"Trickle charging is not recommended for regular use"

I AGREE!!!

IF (yes, IF) there is NO "non-political" reason, Nissan should say so.

Then, with sufficient time available, there is no technical reason to avoid using L1, and it does not harm the battery to use L1 frequently, or even exclusively.

Something like: "We do not recommend frequent L1 charging, but there is no known technical reason to avoid using L1 charging."

Nubo said:

I've read that certain batteries actually charge better at higher rates vs. trickle-charging. This is due to the way that some chargers determine the charging cutoff point. For consumer-type rechargeable batteries, a "smart charger" will usually use a combination of Delta-V (change in voltage over time), and DT/Dt (rate of temperature change over time). Changes in these values are interpreted as "signals" that the pack has reached a certain state of charge. At very low current levels, these "signals" can be harder to detect and the charger may have to fall back to it's fail-safe method of temperature cutoff, resulting in some degree of overcharging.

This info comes from consumer-grade cells and I have no idea if this has any bearing on the LEAF battery chemistry or charging algorithms.

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The delta V and temperature bump are end of charge points for NiMH cells. They're charged with constant current up to the end of charge point. These methods are also used when charging the earlier EVs that use nickel metal hydride cells. So yes - there is absolutely an "EV" connection here - it just doesn't apply to the Leaf.

Lithium is charged with a 2-stage process of constant current then constant voltage - just like lead acid cells. Lithium doesn't get the 'float' stage that lead gets, and lithium doesn't get the 'scheduled overcharge' that some lead gets for cell balancing.

Lead acid batteries lose about 20% of their charge each month, so they are routinely 'trickle charged' at maybe 1-2A to keep them full. Lithium only loses about 3% per month so doesn't need the 2A tourniquet to stop the bleeding. In a real sense, the Leaf's level 1 charge isn't a true 'trickle charge' as it's feeding about 5A into the pack initially.

garygid said:

I AGREE!!!

IF (yes, IF) there is NO "non-political" reason, Nissan should say so.

Then, with sufficient time available, there is no technical reason to avoid using L1, and it does not harm the battery to use L1 frequently, or even exclusively.

Something like: "We do not recommend frequent L1 charging, but there is no known technical reason to avoid using L1 charging."

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That would be a much more clear message than saying "we felt it useful to include a Level 1 EVSE in a bag in the trunk but just like common sense we don't recommend you use it."

Jimmydreams said:

mogur said:

One interesting thing I discovered in studying the schematics is that the Leaf has the same oddity that most other Japanese cars seem to have: The accessory outlet is off if the car is not "On" or in "Acc". Our Acura did the same and it is highly annoying if you want to charge a cell phone or such when the car is off. I will be rewiring the Leaf just as I did on the Acura.

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Yeah, but leave your radar detector in the car in the "ON" position for a few days = dead battery. It's happened to me on a few occasions. (I drive slower now and don't need a radar detector).

To each his/her own, I guess.

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Not me, already thinking about how I'm going to custom-mount my V1

I suspect the reason might be two-fold. As some have mentioned already, the length of time might be a problem for some people, and BTW, this should always be phrased as "L1 charges at 5 miles of range for every hour of charging." instead of "It take 20 hours to charge at L1." This tells people who need to go X miles that they only need to charge enough to get where they are going instead of waiting for a full charge. A lot of my customers are under the impression they have to keep charging till full and this scares them.

The other reason may have to do with the overhead of charging and that the total kWh going into the pack is slightly higher due to the higher percentage of energy devoted to the overhead at L1 vs. L2.

Just a guess, but that might be their reasoning. I agree that they should tell us why they are concerned.

PaulScott said:

As some have mentioned already, the length of time might be a problem for some people, and BTW, this should always be phrased as "L1 charges at 5 miles of range for every hour of charging." instead of "It take 20 hours to charge at L1." This tells people who need to go X miles that they only need to charge enough to get where they are going instead of waiting for a full charge. A lot of my customers are under the impression they have to keep charging till full and this scares them.

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I completely agree. If you have 12 hours each night to charge then you can refill 60 miles each night. Actually I think L1 will prove faster than 5mph up to 80% charged. So a person may well get 6 to 7mph during the first 10 hours from a low start.

PaulScott said:

A lot of my customers are under the impression they have to keep charging till full and this scares them.

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This is exactly why I never supported the whole "it takes 20 hours or 8 hours to charge" and will just state that Level 1 charges at a rate of 5.5 miles per hour and Level 2 charges at a rate of 12.5 miles per hour.

Assuming:

Level 1 = 120 volts @ 12 amps
Level 2 = 240 volts @ ~14 amps (Maximum of 208 volts @ 16 amps for a 3.3 KW charger)
Pack Capacity = 24 KWh, but takes 26.4 KWh of energy to completely charge (10% inefficiency)
24 KWh = Average of 100 miles

AndyH said:

Lead acid batteries lose about 20% of their charge each month, so they are routinely 'trickle charged' at maybe 1-2A to keep them full. Lithium only loses about 3% per month so doesn't need the 2A tourniquet to stop the bleeding. In a real sense, the Leaf's level 1 charge isn't a true 'trickle charge' as it's feeding about 5A into the pack initially.

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Hmmm ... is this what the manual actually means ?

They are just saying don't top off the battery all the time ?

L2 current at 240v (just like 208v) is still the same 16 amps, we believe.

Quite possibly, using an L1 EVSE (120v on a 20-amp circuit) set to "16-amps max output", the LEAF's charger would "eat" all 16 amps.

evnow said:

AndyH said:

In a real sense, the Leaf's level 1 charge isn't a true 'trickle charge' as it's feeding about 5A into the pack initially.

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Hmmm ... is this what the manual actually means ?

They are just saying don't top off the battery all the time ?

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Probably not. Maybe a tech writer decided that the 120V cord can only supply a trickle compared with 16A from an L2 EVSE. :?

When we plug-in with half charge remaining, the pack will measure about 345V. The L1 at 12A is about 1440W - so we'll get about 4A into the pack. If the charger maxes out at 3300W when fed 240V, the L2 will push a bit over 13A into the pack.

Trickle charge is designed to make up for the self discharge. For our 24kWh pack, we're talking about 720Wh per month self discharge - roughly 1/2 an hour of L1 time per month...

The L1 & L2 EVSEs do not "push" any amount of current in.
They simply advise the car that NN-amps (12, 16, etc.) is the Maximum that the car should attempt to "draw" (long term).

A particular EVSE might include a circuit to measure the out-going current, and open its relay if it thinks "too much" is being drawn. However, I think that is not a required EVSE function.

EVDRIVER said:

Sometimes hammering a lead pack with current makes them last longer. Over charging or deep cycling them will kill them, Heat is a separate issue. Putting butter on battery terminals before mounting the cables will increase current by as much as 10%.

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Hammering a pack with current will never make it last longer. No need to deep cycle lithium batteries and butter on the terminals has nothing to do with charge current.

Hammering the pack may well work a bit with lead-acid but I am not sure about lithium.
Just saying try not to apply other battery habits to Leaf.

Good primer on lithium-ion chemistry:
http://batteryuniversity.com/index.php/learn/article/charging_lithium_ion_batteries

DarkStar said:

Assuming:

Level 1 = 120 volts @ 12 amps
Level 2 = 240 volts @ ~14 amps (Maximum of 208 volts @ 16 amps for a 3.3 KW charger)
Pack Capacity = 24 KWh, but takes 26.4 KWh of energy to completely charge (10% inefficiency)
24 KWh = Average of 100 miles

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I agree with your assumptions, except possibly the Level 2 amps. For those who believe 100 miles on a full charge is too high, let me point out that we now know Nissan has always been figuring "empty" as when the Low Battery Warning light comes on, and that is probably more like 20 kWh down in the battery. The EPA says 100 miles is optimistic, and I'll agree, based on that definition of empty. But I think we'll find we can easily eke out 100 miles if we squeeze every electron possible out of the battery, and limp home in turtle mode. And we would indeed need roughly 26 1/2 kWh at the wall to recharge from that point.

Speak for yourself. If you don't know how to drive efficiently, then yes, you might have to "eke" out 100 miles. I can get 120 miles out of my RAV, and I've got enough time in the LEAF to know 120 miles is easy to do.

Paul
Black SL/ETEC
2002 RAV4 EV
2007 Vectrix

AndyH said:

Trickle charge is designed to make up for the self discharge.

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I think the manual says - don't do this. Atleast that is a possible explanation.

Pipemajor said:

Good primer on lithium-ion chemistry:
http://batteryuniversity.com/index.php/learn/article/charging_lithium_ion_batteries

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Good primer but 5-7 years out of date.

No - don't hammer lithium. Don't think of lead - lead is dead.

Part of the problem we have in this brave new world of lithium EVs is that the DIYers and older EVers have to unlearn their mad 'keep lead alive' skillz.

planet4ever said:

I agree with your assumptions, except possibly the Level 2 amps. For those who believe 100 miles on a full charge is too high, let me point out that we now know Nissan has always been figuring "empty" as when the Low Battery Warning light comes on, and that is probably more like 20 kWh down in the battery. The EPA says 100 miles is optimistic, and I'll agree, based on that definition of empty. But I think we'll find we can easily eke out 100 miles if we squeeze every electron possible out of the battery, and limp home in turtle mode. And we would indeed need roughly 26 1/2 kWh at the wall to recharge from that point.

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No way. The 100 mile range is based on LA4 - it's old but still real-world. Even Perry's said that the hypermilers will be in the 130 mile area.

The EV endurance testing keeps the wheels turning until the car stops or can't hold a minimum speed - the testing doesn't pay attention to the lights on the dash...

PaulScott said:

Speak for yourself. If you don't know how to drive efficiently, then yes, you might have to "eke" out 100 miles. I can get 120 miles out of my RAV, and I've got enough time in the LEAF to know 120 miles is easy to do.

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Sorry, my wording may not have been the best. "eke" is indeed a loaded term. What I said was easily eke. What I was thinking was that even gudy could get 100 miles if he pushed it to the limit.

And, Andy, I agree with you. The EPA test will not automatically stop when you go into turtle mode.