Toyota on Lithium Deep Cycle Batteries

[hellosailor]

"A crucial problem is that the Prius battery will last well over 100,000 miles, but only because it is babied. It is seldom charged above 60 percent of capacity, or allowed to fall below 40 percent. If it were charged fully and allowed to run down, like a laptop battery, it would, over hundreds of cycles, lose its ability to hold a charge, Toyota says. That suggests a replacement cost in the thousands of dollars. "

http://www.nytimes.com/2006/10/25/au...ef=autospecial

Interesting comment from Toyota, about the special problems connected with Lithium-based deep cycle batteries. For those of you who have wondered when boats might get "new" battery technology with more power density than lead acid...I guess the answer is "Not right for us."

[Alan Wheeler]

Hmmmmm, wonder why only 60% full charge. You would think they would make the 60% part the full charge limit and anything above that over charged. I mean, they must surely have a special charger for these right??

[hellosailor]

Special charger? Ya, a complete energy management system that also controls charging, custom built all the way.

Makes no sense to me either, but that's what they are quoted as saying.

[Rick]

Lithium-ion battery charging/cycling

When charged to a maximum "full" state lithium-ion batteries are driven to 4.2V per cell. Near that voltage there begins a plating out of lithium at the anode which can oxidize and vent with some danger of fire and/or explosion, given sufficient material, time, and temperature.

When discharged to 1.25 Volts per cell there is a danger of copper dendrite formation between the anode and cathode, again giving rise to potential instability when recharged...not safe.

When cycled between levels about 3.95 Volts per cell and 1.3 Volts per cell one gains reliability yet does not optimize the number of likely cycles for greatest life. Somewhere between the approximate "safe" cycling over an 80% dynamic range (versus the not-so-safe potential 100% rating) and a high cycle life of a 60% dynamic range is the optimum cost per cycle over life dynamic range.

I believe that the article misinterpreted such specifications to state incorectly that the battery is only charged to a 60% state-of-charge instead of correctly stating that a 60% dynamic range as compared to a possible 100% dynamic range. With a 60% dynamic range usage the battery is charged to around an 80% or up to 90% state-of-charge depending upon the "safe" reserve allowed at the lower end to accommodate self-discharge for sufficiently long periods without dendrite formation.

[S/V Elusive]

YEAH Rick! Thanks for that great explaination.

[Tx J]

Tesla Motors [and others] has done a lot of research, and accumulated huge data, on the charging parameters and usage of Li batteries.

IIRC, Tesla prefers a mid-range use/charge cycle for longevity and performance, about a 90-40/30% cycle, only doing a 100% charge if you will need maximum range for a trip, and not going below ~10%. The vehicle BMS and frequently updated software make most of the charging decisions.

There are many other factors involved too, such as charge rates [Teslas have various chargers, from slow, low amp, to fast very high amp]. Their fast Superchargers are cautioned against for regular use to maximize longevity.

[B23iL23]

I have a Tesla Mode X with over 70k miles and regularly let it drop to 5% (because I'm a thrill seeker) and then back up to 90+%. Never had a problem and no issues with any degradation as a result.


if Toyota (who NEVER had any love for EVs) are having problems then its their BMS that is the issue and not the battery.

[a64pilot]

My old Prius has I believe a NIMH battery, not Lithium, and the car won’t charge it above 80% nor below 40%.
To start with a Hybrid cycles it’s battery literally at least hundreds of times more than an electric car, the Prius in city driving is cycling the battery probably every 10 or 15 minutes, on the highway nearly never.

So it’s not just Li based batteries, it’s even lead acid too if you look, but lead due to sulphation needs to be fully charged, but if shallow cycled it will last a lot longer.

The reason laptop batteries and cell phone batteries don’t last longer than they do is they are pushed so hard and overcharged and over discharged as how many hours a battery lasts is nearly the first thing quoted in an test, and is of course the major sales issue with electric cars.
So range being such a huge selling point and the obvious fact that if you push your pack harder you will get greater range, do you think maybe some are being pushed harder than they should?

First before anyone gets upset the Tesla battery is nothing more or less than the venerable Panasonic 18650 cell, just scads of them. This is good because there is already a tremendous amount of data on them, they are a known quantity.

Besides overcharging and under charging the other great killer of most all batteries is heat, they get hot either being discharged or charged, the rate of charge or discharge will determine how much heat is generated.

My Prius has a battery cooling fan that if the AC isn’t on and no radio and your sitting still, motor off you can hear it sometimes, it’s not always on, it has a temp sensor.

One of the worst things you can do to an EV battery is pull off of the highway and Supercharge it. Due to heat build up. It comes off the highway warm, and they you go ramming in huge amounts of power in a short time, further heating it up.
Anyone who has an EV would be smart to use the middle 1/3 of its range, just like a hybrid does, and not Supercharge it. But then of course you have only 1/3 the range.

By the way, this is old data, been known for decades.

Prius owners have been building their own plug in hybrids for a long time, they usually use packs sourced from the junk yard and add them to the car, but other than the pride in doing so it doesn’t accomplish much, they also push the packs harder, of course shortening the cycle life. So they discharge the additional packs, but leave them discharged and not recharge them with the engine as that burns more fuel, but running around with a heavier car with the extra packs, burns more fuel too, so the plug in thing doesn’t accomplish as much as you May hope.

Weight in a car has enormous effect. Back in the 70’s Lee Iaccoa was pushing to eliminate the spare tire, if you did so on a car on the drawing board the car you ended up with was over 400 lbs lighter. You see to meet cargo space and leg room etc if the spare wasn’t there, the car could be smaller and still have the same room and carrying capacity etc, being smaller meant a slightly smaller engine and still meet acceleration requirements etc. smaller engine means smaller transmission, which means smaller brakes, and tires and suspension etc, the snowball effect is significant.

So while it sounds good to have a big battery on a plug in hybrid, the extra weight and size, means a larger and heavier car to meet the same space requirements and that pretty much negates the advantage of the greater all electric range.

We want all of this simple so we can understand it, but it’s not simple at all actually, it’s quite complex.

The upcoming electric Pickup trucks and SUV’s really ought to be outlawed right from the beginning, they aren’t going to do as much good as hybrids like a Prius would.
But if they were instead small, lightweight, aerodynamic vehicles, then they could do an enormous amount of good. I’m not talking tiny cramped little things, just not huge SUV’s.

[Tx J]

Originally Posted by a64pilot

My old Prius has I believe a NIMH battery, not Lithium, and the car won’t charge it above 80% nor below 40%.
To start with a Hybrid cycles it’s battery literally at least hundreds of times more than an electric car, the Prius in city driving is cycling the battery probably every 10 or 15 minutes, on the highway nearly never.

So it’s not just Li based batteries, it’s even lead acid too if you look, but lead due to sulphation needs to be fully charged, but if shallow cycled it will last a lot longer.

The reason laptop batteries and cell phone batteries don’t last longer than they do is they are pushed so hard and overcharged and over discharged as how many hours a battery lasts is nearly the first thing quoted in an test, and is of course the major sales issue with electric cars.
So range being such a huge selling point and the obvious fact that if you push your pack harder you will get greater range, do you think maybe some are being pushed harder than they should?

First before anyone gets upset the Tesla battery is nothing more or less than the venerable Panasonic 18650 cell, just scads of them. This is good because there is already a tremendous amount of data on them, they are a known quantity.

Older Teslas use the 18650, newer models are using the new designed 21700 sized cell [4-8000 of them]. Tesla has built/building billion dollar Gigafactories to produce cells, packs, motors, etc [those factories are about the world's largest industrial buildings].
https://en.wikipedia.org/wiki/Gigafactory_1

Besides overcharging and under charging the other great killer of most all batteries is heat, they get hot either being discharged or charged, the rate of charge or discharge will determine how much heat is generated.

My Prius has a battery cooling fan that if the AC isn’t on and no radio and your sitting still, motor off you can hear it sometimes, it’s not always on, it has a temp sensor.
Teslas go beyond simple fans, some have a complete autonomous A/C/refrig/heat system devoted to the batts.

One of the worst things you can do to an EV battery is pull off of the highway and Supercharge it. Due to heat build up. It comes off the highway warm, and they you go ramming in huge amounts of power in a short time, further heating it up.
Anyone who has an EV would be smart to use the middle 1/3 of its range, just like a hybrid does, and not Supercharge it. But then of course you have only 1/3 the range.

By the way, this is old data, been known for decades.
Tesla and others continually expand, refine, and change that database. It never stays "old" for long.

Prius owners have been building their own plug in hybrids for a long time, they usually use packs sourced from the junk yard and add them to the car, but other than the pride in doing so it doesn’t accomplish much, they also push the packs harder, of course shortening the cycle life. So they discharge the additional packs, but leave them discharged and not recharge them with the engine as that burns more fuel, but running around with a heavier car with the extra packs, burns more fuel too, so the plug in thing doesn’t accomplish as much as you May hope.

Weight in a car has enormous effect. Back in the 70’s Lee Iaccoa was pushing to eliminate the spare tire, if you did so on a car on the drawing board the car you ended up with was over 400 lbs lighter. You see to meet cargo space and leg room etc if the spare wasn’t there, the car could be smaller and still have the same room and carrying capacity etc, being smaller meant a slightly smaller engine and still meet acceleration requirements etc. smaller engine means smaller transmission, which means smaller brakes, and tires and suspension etc, the snowball effect is significant.

So while it sounds good to have a big battery on a plug in hybrid, the extra weight and size, means a larger and heavier car to meet the same space requirements and that pretty much negates the advantage of the greater all electric range.

We want all of this simple so we can understand it, but it’s not simple at all actually, it’s quite complex.
I agree 100%, very complex, and yet simpler too.

The upcoming electric Pickup trucks and SUV’s really ought to be outlawed right from the beginning, they aren’t going to do as much good as hybrids like a Prius would.
Wrong, that's where the US market is.
But if they were instead small, lightweight, aerodynamic vehicles, then they could do an enormous amount of good. I’m not talking tiny cramped little things, just not huge SUV’s.
They are coming out bigger, lighter, and more aerodynamic.

Well, you're also parroting a lot of the tired anti-EV and oilco tropes about EV's.
They, EVs, will simply replace many/most ICE engined vehicles in the next 10 years or so, they are becoming that superior in many parameters; and they will continue their rapid evolutionary process.

I've switched to an EV lawn tractor, would never consider another ICE one, the EV one is so much superior in most respects [my gas tractor is largely idle now, but it does ride smoother having larger tires, for now ].

If the American vehicle industry doesn't get up to speed, and achieve tech parity with other global players, it will die.

This really is a 'horse-and-buggy' versus 'motor cars' moment in history.
Many other vehicle companies are advancing well beyond them.
And of course the tech will change and improve, the current Li battery tech will evolve and be replaced by better stuff. The pace of change is accelerating.

BTW, there's even an EV shorthaul/regional passenger airliner in production: https://en.wikipedia.org/wiki/Eviation_Alice .
Cape Air [MA] has ordered 92 of them, expected in service soon: " In October 2019, Eviation planned a 2020 first flight and a 2022 FAA certification. By then, over 150 Alice aircraft had been ordered by two American companies.".
No, I haven't checked 'Landings', et al, but would expect the usual resistance; some groups always need to be dragged into the present-future....

We'll see. Meanwhile I've ridden ponies and horses since about 5yo, but to get around I've driven ICE vehicles. It's time to take the next step [if there was a big affordable EV SUV ;[ , before I croak].

[Woodland Hills]

To be honest, I really don’t care about the environmental impact of EVs. I want another electric car because they are so much fun to drive fast! Instant power is addictive and being dead silent, you can use that power anywhere anytime.