Nissan does not recommend Trickle-Charge?

[Simmer]

Just got a new Leaf and love it.

However, on page CH-7 under 'Trickle charge' of the Owner's Manual it says:

Trickle charging is not recommended for regular use.

Does anyone know why Nissan does not recommend Trickle Charging the Leaf? :?:
Does it destroy the battery over time?

Thanks

 

[surfingslovak]

Does anyone know why Nissan does not recommend Trickle Charging the Leaf? :?:
Does it destroy the battery over time?

While trickle charging does not provide the best experience due to long charge times, it is not harmful to the battery. It also is less efficient than level 2 charing, and wastes more electricity. There are older threads on the forum. Also, it's likely covered in the wiki.

 

[planet4ever]

Here is one of those older threads, with a useful link to other threads on the subject: Trickle Charger - using it long term - OK or not

By the way, the wiki disappointed me this time, based on a quick look. I may try to do some work on it.

Ray

 

[johnrhansen]

I'm not claiming to be an expert by any means. I was reading in the battery wiki somewhere that someone figured out that the ideal charge rate for the life of the battery the size of the leaf's was 12 KW. Trickle charge is more like 1. In my car, normal charging is 6. much closer to the ideal.

here's my speculation as to why. I also read that the battery is happiest a mid charge level around 40-60 percent or something like that. So what you'd want to do is to leave the battery at that level as long as you can and charge it just before you leave in the morning. If you charge at level 1, it will spend more time at a higher charge level than if you charge at level 2.

I can't help but to conclude that level 2 charging is best for the battery. Maybe not by much... Does my logic make sense?

 

[MikeD]

Simmer: IMHO I believe the statement was made mainly over the issue of relative safety. On page CH-7 it also reads "Trickle charge can be used when it is necessary to perform an emergency charge at a destination such as a friend’s house. Trickle charge uses the EVSE (Electric Vehicle Supply Equipment) or an SAE J1772 compliant cord set to connect the vehicle to an AC 110 - 120 volt, 15A dedicated outlet. The outlet should be protected by a dedicated circuit breaker or fuse to avoid overloading the circuit or other electrical hazard.".

It is clearly safer to charge on a regular basis with a direct wired EVSE on a fixed dedicated circuit (ensuring no possibility of plug/receptacle overheating or accidental user shock at the plug or of circuit overload) where the charging cord is also presumably subjected to less flexing and twisting and less possibility of kinking over a portable EVSE. It also avoids the safety issue of whether or not the receptacle is GFCI protected or whether or not the user has to use an extension cord, which is an additional safety concern.

Using the Leaf's portable EVSE on a regular basis also probably means you have no spare backup EVSE should it develop a defect.

 

[DanCar]

Nissan should explain why they made that statement. When the cars first came out they required level 2. Then later they removed the requirement. They have made other seemingly erroneous statements such as fast charging will degrade battery. We know that temperature is a much bigger factor, which they failed to mention.

 

[EVDRIVER]

They required L2 because they wanted to manage the entire process to insure satisfaction of the roll out and they had an agreement with AV, now they don't care as the process is on the dealers. Using L1 does not harm the battery, they discourage it because too many folks have shared and poor quality 120V outlets and it frustrates buyers because of the slow speed. Don't expect an explanation and if you get one it will not be accurate. There is nothing more to it than this.

 

[MikeD]

EVDRIVER: You wrote "Don't expect an explanation and if you get one it will not be accurate.". I don't understand what you meant by this, could you elaborate a little more? Are you talking about a dealership's explanation? I thought the "Leaf Owner's Manual" covers the OP question pretty well. One shortcoming that I notice, however, is this manual doesn't recommend GFCI protection very clearly, but this might be due to concern about nuisance trips that could interupt a charging session early -- if true that nuisance trips will happen every now and then, all the more reason to avoid cord and plug connected EVSEs if at all possible for normal charging at home.

 

[surfingslovak]

One shortcoming that I notice, however, is this manual doesn't recommend GFCI protection very clearly, but this might be due to concern about nuisance trips that could interupt a charging session early -- if true that nuisance trips will happen every now and then, all the more reason to avoid cord and plug connected EVSEs if at all possible for normal charging at home.

Mike, if you don't mind me asking, how much level 1 charging have you done so far?

 

[MikeD]

surfingslovak: I have no personal charging experience with any cord and plug connected EVSE, including the portable EVSE that came with my Leaf. I also don't know if many people have had much trouble with receptacle level GFCI tripping (as opposed to internal EVSE GFI tripping) while charging. I do know that GFCI protection of receptacles in locations that can become wet is fairly desirable from a safety standpoint and, even better, not usually costly to provide.

Are humans being penny wise and pound foolish when it comes to providing adequate and sustainable home charging support?

 

[TimLee]

I do know that GFCI protection of receptacles in locations that can become wet is fairly desirable from a safety standpoint and, even better, not usually costly to provide.

Although generally true, the risk from a portable EVSE isn't very significant, because it should NEVER be plugged into the vehicle before it has been plugged into the wall. Then when it is plugged into the wall, the current draw of the portable EVSE electronics energizing is pretty small. But some users will fail to do it in the correct sequence.
I think Nissan was wanting to discourage extensive use of portable 120V EVSEs. Primarily due to some users improperly connecting it to the vehicle before plugging it in, due to multiple outlets often being on the same circuit, and due to the outlets often times only being on a 15 amp circuit, when use of a 20 amp single use circuit is the better practice. They just want to discourage bad practice and user risk.

 

[donald]

As far as I understood the term 'trickle charge', Li-ion must NOT be trickle charged. It is not the correct form of charging for them.

Above around 0.15C an Li-ion battery has only one way to charge - firstly, a constant current up to 4.2V/cell, then a ramp down to some fraction of the desired charging current before charging is halted.

If, by 'trickle charge', you simply mean 'a slow charge', then there is no issue with Li to run a lower charge rate than 0.15C. In this case, there is generally no saturation charge phase after the cells have reached 4.2V. Instead, the charging strategy simply delivers the <0.15C up to 4.2V/cell, and then charging is stopped.

You cannot continue to trickle charge the self-discharge rate after the cell reaches 4.2V/cell (like would happen naturally with a Pb cell), because you'll start plating the cells with Li metal. The safety systems will normally prevent this, though it is always possible that such protection circuits themselves may fail and the cells continue to increase their voltage. Li metal plating may then lead to a short in a cell, and a subsequent 'thermal event'.

For cells that have already reached 4.2V/cell and are at the end of their saturation charge, the correct procedure to maintain 100% charge is to cycle the cells allowing them to discharge back down to, say, 4.0V/cell, then recharge to 4.2V.

In the case of emergency systems using Li-ion power that need to be on continuous standby for immediate use, the recharge will cycle to a lower value, say 4.05V. This prevents voltage overstress - you should avoid leaving an Li cell at 4.2V for long periods.

 

[DanCar]

Elsewhere on this forum it has been stated that the battery is only charged to 93% of total potential. That suggest that the leaf only charges to 4.2V * .93 = 3.9V when "100%" charged.

 

[ASP]

Elsewhere on this forum it has been stated that the battery is only charged to 93% of total potential. That suggest that the leaf only charges to 4.2V * .93 = 3.9V when "100%" charged.

Really? That's interesting. I'm waiting for my JuiceBox and that means once I get it I will effectively have 7% more capacity when it says 100%?

 

[ColumbiaRiverGorge]

My LEAF battery app. today indicated I charged to 95.3% state of charge which is the highest I have seen since using the app. for a few monhs. Usually requesting 100% charge results in 93 to 94% SOC. I have been trickle charging at work for two years with no ill effects. This same EVSEupgrade also does my home L2 charginh

 

[mrdcmills]

I've gone 12,500 miles on the 120v EVSE that came with the car. No problems so far. I charge 80% Sun-Thurs and 100% Fri-Sat for extra weekend driving. Still have the car for 29 more months, might upgrade to 240v when prices come down.

 

[TomT]

Maximum charge is controlled by the BSM in the car, not the EVSE, so, no, it won't make any difference.

Elsewhere on this forum it has been stated that the battery is only charged to 93% of total potential. That suggest that the leaf only charges to 4.2V * .93 = 3.9V when "100%" charged.

Really? That's interesting. I'm waiting for my JuiceBox and that means once I get it I will effectively have 7% more capacity when it says 100%?

 

[epic]

I do know that GFCI protection of receptacles in locations that can become wet is fairly desirable from a safety standpoint and, even better, not usually costly to provide.

Although generally true, the risk from a portable EVSE isn't very significant, because it should NEVER be plugged into the vehicle before it has been plugged into the wall. Then when it is plugged into the wall, the current draw of the portable EVSE electronics energizing is pretty small. But some users will fail to do it in the correct sequence.
I think Nissan was wanting to discourage extensive use of portable 120V EVSEs. Primarily due to some users improperly connecting it to the vehicle before plugging it in, due to multiple outlets often being on the same circuit, and due to the outlets often times only being on a 15 amp circuit, when use of a 20 amp single use circuit is the better practice. They just want to discourage bad practice and user risk.

Hmm--So, i pug in wall then car?
I thought i read the opposite on here.plug in car then wall?Which 1?
I have been pluging in car then wall since i thought i read that.
Please advise

 

[cwerdna]

Topic's come up a bunch of times before. See http://www.mynissanleaf.com/viewtopic.php?f=9&t=9828&start=0" onclick="window.open(this.href);return false;

I wish I could find the original post I made that I refer to at http://www.mynissanleaf.com/viewtopic.php?p=278951#p278951" onclick="window.open(this.href);return false;.

 

[surfingslovak]

Topic's come up a bunch of times before. See http://www.mynissanleaf.com/viewtopic.php?f=9&t=9828&start=0" onclick="window.open(this.href);return false;

I wish I could find the original post I made that I refer to at http://www.mynissanleaf.com/viewtopic.php?p=278951#p278951" onclick="window.open(this.href);return false;.

Thank you, Andrew. Also, to address some of the questions voiced upthread, the term "trickle charging" was coined by Nissan and it expresses the fact that the charge will take a long time. Obviously, the onboard charger is used during the process, just like it would with level 2 charging. The only difference is that the current drawn from the wall is quite limited, so that the EVSE would not trip a breaker. This has nothing to do with trickle charging used for lead-acid and other type of batteries.

Regarding the cell voltages mentioned above: lithium manganese cells reach their energy maximum at a slightly lower voltage than cobalt cells. 4.17V is often quoted on a full charge. While you can charge the raw cell to a higher voltage, nothing is really gained from it after this point. The LEAF only allows 4.10V and calls it 100% charge. Conversely, 80% charge is 4.05V on the cell level.

Since the charge and discharge curves are highly nonlinear, simple ratios cannot be used to estimate the SOC. We have to look at the datasheet and try to estimate the stored energy and SOC from there. The LEAF uses a computer for that, and some of the debates we had about capacity loss last year centered around the accuracy of this software and related sensors used for coulomb counting and voltage measurements.

Are humans being penny wise and pound foolish when it comes to providing adequate and sustainable home charging support?

Mike, the portable EVSE is supposed to be that system. While your concern is both laudable and understandable, some of us might have to learn to live with imperfect compromises. Take an office park I and several MNL readers frequent. While the operator might not want to invest $200K into an installation of a dozen of level 2 stations, they are perfectly happy to provide a row of wall outlets. The drivers have to bring their own EVSE equipment, and either be content with level 1 charging or not charge at all. This type of dilemma might go away in the future, but for the time being, it's an important aspect of the nascent electric vehicle ecosystem.

Hmm--So, i pug in wall then car?
I thought i read the opposite on here.plug in car then wall?Which 1?

Yes, this is the recommended sequence, I believe.