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Discussion Starter · #1 ·
There should be a failsafe program that will allow the volt’s GAS engine to be jumpstarted when the 12v AGM is dead.
My 2017 went completely dead after 5 days parked at the airport. I could not get it going with an emergency jumper all it did was provide some power to the electrics but failed after the AGM sucked it dry. I could not get moving immediately as all our luggage was on the ground as the jumper was still attached in the luggage area etc.
I basically had to get another vehicle to charge up the AGM suffiently to safely get going.

Dead batteries happen and there should be a way to get that motor going while parked in an emergency.

If it is in the manual, sorry but I could not find it.
 

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There should be a failsafe program that will allow the volt’s GAS engine to be jumpstarted when the 12v AGM is dead.
My 2017 went completely dead after 5 days parked at the airport. I could not get it going with an emergency jumper all it did was provide some power to the electrics but failed after the AGM sucked it dry. I could not get moving immediately as all our luggage was on the ground as the jumper was still attached in the luggage area etc.
I basically had to get another vehicle to charge up the AGM suffiently to safely get going.

Dead batteries happen and there should be a way to get that motor going while parked in an emergency.

If it is in the manual, sorry but I could not find it.
If the 12V AGM battery had developed an internal short in one of the 6 battery cells it could account for why the small LiPo jump starter could not jump start your Volt. If you had disconnected the battery cable from the negative terminal of the 12V AGM battery the LiPo jump starter would have been able to boot up the Volt's 12V systems. Once the Volt's system had been booted up the Volt's accessory power module (APM) provides power for the Volt's 12V systems, you could disconnect the LiPo jump starter and even leave the 12V AGM battery disconnected and the Volt would continue running. (Not sure why you could not keep your Volt running; once the Volt powers up the APM should keep the Volt running even without the LiPo jump starter connected and a dead 12V battery (a failed 12V AGM battery with a dead short in one of the cells would draw an excessive amount of power put a large load on the APM system.) If there is a problem with the Volt's APM system that might ultimately be the source of your 12V AGM issue.

There is another possibility. If by mistake you had started the Volt in maintenance mode (initiated by pressing and holding the Start button for 5 seconds) then the APM would not be activated and the Volt would only be running on the 12V AGM battery and/or the LiPo jump starter for as long as the 12V battery or jump starter charge lasted, then the Volt would shut down for lack of 12V power.

There is no conventional starter motor or alternator in the Volt. The APM takes the place of a conventional alternator and provides 12V power for the Volt's 12V systems and accessories when the Volt is powered on. When the Volt needs to spin up the gas engine, motor generator A (one of the Volt's two electric motor/generators) is coupled to the ICE via a clutch and planetary gears and spins up the gas engine. In this application MGA is functioning as a 100 HP electric motor powered by the Volt's 340V traction battery. MGA effortlessly spins up the Volt's gas engine.

If you want to start the Volt's ICE, open the hood and the gas engine will start provided the Volt has been powered on.
 

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Not sure you are aware... the 12V does not start the ICE, the traction battery does. But in order for that to happen, the car has to boot properly. That is why you got stuck, the 12V was too dead to boot the car, so nothing could happen.

There was a bug in early Volts that left some sort of bluetooth module stay on and it drained some AGMs. Wonder if you had a similar issue? Five days should not be long enough to cause an issue. The fact that a jump pack didn't work makes me really suspect you have something draining your AGM all the time (anything aftermarket you hooked up?), or you have a bum AGM.
 

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Your AGM 12V battery probably needs to be replaced if it only lasted 5 days, or as said above you have something continuously draining it. Your jump pack may also be suspect if it didn't get things going and you required a vehicle boost.

The "failsafe" with any vehicle is a proper jumpstart with a decent jump battery/vehicle and good cabling....
 

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Your AGM 12V battery probably needs to be replaced if it only lasted 5 days, or as said above you have something continuously draining it. Your jump pack may also be suspect if it didn't get things going and you required a vehicle boost.

The "failsafe" with any vehicle is a proper jumpstart with a decent jump battery/vehicle and good cabling....
This is correct. The failsafe is a jump start, just like with any other car. There are no cars that can self-rescue from a dead starter battery. It requires some outside energy like jumper cables, a jump pack, a trickle charger, etc. Other options include: Cars with a manual transmission can bump start if you are on a hill or have several strong friends handy. A Model T can hand crank.

The high voltage traction battery is disconnected and its power is inaccessible when the car is off, for safety. It will not reconnect until the car's systems have booted up, again for safety. Therefore it can not be available for starting the car. It is designed this way on purpose.
 

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So let me understand this - Your high voltage battery was also dead - you had no EV range? My understanding is the high voltage battery charges the 12v battery - as Barry says in another post "The 12V battery charges whenever the car is turned on, even if the engine is not running. Its voltage also is maintained whenever the car is plugged in." So once you got the car on, you should have been good to go. So no need to get the engine going, although I would guess Hold mode would work for that.

I would have thought it would have worked to put the charger on the jump start points under the hood, turn it on, and go. No need to unload and reload. No need to get the ICE going to recharge the 12v battery. No need for the 12v battery charged in order to drive. It's just there to activate the main system battery.
 

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Discussion Starter · #7 ·
Thanks for the replies as this has been really bugging me. Not sure if I would take this on a trip where it would be left for an extended period atleast without testing it first. On the positive it has been a reliable daily driver.

Jcanoe thanks for the detailed explanation. Not sure if I triggered maintenance mode. I particularly remember leaving the family outside in the snow while I accessed the jumper and AGM via the backseat as the hatch would not unlock. Then the electronics came briefly. Not enough time to disconnect or even load the car to get going safely it was dead by that point.

There are lots of interesting details and tips in your post that I did not try like isolating the AGM or opening the hood.
Too bad I could not easily find all that in GM’s online volt manual from my phone at the time, it might have saved allot of hassle.
 

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There should be a failsafe program that will allow the volt’s GAS engine to be jumpstarted when the 12v AGM is dead.
My 2017 went completely dead after 5 days parked at the airport. I could not get it going with an emergency jumper all it did was provide some power to the electrics but failed after the AGM sucked it dry. I could not get moving immediately as all our luggage was on the ground as the jumper was still attached in the luggage area etc.
I basically had to get another vehicle to charge up the AGM suffiently to safely get going.

Dead batteries happen and there should be a way to get that motor going while parked in an emergency.

If it is in the manual, sorry but I could not find it.
I have no experience to back this up, but if the VOLT is the car that's dead, you're supposed to use the jump connectors under the hood. If you're jumping another car, you're supposed to use the battery connectors in the cargo area. I've always wondered if that was specifically that way because there were diodes or relays in place to cut the 12V AGM out of the circuit when it's dead, at least during startup, specifically so that it doesn't become a giant electron trap.
 

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I have no experience to back this up, but if the VOLT is the car that's dead, you're supposed to use the jump connectors under the hood. If you're jumping another car, you're supposed to use the battery connectors in the cargo area. I've always wondered if that was specifically that way because there were diodes or relays in place to cut the 12V AGM out of the circuit when it's dead, at least during startup, specifically so that it doesn't become a giant electron trap.
I believe the Volt's jump starter connection points under the hood are on a fused circuit. The Volt draws no more than 500W (~40 amps @ 12.6V) to boot up the electronics. If you are jumping another vehicle, one that is not another Volt, the vehicle needing the jump will have a 12V starter motor, can draw more than 100 amps when turning over the engine. To jump another vehicle the jumper cables must be directly connected to the Volt's 12V AGM battery terminals.
 

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I believe the Volt's jump starter connection points under the hood are on a fused circuit. The Volt draws no more than 500W (~40 amps @ 12.6V) to boot up the electronics. If you are jumping another vehicle, one that is not another Volt, the vehicle needing the jump will have a 12V starter motor, can draw more than 100 amps when turning over the engine. To jump another vehicle the jumper cables must be directly connected to the Volt's 12V AGM battery terminals.


This is correct. On the Gen1, the charging post under the hood is the same electrical point as the + term of the AGM with the only difference being a couple of additional fuse(s) in series...
 

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One thought is that if you use the connection points under the hood to jump a dead 12v the ICE should start up because the hood is open. This would not happen if you are jumping the 12v directly in the cargo area. Maybe this is part of why the Volt engineers want you to jump the Volt with the under hood connections. You could then put the Volt into MM and charge up the main HV battery in addition to charging the 12v.

Not sure how the Volt reacts with a damaged or shorted, or even a disconnected 12v after it is "running".

VIN # B0985
 

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One thought is that if you use the connection points under the hood to jump a dead 12v the ICE should start up because the hood is open. This would not happen if you are jumping the 12v directly in the cargo area. Maybe this is part of why the Volt engineers want you to jump the Volt with the under hood connections. You could then put the Volt into MM and charge up the main HV battery in addition to charging the 12v.

Not sure how the Volt reacts with a damaged or shorted, or even a disconnected 12v after it is "running".

VIN # B0985
My understanding is that the Volt will continue to run if the negative lead of the 12V battery is disconnected after the Volt has been started. When connected the 12V helps smooth out the peaks and valleys of DC voltage levels in the 12V system, acting as a large filter for voltage spikes. Many conventional vehicles can run with the 12V battery disconnected, relying on the alternator for 12V system power. The Volt is designed to run with the 12V battery connected but if the 12V battery is completely dead or you suspect an internal short in the 12V battery the Volt will run without the 12V until you can install a replacement 12V battery.
 

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The manual does say you can use a Volt to jump start another vehicle by connecting directly to the Volt's 12V battery terminals. However, I would be reluctant to do that due to potential damage to the electronics. That is a more common concern with all kinds of modern cars, and the Volt probably has more electronics than average. I now carry a portable jump starter for starting other cars (mine or other people's). I have one of the new battery-less ones that has super capacitors.
 

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The manual does say you can use a Volt to jump start another vehicle by connecting directly to the Volt's 12V battery terminals. However, I would be reluctant to do that due to potential damage to the electronics. That is a more common concern with all kinds of modern cars, and the Volt probably has more electronics than average.
Same here. I'm NOT pulling all my stuff out of the trunk and opening everything up just to give someone else a jump-start and I don't really want some unknown person under the hood of my Volt. A "Booster Pack" is the way to go these days.


Basically the Booster pack starts the computers, the computers start the High Voltage Battery (HVB) and the HVB starts the engine. If that doesn't work right off the bat you have bigger issues that need to be addressed.
 

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Same here. I'm NOT pulling all my stuff out of the trunk and opening everything up just to give someone else a jump-start and I don't really want some unknown person under the hood of my Volt. A "Booster Pack" is the way to go these days.


Basically the Booster pack starts the computers, the computers start the High Voltage Battery (HVB) and the HVB starts the engine. If that doesn't work right off the bat you have bigger issues that need to be addressed.
What about a helping a family member whose vehicle needs a jump assuming they can provide excellent references?
 

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Great info! I do carry a spare 12V battery/compressor pack everywhere but not the tools to disconnect a shorted 12V battery. I will add the tools to the tool compartment. I carry the pack so I do not have to use my Volt battery to jump start other cars.
 
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