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Discussion Starter #1
Humor me please. I've just gotten my 2017 pachy back from the shop for the third time in a 2 month period. Very strange experience. Problem started with the sulfur smell when charging with the level 1 charger. Around the same time I was also noticing strangely loud ICE engagement when main battery still had plenty of life on it. At the time, I chalked the erratic ICE behavior up to colder weather (mid 30's to 40F), and thought it was separate from the 'boiling 12v battery when charging problem'. First dealer performed some needed software updates but was unbelievably ill equipped to service the hybrid (if you can believe it, they didn't have a functioning charger there). Problem recurred immediately -- dangerously high levels of hydrogen sulfide in my attached garage when charging. Stopped charging the van at home and booked an appointment with the other local dealership. In the meantime I went to Autozone and got the 12v battery checked there. Voltage was ok, but CCA reading is low. No clear indication of a shot cell, but a weakened battery. Here's where it gets weird: When the second dealership charged the van on their level 2 charger, I was told that they had no problem. I then brought in my level 1 charger. Sulfur smell and battery hot to the touch after 50-70% charge is reached. They profess to be mystified and 'open a case' with Chrysler tech support. It all culminates, as anyone here would have predicted (and as I explicitly suggested from the get go) with a new 12v battery being installed. This leaves me with 2 questions: why would the problem happen on level 1 and not on level 2 charging? Has anyone else had a similar experience? (I find this so baffling that I suspect the dealer didn't actually check this carefully). But secondly, mustn't their be a problem in how the condition of the 12v battery is monitored by the vehicle, such that it is 'trying' to charge the 12v when not needed? (On another thread someone even spoke as if it were a known thing that the Pachy doesn't have an adequate 12v battery monitoring system in place.).

Here's my new theory -- sorry for the agonizingly long build up: could the strange/apparently unnecessary ICE engagement also be related to the vehicle 'thinking' that the 12v needs charging? Is the 12v charged from an alternator off the ICE? Or does all charging of the 12v go through the main battery pack? I ask because today, with a new 12v, the van runs amazingly smoothly, with no ICE activation at all -- though it is 39-40F.

Thanks.
 

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I don't believe there is an alternator - so it comes from the main battery pack. The 12v battery seems to be the source of most problems.
 

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I don't believe there is an alternator - so it comes from the main battery pack. The 12v battery seems to be the source of most problems.
So if there is not alternator, is there any way the vehicle's mistaken sense that the 12v needs charging be the cause of the strange ICE engagement? Also curious to know if anyone has experienced the two problems together, the way that I have.
 

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I say there's no way to know. Only the programmer knows the settings. I'd say the 12v battery has issues and must be triggering many flags to the computer.

Sent from my SM-G960W using Tapatalk
 

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In my observations, when you are charging the motive battery the 12v battery also gets charged. The level 1 charger takes a lot longer to do its job than a level 2 charger so that means that the 12v battery is under charge for 12 hours instead of 2. If it has a bad cell then the charging current to the 12v battery won't taper off and the battery will off-gas because it is being overcharged.

The charging of the 12v battery is the responsibility of the onboard charging module (OBCM), the battery pack control module (BPCM) and the hybrid control processor (HCP). The first is embedded in the high voltage battery, the second is attached to it (I think) and the last one is part of the power inverter module (PIM) which is bolted to the transmission. I quote from a technical description of the battery management system:

The PHEV uses several key off specific battery management functions.

- 12V battery maintenance periodic wake-up
- Thermal periodic wake-up

The BPCM will periodically wake up to determine if the LV battery needs to be charged. If it does then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the Hybrid Control Processor (HCP) which will wake up the rest of the necessary Electronic Powertrain (ePT) modules and charge the LV battery.

In addition, the BPCM will periodically wake up to check the temperature of the HV battery pack. If the temperature is found to be too low then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the HCP which will wake up the rest of the ePT and warm the HV battery.


So @1tg1 is correct, there is no alternator. The 12v battery is charged from the motive battery. The motive battery is charged by one of the motors in the transmission. In my opinion the cycling of the ICE could be related. If the 12v battery is low and the ambient temperature is low then the ICE could come on periodically in order to warm up the motive battery while it in turn charges the 12v battery. Obviously it is not going to do that while it is parked in your garage, instead it will use the power from your EVSE, but it certainly will be free to do so when you are out driving.
 

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In my observations, when you are charging the motive battery the 12v battery also gets charged. The level 1 charger takes a lot longer to do its job than a level 2 charger so that means that the 12v battery is under charge for 12 hours instead of 2. If it has a bad cell then the charging current to the 12v battery won't taper off and the battery will off-gas because it is being overcharged.

The charging of the 12v battery is the responsibility of the onboard charging module (OBCM), the battery pack control module (BPCM) and the hybrid control processor (HCP). The first is embedded in the high voltage battery, the second is attached to it (I think) and the last one is part of the power inverter module (PIM) which is bolted to the transmission. I quote from a technical description of the battery management system:

The PHEV uses several key off specific battery management functions.

- 12V battery maintenance periodic wake-up
- Thermal periodic wake-up

The BPCM will periodically wake up to determine if the LV battery needs to be charged. If it does then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the Hybrid Control Processor (HCP) which will wake up the rest of the necessary Electronic Powertrain (ePT) modules and charge the LV battery.

In addition, the BPCM will periodically wake up to check the temperature of the HV battery pack. If the temperature is found to be too low then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the HCP which will wake up the rest of the ePT and warm the HV battery.


So @1tg1 is correct, there is no alternator. The 12v battery is charged from the motive battery. The motive battery is charged by one of the motors in the transmission. In my opinion the cycling of the ICE could be related. If the 12v battery is low and the ambient temperature is low then the ICE could come on periodically in order to warm up the motive battery while it in turn charges the 12v battery. Obviously it is not going to do that while it is parked in your garage, instead it will use the power from your EVSE, but it certainly will be free to do so when you are out driving.
So my question is: you say “The BPCM will periodically wake up to determine if the LV battery needs to be charged. If it does then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the Hybrid Control Processor (HCP) which will wake up the rest of the necessary Electronic Powertrain (ePT) modules and charge the LV battery.” Does this happen even when the van is shut off and sitting in a parking lot for several days? If so, then there’s no good explanation for why my PacHy’s 12v battery went completely dead after being parked for 14 days.
 

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So my question is: you say “The BPCM will periodically wake up to determine if the LV battery needs to be charged. If it does then the BPCM will signal on a hard-wired line to the OBCM. The OBCM will then relay that information through another hard-wired signal to the Hybrid Control Processor (HCP) which will wake up the rest of the necessary Electronic Powertrain (ePT) modules and charge the LV battery.” Does this happen even when the van is shut off and sitting in a parking lot for several days? If so, then there’s no good explanation for why my PacHy’s 12v battery went completely dead after being parked for 14 days.
The owner's manual says that it will wake up every 21 days to see if the 12v battery needs charging. From page 502:

NOTE: The hybrid has feature of periodic wake-up that
occurs every 21 days. This feature charges the 12V battery
from the high voltage battery. This will happen as long as
the high voltage battery remains above the minimum state
of charge. Refer to “Starting The Vehicle” in “Starting And
Operating” for further information.


So if the battery was weak to begin with then it could well have gone dead before the 21 days rolled around.
 
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