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OK, I've read the threads, and will be parking my 2017 Volt in my garage for 30 days. As per instruction manual, I plan on running the main battery down to a few bars and not plug in the charger. I have an AGM trickle charger I will connect to the jumper points under the hood (as I don't feel like disconnecting the negative 12 Volt battery terminal). I plan on closing the hood, but not latching it down snug -- IS THAT OK?

Thanks for the help!
 

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I think you will be OK. I tried various methods with my Gen 1, leaving it for 1-2 months at a time parked in the garage. I tried running the battery down to about 50% and leaving it unplugged with a "battery tender jr" on the under-hood 12V terminals. This worked fine. The most recent time I tried something different. Left it plugged in to the L2 charger (so the A/C could keep the battery cool during the hot summer days) and also hooked the battery tender jr to a quick-disconnect plug I mounted directly to the 12V AGM battery terminals. I put the battery tender jr on a timer so it only ran for 3-4 hours in the middle of the night (to minimize heat buildup in the battery tender jr since it got pretty warm during the day when the garage was warm). This worked fine also.

Since you are depleting the main battery down to a few bars, hot weather is not as much of a concern compared to leaving it with a full charge. The car will only run it's battery cooling system if it has close to a full charge.

If I were leaving my Volt during the winter months (usually in the 70's with occasional cold fronts, sometimes as low as 20 degrees for a few days) I would probably do as you are doing, leave it unplugged, battery down to about 2 bars and a trickle charger on the 12V battery.

ps I see you are a ham also.
73 de kh6idf
 

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i thought GM recommended keeping the car plugged in during protracted storage. Double check the owners manual and check with your volt advisor. this keeps the 12 volt battery ok also i believe
 

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OK, I've read the threads, and will be parking my 2017 Volt in my garage for 30 days. As per instruction manual, I plan on running the main battery down to a few bars and not plug in the charger. I have an AGM trickle charger I will connect to the jumper points under the hood (as I don't feel like disconnecting the negative 12 Volt battery terminal). I plan on closing the hood, but not latching it down snug -- IS THAT OK?

Thanks for the help!
Won't hurt nothing.

But 30 days is hardly the long term storage being talked about. Half a year, maybe. For 30 days, I'd just plug it in and let it do its things.
 

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Last year I was traveling and was away for about 30 days. It was in December and in Colorado. I kept my 2015 Volt in the garage. Garage is outside and separated from the main home, so it is cold there in winter. Kept the car all period plugged into 120V outlet without any issues. I think the manual clearly states to keep it plugged when not in use.
 

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If we truly were talking long term storage (6 months), I would recommend putting the car on jackstands to unload the suspension and to prevent flatspotting. Plug the tailpipe with a rag to prevent mice from entering. Put a small cloth bag with some mothballs under the hood to dissuade rodents from chewing wiring. Fill the gas tank up an add stabil.

Also follow the users manual for the electrical recommendations.
 

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From the manual...

For storage up to four weeks:

Plug in the high voltage battery charge cord if temperatures will exceed 35 °C (95 °F) and keep the 12-volt battery cables connected.
For storage from four weeks to 12 months:

--Discharge the high voltage battery until two or three bars remain on the battery range indicator (Battery symbol) on the instrument cluster.
--Do not plug in the high voltage battery charge cord.
--Remove the black negative (−) cable from the 12-volt battery. Attach a trickle charger to the battery terminals or keep the 12-volt battery cables connected and trickle charge from the underhood remote positive (+) and negative (−) terminals. See Jump Starting - North America (p305) for the location of these terminals.
 

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OK, I've read the threads, and will be parking my 2017 Volt in my garage for 30 days. As per instruction manual, I plan on running the main battery down to a few bars and not plug in the charger. I have an AGM trickle charger I will connect to the jumper points under the hood (as I don't feel like disconnecting the negative 12 Volt battery terminal). I plan on closing the hood, but not latching it down snug -- IS THAT OK?

Thanks for the help!
 

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I believe the manual says to keep the car plugged in in hot or cold weather. Check the manual.
The 12v AGM is interesting. As I have gone thorugh this already I will share.

The 12v AGM only charges when the electronics are awake. This only happens when the car is running or when the Hi voltage battery is charging. After charging, the electronics go to sleep, including the charge for the 12v AGM.

If you do not put some kind of trickle charger on the 12v AGM, the electronics that are still on to monitor the car will eventually drain it dead. And I found it real interesting trying to recharge a dead AGM battery, much less being able to access it.

I think my car sat for a little over 30 days before the 12v AGM lost charge. I had the charger plugged in and didn't know any better at the time, thinking the 12v AGM would be charged through the system. It took a lot of research to understand WHY the AGM lost charge and; how to prevent it.

Another thing to keep in mind, the 12v AGM battery is a sealed battery, and has a limited amount of moisture in it. The AGM battery is manufactured with ONE WAY seals to allow moisture and pressure to be released if needed.

If you put a regular charger or charge with a heavy (high) charge, you will create heat and pressure in the AGM and some of that moisture will be released. YOU CANNOT PUT LIQUID BACK INTO THE AGM BATTERY. Do this enough times and you will need a new battery.

The AGM requires a controlled charged with a battery charger that specifically states it can charge an AGM battery.

For what its worth, info for the masses.
 

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Save yourself all that trouble with the charger. If you expect very hot or cold weather, leave it plugged in.

Otherwise, put it in transport mode:

1. Power on
2. Activate the hazard flashers
3. Press the brake pedal and keep it down
4. Press and hold the Power button for 15 seconds until the dash display says Transport Mode On

This minimizes battery drain. I've kept my 2014 and 2016 Volts in transport mode for up to 5 weeks with negligible drain on the 12v battery.

(If you're compulsive about prolonging battery life, discharge the battery first, as described in the manual. Ideally 1 to 2 bars but everything below full helps. I try to get it to half or less.)

When you get home, use the same sequence to turn it back on again.

And see the Long Term Storage Guide which beats this topic into the ground.
 

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We store the vehicle for ~3.5 months during cool months, and given the advice in the manual and here on the forum (http://gm-volt.com/forum/showthread.php?18435-Long-Term-Storage-Guide), discharge the main battery to ~20%, and put the AGM on a trickle charger that states it is designed to charge at the lower AGM voltage. Concerned about possibly overcharging as my trickle charger design is somewhat vague on AGM but the float voltage looked OK, I used a timer to limit any overcharge exposure. (Shumacher sem-1562a 1.5A).

From Battery University
"As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive."

My experiment was to charge 1 day per week for 8hrs. It was a guess on the vehicle drain current (1.5A X 8hr = 12AH). When returning after 14 weeks the AGM voltage showed a full charge. So the vehicle drain current is somewhat less than 12AH per week.
Next time I plan to repeat the process.
Cheers
 
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