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Discussion Starter · #1 ·
Yesterday we had a horrendous storm, lightning getting closer, and I had just received the notification that my 2017 was done charging. Went out in the garage to unplug it so that if we get a close strike, the surge wouldn't damage anything but the car was still whirring with a fan on. I chose the lesser of two evils and just unplugged it figuring it'd be better to do that than risk a lightning strike. As soon as I unplugged it, the fan went off. I'm just wondering: what did I prevent from occurring when I did that. Is that bad for the battery because it doesn't cool it down all the way?

Also, unrelated, when I drive my kid to the bus stop, it's less than a mile round trip and I usually use .1 or .2 kW. I've read here that it's always best to keep it plugged in so the car can do whatever "maintenance" it needs, but is that really good: to plug it back in with only .2 kW used? What I've been doing is kind of splitting the difference. I work at home so if I don't go anywhere most days and I'm just doing bus stop trips, I'll do three or four without plugging it back in and I'll plug it in on the third or fourth day with maybe 1 kW used.

Wondering...

Mike
 

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I wonder the same thing.
We usually only do short trips of 1-2 Kwh drain, and I always plug in, following the manual directions.
I believe that is the correct procedure to follow. Although, personally it seems like overkill.
BUT, come winter with cold temperatures, I think that will change and become a needed operation, especially if not in the garage.
 

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I have a similar situation here is Arizona with daily 0.5 mi trips to the mailbox and other short trips. I always plug in to allow thermal management of the battery per the owner's manual. GM is pretty conservative on managing the battery temps, so it really isn't any big deal to unplug when you feel the need.

BTW, if you are unplugging due to lightning, and you are using the 120v EVSE, be sure to unplug the EVSE from the wall outlet as well. Learned that lesson the hard way as a lightning event took out my OEM EVSE along with other electronics in the house. The insurance company considered the EVSE an "accessory" to the car and needed to be covered by the auto policy. The deductible was higher than the cost of the replacement EVSE, so it was my dime to replace it.

VIN # B0985
 

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If you have used very little charge, in terms of charge level and battery stress, it is fine to either leave it unplugged or to plug it in. The car is smart enough not to overcharge it, so no worries there.

The main reason to leave it plugged in when you don't need a charge is to allow the thermal management to work. It needs to be plugged in while parked for that to work.

In hot weather, the car will actively cool the battery. I think this mainly happens over about 90 degrees F or if the battery is hot from use or charging. A hot battery ages faster, so it is good to keep it cool.

In extremely cold weather, the car will heat the battery so it stays ready for driving. I think this mainly happens below freezing temperatures. I don't think cold temperatures age the battery, but when you start driving, the car may run the engine temporarily instead of using the battery if the battery is too cold.

In moderate temperatures, there is no need to leave it plugged in and there is no problem letting the charge level get low with repeated use as long as you have the range you will want for your next trip. And as mentioned, this lowers the lightning risk.

One other benefit of leaving it plugged in is that the car will monitor and charge the 12V battery, but with a good battery the car should not really need that for many days or even several weeks of being parked.
 

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I never leave mine plugged in 24/7 and I never plug it in unless the battery is at 50% SOC or less - Old habits from driving BEV's for the past 6 or 7 years. If you read here a year or two from now that my Volt is having battery problems, you'd know for sure this is NOT what you should do, but I'm pretty confident by now in my own 'care and feeding' of lithium cells for longest life, so that's what I'm doing - Your results may vary

Don
 

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I also drive mostly short distances in my 2017 Volt. In spring, summer and fall will usually only plug in my Volt when the battery state of charge is close to 50%. In winter I leave the Volt plugged in inside my garage to maintain a minimum battery temperature of ~32F and also for preconditioning the cabin before I drive the Volt. The exception in summer is when the temperature in my garage goes above 95F, then I will plug in the Volt starting at around 2:30 PM. The Volt will usually charge for 1 - 2 hours, the Volt's fan and AC always come on when charging has been completed. I recently learned that if I unplug the Volt after charging has been completed but before the Volt has completed cooling the battery that the fan and AC will shut off. I was about 7 minutes into an estimated 10 minute cooling cycle so I saw no harm in leaving the Volt unplugged as there was a thunderstorm in progress when I unplugged the Volt.

The only downside to constantly plugging and unplugging the Volt is that you may wear out the charging port or EVSE connector sooner than it would otherwise wear out. These parts can be readily replaced, the replacement cost is not excessive ~$250 USD.
 

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Lithium ion doesn't like fully charged or fully empty SOC. That's why the Volt only uses the center portion of the battery. Not plugging it in or plugging it in doesn't matter because either way you aren't taking it to either extreme. As for lightning strikes you want to disconnect it. We don't get lightning strikes here but do get trees falling on power lines in wind storms with the same end effect so I installed a 20 amp rocker switch on the line to disconnect the EVSE from the line without having to unplug it. Sometimes we can get a power surge just 'cause a tree decides to fall or more likely because a car has run into a power pole so I keep the car unplugged when not charging and the rocker switch off. We don't get temperature extremes here so don't have to worry about battery temp.
 

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I plug mine in whenever I'm home. I might unplug it if expecting severe thunderstorms. I think the battery management is very conservative for battery health and there's no need to overthink or worry about overcharging or damage from keeping it charged. Maybe li-ion batteries don't like to stay at full charge, but the Volt battery doesn't get charged to full capacity. It's never fully charged or discharged by design.
 

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To add to all the great responses above I did a few tests using my Level 2 OpenEVSE charger over the past year of ownership. It appears that the battery temperature management system only comes into affect when the battery temperature drops below 1 deg C (34 deg F) or climbs above 30-32 deg C (86-90 deg F). That seems to correlate with other things I have read. So it really is unnecessary to have it plugged in at temperatures between those two values, under normal use circumstances...
 

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Lithium ion doesn't like fully charged or fully empty SOC. That's why the Volt only uses the center portion of the battery. Not plugging it in or plugging it in doesn't matter because either way you aren't taking it to either extreme. As for lightning strikes you want to disconnect it. We don't get lightning strikes here but do get trees falling on power lines in wind storms with the same end effect so I installed a 20 amp rocker switch on the line to disconnect the EVSE from the line without having to unplug it. Sometimes we can get a power surge just 'cause a tree decides to fall or more likely because a car has run into a power pole so I keep the car unplugged when not charging and the rocker switch off. We don't get temperature extremes here so don't have to worry about battery temp.
The rocker switch only disconnects the hot lead (normally the black wire). The neutral and ground leads will remain connected to the outlet. If you really want to disconnect the EVSE from the electrical feed you need to unplug from the outlet.

VIN # B0985
 

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GM spent a LOT of money and a LOT of time engineering the Volt.
Don't try to "outsmart" it, do what the owners manual says to do (I.E. plug it in when you have it parked at home).

Though I do disconnect and also unplug my EVSE from the wall when we have lightning storms.
 

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I'm with Dutch, although I continually succumb to the urge to "outsmart" the engineers. My 6 year experience with VW "Clean"
Diesels actually taught me the opposite, as VAG released these cars to the public with some interesting and confusing engineering flaws, not to mention a woefully ill-prepared dealer service network.

All that said, while away from Fort Worth all of July (ambient highs 102-108!), ELR in the non-A/C garage, I decided to leave it unplugged, perhaps risking (minimal?) battery stress, but avoiding the very real possibility of a lightening strike.
 

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I like the idea of a cutoff switch. But if you have the charge alarm set, every time you hit the switch (or unplug the EVSE) you have to first unplug the car.
 

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Discussion Starter · #14 ·
Lots of helpful responses here. I guess I'll just plug it in all the time because the garage sees >90 degrees for probably 8 months of the year at least at some point during the day. Unfortunatly when there's lightning, I only unplug it from the car figuring I'll save the most expensive part. If lightning gets the EVSE, I guess I can take the hit on getting a new one. The problem is: it is plugged in right above the car on the ceiling so I'd have to back the car out and get a ladder to unplug it. Some sort of kill switch that kills all three leads would be nice, but not worth the trouble, at least for me.

I guess I could get two short extension cords and make a sort of loop that hangs down where I could unplug it. Hmm. Maybe.

Mike
 

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Yes, keeping your Volt plugged in is never a bad decision unless there is electrical storm activity in the vicinity. Extension cords are not recommended for use with the EVSE. Why not turn off the power to the circuit at the breaker panel. (Flipping off the circuit breaker won't protect the EVSE from a power surge on the neutral or ground wire connection.)

I would choose to plug in once per day, either in the evening or in the hottest part of the day so that the TMS would cool the battery at the completion of the charging cycle (a warm battery is actually more efficient for charging as the electron transfer takes place more efficiently at higher temperatures. Unless the battery temperature is extremely warm the TMS will defer cooling the battery until charging has been completed.) If you drive the Volt in the morning and put the Volt inside the garage the Volt's battery will start at ~85F, then slowly warm to the temperature inside the garage. Due to the large thermal mass and insulating property of the Volt's battery location and construction a 400lb battery takes many hours (6-8 hours +) before the battery temperature might be warm enough to trigger the TMS to cool the battery (provided the Volt was plugged in.)

If you plan to leave the Volt parked, not driven for longer than 4 weeks be sure to read the Owner's Manual instructions for long term storage (unplug Volt, leave battery with 3 bars worth of battery charge, disconnect 12V battery or connect a 12V battery tender to the 12V battery (the battery tender must be designed for AGM type batteries to avoid overcharging the 12V.)
 

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I keep mine always plugged in, but I never take short trips to the mailbox. I also haven't unplugged during thunder and lightning storms. I have a wholehouse surge protector on my main box. I do unplug during power outages, as my standby generator would autostart and try to charge my Volt. That works fine, but it's super expensive, since the generator burns 1 to 2 gals of LP per hour.
 

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I keep mine always plugged in, but I never take short trips to the mailbox. I also haven't unplugged during thunder and lightning storms. I have a wholehouse surge protector on my main box. I do unplug during power outages, as my standby generator would autostart and try to charge my Volt. That works fine, but it's super expensive, since the generator burns 1 to 2 gals of LP per hour.
If you do a little research on the whole house surge protector you will most likely find that it does not protect against lightning. Unplugging is your only protection that works.

VIN # B0985
 

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If you do a little research on the whole house surge protector you will most likely find that it does not protect against lightning. Unplugging is your only protection that works.

VIN # B0985
I remember back in the day when people where trying to get BC Hydro to replace blown computers when a tree fell on the line (same effect as lightning), Their response was "we have surge suppressors on the line, that can't happen". Until once when it happened it took out all the appliances in a several block area. They replaced the appliances.
 

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If you do a little research on the whole house surge protector you will most likely find that it does not protect against lightning. Unplugging is your only protection that works.

VIN # B0985
Nothing protects completely from lightning. Cutoff switches, breakers, or even unplugging only give you protection from a smaller radius. If the lightning strikes close enough to your EVSE/car, the energy will find conducting surfaces and fry them. Obviously a direct hit would be another story entirely.
 
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