Charge: As soon as possible, or as late as possible?

plj · May 20, 2018

Top line: Charge before your trip, not after your trip.

Here's an article that caught my eye:
Enhancing electric vehicle sustainability through battery life optimal charging.
Transportation Research Part B 112 (2018) 1–18
https://doi.org/10.1016/j.trb.2018.03.016

The abstract:
"In this article, we investigate the potential for battery life prolongation through optimized charging under consideration of individual mobility requirements. Based on a comprehensive battery aging model we introduce a continuous quadratic programming model to derive battery life optimal charging (OPT). The strategy indicates when and how much to charge to maximize the potential range throughout the battery life. We find that OPT has the potential to more than double the expected battery life compared to simple and often abundant recharging activities as observable today. The degree of battery life prolongation strongly depends on the operating temperature. Since optimal charging would require deterministic knowledge of future trips and corresponding charging levels we investigate a more convenient charging heuristic derived from “As-Late-As-Possible” (ALAP) charging. ALAP charging considers range buffers between 5% and 60% over the range required until the next re-charging opportunity. We analyze the trade-off between (long-term) battery life and (short-term) range flexibility. We find that for decreasing temperatures the trade- off between battery life and flexibility is solved with increasing range buffers. From our results battery degradation aware charging heuristics can be easily derived and applied in real-world settings."

While I don't pretend to have read the article, let alone understand it, I interpret it to mean charge as late as possible. That is, minimize time the battery is at a high state of charge.

plj · May 20, 2018

Here's more from the paper:

6. Conclusion and implications
While latest studies on EV user behavior indicate that users prefer frequent and full recharging (AFAP), changing this charging behavior can tremendously extend battery life. Based on simulation results built on a comprehensive battery cell aging model and empirical mobility data, we show that a battery degradation minimal (optimal) charging strategy (OPT) extends battery life by a factor of two or higher. AFAP is especially harmful in cases of higher average operating temperatures. OPT is close to as-late-as-possible (ALAP) charging at high temperatures of 35 °C. OPT is highly correlated and converging towards ALAP for lower temperatures.

However, ALAP and OPT require full information about the next-range requirements, that cannot be expected to be available precisely in real-life settings. We therefore investigated the trade-off between flexibility and battery life by introducing flexible range buffers between 5% and 60% to ALAP, i.e. ALAP b .

We find that a lower range buffer of 30% is beneficial for high temperatures (35 °C). For decreasing temperatures the best trade-off between battery life and flexibility is achieved with increased range buffers, i.e. 35 and 50% for a temperature of 20 and 10 °C, respectively. For low temperatures, which can be achieved for example using battery cooling systems, ALAP b charging with a range buffer of 50% can be applied as an easy-to-use charging heuristic and allows for both battery life extension, flexibility and therefore user convenience.

In summary, while none of the presented ALAP b strategies including range buffers perform close to OPT, the harm of range buffers reduces with decreasing temperature such that this trade-off is less pronounced in climate zones with average (operational) temperatures around 10 °C or with active battery cooling systems that enable a performance in such a temperature range. However, ALAP b charging can be implemented as an easy-to-use smart charging heuristic, that leads to considerable battery life extension compared to the currently applied, naive AFAP charging.

GetOffYourGas · May 23, 2018

I find it amusing that they refer to "AFAP" (which is the same as the "ABCs" - Always Be Charging - you hear pronounced on forums) as "naive" charging.

I don't have access to the article, nor am I about to pay for it, but the gist is lower SoC is better, which is widely known. You have to balance that with the buffer you personally feel comfortable with. Unfortunately, GM has not given us sufficient controls to let us do this with our Bolts.

SparkEVPilot · May 23, 2018

plj said:
Here's more from the paper:

6. Conclusion and implications
While latest studies on EV user behavior indicate that users prefer frequent and full recharging (AFAP), changing this charging behavior can tremendously extend battery life. Based on simulation results built on a comprehensive battery cell aging model and empirical mobility data, we show that a battery degradation minimal (optimal) charging strategy (OPT) extends battery life by a factor of two or higher. AFAP is especially harmful in cases of higher average operating temperatures. OPT is close to as-late-as-possible (ALAP) charging at high temperatures of 35 °C. OPT is highly correlated and converging towards ALAP for lower temperatures.

However, ALAP and OPT require full information about the next-range requirements, that cannot be expected to be available precisely in real-life settings. We therefore investigated the trade-off between flexibility and battery life by introducing flexible range buffers between 5% and 60% to ALAP, i.e. ALAP b .

We find that a lower range buffer of 30% is beneficial for high temperatures (35 °C). For decreasing temperatures the best trade-off between battery life and flexibility is achieved with increased range buffers, i.e. 35 and 50% for a temperature of 20 and 10 °C, respectively. For low temperatures, which can be achieved for example using battery cooling systems, ALAP b charging with a range buffer of 50% can be applied as an easy-to-use charging heuristic and allows for both battery life extension, flexibility and therefore user convenience.

In summary, while none of the presented ALAP b strategies including range buffers perform close to OPT, the harm of range buffers reduces with decreasing temperature such that this trade-off is less pronounced in climate zones with average (operational) temperatures around 10 °C or with active battery cooling systems that enable a performance in such a temperature range. However, ALAP b charging can be implemented as an easy-to-use smart charging heuristic, that leads to considerable battery life extension compared to the currently applied, naive AFAP charging.

OK. Now explain this in layman's terms so an old geezer like me can understand what they are suggesting.

SparkEVPilot · May 24, 2018

SparkEVPilot said:
plj said:

Here's more from the paper:

6. Conclusion and implications
While latest studies on EV user behavior indicate that users prefer frequent and full recharging (AFAP), changing this charging behavior can tremendously extend battery life. Based on simulation results built on a comprehensive battery cell aging model and empirical mobility data, we show that a battery degradation minimal (optimal) charging strategy (OPT) extends battery life by a factor of two or higher. AFAP is especially harmful in cases of higher average operating temperatures. OPT is close to as-late-as-possible (ALAP) charging at high temperatures of 35 °C. OPT is highly correlated and converging towards ALAP for lower temperatures.

However, ALAP and OPT require full information about the next-range requirements, that cannot be expected to be available precisely in real-life settings. We therefore investigated the trade-off between flexibility and battery life by introducing flexible range buffers between 5% and 60% to ALAP, i.e. ALAP b .

We find that a lower range buffer of 30% is beneficial for high temperatures (35 °C). For decreasing temperatures the best trade-off between battery life and flexibility is achieved with increased range buffers, i.e. 35 and 50% for a temperature of 20 and 10 °C, respectively. For low temperatures, which can be achieved for example using battery cooling systems, ALAP b charging with a range buffer of 50% can be applied as an easy-to-use charging heuristic and allows for both battery life extension, flexibility and therefore user convenience.

In summary, while none of the presented ALAP b strategies including range buffers perform close to OPT, the harm of range buffers reduces with decreasing temperature such that this trade-off is less pronounced in climate zones with average (operational) temperatures around 10 °C or with active battery cooling systems that enable a performance in such a temperature range. However, ALAP b charging can be implemented as an easy-to-use smart charging heuristic, that leads to considerable battery life extension compared to the currently applied, naive AFAP charging.

Click to expand...

Is this what they are suggesting:

I arrive home with 30 miles on the GOM and park my EV for the night. The next day I expect to drive 50 miles. So, knowing the average mi/kWh for my vehicle, the expected air temperature the next day and the road over which I will travel, I calculate how many kWh I need to add to my HV battery to cover the mileage I expect to drive plus an acceptable buffer. The initial GOM mileage may be considered the "buffer" for air temperature effects plus any unexpected factors that may impact my average mi/kWh. And, this number may have to be adjusted up or down depending on environmental and road concerns. Once I have determined how many kWh I need to add to my battery, plus any charging losses, I determine the required number of hours of charging and program my EVSE to have the EV charged sufficiently to cover my trip when I am ready to leave the next day. Then, if I do not plan to use my EV for a period of time, I leave the battery at a low SOC and do not recharge the battery until just before my next trip.

In short, do not charge more than what is needed to cover the trip and return home with something still in the battery and do not recharge the battery until just before you plan to use the EV again for another trip. Is this what the article suggests?

GetOffYourGas · May 24, 2018

That was how I read it too. Sounds like a lot of work, but they are claiming double the battery life over "naive" charging. I don't know under what conditions, though.

SparkEVPilot · May 24, 2018

GetOffYourGas said:
That was how I read it too. Sounds like a lot of work, but they are claiming double the battery life over "naive" charging. I don't know under what conditions, though.

There may be something to this if you consider that every electronic device powered by a lithium battery is usually only partially charged [ low SOC] when it is first purchased. Is that done to prolong the battery life between the time of manufacture and the time of purchase? I wonder, given we did not fully recharge our lithium battery powered device every night, if the battery would last longer?

GetOffYourGas · May 25, 2018

SparkEVPilot said:
GetOffYourGas said:

That was how I read it too. Sounds like a lot of work, but they are claiming double the battery life over "naive" charging. I don't know under what conditions, though.

Click to expand...

There may be something to this if you consider that every electronic device powered by a lithium battery is usually only partially charged [ low SOC] when it is first purchased. Is that done to prolong the battery life between the time of manufacture and the time of purchase? I wonder, given we did not fully recharge our lithium battery powered device every night, if the battery would last longer?

I have an iPhone 5C that I try not to charge above 80%. After almost 5 years, the phone still holds a charge pretty well. Others who plug in their phone all night every night (so it sits at 100% for 10-12 hours/day) have seen their battery life go to nothing. Anecdotal, but true.

SparkEVPilot · May 25, 2018

GetOffYourGas said:
SparkEVPilot said:

GetOffYourGas said:

That was how I read it too. Sounds like a lot of work, but they are claiming double the battery life over "naive" charging. I don't know under what conditions, though.

Click to expand...

There may be something to this if you consider that every electronic device powered by a lithium battery is usually only partially charged [ low SOC] when it is first purchased. Is that done to prolong the battery life between the time of manufacture and the time of purchase? I wonder, given we did not fully recharge our lithium battery powered device every night, if the battery would last longer?

Click to expand...

I have an iPhone 5C that I try not to charge above 80%. After almost 5 years, the phone still holds a charge pretty well. Others who plug in their phone all night every night (so it sits at 100% for 10-12 hours/day) have seen their battery life go to nothing. Anecdotal, but true.

The Chevy Spark EV and the Chevy Bolt EV both have a charging option called "Programmed Departure Time". This option allows one to specify the departure time at which the car will be fully charged. So, with a little calculation work, a driver can set the programmed departure time at a time later than the actual disconnect / departure time so the car is only 80% fully charged when the car is disconnected. You just need to know the amount of time it takes to charge from 80% to 100% for whatever charging voltage and current you are using. For example, it takes my Spark EV 4.5 hours to charge from 80% to 100% full charge when using an L1 EVSE at 120 VAC and 8 amps. So, if I want to leave at 8 am with 80% in my battery, I can set my departime time to 12:30 pm and just disconnect at 8 am when I am ready to leave. I will be trying this during the next week or two using L1 at 120 VAC at 8 amps and 12 amps and L2 at 240 VAC at 16 amps.

trevmar · May 25, 2018

FWIW I'm an electrochemist who spent (or wasted) over 40 years trying to make electrons swim. In the 1970's we found users of nickel-cadmium batteries in walkie-talkies got much better life when the devices were being heavily used (and abused) as opposed to spending all their lives on "float" charge. I didn't work much on lithium-ion but the principles are the same - when the electrodes are fully charged it is very stressful on them and the separator, you are driving the material lattice structure to a state that is not 'normal'.

Think of metals - very few (gold, platinum) are found native in nature, the rest always appear as salts like oxides, sulfates, etc, and we then put enormous amounts of energy into them to smelt them into useful base metals like lithium, iron, aluminum, etc. What's the first thing iron (steel) does when it sees the real world? Rusts! (i.e. reverts to the state it was originally in the earth)

So in my view a fully charged battery is inherently unstable - clever design will help get the maximum amount of useful electrical energy out of it, but it doesn't enjoy being in that state, and storing it (especially at high temperatures, which accelerate all chemical reactions) makes it worse

Entropy rules our universe (apparently), even though I probably made more money knowing how to galvanize a bucket than actually understanding the theory.

SparkEVPilot · May 26, 2018

SparkEVPilot said:
GetOffYourGas said:

SparkEVPilot said:

There may be something to this if you consider that every electronic device powered by a lithium battery is usually only partially charged [ low SOC] when it is first purchased. Is that done to prolong the battery life between the time of manufacture and the time of purchase? I wonder, given we did not fully recharge our lithium battery powered device every night, if the battery would last longer?

Click to expand...

I have an iPhone 5C that I try not to charge above 80%. After almost 5 years, the phone still holds a charge pretty well. Others who plug in their phone all night every night (so it sits at 100% for 10-12 hours/day) have seen their battery life go to nothing. Anecdotal, but true.

Click to expand...

The Chevy Spark EV and the Chevy Bolt EV both have a charging option called "Programmed Departure Time". This option allows one to specify the departure time at which the car will be fully charged. So, with a little calculation work, a driver can set the programmed departure time at a time later than the actual disconnect / departure time so the car is only 80% fully charged when the car is disconnected. You just need to know the amount of time it takes to charge from 80% to 100% for whatever charging voltage and current you are using. For example, it takes my Spark EV 4.5 hours to charge from 80% to 100% full charge when using an L1 EVSE at 120 VAC and 8 amps. So, if I want to leave at 8 am with 80% in my battery, I can set my departime time to 12:30 pm and just disconnect at 8 am when I am ready to leave. I will be trying this during the next week or two using L1 at 120 VAC at 8 amps and 12 amps and L2 at 240 VAC at 16 amps.

Update: Using L1 EVSE charging at 120 VAC and 8 amps, it takes 4.5 hours for my 2014 Spark EV to charge from 80% SOC to 100% SOC. Using L2 EVSE charging at 240 VAC and 16 amps, it takes 1.5 hours for my 2016 Spark EV to charge from 80% SOC to 100% SOC. At the end of charging, the GOM on my 2014 Spark EV read 98 miles and the GOM on my 2016 Spark EV read 106 miles. Therefore, I should have 80% SOC for my 2014 Spark EV if, using my L1 EVSE at 120 VAC and 8 amps, I set my departure time 4.5 hours later than I actually plan to leave. I should have 80% SOC for my 2016 Spark EV if, using my L2 EVSE at 240 VAC and 16 amps, I set my departure time 1.5 hours later than I actually plan to leave. Next, I plan to test this and see if my GOM for each car actually reads about 80 miles when I stop charging at my actual departure time.

GetOffYourGas · May 26, 2018

SparkEVPilot said:
SparkEVPilot said:

GetOffYourGas said:

I have an iPhone 5C that I try not to charge above 80%. After almost 5 years, the phone still holds a charge pretty well. Others who plug in their phone all night every night (so it sits at 100% for 10-12 hours/day) have seen their battery life go to nothing. Anecdotal, but true.

Click to expand...

The Chevy Spark EV and the Chevy Bolt EV both have a charging option called "Programmed Departure Time". This option allows one to specify the departure time at which the car will be fully charged. So, with a little calculation work, a driver can set the programmed departure time at a time later than the actual disconnect / departure time so the car is only 80% fully charged when the car is disconnected. You just need to know the amount of time it takes to charge from 80% to 100% for whatever charging voltage and current you are using. For example, it takes my Spark EV 4.5 hours to charge from 80% to 100% full charge when using an L1 EVSE at 120 VAC and 8 amps. So, if I want to leave at 8 am with 80% in my battery, I can set my departime time to 12:30 pm and just disconnect at 8 am when I am ready to leave. I will be trying this during the next week or two using L1 at 120 VAC at 8 amps and 12 amps and L2 at 240 VAC at 16 amps.

Click to expand...

Update: Using L1 EVSE charging at 120 VAC and 8 amps, it takes 4.5 hours for my 2014 Spark EV to charge from 80% SOC to 100% SOC. Using L2 EVSE charging at 240 VAC and 16 amps, it takes 1.5 hours for my 2016 Spark EV to charge from 80% SOC to 100% SOC. At the end of charging, the GOM on my 2014 Spark EV read 98 miles and the GOM on my 2016 Spark EV read 106 miles. Therefore, I should have 80% SOC for my 2014 Spark EV if, using my L1 EVSE at 120 VAC and 8 amps, I set my departure time 4.5 hours later than I actually plan to leave. I should have 80% SOC for my 2016 Spark EV if, using my L2 EVSE at 240 VAC and 16 amps, I set my departure time 1.5 hours later than I actually plan to leave. Next, I plan to test this and see if my GOM for each car actually reads about 80 miles when I stop charging at my actual departure time.

Yup. This is a great way to control your SoC, and I use it myself. Very roughly speaking, the Bolt charges at about 10-11% per hour on L2. The calculation is pretty easy. On Monday-Thursday, I set my departure for 4 hours past when I actually leave, and the car is at 60% when I do leave. I don't drive much during the week, so typically it is only down to about 40% when I plug in again. 40-60% is pretty gentle on the battery. Then I charge to full on Fridays to prepare for the weekend when I do most of my driving.

SparkEVPilot · May 26, 2018

GetOffYourGas said:
SparkEVPilot said:

SparkEVPilot said:

The Chevy Spark EV and the Chevy Bolt EV both have a charging option called "Programmed Departure Time". This option allows one to specify the departure time at which the car will be fully charged. So, with a little calculation work, a driver can set the programmed departure time at a time later than the actual disconnect / departure time so the car is only 80% fully charged when the car is disconnected. You just need to know the amount of time it takes to charge from 80% to 100% for whatever charging voltage and current you are using. For example, it takes my Spark EV 4.5 hours to charge from 80% to 100% full charge when using an L1 EVSE at 120 VAC and 8 amps. So, if I want to leave at 8 am with 80% in my battery, I can set my departime time to 12:30 pm and just disconnect at 8 am when I am ready to leave. I will be trying this during the next week or two using L1 at 120 VAC at 8 amps and 12 amps and L2 at 240 VAC at 16 amps.

Click to expand...

Update: Using L1 EVSE charging at 120 VAC and 8 amps, it takes 4.5 hours for my 2014 Spark EV to charge from 80% SOC to 100% SOC. Using L2 EVSE charging at 240 VAC and 16 amps, it takes 1.5 hours for my 2016 Spark EV to charge from 80% SOC to 100% SOC. At the end of charging, the GOM on my 2014 Spark EV read 98 miles and the GOM on my 2016 Spark EV read 106 miles. Therefore, I should have 80% SOC for my 2014 Spark EV if, using my L1 EVSE at 120 VAC and 8 amps, I set my departure time 4.5 hours later than I actually plan to leave. I should have 80% SOC for my 2016 Spark EV if, using my L2 EVSE at 240 VAC and 16 amps, I set my departure time 1.5 hours later than I actually plan to leave. Next, I plan to test this and see if my GOM for each car actually reads about 80 miles when I stop charging at my actual departure time.

Click to expand...

Yup. This is a great way to control your SoC, and I use it myself. Very roughly speaking, the Bolt charges at about 10-11% per hour on L2. The calculation is pretty easy. On Monday-Thursday, I set my departure for 4 hours past when I actually leave, and the car is at 60% when I do leave. I don't drive much during the week, so typically it is only down to about 40% when I plug in again. 40-60% is pretty gentle on the battery. Then I charge to full on Fridays to prepare for the weekend when I do most of my driving.

Thanks for confirming that this will work. All of my current data from my vehicle suggests I will be right on target for 80% SOC tomorrow morning at 7:30am. I like being able to individually program each day of the week.

SparkEVPilot · May 27, 2018

SparkEVPilot said:
GetOffYourGas said:

SparkEVPilot said:

Update: Using L1 EVSE charging at 120 VAC and 8 amps, it takes 4.5 hours for my 2014 Spark EV to charge from 80% SOC to 100% SOC. Using L2 EVSE charging at 240 VAC and 16 amps, it takes 1.5 hours for my 2016 Spark EV to charge from 80% SOC to 100% SOC. At the end of charging, the GOM on my 2014 Spark EV read 98 miles and the GOM on my 2016 Spark EV read 106 miles. Therefore, I should have 80% SOC for my 2014 Spark EV if, using my L1 EVSE at 120 VAC and 8 amps, I set my departure time 4.5 hours later than I actually plan to leave. I should have 80% SOC for my 2016 Spark EV if, using my L2 EVSE at 240 VAC and 16 amps, I set my departure time 1.5 hours later than I actually plan to leave. Next, I plan to test this and see if my GOM for each car actually reads about 80 miles when I stop charging at my actual departure time.

Click to expand...

Yup. This is a great way to control your SoC, and I use it myself. Very roughly speaking, the Bolt charges at about 10-11% per hour on L2. The calculation is pretty easy. On Monday-Thursday, I set my departure for 4 hours past when I actually leave, and the car is at 60% when I do leave. I don't drive much during the week, so typically it is only down to about 40% when I plug in again. 40-60% is pretty gentle on the battery. Then I charge to full on Fridays to prepare for the weekend when I do most of my driving.

Click to expand...

Thanks for confirming that this will work. All of my current data from my vehicle suggests I will be right on target for 80% SOC tomorrow morning at 7:30am. I like being able to individually program each day of the week.

Update: It works! I planned to have 80 miles on my GOM at 7:30am this morning and I had 81.

Mug2004 · Oct 29, 2018

This is another reason to make the "Target charge option" found in the 2019 Bolt EV available to pre-2019 models as an update/ upgarde

EVHOO · Dec 10, 2018

This is an interesting and useful discussion. My wife's Bolt is used mostly for in town driving, where she (or I sometimes) drives it in the L mode which maximizes the regeneration in slowing or stopping. The regeneration is effectively a very short charge. Can one assume that this normal operation doesn't substantially affect the life of the battery?

My second question is about the hilltop mode. As we don't live on a hilltop, and I understand that the Bolt's integral charging system doesn't allow the the battery to be fully charged, even with hilltop mode in the OFF setting, is there any reason to use the hilltop mode setting for us? Since having the hilltop mode would reduce the number of charging cycles required, would that tend to extend the battery life? Or, does the hilltop mode give some effect that would be greater than what one derives from fewer charging cycles. (I'm assuming that either way, I would be charging as late as possible per the above discussion.)

WetEV · Dec 11, 2018

EVHOO said:
This is an interesting and useful discussion. My wife's Bolt is used mostly for in town driving, where she (or I sometimes) drives it in the L mode which maximizes the regeneration in slowing or stopping. The regeneration is effectively a very short charge. Can one assume that this normal operation doesn't substantially affect the life of the battery?

My second question is about the hilltop mode. As we don't live on a hilltop, and I understand that the Bolt's integral charging system doesn't allow the the battery to be fully charged, even with hilltop mode in the OFF setting, is there any reason to use the hilltop mode setting for us? Since having the hilltop mode would reduce the number of charging cycles required, would that tend to extend the battery life? Or, does the hilltop mode give some effect that would be greater than what one derives from fewer charging cycles. (I'm assuming that either way, I would be charging as late as possible per the above discussion.)

As the regeneration is a very small cycle in town, usually less than 1% it doesn't seem to have a large impact on life. EVs driven in the mountains, with large and prolonged regeneration do seem to have less battery life.

In general, a small cycle near the midpoint would give the best total energy stored and released over the battery's lifetime. From
https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

This graph shows for a given peak charge (100%, 85% and 75%) how many cycles a specific battery would last. Note that the total energy or miles in an EV would be greatest with a 75% to 25% cycle.

DucRider · Dec 11, 2018

People are big on quoting studies from Battery University done on small (cell phone) batteries with no thermal management (and no top and bottom buffers to speak of).

The Bolt has been on the road for 2 years, and there have been no significant reports of less degradation by those that take extra measures to baby their batteries.

My Honda Fit EV was plugged in to charge to 100% immediately after arriving home (the worst case scenario according to pundits). We did this for close to 5 years with no noticeable range loss. We did notice a couple of mile drop when new tires were put on after ~4 years, so we did maybe lose a few % points of range from when new (EPA rating of 82 miles).

Nissan and the LEAF battery issues have created a mindset that hinders the adoption of EV's. If I tried to explain to my wife that she had to go through the procedures many swear by to preserve battery life, we wouldn't be driving an EV. This is true of much of the public. Tesla recommends not charging to 100%, but it is likely that is because they have opened up at least some of the top buffer of the battery to allow for the greatest possible range. The Bolt top buffer is locked out and can never be accessed by the user.

GM says it is not a problem to top off whenever you want, charge to whatever level you want (not charging to "100%" does allow room for full regen at the start of a trip - hence hilltop reserve).

Will setting a lower charge rate, charging just before driving, keeping the battery between X% and X% charge hurt the battery. Very unlikely.
Will doing those things make a significant difference in battery degradation. Empirical data suggests not. Let the flames begin :twisted:

SparkE · Dec 11, 2018

I've sseen reports (by anal-retentive Bolt owners) who are tracking their battery capacity, and battery loss is 5-10% over a 18-month to 2-year period (over 40K miles - one was 70K miles).

WetEV · Dec 12, 2018

DucRider said:
People are big on quoting studies from Battery University done on small (cell phone) batteries with no thermal management (and no top and bottom buffers to speak of).

More importantly, there are differences in the chemistry of cells, and Battery University sometime glosses over that.

DucRider said:
The Bolt has been on the road for 2 years, and there have been no significant reports of less degradation by those that take extra measures to baby their batteries.

Too early to determine which measures are best for batteries from experience in the Bolt. It is hard to measure capacity much closer than 5%. As reported losses are (as far as I know) all less than 10%, then it is hard to tell the difference between measurement errors and differences on one hand, and true capacity changes on the other hand. If one car measures 4% loss and another car measures 6% loss and the measurement error is 5% is there a real difference?

DucRider said:
My Honda Fit EV

Which uses a rather different chemistry, lithium titanate. At standard conditions (25C), should last about 2.5 times longer, and more at higher temperatures. Better, yes, and more expensive, yes. Very limited volume and distribution...

Charge: As soon as possible, or as late as possible?

Help Support Chevy Bolt EV Forum:

Active member

Active member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

New member

Member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!