Charging Plan to Help Battery Life

I have a 50-mile commute and can charge at work.
My question has to do with the best strategy for charging to maintain battery health and limit pack degradation. Charge on only one end, or charge at home and work so that the battery cycles between 6 and 10 bars, and is rarely below 4 bars?

I charge to 80%.
The roundtrip takes 8 bars. I typically get home with the two red bars remaining.
For the past several months, I have been charging at work and running it up to 80% or 10 bars, from 5 or 6 when I arrive. The same thing at home; arrive back with 5 or 6 bars, recharge to 10 bars overnight.
Is it best to keep the battery pack at 6 - 10 bars by charging at work and home, rather than only charging at home; which brings the pack down to 1 or 2 bars.
(Cost is not really an issue.)
To add another parameter, I can charge either L2 or L1 at work, unless the L2s are ICED, where I revert to L1.

I think it is a little difficult to choose. 80% SOC to 2 bars (22-30% SOC) has more cicle amplitude than 80% to 6 bars (50-57% SOC), but the pack spends less time at relatively high SOC. The very best would be to cicle between 60% and 30% SOC. To do that you need to leave home with 7 bars, arrive with 3 bars and then charge to just 7 bars. This can be done by programming the charge timer to only charge a little less than 2 hours at work and at home.

I don't think there is a clear answer here, but I use several principles to help decide charging strategy:

1) Shallower depth of discharge (DOD) is better for the battery (e.g., 60% to 40% and back again is better than 80% to 20% and back). How much better at given levels of DOD is unclear.

2) Keeping the pack at a lower average SOC over time (down to perhaps 30-35%, lower than that probably isn't as good for the pack) is better for the pack than keeping it at a higher SOC.

3) You especially want to keep the SOC relatively low if the temperature is high

Here is what I would do if I wanted to baby the pack as much as possible (and personally, I do want to do this):

--Charge to 7 bars just before leaving for work in the morning (you either need a Gid-meter or do some experimentation about time charging time needed to add 4 bars; I would estimate 5.5 hours on L1, perhaps 2 hours on L2)
--Let the car sit at 3 bars most of the day
--Charge back to 7 bars just before returning from work
--Let the car sit at 3 bars most of the night

This is easy with a Gid-meter (or future Leaf scan), since you can go by percentage SOC and use the rule of thumb for L2 of 3% increase in SOC per 10 minutes of charging. As mentioned in previous threads, I do this routinely and can hit a particular SOC target within 1-2% either way. Hope this helps.

thanks for this input, guys.
yes, my car on L2 charges four bars in just under two hours.
It would be easy to set the timer in the car to do that.
start, at say, 3 pm and end at 5 pm; typically leaving work between 5 and 6.

at home, i would do the same, ending around 8 am.

as the Leaf timer, does not allow lower than 80% on the settings, I could not use end-of-time charging. I would always get to 10 bars sted 7.

any thoughts on whether L1 or L2 is better at work?
do others agree with the 3- 7-bar theory, as per above posts?

I would use the end timer to charge 100% at work. If you are on L1 at work then add 80% at home.
If you need to share the L2 at work then I would probably go immediate 80% at work and charge at home if needed.

thankyouOB said:

any thoughts on whether L1 or L2 is better at work?

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I don't think it makes much difference. I would favor L2 because you would have the pack at a higher SOC for a shorter period of time, but don't have any theories or data to back this up.

Stoaty said:

Here is what I would do if I wanted to baby the pack as much as possible (and personally, I do want to do this):

--Charge to 7 bars just before leaving for work in the morning (you either need a Gid-meter or do some experimentation about time charging time needed to add 4 bars; I would estimate 5.5 hours on L1, perhaps 2 hours on L2)
--Let the car sit at 3 bars most of the day
--Charge back to 7 bars just before returning from work
--Let the car sit at 3 bars most of the night

This is easy with a Gid-meter (or future Leaf scan),...

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I agree with this approach. Also, please note that I think Phil has said that he may build LEAFscan to allow us to program the 80% level to be whatever level we want. That should allow you to make this type of babying fully automatic!

Stoaty said:

Here is what I would do if I wanted to baby the pack as much as possible (and personally, I do want to do this):

--Charge to 7 bars just before leaving for work in the morning (you either need a Gid-meter or do some experimentation about time charging time needed to add 4 bars; I would estimate 5.5 hours on L1, perhaps 2 hours on L2)
--Let the car sit at 3 bars most of the day
--Charge back to 7 bars just before returning from work
--Let the car sit at 3 bars most of the night

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That would be my suggestion as well. From a practical perspective this is a bit of a nuisance because you have to constantly switch between the two charging timers. (And if you forget to do it you are screwed)

smkettner said:

I would use the end timer to charge 100% at work. If you are on L1 at work then add 80% at home.
If you need to share the L2 at work then I would probably go immediate 80% at work and charge at home if needed.

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100%?
i thought that was to be avoided, as much as practical.

Sitting at 100% for an extended period is not recommended. That is why I recommend the end timer.
Heat would seem to be the biggest issue to avoid. Plenty seem to charge to 100% with little to no effect as they drive a lot and use it.

You didn't mention what kind of (daytime) temps you're seeing, but I have a new rule: I now avoid charging when the battery pack is warm (>6TB). So in your case, I wouldn't do the "charge at work" thing on a warm day or if you're Leaf is sitting in the sun (the only time I see 7TB bars is on the way home from work on a hot day).

Otherwise I don't see much difference in your charging scenarios; I typically charge to 80% (on an end timer) and do a round-trip drive to work everyday.

I have a very similar commute, 50 miles round trip with L2 at home and work. The one big factor I take into account (especially recently) is the temperature. If the high for the day is up at say 95 degrees, the parking lot at work will be well over 100 on the black asphalt. The one time I charged at work with the temp right at 100 degrees, I got the 7th temperature bar on the way home. On days like that, I would think it much more beneficial to the battery to charge only at night when the ambient temp goes down.

zarwin said:

I have a very similar commute, 50 miles round trip with L2 at home and work. The one big factor I take into account (especially recently) is the temperature. If the high for the day is up at say 95 degrees, the parking lot at work will be well over 100 on the black asphalt. The one time I charged at work with the temp right at 100 degrees, I got the 7th temperature bar on the way home. On days like that, I would think it much more beneficial to the battery to charge only at night when the ambient temp goes down.

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This is an important point. Agree 100%.

I have a good arrangement. I get up around 5:30 a.m. each day. I plug in then, and usually leave around 9:00 a.m. So not only is it the coolest part of the day, it doesn't even stay charged at 80% for any significant amount of time. Living in Tucson it is probably all for naught anyway.

i could have sworn that i posted to this thread months ago. but my advise; charge to 80% both at home and work.

i did a 50 mile RT commute and did a full charge at home, no charge at work and ended up with 30-40% SOC at the end of the day

I could have sworn I'd read this thread before, too. And in my delirium, I remember a post something like this:

"For maximum life, charge it to 50%, leave it, and ride your bike to work"

thankyouOB said:

For the past several months, I have been charging at work and running it up to 80% or 10 bars, from 5 or 6 when I arrive. The same thing at home; arrive back with 5 or 6 bars, recharge to 10 bars overnight.

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Can you describe your charging location where you work? Covered parking or sitting in the open on open hot asphalt?

Stanton said:

You didn't mention what kind of (daytime) temps you're seeing, but I have a new rule: I now avoid charging when the battery pack is warm (>6TB). So in your case, I wouldn't do the "charge at work" thing on a warm day or if you're Leaf is sitting in the sun (the only time I see 7TB bars is on the way home from work on a hot day).

Otherwise I don't see much difference in your charging scenarios; I typically charge to 80% (on an end timer) and do a round-trip drive to work everyday.

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parking is in an underground facility -- very lucky me -- and the temps are about 75 degrees.
hotter than my driveway where I charge at night.

When I charge at home, I start out with 5 on the heat-bar side (lefthand side) and it stays that way for the morning ride; and at work, it goes to six bars, when I get in the car to go home and stays that way on the trip.

It would be nice to know exactly how much the temperature rises with an L2 charge.. it may actually cool the battery down a bit.

Herm said:

It would be nice to know exactly how much the temperature rises with an L2 charge..

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About 5 degrees, but it seems to depend on the SOC.

Herm said:

It may actually cool the battery down a bit.

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There is no evidence of that, but we won't know for sure until someone has plotted battery sensor temperature across the entire charge cycle from the CAN bus.