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Discussion Starter #1
Hello Everyone,
I am new to the forum and I apologize if this question has been already answered(I did a quick search and did not find it).

I have a 2013 Chevy Volt that stopped charging from the wall charger. The 12V battery was fairly old and showing a low charge. I therefore replaced it with a high grade AGM battery and everything worked fine for a couple of days - I could charge from the wall and get close to 36 miles on a charge (Not bad for a battery with 120K miles on it). However, after a couple of days, I was unable to charge from the wall charger. I checked the AGM battery (not under load) and it had a 12.58V, however, the charger indicated it was only at 75%. I then charged the battery to 100% (was well over 13V when put back into the Volt) and once again I could charge from the wall. I was going to replace the ACM thinking the DC-DC converter is going, however, when I plugged in my OBD2, the code was P0AF8 which is for the Hybrid/EV Battery system voltage. I have taken it into two Dealers, and one recommended replacing the BECM and the other the Battery Relay Assembly (I am not sure how they deduced the relay assembly and they could not really explain it). Any ways, I would appreciate your insight and feedback. Also, do you think replacing the ACM would fix the issue?

Thanks

JJ
 

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What happens when you start the Volt and then open the hood? (do this while parked outside or with the garage door open) The gas engine should start and unless the traction battery pack is fully charged the Volt should start charging, continuing charging for ~20 minutes. You should observe one or two bars of the battery state of charge increase. If the Volt stops charging before the battery is fully charged, if you wish, you can shut off the Volt, then restart and the Volt should charge for another ~20 minutes. This test may provide some insight into whether the problem is with the on-board charger or the BECM and/or battery relay assembly.

It was a good idea to replace the 12V battery with the correct AGM-type replacement battery. 12.58V is fine with no load.
 

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Be aware that when you charge the battery with a battery charger that it has to be one capable of charging an AGM battery. Not all are and the requirements are different to a regular lead acid battery. The requirements of a gel battery is different again. You shouldn't be charging an AGM or gel battery with any which battery charger.
 

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Discussion Starter #4
Thanks and i will try tomorrow. Question: What about the ACM? Is it possible the DC-DC converter is just not working?
 

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Discussion Starter #6 (Edited)
Clever response - Able to get my Traction battery in my Gen1 Volt (2013)to charge again (I had to charge the 12V battery to over 13V outside the car to a full charge) and took it out for a spin till the Traction battery dropped to 21 miles. I then opened the hood and it immediately went to the Gas Engine (ICE). After about 18 minutes, the traction battery was charged to 23 miles. I then turned off the car, shut the hood, and restarted. The car went to the Traction battery and was at 23 miles. I then opened the hood again and the car went to ICE. After 25 minutes, the Traction battery was at 25. Pls note that in this state (12V Battery fully charged), the volt traction battery will charge via the EVSE/OBCM (off the wall charger) and work for 2-3 days until the charge on the 12V battery drops. Once the 12V battery drops, the traction battery will not charge through the EVSE/OBCM. Once the traction battery stops charging through the EVSE/OBCM, I get a Check Engine Light (CEL). I then attach my OBDII and get the following two permanent codes:
P0AF8 - Hybrid/EV Battery System Voltage
P0D22 - Battery Charger Output Current Performance.
I also get a P1E00 which is a code with no Definition on my OBDII. However, my OBDII does say that common fixes are a) replacing Power Inverter Module Assembly Cable Cover, b) replacing X98 Hybrid/EV Battery Charger Receptacle w/POCD2,POd26
Thanks again for you help and apologize for the slow response. Any additional insight would be very appreciated.
JJ
 

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Discussion Starter #7
Clever response - Able to get my Traction battery in my Gen1 Volt (2013)to charge again (I had to charge the 12V battery to over 13V outside the car to a full charge) and took it out for a spin till the Traction battery dropped to 21 miles. I then opened the hood and it immediately went to the Gas Engine (ICE). After about 18 minutes, the traction battery was charged to 23 miles. I then turned off the car, shut the hood, and restarted. The car went to the Traction battery and was at 23 miles. I then opened the hood again and the car went to ICE. After 25 minutes, the Traction battery was at 25. Pls note that in this state (12V Battery fully charged), the volt traction battery will charge via the EVSE/OBCM (off the wall charger) and work for 2-3 days until the charge on the 12V battery drops. Once the 12V battery drops, the traction battery will not charge through the EVSE/OBCM. Once the traction battery stops charging through the EVSE/OBCM, I get a Check Engine Light (CEL). I then attach my OBDII and get the following two permanent codes:
P0AF8 - Hybrid/EV Battery System Voltage
P0D22 - Battery Charger Output Current Performance.
I also get a P1E00 which is a code with no Definition on my OBDII. However, my OBDII does say that common fixes are a) replacing Power Inverter Module Assembly Cable Cover, b) replacing X98 Hybrid/EV Battery Charger Receptacle w/POCD2,POd26
Thanks again for you help and apologize for the slow response. Any additional insight would be very appreciated.
JJ
 

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Discussion Starter #8
OK,
The goal is to try and determine if the problem is the EVSE, On-board-charger, BECM, Hybrid battery, Assembly relay, or the APM (or something else). Here are my thoughts and I would appreciate feedback:

1) If the ICE is running, it is able to charge the Hybrid battery -> This
indicates the battery relay assembly and generator are working.
2) The Volt runs flawlessly off the Hybrid battery with no hickups when it starts
in electric mode -> This seems to indicate the inverter and battery
relay assembly are working.
3) If the EVSE and on-board-charger have enough 12V power, they will charge
the Hybrid battery just fine. This seems to indicate the on-board-charger,
BECM and the Battery Relay Assembly are working.
4) It seems like the APM and the 12V AGM battery are the last two options. I
recently replaced the 12V AGM battery and this seems to rule this out.

Is the APM the most likely culprit? Basically, not charging the 12V battery enough?
Any feedback or insight would be appreciated.

Any insight would be appreciated.
 

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OK,
The goal is to try and determine if the problem is the EVSE, On-board-charger, BECM, Hybrid battery, Assembly relay, or the APM (or something else). Here are my thoughts and I would appreciate feedback:

1) If the ICE is running, it is able to charge the Hybrid battery -> This
indicates the battery relay assembly and generator are working.
2) The Volt runs flawlessly off the Hybrid battery with no hickups when it starts
in electric mode -> This seems to indicate the inverter and battery
relay assembly are working.
3) If the EVSE and on-board-charger have enough 12V power, they will charge
the Hybrid battery just fine. This seems to indicate the on-board-charger,
BECM and the Battery Relay Assembly are working.
4) It seems like the APM and the 12V AGM battery are the last two options. I
recently replaced the 12V AGM battery and this seems to rule this out.

Is the APM the most likely culprit? Basically, not charging the 12V battery enough?
Any feedback or insight would be appreciated.

Any insight would be appreciated.
Pickup an inexpensive automotive USB adapter with a DC voltmeter readout. These are under $10, easier to source from Amazon but you may find one at an auto parts store. You plug the USB adapter into the Volt's accessory port and observe the voltage readout. It should start our at ~14.4V and over time drop to ~13.5V or lower but not lower than 12.4V. If you do this with the Volt powered on you are observing the output of the APM. If you turn off the Volt, before opening the driver's door, the accessory port will remain powered on for 10 minutes (at least that is true for the Gen2 Volt like my 2017.) That gives a readout of the 12V AGM battery voltage. It should start out at ~13V and gradually fall to ~12.2V to 12.4V but it should not fall below 12.0V unless you do something like manually turn on the headlights with high beams on too.
 

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Discussion Starter #10 (Edited)
Good idea on the USB adapter with a DC voltmeter readout.
1) When I first start the car, ICE is running, the voltage is 15V and drops down to 14.7V after five minutes and eventually goes to 12.6V.

2)Now, I have let the ICE run for a while and I turn it off. However, I do not open the door. The voltage drops to about 12.4V after about 5 minutes and stays there.

OK, Does this indicate the ACM is working and the battery is charging properly? What bothers me is that when hook up the battery charger, it indicates the 12V AGM is only at a 75% charge.
Any insight would be appreciated.

JJ
 

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Good idea on the USB adapter with a DC voltmeter readout.
1) When I first start the car, ICE is running, the voltage is 15V and drops down to 14.7V after five minutes and eventually goes to 12.6V.

2)Now, I have let the ICE run for a while and I turn it off. However, I do not open the door. The voltage drops to about 12.4V after about 5 minutes and stays there.

OK, Does this indicate the ACM is working and the battery is charging properly? What bothers me is that when hook up the battery charger, it indicates the 12V AGM is only at a 75% charge.
Any insight would be appreciated.

JJ
1) That is within the normal 12V system voltage range for the Volt when powered on; usually the voltage drops to 12.8 to 13.0, not sure why you observed 12.6V. Suggest you observe the 12V system voltage a few more times and see where it settles.

2) That is similar to the 12V readings I observe in my 2017 Volt, maybe even a bit higher.

It appears that the APM is working properly while the Volt is powered on. Charging/maintaining a charge on the 12V takes place while the Volt is powered on. Charging will also periodically take place when the Volt is plugged in. A 75% SOC is normal too; I've only seen that on a new 12V replacement battery. In my Volt the 12V battery readings I observe after shutting off the Volt are ~12.3V (~50% SOC) in a newer battery and 12.2V in a 3 year old battery. It appears the APM is not designed to charge/maintain the 12V battery at anything close to 12.8V to 12.9V (90% to 100% SOC.)
 
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