Question about charging strategy

[sethr]

Hi there; I am wondering if I can get opinions from you all (especially the engineers!) - I drive very infrequently, being retired and in walking distance for most shopping and small errands. Most of my drives are about 20 miles, so I frequently end up after a few trips (spread out over a couple of weeks) with 2 or 3 bars and then charge back to 80%. There are usually a few days to a week before I drive anywhere again. And, I want this car to REALLY last. So here's the real question: Would it be better to charge up to 80%, knowing it might be a few days to a week before I drive again, or leave it with 2-3 bars for those days and charge to 80% just before I will be going somewhere? Thanks for your input!
P.S. I can't find it anywhere on this site - WHAT is a GID? I know it's related to state of charge, but I see no definition. Hard to really follow those discussions without knowing what a GID is! Thanks in advance for that too.

 

[davewill]

Ideal storage battery level is between 50% and 80%. For simplicity, and so that you are ready to go unexpectedly, I'd keep it charged to 80%. But if you really insist on going all out to baby the battery, charge it to 5 or 6 bars. A Gid is the forum's name for the units that are reported by Gary Gidding's SOC meter. A Gid is equal to 80Wh.

 

[EdmondLeaf]

Max GID at 100% registered, 281 and by multiplying it by .08 you will get power in the battery in kWh. Many said between 2 and 10 bars for storage, but who knows for sure

 

[surfingslovak]

If it's not too much trouble, my recommendation would be to charge it up to 5 or 6 bars, and leave it that way. It would only take 1 1/2 to two hours to charge the car to 80% from there, and about 3 or 3 1/2 hours all the way to full. That would be the most notice you would need.

In an emergency, if you needed the car immediately, it will have about half the range at five or six bars. Hopefully that's enough for your needs. If if it's not, you might want to keep it at 80% perpetually. It's difficult to come up with accurate projections, but we looked at a number of reports recently on this forum. They all seem to indicate that maintaining a lower average state of charge is a conservative strategy.

Nekota came up with a good and succinct Gid definition recently:

Gids was first suggested by member 91040 in this post. Gids represent the State of Charge (SOC) of the battery pack and gets it's name from member garygid from his development contributions to a meter to log and analyze the CAN bus on the LEAF to find the SOC messages.

Many said between 2 and 10 bars for storage, but who knows for sure

Richard, I can virtually guarantee you that five bars for storage is a good conservative recommendation. Please don't put that in doubt. As we discussed before, we cannot know how much better it will be for the battery over its lifetime. There are too many factors to consider. However, let's not confuse our inability to predict the future with our effort to outline conservative battery care recommendations. That we can do.

 

[Nubo]

Hi there; I am wondering if I can get opinions from you all (especially the engineers!) - I drive very infrequently, being retired and in walking distance for most shopping and small errands. Most of my drives are about 20 miles, so I frequently end up after a few trips (spread out over a couple of weeks) with 2 or 3 bars and then charge back to 80%. There are usually a few days to a week before I drive anywhere again. And, I want this car to REALLY last. So here's the real question: Would it be better to charge up to 80%, knowing it might be a few days to a week before I drive again, or leave it with 2-3 bars for those days and charge to 80% just before I will be going somewhere? Thanks for your input!
P.S. I can't find it anywhere on this site - WHAT is a GID? I know it's related to state of charge, but I see no definition. Hard to really follow those discussions without knowing what a GID is! Thanks in advance for that too.

Due to the lower bars being "larger", 2 bars is practically 30% state of charge; 3 bars is close to 37%.

 

[LEAFfan]

Nekota came up with a good and succinct Gid definition recently:
Gids was first suggested by member 91040 in this post. Gids represent the State of Charge (SOC) of the battery pack and gets it's name from member garygid from his development contributions to a meter to log and analyze the CAN bus on the LEAF to find the SOC messages.

Gids or the raw number (100% based on 281) represents the present battery capacity out of the 24kW h battery pack;it isn't the SoC%. If you have a battery capacity loss, no matter how big, your capacity bars will still go to 12 bars after a '100%' charge. CWs will tell you that you have an SoC of 100% even though you may have lost some capacity/kW hs. The Gid meter will show you that when you have a battery capacity of 86%, it will read 242 Gids instead of the 281 you would have with a full 100% battery capacity. Once you lose capacity, SoC is virtually useless, but BC% and Gids are gold.

 

[surfingslovak]

Gids or the raw number (100% based on 281) represents the present battery capacity out of the 24kW h battery pack;it isn't the SoC%. If you have a battery capacity loss, no matter how big, your capacity bars will still go to 12 bars after a '100%' charge. CWs will tell you that you have an SoC of 100% even though you may have lost some capacity/kW hs. The Gid meter will show you that when you have a battery capacity of 86%, it will read 242 Gids instead of the 281 you would have with a full 100% battery capacity. Once you lose capacity, SoC is virtually useless, but BC% and Gids are gold.

Thank you, LEAFfan. You are absolutely right, Gids are not an expression of SOC. I agree with that, and Nekota's write-up was likely penned before Phil told us that Gids represented stored or usable energy (unclear which). How about my and Herm's description then. Are they any better?

AFAIK Gids are derived from a Coulomb count of what went into the battery, and they don't reflect the amount of energy the battery is physically holding perfectly accurately. It can only be an estimate, a close guess, but still an estimate.

GIDs are derived from a coulomb count of what is going out of the battery subtracted from an initial model, occasionally recalibrated by measuring the resting voltage, but it could easily be as you describe.

That said, I must caution you not to equate a lower Gid reading to permanent battery capacity loss. There is some correlation, sure, but it's not a 1:1 relationship. If my Gid count today was 20% less than I would expect in an ideal case, that does not necessarily imply that my battery has degraded 20%. A Gid count is not conclusive enough for us to make that determination.

 

[kubel]

My charging strategy is whatever is the most convenient for me. Since I'm on trickle-charging only and do around 60 miles per day, whenever my car is parked, it's usually being charged. So I typically keep it between 2 bars and 10 bars. The only time it stays at 10 bars is in the morning when it finishes charging. Conveniently, that's also a very cool time, so it all works out. When the car is baking out in the sun at the hottest time of the day, it's usually somewhere around 6 to 8 bars, depending on when I started charging and for how long.

 

[TonyWilliams]

I'm happy to see we are all coming on board with the same information. Saves a lot of discourse!!!!!

Gids or the raw number (100% based on 281) represents the present battery capacity out of the 24kW h battery pack;it isn't the SoC%. If you have a battery capacity loss, no matter how big, your capacity bars will still go to 12 bars after a '100%' charge. CWs will tell you that you have an SoC of 100% even though you may have lost some capacity/kW hs. The Gid meter will show you that when you have a battery capacity of 86%, it will read 242 Gids instead of the 281 you would have with a full 100% battery capacity. Once you lose capacity, SoC is virtually useless, but BC% and Gids are gold.

Thank you, LEAFfan. You are absolutely right, Gids are not an expression of SOC. I agree with that, and Nekota's write-up was likely penned before Phil told us that Gids represented stored or usable energy (unclear which). How about my and Herm's description then. Are they any better?

AFAIK Gids are derived from a Coulomb count of what went into the battery, and they don't reflect the amount of energy the battery is physically holding perfectly accurately. It can only be an estimate, a close guess, but still an estimate.

GIDs are derived from a coulomb count of what is going out of the battery subtracted from an initial model, occasionally recalibrated by measuring the resting voltage, but it could easily be as you describe.

That said, I must caution you not to equate a lower Gid reading to permanent battery capacity loss. There is some correlation, sure, but it's not a 1:1 relationship. If my Gid count today was 20% less than I would expect in an ideal case, that does not necessarily imply that my battery has degraded 20%. A Gid count is not conclusive enough for us to make that determination.

 

[EdmondLeaf]

Many said between 2 and 10 bars for storage, but who knows for sure

Richard, I can virtually guarantee you that five bars for storage is a good conservative recommendation. Please don't put that in doubt. As we discussed before, we cannot know how much better it will be for the battery over its lifetime. There are too many factors to consider. However, let's not confuse our inability to predict the future with our effort to outline conservative battery care recommendations. That we can do.

Sorry for using shortcut. I completely agree that that 5 -6 bars is best for storage according what we know. I should explain better about between 2 and 10 bars. We do not want to go to low, and I believe staying at 10 is not to good especially with high ambient temp. I try not to go to crazy with recharging after driving say 20 miles. So if I had 6 bars and left with 3 I will keep car like that for even a 10 12 h, if I know that I do not need a car or I have to charge next day to 80% to go to work. Right now at temp going up my goal is to keep car at 5 -6 bars most of the time and I guess is fair to say at any temp. I think another good recommendation will be to avoid exposure to high temp direct sun (stay below 90F), car should take care of low temp.
I am not an engineer, I am a physiologist (so my advice maybe not that good after all).