Captrowdy
Junior Member
Yes accept the truck should not go into battery saver mode which is the problem. Not draw down by intake heater. It appears to be the fact that after draw down something is causing it to go into battery saver mode daily.
Low voltage on start up.
- Thread starter Captrowdy
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06 Dodge
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A grid heater on a diesel engine warms the income air to aid start up in colder temps even thou a Cummins engine in good running condition should be able to start at -20 below zero without the aid of the grid heater...
06 Dodge
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Yes it will keep voltage low as long as the heater is on, the length of how long it stays on all depends on what the air temp sensor reads for the incoming air... It sounds like this is your first diesel so to you it seems really scary to see the voltage drop down so far while grid heater is on, if you notice that your voltage drop is going down more then usual then it would be a good idea to have both batteries load tested just to be safe, when changed out my 13 year old batteries in my old 2006 CTD one of the things I notice was when grid heater first came on in the morning voltage dropped more then usual into the 10.5 volt range...
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Have to ask just what is battery saver mode? I never had such on my 2006 Cummins so can only guess it something they have added to the newer diesel trucks charging system..
Zorin
Member
OK, this is getting overthought!
To start, when you start a diesel, the amperage draw is immense. On a gas engine, roughly 200 amps - on a diesel it could be from 400-700, depending on ambient temps.
Acceptable voltage drop during cranking, it should not drop below about 10.5 VDC. After that, you won't have enough reserve power for things like the engine computer and other items that need to be alive during cranking.
So, here's the quick way I would (and do) test this. First connect a scan tool or AlphaOBD to the truck, and look for a live data PID for PCM Generator Command or something like that. Connect a DVOM to the battery terminals, and start the truck. Watch the voltage drop. It should go from 12. something to 11-ish during cranking, then the truck should start and once the starter is released it should rebound fairly quickly to whatever the resting state was. At this time, you should be showing some percentage of command from the PCM for the alternator.
**Make sure the engine is fully warm to keep the grid heater out of the equation if you can**
Once it's running, and you are certain the grid heater is not operational, run it till you get your 13-14 VDC reading. NOW begin turning on EVERYTHING in the truck. High beam headlights, rear defrost if you have it, crank the HVAC up on high blower. Use as much electricity as you can!
Note the DVOM reading as you activate each item. You should see a dip and then the PCM should command more alternator output on your scan tool, and you should see the voltage increase on your DVOM.
If you see the PCM commanding more output, but the voltage continues to trend toward the battery resting voltage or lower, it's a pretty safe bet that the alternator is having issues.
If this is the case, CAREFULLY and quickly touch the alternator - if it's blazing hot and putting out very little voltage, that's also another bad sign.
Tim
To start, when you start a diesel, the amperage draw is immense. On a gas engine, roughly 200 amps - on a diesel it could be from 400-700, depending on ambient temps.
Acceptable voltage drop during cranking, it should not drop below about 10.5 VDC. After that, you won't have enough reserve power for things like the engine computer and other items that need to be alive during cranking.
So, here's the quick way I would (and do) test this. First connect a scan tool or AlphaOBD to the truck, and look for a live data PID for PCM Generator Command or something like that. Connect a DVOM to the battery terminals, and start the truck. Watch the voltage drop. It should go from 12. something to 11-ish during cranking, then the truck should start and once the starter is released it should rebound fairly quickly to whatever the resting state was. At this time, you should be showing some percentage of command from the PCM for the alternator.
**Make sure the engine is fully warm to keep the grid heater out of the equation if you can**
Once it's running, and you are certain the grid heater is not operational, run it till you get your 13-14 VDC reading. NOW begin turning on EVERYTHING in the truck. High beam headlights, rear defrost if you have it, crank the HVAC up on high blower. Use as much electricity as you can!
Note the DVOM reading as you activate each item. You should see a dip and then the PCM should command more alternator output on your scan tool, and you should see the voltage increase on your DVOM.
If you see the PCM commanding more output, but the voltage continues to trend toward the battery resting voltage or lower, it's a pretty safe bet that the alternator is having issues.
If this is the case, CAREFULLY and quickly touch the alternator - if it's blazing hot and putting out very little voltage, that's also another bad sign.
Tim
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Zorin,
You are correct a diesel at start up draws lot more power/amps compared to a gas engine and until to day did not realize that the newer trucks need even more power then my 06 did, I was surprised when I looked up what Bat save mode was that I found out my 2022 has a 220 amp alt
I recall my 06 had IIRC a 130-140 amp alt so that tells me these newer trucks need a whole heck of a lot more power to run all of the things they installed on all of the newer trucks... For the OP I would still have the batteries load tested as I have been reading that a lot of 3 years old batteries are going bad....
You are correct a diesel at start up draws lot more power/amps compared to a gas engine and until to day did not realize that the newer trucks need even more power then my 06 did, I was surprised when I looked up what Bat save mode was that I found out my 2022 has a 220 amp alt
I recall my 06 had IIRC a 130-140 amp alt so that tells me these newer trucks need a whole heck of a lot more power to run all of the things they installed on all of the newer trucks... For the OP I would still have the batteries load tested as I have been reading that a lot of 3 years old batteries are going bad....Captrowdy
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06 Dodge
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FYI not everyone has Facelessbook, those who don't will not be able to see what's at that link
Captrowdy
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k update went out this morning and New batteries at 12.3 so must have a parasitic draw that new...started truck normal draw down and slow pick back up to 14.4. then sat waiting in truck as it warmed up. At about 8 and a half mins I noted voltage gage stared twitching between 14.4 to 14.3 big deal right? At 10 mins truck went into Battery saver mode and shut none essentials off! So voltage read 14.4 shut truck off tested batteries and they are at 12.7 Restarted truck everything back on and fine! what the hell?
06 Dodge
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Being you say you still have a problem with New Batteries then you need to have charging system looked in to..
