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Discussion Starter #1 (Edited)
Finally my ACdelco AGM -47 ,abandoned me, and the Volt 2014 (battery age from factory 5.5 yrs), at the airport after 5 days of lethal rest. I have been suspicious of the approching failure since the APM was charging not the usual 2 minutes at 14.5-15 volts, but much longer periods of time, up to 5 minutes or longer...but I had the "life raft", plan B, the little LITHIUM Jump/Starter. Well Plan B FAILED totally, the engine did not start, it just produced a myriad of CEL/MIL, and the astonishment of my wife "I though this car was reliable,what the hell is going on...she said"... The little lithium battery was properly connected at the proper fire wall points, got hot but nothing happened except blinkers running and other unwanted fire-works. The police-security of the airport performed the usual jumping and the engine started(hood open), but only after a solid 2 minutes of charging with the jumping cables connected to a real battery. Happy ending, from there we made it home in electric mode, APM charging well up tp 14.7, and car running as usual.. New AGM-47 on the way. This experience and failure of plan B, made me think : The small lithium battery got extremely HOT during the failed attempt, so was it enough to discharge the juice to "wake up" the computer and the main battery ...What happened?.I suspect all the juice went to the totally depleted 12V AGM battery,,,and the Volt did not move. I SHOULD HAVE (at posteriori everything is easy) OPEN the back compartment which was closed ,since no battery, and DISCONNECT the neg. lead of the 12V battery, then I should have retried the small jumper and probably the car will have started, then reconnect the 12 v battery and continue my life. Other observations : If the car is not parked in a completely flat ground, the car will star moving as soon you try to get out of "park"..The E-BRAKE will not work (wish the Volt would have a pure mechanical emergency brake), so carry a "choke" for the tires,or keep your wife stepping on the hydraulic brakes... In any case the faithful Volt will give you an excitement every 4-5 yrs, especially if you live in a hot place. Just remember disconnect your TOTALLY DEPLETED AGM-47, if you are using small lithium jumper, they give high intensity discharge, but brief service. Cheers
 

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Finally my ACdelco AGM -47 ,abandoned me, and the Volt 2014 (battery age from factory 5.5 yrs), at the airport after 5 days of lethal rest. I have been suspicious of the approching failure since the APM was charging not the usual 2 minutes at 14.5-15 volts, but much longer periods of time, up to 5 minutes or longer...but I had the "life raft", plan B, the little LITHIUM Jump/Starter. Well Plan B FAILED totally, the engine did not started, it just produced a miriad of CEL/MIL, and the astonishment of my wife "I though this car was reliable,what a hell is going on...she said"... The little lithium battery was properly connected at the proper fire wall points, got hot but nothing happened except blinkers running and other unwanted fire-works. The police-security of the airport performed the usual jumping and the engine started(hood open), but only after a solid 2 minutes of charging with the jumping cables connected to a real battery. Happy end, from there we made it home in electric mode, APM charging well up tp 14.7, and car running as usual.. New AGM-47 on the way. This experience and failure of plan B, made me think : The small lithium battery got extremely HOT during the failed attempt, so was enough discharge of juice to "wake up" the computer and the main battery ...What happened?.I suspect all the juice went to the totally depleted 12V AGM battery,,,and the Volt did not moved. I SHOULD HAVE (at posteriori everything is easy) OPEN the back compartment closed ,since no battery, and DISCONNECT the neg. lead of the 12V battery, then I should have retried the small 600 amp. jumper and probably the car will have started, then reconnect the 12 v battery and continue my life. Other observations : If the car is not parked in a completly flat ground, the car will star moving as soon you try to get out of "park"..The E-BRAKE will not work (wish the Volt will have a pure mechanical emergency brake), so carry a "choke" for the tires,or keep your wife stepping in the hydraulic brakes... In any case the faithful Volt will give you an excitement every 4-5 yrs,specially if you live in a hot place. Just remember disconnect your TOTALLY DEPLETED AGM-47, if you are using small lithium jumper, they give high intensity discharge, but brief service. Cheers
The small lithium jump starter should normally be able to start the Volt if the 12V AGM battery is weak. If the 12V AGM battery was fully discharged then most of the power from the jump starter was being drawn into the 12V battery at least for the first few minutes. Normally, when discharged, the internal resistance of a 12V battery is fairly high, this would limit the initial current flow. If the lithium jump starter became hot while connected to the Volt then maybe there is an internal short in one of the 6 cells of the 12V AGM battery. Disconnecting the 12V AGM battery would probably have enabled the Volt to be started. There is probably a simple way to test if there is a short in the 12V AGM battery by measuring the battery's internal resistance. Best to replace the 12V AGM ASAP.
 

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Correct, a fully depleted AGM will take a LOT of energy before bringing up the voltage. More than a little 60WH jump pack can provide. The issue is energy, not current. My AGM depleted to 3V after a 12 day absence in 2015, but was able to jump from another car (unsuccessful from a battery charger) to restart. Still on the same 12V AGM today.

There have been various reports about the jump packs. Sometimes they'll work, sometimes not. I carry one myself. Like you said, disconnecting the AGM first would give the best chance for success.
 

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Discussion Starter #4
With the small lithium charger the number of alerts/MIL/CEL was massive,including low batt., all self resolved with new battery. During this mess it was difficult to know if the car was on or off, would not shut down...then is when I tried reverse, and the car started moving forward towards a wall,the garage was down hill..the pedal brake worked well but the electric "emergency " brake was useless, the front of the car finished a few inches from the wall. Pray this does not happen on top of a mountain.LOL
 

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I have a small lithium jumper too. Will remember to remove the rear battery terminal if I can’t start it with the jumper.

Thanks for the information!


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I have a small lithium jumper too. Will remember to remove the rear battery terminal if I can’t start it with the jumper.

Thanks for the information!


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You never want to have the main battery disconnected for any reason when trying to jump start a car. Though the 12v battery may be completely depleted, disconnecting it and trying to jump start with an external pack can short out multiple modules. The battery has the secondary function of being the "filter" for the electrical system. If you watch the voltage on an oscilloscope its not smooth with the battery disconnected, It pulses erratically. The battery helps calm the pulses and averages it to a more stable voltage. IE if it fluctuates 14.5-15 without the battery it should stabilize at 14.7 with the battery and so on and so forth. Having the battery disconnected while everything is running can also cause arcing between the negative post and terminal if they are close or if you plug it back in. That arc is tens of thousands of volts (low current though) and will find its way to the weakest module and possibly fry it.

The issue I think you had was trying to jump it from the engine bay. You need to jump it directly at the battery. There is too much voltage drop in the cables that travel from the engine bay to the battery in the trunk to try and jumpstart a completely dead battery. Next time attempt it at the battery itself. Hook it up, wait a couple minutes as you need the current flow to start from jumper to battery. Then attempt to start.
 

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You never want to have the main battery disconnected for any reason when trying to jump start a car. Though the 12v battery may be completely depleted, disconnecting it and trying to jump start with an external pack can short out multiple modules. The battery has the secondary function of being the "filter" for the electrical system. If you watch the voltage on an oscilloscope its not smooth with the battery disconnected, It pulses erratically. The battery helps calm the pulses and averages it to a more stable voltage. IE if it fluctuates 14.5-15 without the battery it should stabilize at 14.7 with the battery and so on and so forth. Having the battery disconnected while everything is running can also cause arcing between the negative post and terminal if they are close or if you plug it back in. That arc is tens of thousands of volts (low current though) and will find its way to the weakest module and possibly fry it.

The issue I think you had was trying to jump it from the engine bay. You need to jump it directly at the battery. There is too much voltage drop in the cables that travel from the engine bay to the battery in the trunk to try and jumpstart a completely dead battery. Next time attempt it at the battery itself. Hook it up, wait a couple minutes as you need the current flow to start from jumper to battery. Then attempt to start.
volt doesn't have a traditional alternator,so the ac ripple(bridge diodes only clip the ac signal) from the alternator won't be a problem.also,the ac ripple is usually in the 2-4v range.I'd have no problem w/ disconnecting the volt battery to use the jumper box.
 

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You never want to have the main battery disconnected for any reason when trying to jump start a car. Though the 12v battery may be completely depleted, disconnecting it and trying to jump start with an external pack can short out multiple modules. The battery has the secondary function of being the "filter" for the electrical system. If you watch the voltage on an oscilloscope its not smooth with the battery disconnected, It pulses erratically. The battery helps calm the pulses and averages it to a more stable voltage. IE if it fluctuates 14.5-15 without the battery it should stabilize at 14.7 with the battery and so on and so forth. Having the battery disconnected while everything is running can also cause arcing between the negative post and terminal if they are close or if you plug it back in. That arc is tens of thousands of volts (low current though) and will find its way to the weakest module and possibly fry it.

The issue I think you had was trying to jump it from the engine bay. You need to jump it directly at the battery. There is too much voltage drop in the cables that travel from the engine bay to the battery in the trunk to try and jumpstart a completely dead battery. Next time attempt it at the battery itself. Hook it up, wait a couple minutes as you need the current flow to start from jumper to battery. Then attempt to start.
Wouldn't the traction battery function as a smoothing capacitor without the 12v battery in the circuit? I thought that the 12v battery had only to provide power initially to fire up the system and then was used for the lighting (headlights, etc.). I can see where your description would definitely apply to a normal ICE system. Thoughts from anyone?
 

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Discussion Starter #10 (Edited)
ERDT /SOMMS senior member has run his Volt without any battery(12volts) after starting the car !!!. The APM will keep all 12volt needs going ...See erdt/Somms thread below.
 

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When you connect the clip leads from a 12V lithium jump starter to the Volt it is connected, in parallel fashion, to the vehicle's 12V circuit. The 12V lithium battery would provide much the same voltage buffering as the 12V AGM battery does when it is connected. The manufacturers of these small jump starter packs caution against leaving the jump starter connected after the vehicle has been started. Excessive voltage from the vehicle's electrical system can damage the jump starter battery once the vehicle is running.

I don't understand how the arcing of a 12V negative lead to the 12V AGM battery post could be higher than 12 - 15 V (whatever voltage the 12V lithium battery and/or 12V AGM battery + the Volt's accessory power module (APM) is outputting at that moment.)

If the 12V AGM is fully discharged due to a failed battery or a glitch in the Volt's 12V electrical system you won't be able to pop the hatch. In that case you could try connecting the 12V lithium jump starter leads to the Volt's jump starting connection points located under the hood, then open the hatch. Once the hatch has been opened you can attempt to jump start the Volt by attaching the 12V lithium jump starter pack's clip leads to the 12V AGM battery located under the hatch floor cover.
 

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I don't understand how the arcing of a 12V negative lead to the 12V AGM battery post could be higher than 12 - 15 V (whatever voltage the 12V lithium battery and/or 12V AGM battery + the Volt's accessory power module (APM) is outputting at that moment.)

If the 12V AGM is fully discharged due to a failed battery or a glitch in the Volt's 12V electrical system you won't be able to pop the hatch. In that case you could try connecting the 12V lithium jump starter leads to the Volt's jump starting connection points located under the hood, then open the hatch. Once the hatch has been opened you can attempt to jump start the Volt by attaching the 12V lithium jump starter pack's clip leads to the 12V AGM battery located under the hatch floor cover.
It is not 12-15v. The arc itself is tens of thousands of volts. Its exactly how a spark plug works. We charge a primary winding that induces voltage in a secondary. We open the circuit and it causes a discharge forcing the voltage to jump the spark gap, current is reduced while voltage increases in order to accomplish this (In simple terms). I have seen this fry caps and resistors in modules first hand. Yes its not the norm but on rare occasion it does happen.

As far as your second part. That is exactly how I would do it.
 

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Wouldn't the traction battery function as a smoothing capacitor without the 12v battery in the circuit? I thought that the 12v battery had only to provide power initially to fire up the system and then was used for the lighting (headlights, etc.). I can see where your description would definitely apply to a normal ICE system. Thoughts from anyone?
You're probably right. Thats exactly how it works on an ICE with an alternator. I am not super familiar with how the Voltec system handles it yet so if there is an intermediate module with a capacitor that can smooth the voltage fluctuations then you would be fine. However, just because you can do something or someone else has done something does not mean you should.
 

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It is not 12-15v. The arc itself is tens of thousands of volts. Its exactly how a spark plug works. We charge a primary winding that induces voltage in a secondary. We open the circuit and it causes a discharge forcing the voltage to jump the spark gap, current is reduced while voltage increases in order to accomplish this (In simple terms). I have seen this fry caps and resistors in modules first hand. Yes its not the norm but on rare occasion it does happen.

As far as your second part. That is exactly how I would do it.
Thanks. A spark plug is connected by the spark plug wire to an ignition coil or an integrated coil module. The module contains the coil winding needed to step up the voltage. What component in the Volt would serve to step up the voltage in the 12V system?
 

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Thanks. A spark plug is connected by the spark plug wire to an ignition coil or an integrated coil module. The module contains the coil winding needed to step up the voltage. What component in the Volt would serve to step up the voltage in the 12V system?
Go to any car with the engine running and unplug the battery, you will see it spark. Its the nature of electricity. It wants to complete the circuit so if there is enough amperage behind it it can step up the voltage (while reducing current) to force electricity to jump the gap. In an ignition system we use the windings because that is the only way to step it up without using an enormous amount of current. With a normal car the charging system provides more than enough current to allow the spark to jump. Now specifically to the Volt as I posted earlier. I am not 100% familiar with the intermediate modules that may contain capacitors to sort this sort of thing out but if those weren't there then you could damage the 12v system.
 

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You're probably right. Thats exactly how it works on an ICE with an alternator. I am not super familiar with how the Voltec system handles it yet so if there is an intermediate module with a capacitor that can smooth the voltage fluctuations then you would be fine. However, just because you can do something or someone else has done something does not mean you should.
I didn't mean to imply that the Voltec system used a capacitor to smooth the spikes, but that the traction battery, itself, would act like a smoothing capacitor, just as you described one of the functions of a 12v battery in an ICE system. AFAIK, there is no capacitor in the charging system of the Voltec.
 

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Wouldn't the traction battery function as a smoothing capacitor without the 12v battery in the circuit? I thought that the 12v battery had only to provide power initially to fire up the system and then was used for the lighting (headlights, etc.). I can see where your description would definitely apply to a normal ICE system. Thoughts from anyone?
Because the traction battery is completely disconnected from everything other than the charging system when the car is off.
 

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I had no problems leaving my Gen1 Volt for 3.5 weeks in the outback of airport parking when I went to alaska.

I did use the onstar app once to ping it and remote start it halfway through my trip before I got on a cruise down the inside passage for my return trip.

Actually that's probably the only time I've used the onstar app and had it work perfectly too. The new app is a POS and the cadillac app for the ELR is just as bad.
 

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The issue I think you had was trying to jump it from the engine bay. You need to jump it directly at the battery. There is too much voltage drop in the cables that travel from the engine bay to the battery in the trunk to try and jumpstart a completely dead battery. Next time attempt it at the battery itself. Hook it up, wait a couple minutes as you need the current flow to start from jumper to battery. Then attempt to start.
You nailed it with the engine bay. From what I've read, this uses a lower current (if that's the correct technical term) to the battery. My 2014 battery has been drained 3 times in 6 months. I'm told there is still a quirk in shutting down that can leave some systems running without you knowing. The big problem is the hatch won't open. But hooking the charger up to the engine bay gave it enough juice to open the trunk, which then let the road service guy to do a direct jump.The
The engine bay only works for a low battery. But a low battery is more than enough to start the Volt in normal circumstances. It's a holdover from the Cruze and the other Chevys with the battery in the trunk. And unintentionally helpful because of the horrible lack of a manual trunk release.
 

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And unintentionally helpful because of the horrible lack of a manual trunk release.
All you need is a medium flat bladed screwdriver. Crawl in the back, pop the plastic cover off the hatch latch, insert screwdriver, turn to unlock.
 
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