Changed his alternator and the problem is gone and the high AC leakage is gone also. Not saying this is your problem, but these tests can be done in 10 minutes or less most of the time. Post #2 by Nige is correct, 25.8 volts is way to low. Normal would be around 27.5 to 28 and a bit unless if you have a faulty battery or cables. Have you tested the positive and negative cables for voltage drop. Worth doing some tests before firing the parts cannon. Simon C
Jeez I feel like I’m crazy here. 28 volts? Normal? I’ve never seen a 24 volt machine charge at 28 volts. 27.5 yes but not very often. I may not have the experience you do but I’ve been working on CAT equipment for 20 years. I’m sorry, not trying to argue with you or anything just surprised. Maybe the alternator does have an issue like your friend’s Honda. I have never seen an alternator intermittently not charge. They don’t charge at all or over charge. But hey, first time for everything. An electrical class I took a long time ago said charging range for 24 volt machines is 25.5-27.5. Again not trying to argue just sharing info. Does your machine display this message frequently enough you can run it with a your voltage meter in the cab? Or secured outside a window so you can see what voltage the alternator is putting out when the message comes on the screen?
I sometimes think we get hung up on values that aren’t accurate or understood very well. When people mention single phase power, they say 110, 115, 120 or for double phase they say 215, 220, 240. A 24 volt system, in my experience charges at about 27.5 volts optimal, depending on which meter I use. Since I rarely have my meters calibrated anymore, I just round that to 27 volts. I have been told a perfect 12volt battery charges to 12.6. Is that true? I think so. I do know a 12 volts system will charge to 14-14.5 volts, have as high as 15.5 and overcharged at 17.5. Same with 24 volt systems. Anything over 25 is good anything over 28 is bad. The AC leakage, is a good indicator of the field integrity. I do know that on new machines and vehicles, battery’s and charg systems are very finicky. When it comes to HD’s, first and most important, is a good battery. That fixes about 90% of the problems that arise.
Was the generator voltage measured?
Sorry but this is from Caterpillars Systems Operating testing and Adjusting A 13.1 volt charge rate times 2 is only 26.2 volts which is the minimum to charge 2 batteries not one without charging issues. I use 2 different Fluke 87-V meters and they both read within 0.01 volts of each other. And for people who don't know, if one diode is burnt you will still get 1/3 output which will be sufficient until the cold weather hits, the extra lights and heaters come on and the batteries don't get sufficiently charged. I have had alternators that charged for 1/2 hour till everything is very hot then dropped out completely. Not here to make someone feel bad just sharing what I have always used from the source I learned it from and which is what my meters have always shown. If I can help , be more than glad to share. Simon C
Interesting. Thanks for posting that. What’s The media number of that book?
It is SENR2947-01 Dated May1995, and yes there will be newer ones but doubt the numbers will have changed much. Nige would have the latest and greatest. Maybe he will post if something is wrong, but I have seen these exact numbers on my meters many times. Hope it helps. I was not born knowing these things, have learned over a long time. Simon C
Latest is marked CHG12 from 2009.
Great thank you! That was my next question, if you regularly see 28 charging volts on your meter.
Because I live where it does go to -30C for at least 10 days of winter or more and maybe 1-5 days around minus 40C I can tell you that charging and starting systems get tested to the max. After a start up which does suck the batteries down a lot especially if they are using a Proheat to heat the block powered off of the batteries, it is not uncommon to see 28.4 volts on start up and will stay that much all day if the heaters get turned on and the lights are on. Just my personal experience. Have worked in minus 45F in Northern Ontario before and start circuits get torture tested. Often see 27.5 or more, if engine is revved rarely see less than that. Simon C
Was wondering Nige if your newer Document CHG12 has very much difference from what I posted in picture on posting#12. Simon C
For your information, see the Caterpillar SENR2947 manual, section "Alternator Test Description (SENR2947-12)." In 24-volt systems, a voltage below 26.2 volts is considered a malfunction, as is a voltage above 28.9 volts. In this case, the voltage on the running vehicle with four batteries was 25.8 volts.
I dunno. You tell me.
Once, a customer argued with me that the problem wasn't the alternator, but the machine and its wiring, or the batteries. This was on a D6R. The customer had installed some alternator, repaired at a dubious service center, and it was outputting 33 V into the electrical system. This customer tried to convince me the alternator was working properly. I had to remove the main + cable from the alternator with the engine running to confirm that it was outputting 33 volts, even without the tractor's system. You can do the same on this excavator: remove the cable and measure the alternator voltage with the engine running at full speed.
Thanks Nige. The numbers are all the same, but the newer layout is better to help people. So my old publication will still work. Simon C
Hard to beat metered results as long as the test is done correctly. One customer told me his starter was not defective, I told him I would remove for free and reinstall the new one if his was okay. Told him if his was no good, he would pay for it all. I tested with my meters and pulled the hydraulic pump and oil to get starter out. His starter was no good, and he finally admitted someone had sold him a defective starter. He paid for it all. Simon C
Like the idea, that the cable can be removed from battery end and tested. Experience is worth trying. Simon C
Thank you, I have never used the starting and charging system analyzer. He was measuring voltage at the batteries, I wonder what he’s getting at the alt.
You should get the same voltage at battery as compared to the alternator positive output post minus a tiny loss for cables and maybe a circuit overload breaker.. If the voltage is way lower at the battery as I have found before then, then there is loss of potential in the cable or circuit breaker if it has one. Simon C
Not taking side on the charging rate debate, but -temperature- definitely affects charging voltage. The lower the temperature the higher the voltage required for the same amps 'rate'. The battery internal resistance increases at lower temperatures and requires a higher voltage to overcome the resistance. Example: a charge rate (amps) at 25c might require 27.6v but the same "rate" at 0c would require 28.7v It stands to reason that someone checking 'voltage' in a controlled heated environment would see lower voltage readings. The lower temperature/higher voltages also shortens the battery's life.
That is a good explanation for those folks that don't or haven't thought about the effects of cold on batteries and charging systems. Cannot disagree with a word you quoted. Good job. Simon C
Ok. So I installed a permanent voltage meter on my machine in the battery compartment. Hooked it up to key-on power. Been trying to figure this dumb code out for months. It is 69:167-08 someone thought it was my green alternator exciter wire. So I Found the other end of it in the pump ecm housing. Green 403 wire on diagram. No continuity. It had a break in it. Bought a wire break tester. It was severed about 10 inches away from the alternator. Pulled on the wire and it popped right in half. Butt spliced it and the code is gone. The voltage is reading 27.8 at full throttle now.
Hi Cor21e, Thanks for the feed back, Good to here you have finally cracked it. I read some of this post back in September but I did not comment as it seemed you were getting plenty of help. I thought i would just say to you not to have a melt down as you may see your charge voltage go to 28.4V on your screen at times and that is perfectly normal. What is also worth considering is that if one smaller wire in your loom has fractured due to presumably vibration or flexing, what is the state of the other wires in the area of that fracture? Cheers
Thanks. The loom for the alternator has very few wires in it. The machine has 14,000hrs. But runs like a top now. I know i will have problems like this but I bought the machine for dirt cheap so maybe its worth it???
Thanks for the follow up. Been wondering about this one because I’ve never seen or heard of that fault before. Good info in this thread. Thanks! FWIW 403 green is the r terminal. Used for engine running and charge signal. Glad you found the problem!
Butt splicing doesn't have a reputation for longevity on this type of equipment as dirt/condensation can get into it relatively easily. A soldered joint covered with heat shrink or a single wire repair connector might be a better bet in the long term.