"Full" battery levels dropping daily

[GetOffYourGas]

Out of curiosity, for those who use the heater, to what temperature do you set it? I set mine to 65F, which is comfortable enough (given I'm wearing a winter coat). I find that even setting it to 70F uses a lot more energy.

Another trick I've used is to first preheat the car and then put the fan speed down to 1 bar. This moves a little air around without pulling in excessive amounts of cold air to heat up.

 

[LeftieBiker]

When the weather is frigid it matters little what setting you use, at least in most BEVs, because the air never warms enough to cycle the heater off. Mine is at 84F right now, but the air coming out is more like 60-70F. I use the second fan speed when possible, and the Leaf's 'partial recirculate' trick.

 

[GetOffYourGas]

When the weather is not frigid, do you still set it to 84? That is way too hot for me, regardless of the time of year. What's the point if, as you say, the car never cycles the heater off anyway?

As for the fan speed, that definitely makes a difference. The Bolt doesn't have a "partial recirc" mode AFAIK, so that doesn't apply here.

 

[SeanNelson]

Out of curiosity, for those who use the heater, to what temperature do you set it?

I crank mine up to around 28C (~82F) to get the cabin heated up, then set it down to around 23 or 24C (73 to 75F). Depending on the drive that gives me an efficiency of around 25kWh/100km like that (around 2.5 miles/kWh), plus or minus. No range worries for me with the Bolt's big battery. That's at outside air temperatures of around 0C (32F), plus or minus a few degrees.

Occasionally I put on lots of layers of clothing and drive without any heat other than the seats and steering wheel, and similar drives beat the EPA rated efficiency of 15.7kWh/100km despite the cold weather.

 

[LeftieBiker]

When the weather is not frigid, do you still set it to 84? That is way too hot for me, regardless of the time of year. What's the point if, as you say, the car never cycles the heater off anyway?

As for the fan speed, that definitely makes a difference. The Bolt doesn't have a "partial recirc" mode AFAIK, so that doesn't apply here.

When the weather is normal I set the temp at 74-76, and the cabin temp gets to maybe 55-65F. As for the Bolt not having partial recirc, I suggest people play with it. The Leaf's version is poorly documented, and only became widely known last year.

 

[Fiero2]

You are right. The graph shows 49% of my energy goes to climate. I have been warming my car up in the garage before go out in 5 degreeF. Not good. Will work on some different habits and see if I can improve on this baseline for Michigan winter driving.

 

[SparkE]

You are right. The graph shows 49% of my energy goes to climate. I have been warming my car up in the garage before go out in 5 degreeF. Not good. Will work on some different habits and see if I can improve on this baseline for Michigan winter driving.

Plug your vehicle into 240V (24Amp or higher) charging, THEN pre-condition your car for 10 minutes. Most of the electricity will come from the wall instead of from the battery. Using the included EVSE, *some* of the electricity will come from the wall, but far from all. (It's still better than ALL of it coming from the wall).

An added benefit is that this also warms up the battery a bit before driving.

 

[Perfesser]

When it comes to wintertime misery, I won't get (and don't deserve) much sympathy, but here goes anyway.

The Oregon coast has relatively mild winters, which means lows in the mid-30s and highs in the low 40s. If the sun comes out (it occasionally happens), I don't need any added heat. But when a cold rain is hitting the windshield (i.e., most of the time), you cannot keep the windshield clear without turning on the defroster, including both heater and fan. This is when the range suffers. I have tried the defroster with NO heat and it provides a modicum of defrosting, but then I have cold air blowing in my face.

An electrically heated windshield would be a nice solution. Any more practical ideas?

 

[LeftieBiker]

Look for the best-reviewed 12 volt (plug-in) standalone windshield defroster available, because the bad ones are pretty worthless. A good one might do the trick for you.

http://www.backyardmechanic.org/our-picks-for-best-12-volt-portable-car-window-defroster/

 

[GetOffYourGas]

When it comes to wintertime misery, I won't get (and don't deserve) much sympathy, but here goes anyway.

The Oregon coast has relatively mild winters, which means lows in the mid-30s and highs in the low 40s. If the sun comes out (it occasionally happens), I don't need any added heat. But when a cold rain is hitting the windshield (i.e., most of the time), you cannot keep the windshield clear without turning on the defroster, including both heater and fan. This is when the range suffers. I have tried the defroster with NO heat and it provides a modicum of defrosting, but then I have cold air blowing in my face.

An electrically heated windshield would be a nice solution. Any more practical ideas?

Currently it is 0F here (-19F windchill) and snowing. Frankly, I would rather have this weather than mid 30s with a cold rain. That, IMO, is the absolute worst since you get drenched to the bone, and feel much colder. So sure, you have my sympathy there.

What I find works in that weather is to allow the heater to run, blowing over the windshield. Set the fan speed to 1 bar. At first, the heater will draw lots of power, but after a short time it will level off. It takes little energy to maintain that setup. If you do a lot of short trips, then all you see is the energy-intensive ramp up time. If you take a long trip, the actual hit to your range will be minimal and you will see your expected range trending upward.

 

[EVHOO]

My wife drives a Bolt that we purchased at the end of 2017. (She lets me drive it if I'm good.)

We were not fully charging the battery as I was concerned about overcharging it. Then I read that the charging system is set up to only charge the battery to about 80% of the battery designed value, so overcharging is not a concern. So, we left our level 1 charger plugged in overnight, even though we had plenty of mileage available. I just wanted to see what the mileage would read at the charging limit.

This morning, it read 307 miles when we unplugged and left for church, which is about 10 miles away. On the way, we turned the defroster on briefly and the mileage dropped to about 275 miles. A minute later, I turned the defroster off, and no heat or seat warmers were on, and the level stayed at 275.

Is this abrupt drop with the defroster on just the result of how the system computes the estimated mileage?

Thanks.

 

[gpsman]

In a nutshell, yes.

 

[SeanNelson]

...I read that the charging system is set up to only charge the battery to about 80% of the battery designed value, so overcharging is not a concern.

That's only true if you enable "Hilltop Reserve" mode. If I remember correctly as it comes from the factory it will charge to 100% unless you go in and change that setting.

 

[EVHOO]

I was concerned about the fact when we let our Bolt fully charge, the mileage available at the end of charging was 307 miles. (not the max mileage, but the nominal I guess I would call it) I just checked tonight and found that the hilltop reserve was off, so I set it to on, so that should reduce the nominal range to 276 at the end of charging., I am guessing. I just went out to the garage, and I see that it will take about 15 hours to fully charge with our level 1 charger, and the current nominal battery mileage is at 225, so 225+4x15= 275. So that seems to be consistent. (I know it's not exactly 4.00 miles per hour of charging, but it's a nice round number.

The dealer that sold us the car located the color Bolt we wanted in another state. The NC dealer had to have it brought down to NC from VA. I expected it to be put on a truck to be moved, I was surprised to find that a couple at the dealership drove a car up to the dealer in VA, and then one of them drove the Bolt back to NC, a distance of around 270 miles. Because the weather was cold, the heater was required, so they drove part of the way and spent the night in a motel while recharging the car. I'm guessing that the dealer in VA had turned the Hilltop setting off to get the maximum range on the battery for the trip. Now that I know how it works, I expect to leave it in that mode, unless we take a trip to the beach needing some extra miles.

 

[IMAdolt]

I was concerned about the fact when we let our Bolt fully charge, the mileage available at the end of charging was 307 miles. (not the max mileage, but the nominal I guess I would call it) I just checked tonight and found that the hilltop reserve was off, so I set it to on, so that should reduce the nominal range to 276 at the end of charging., I am guessing. I just went out to the garage, and I see that it will take about 15 hours to fully charge with our level 1 charger, and the current nominal battery mileage is at 225, so 225+4x15= 275. So that seems to be consistent. (I know it's not exactly 4.00 miles per hour of charging, but it's a nice round number.

The dealer that sold us the car located the color Bolt we wanted in another state. The NC dealer had to have it brought down to NC from VA. I expected it to be put on a truck to be moved, I was surprised to find that a couple at the dealership drove a car up to the dealer in VA, and then one of them drove the Bolt back to NC, a distance of around 270 miles. Because the weather was cold, the heater was required, so they drove part of the way and spent the night in a motel while recharging the car. I'm guessing that the dealer in VA had turned the Hilltop setting off to get the maximum range on the battery for the trip. Now that I know how it works, I expect to leave it in that mode, unless we take a trip to the beach needing some extra miles.

It's generally excepted that you should charge it up full (100%) and run it down low (not 0 but low) once and a while, not to make a habit of it but like every couple months or a few times a year? To make sure everything is getting a chance to balance properly.

 

[GetOffYourGas]

It's generally excepted that you should charge it up full (100%) and run it down low (not 0 but low) once and a while, not to make a habit of it but like every couple months or a few times a year? To make sure everything is getting a chance to balance properly.

Honest questions - Who recommends that? And what do we know about how Chevy balances the cells in the battery?

We know about Leaf batteries because many people have done deep dive studies, watching the cells balance, etc. Have there been studies into the Bolt's battery? Has GM or LG said anything official? Or are we just extrapolating from other vehicles' behavior?

We do know some things about lithium batteries, which applies to some extent to all chemistry variations. For example, sitting at a very high or very low SoC is stressful and causes degradation over time. Also shallower charges are less stressful than deeper charges. For example, charging from 25-75% twice is much easier on the battery than charging from 0-100% once.

 

[IMAdolt]

It's generally excepted that you should charge it up full (100%) and run it down low (not 0 but low) once and a while, not to make a habit of it but like every couple months or a few times a year? To make sure everything is getting a chance to balance properly.

Honest questions - Who recommends that? And what do we know about how Chevy balances the cells in the battery?

We know about Leaf batteries because many people have done deep dive studies, watching the cells balance, etc. Have there been studies into the Bolt's battery? Has GM or LG said anything official? Or are we just extrapolating from other vehicles' behavior?

We do know some things about lithium batteries, which applies to some extent to all chemistry variations. For example, sitting at a very high or very low SoC is stressful and causes degradation over time. Also shallower charges are less stressful than deeper charges. For example, charging from 25-75% twice is much easier on the battery than charging from 0-100% once.

Ya and I don't think anyone argues that but the issue is what we don't know, we don't know how the BMS operates, we don't know how the chemistry reacts to this or that but what we do know is how lithium chemistries typically behave and cycling a battery from high to low or low to high a few times a year over 10-20 years for the purposes of balancing is such a low number it won't effect longevity in any measurable way, especially considering we would do this immediately prior to a discharge or recharge keeping out of the top or bottom of the batteries SoC, this would typically happen more often regardless with I'd think very rare exceptions. One being a person or people habitually charging to hilltop and never traveling more then 50 miles at a time.

The only real advice chevy gives out is "keep it charged and plugged in"

 

[GetOffYourGas]

Ok, so when you say it is "generally excepted" [sic], it's exactly like I said - extrapolated from other vehicles' BMS behavior. I'm not disagreeing with you that it isn't something to worry about. I really haven't seen any evidence that an occasional charge to 100% is particularly bad for the battery. Letting it sit at 100% for days on end would be a different thing.

The other issue to consider is simply calibrating the computer's estimate of charge remaining. Determining the SoC of a battery at rest is difficult to say the least. The computer monitors the voltage but also current in/out of the battery. A full charge-discharge cycle is the best way to calibrate it. This goes for something as small as your phone's battery all the way up to a 100kWh Tesla battery.

 

[IMAdolt]

So I think we're saying the same thing, I just brought it up since the commentor hinted at habitually charging to hill top and if not typically driving long distances then an occasional battery cycle is a good idea even it it's not really" necessary" we don't really know at this point but it won't hurt.

 

[GetOffYourGas]

We're mostly saying the same thing. I wasn't trying to disagree with you. When I first read your comment, I thought you had information about the Bolt's BMS which I did not.