philc Report post Posted February 10, 2018 I started up the coach today to start on some maintance things that need attending and I was met with a chime going off telling me low battery. The volt gauge would fluctuate between 12 and 14 volts up and down for about a minute then stay steady at around 13.6 volts. I pulled out of the garage shut it down and restarted about an hour later same thing happened. First thing I did to troubleshoot was to put a volt meter on the alternator and sure enough it would bounce up and down between 12 and 14 volts and after a minute or so it would start charging steadily. So I guess my question is, is the alternator itself on it’s way out or is there some type of relay or a malfunction in the ECM that could be the culprit. The coach stays plugged in all the time and the chassis batteries have a tender connected to them so I don’t believe it to be a battery issue. Also checked as many grounds and connection I could find all seems ok. Any other suggestions or help would be greatly appreciated Phil Share this post Link to post Share on other sites
desertdeals69 Report post Posted February 10, 2018 Take the alternator to a rebuild shop and have them load test it and they can tell you if it is putting out the correct volts and amps. Share this post Link to post Share on other sites
campcop Report post Posted February 10, 2018 Are you sure it’s not the air heater on the engine drawing amps when you first start it up. Ours does that for several minutes. Even the lights will dim a bit when the heater cycles.. thats a common complaint over on the TVRN from folks that have just noticed this happen or new owners. Share this post Link to post Share on other sites
wildebill308 Report post Posted February 10, 2018 3 hours ago, Philc said: I started up the coach today to start on some maintance things that need attending and I was met with a chime going off telling me low battery. The volt gauge would fluctuate between 12 and 14 volts up and down for about a minute then stay steady at around 13.6 volts. I pulled out of the garage shut it down and restarted about an hour later same thing happened. First thing I did to troubleshoot was to put a volt meter on the alternator and sure enough it would bounce up and down between 12 and 14 volts and after a minute or so it would start charging steadily. So I guess my question is, is the alternator itself on it’s way out or is there some type of relay or a malfunction in the ECM that could be the culprit. The coach stays plugged in all the time and the chassis batteries have a tender connected to them so I don’t believe it to be a battery issue. Also checked as many grounds and connection I could find all seems ok. Any other suggestions or help would be greatly appreciated Phil Phil, try holding down your battery switch to tie your battery's together. Let us know if that helps. Bill Share this post Link to post Share on other sites
philc Report post Posted February 10, 2018 52 minutes ago, campcop said: Are you sure it’s not the air heater on the engine drawing amps when you first start it up. Ours does that for several minutes. Even the lights will dim a bit when the heater cycles.. thats a common complaint over on the TVRN from folks that have just noticed this happen or new owners. When you say air heater on the engine i assume you are referring to the grid heater for starting. I guess its possible though it has never done this before. If you are referring to the cockpit heat all lights and accessories are off. Share this post Link to post Share on other sites
philc Report post Posted February 10, 2018 41 minutes ago, WILDEBILL308 said: Phil, try holding down your battery switch to tie your battery's together. Let us know if that helps. Bill Bill I tried holding down the battery switch it helped slightly i'm guessing the added amps the house batteries gave it but the alternator still charged on and off for about a minute. Share this post Link to post Share on other sites
philc Report post Posted February 10, 2018 On the Cumming engine does the grid heater in the engine cycle on and off until the engine reaches a certain operating temp.? If so I guess it would be cycling the heater on and off for a longer period of time in colder weather. My garage I keep between 45 and 50 degrees in the winter. This is the first year its been kept indoors for the off season and the past two years of ownership I never really started it up until the end of April when the temps are in the 60's. I wonder if its all related. I'm going to give freightliner a call and see if they can shed any light on the situation. Phil Share this post Link to post Share on other sites
richard5933 Report post Posted February 10, 2018 Is your engine hunting for proper idle speed during this or is the engine running smoothly? If the engine is trying to find its idle after a cold start that may be the only issue. Otherwise, I'd first start with all the easy things like checking connections, belts, ground straps, etc. These can all create problems that are normally not noticeable but which will show at times of higher demand, like after a cold start. Beyond that I'm not really able to offer much advice since your system has many more moving parts that what I'm used to. On our bus I'd check to see if the regulator is sticking, but I'm sure that you have an electronic system and not a mechanical regulator. I'd would suggest though that any type of heater or accessory sounds like a red herring here, assuming that it hasn't been a problem in the past. These diesel engines typically have a more-than-adequate alternator which can run all the accessories installed and then some. Share this post Link to post Share on other sites
abyrd Report post Posted February 10, 2018 6 hours ago, Philc said: I started up the coach today to start on some maintance things that need attending and I was met with a chime going off telling me low battery. The volt gauge would fluctuate between 12 and 14 volts up and down for about a minute then stay steady at around 13.6 volts. I pulled out of the garage shut it down and restarted about an hour later same thing happened. First thing I did to troubleshoot was to put a volt meter on the alternator and sure enough it would bounce up and down between 12 and 14 volts and after a minute or so it would start charging steadily. So I guess my question is, is the alternator itself on it’s way out or is there some type of relay or a malfunction in the ECM that could be the culprit. The coach stays plugged in all the time and the chassis batteries have a tender connected to them so I don’t believe it to be a battery issue. Also checked as many grounds and connection I could find all seems ok. Any other suggestions or help would be greatly appreciated Phil What you are seeing is pretty much is the same as I see on mine. The voltage will fluctuate between 12.8v to 13.8v as the intake heater cycles, the only time I ever got the alarm was when I didn't use the rig for a couple of month and I forgot to turn the chassis disconnect switch off. I believe there is enough parasite load to discharge the chassis battery while sitting. I replace the factory installed battery combiner solenoid with a Cole Hersee Smart Battery Isolator, 200 Amp rating, PN48530. (Blue Sea also make a marine version of this relay, I have two of them on my boat that has two engines and an inverter/charger.)The relay automatically switches allow the main engine alternator to charge both coach and chassis batteries when running and all allow the inverter/charger to charge both banks when on shore power or coach generator. The only downfall is you don't want you charger/inverter operating in the charging mode when coach main engine is running. Previous to installing this smart relay my chassis engine alternator did not charge coach batteries when traveling. Only way to charge coach batteries was to run generator or plug in to shore power. I have forgotten this couple of times and the alternator idiot lamp came on, no harm was done. Jim Share this post Link to post Share on other sites
manholt Report post Posted February 11, 2018 Only thing I can think off is a slipping belt. Share this post Link to post Share on other sites
philc Report post Posted February 11, 2018 1 hour ago, richard5933 said: Is your engine hunting for proper idle speed during this or is the engine running smoothly? If the engine is trying to find its idle after a cold start that may be the only issue. Otherwise, I'd first start with all the easy things like checking connections, belts, ground straps, etc. These can all create problems that are normally not noticeable but which will show at times of higher demand, like after a cold start. Beyond that I'm not really able to offer much advice since your system has many more moving parts that what I'm used to. On our bus I'd check to see if the regulator is sticking, but I'm sure that you have an electronic system and not a mechanical regulator. I'd would suggest though that any type of heater or accessory sounds like a red herring here, assuming that it hasn't been a problem in the past. These diesel engines typically have a more-than-adequate alternator which can run all the accessories installed and then some. Richard The engine runs smooth and idles fine slight change in rpm when the alternator cycles on and off Phil Share this post Link to post Share on other sites
abyrd Report post Posted February 11, 2018 Good point Carl, always look for the simple things first. Jim Share this post Link to post Share on other sites
philc Report post Posted February 11, 2018 1 hour ago, abyrd said: What you are seeing is pretty much is the same as I see on mine. The voltage will fluctuate between 12.8v to 13.8v as the intake heater cycles, the only time I ever got the alarm was when I didn't use the rig for a couple of month and I forgot to turn the chassis disconnect switch off. I believe there is enough parasite load to discharge the chassis battery while sitting. I replace the factory installed battery combiner solenoid with a Cole Hersee Smart Battery Isolator, 200 Amp rating, PN48530. (Blue Sea also make a marine version of this relay, I have two of them on my boat that has two engines and an inverter/charger.)The relay automatically switches allow the main engine alternator to charge both coach and chassis batteries when running and all allow the inverter/charger to charge both banks when on shore power or coach generator. The only downfall is you don't want you charger/inverter operating in the charging mode when coach main engine is running. Previous to installing this smart relay my chassis engine alternator did not charge coach batteries when traveling. Only way to charge coach batteries was to run generator or plug in to shore power. I have forgotten this couple of times and the alternator idiot lamp came on, no harm was done. Jim Jim What you say kind of makes sense I never had this happen before but then again I never started the engine when it was below 60 degrees. I ‘m going to have to experiment with a few different things,. I like the idea of that battery isolator. I have a battery tender connected to my batteries and is on whenever I plug in. Thanks Phil Share this post Link to post Share on other sites
philc Report post Posted February 11, 2018 14 minutes ago, manholt said: Only thing I can think off is a slipping belt. That’s one of the first thing I checked. I would think it would probably squeal as well Share this post Link to post Share on other sites
richard5933 Report post Posted February 11, 2018 Phil, If this is your first experience starting the engine in colder weather, it might be a good idea to either read through the manual or call the dealer for a few pieces of information related to how your specific engine behaves in colder weather. If you did not have an engine heater plugged in to pre-warm the engine then it is normal for a diesel to have a few moments of 'hunting' for the correct idle speed before evening out. During the time your engine is trying to get itself going there's a good chance that your alternator is not doing anything and the light would be on (or on & off). Even on our purely mechanically-controlled engine there is a specific sequence of things that take place on startup, all controlled through relays and pressure sensors. It runs through a series of checks before letting the next thing happen. In warmer weather these all happen so fast that you really can't see them, but on a cold start they seem to happen in slow motion. The system checks for oil pressure, coolant level, air pressure, and so on and so on. The regulator won't call for the alternator to make power until certain set points are reached to keep the engine from being taxed until all systems are good to go. I bet that your engine goes through a similar system, although electronically rather than mechanically. Once your engine idle smooths out does the light go off and the voltage read correctly? If so, I wouldn't worry too much just yet. If you've had a battery tender on while parked your alternator will likely not be calling for charge since there is no need, so the voltage might not be at peak and the gauge won't show a high rate of charge on start up. Also, on some systems having a external battery charger going simultaneously with your engine running will cause problems and errant dash lights to turn on. Some systems will see the outside charge coming in which causes the regulator on the engine's alternator to think it doesn't need to charge, and this will cause the dash light to come on since the alternator is not charging. Share this post Link to post Share on other sites
campcop Report post Posted February 11, 2018 22 hours ago, Philc said: When you say air heater on the engine i assume you are referring to the grid heater for starting. I guess its possible though it has never done this before. If you are referring to the cockpit heat all lights and accessories are off. Yes, the grid heater and yes on ours it cycles for a few minutes or less depending on the temps. Share this post Link to post Share on other sites
hayesfamily Report post Posted March 14, 2018 Speaking from the world of Gas Naturally aspirated engine knowledge - If you are that concerned I would get the alternator to a real genny shop not a Auto Zone or anything like that but someone who specializes in rebuilds of starters and Alternators. They will be able to tell you if the brushes are OK,and verify the diode and Voltage regulator are GOOD then go from there with trouble shooting. This way you are 100 sure you dont have a bad alternator. After that you have all the other options here. Share this post Link to post Share on other sites
philc Report post Posted March 14, 2018 Thought I posted this but I guess I never hit send. Oops I experimented and left the heat on in the garage at 70 for a week started the coach and all was well. I’m guessing my lack of never having to start coach in the cold weather before had something to do with it. Grid heater never really had to work to hard in the warm weather. (I hope) If it happens again I’m just going to pull the alternator and have it bench tested as a few of you have recommended.I will find out in two weeks when I take it on the first trip of the season. Thank you all for your replies and especially to HayesFamily for posting otherwise I would have probably not have noticed my not submitting this post Phil Share this post Link to post Share on other sites
