NiMH and my Leaf

[Desertstraw]

I have now had my Leaf for 16 months with about two years left on my lease. As long as I have charge in the battery, I am very well pleased with the car. However being on the cautious side, I am uncomfortable attempting a trip of more than 60 miles although I have gone farther. My problem is not range anxiety but what I call range lust, the car meets my basic needs but I just want to hit the road and keep driving.

The expiration on my lease will come at about the time that another event will occur, the NiMH battery will come out of patent. We know that both the EV1 and Toyota RAV4 Electric had true ranges of over 100 miles. If someone would bring out a NiMH powered electric car, I think that I would buy it rather than get another Li powered car. We know that NiMH batteries are very dependable and by now manufacturing costs should be down quite a bit. A car like the EV1 which just everybody loved could probably be built today to sell for less than $20,000.

I should be interested in the thoughts of others about this.

 

[adric22]

I've wondered the same thing. I believe NiMh is heavier, though. It seems most of the research has been with Lithium batteries, though.

I definitely think NiMh "CAN" work as a viable battery in an EV, but I'm not sure it is the best choice.

 

[TomT]

NiMH batteries are both heavier and have a lower power density. In most all respects it would be a step backwards from LI. MiMH is used in very few devices these days in place of Li except those where price is far and away the over-riding consideration. It's ancient technology.

We know that both the EV1 and Toyota RAV4 Electric had true ranges of over 100 miles. If someone would bring out a NiMH powered electric car, I think that I would buy it rather than get another Li powered car.

 

[adric22]

Oh, and that also raises the question about hybrids that continue to use NiMh? Will their battery packs get cheaper?

 

[cwerdna]

NiMH batteries are both heavier and have a lower power density. In most all respects it would be a step backwards from LI. MiMH is used in very few devices these days in place of Li except those where price is far and away the over-riding consideration. It's ancient technology.

I agree about NiMH being used in few devices, but amongst hybrids and plug-in cars at http://www.hybridcars.com/news/september-2012-dashboard-53157.html" onclick="window.open(this.href);return false;, in terms of units, NiMH is still by far the dominant battery chemistry.

That will change when Toyota moves its hybrids away from NiMH. Unclear when that'll happen though, but I'd guess it could happen as early as the next gen of Prius.

 

[Nubo]

NiMH batteries are both heavier and have a lower power density. In most all respects it would be a step backwards from LI. MiMH is used in very few devices these days in place of Li except those where price is far and away the over-riding consideration. It's ancient technology.

How do those metrics compare at the 5 or 10 year mark, 50K, 100K mark, etc? Lithium seems great out of the gate, but longevity seems suspect.

 

[TomT]

It's too early to tell for EVs but for my power tools and other electronic devices, Li has lasted much better than NiMH...

How do those metrics compare at the 5 or 10 year mark, 50K, 100K mark, etc? Lithium seems great out of the gate, but longevity seems suspect.

 

[cwerdna]

How do those metrics compare at the 5 or 10 year mark, 50K, 100K mark, etc? Lithium seems great out of the gate, but longevity seems suspect.

It'll be interesting to see if lithium ion-batteries in the eAT-PZEV Volt and PiP can go w/o warranty replacement by the end of their 10 year/150K mile battery warranty in CA and CARB states.

The NiMH HV battery in the regular (04+) Prius seems to usually have pretty good chance of lasting the 10 years/150K miles. The most I'm aware of on an original battery was 465K miles. The owner of that 09 (!) Prius traded it in w/that many miles.

 

[TEG]

I think Li-Ion is likely to continue supplanting the remaining NiMH applications soon regardless of the patent situation.

NiMH may have had some calendar life, and power density advantages, but Li-Ion improvements keep making them seem better and better in general comparison. The price of Nickel has gone up a lot since the 1990s. And the weight disadvantage is probably reason enough that we won't go back.

 

[adric22]

It's too early to tell for EVs but for my power tools and other electronic devices, Li has lasted much better than NiMH...

Part of that might be for ironic reasons. I think many cheap power tools had limited or a total lack of cell balancing and management. You can sort of get away with out that on NiMh. But Lithium absolutely requires it. And so I think a lot of power tools have dead batteries because people would keep using the things until they just stopped working and had no choice but to recharge the battery. Where most of the lithium devices these days will actually monitor the cells and force the device to stop working at a certain depth of discharge.

 

[Desertstraw]

Several people have pointed out the weight advantage of Li. I don't see how it matters when the EV1 and Toyota RAV4 Electric had much greater ranges than the Leaf. Moreover my Prius sat out in the Arizona sun for ten years and this did not affect the battery efficiency. If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

 

[DaveinOlyWA]

Several people have pointed out the weight advantage of Li. I don't see how it matters when the EV1 and Toyota RAV4 Electric had much greater ranges than the Leaf. Moreover my Prius sat out in the Arizona sun for ten years and this did not affect the battery efficiency. If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

weight was the problem with them as well. the EV1 weighs almost as much as the LEAF does and its a TWO seater.

the RAV 4 EV was much heavier but larger platform so it could get away with it and not sacrifice passenger space. NiMH is out. of that there is no doubt. its more toxic and heavy and lets not allow hybrid performance to cloud our judgments. the Prius pack only runs from 40-80% SOC which is a bigger reason for its longevity than the chemistry involved

unlike the LEAF which gets 100% of every inch of travel from the batteries, the Prius gets 100% of every inch of travel from gasoline. granted some regen, some battery boost but i be willing to bet that TaylorSF's 55,000 miles is probably equivalent to 200-300,000 miles on a Prius

 

[Desertstraw]

What can be done with NiMH battery.

For immediate release: October 23, 1997
Contact: Karl E. Thidemann, 508 658-2231
Visit our web site at http://www.solectria.com" onclick="window.open(this.href);return false;
Spectacular EV Run Demonstrates Parity
Solectria Sunrise™: From Boston to New York on One Charge (Wilmington, MA)
Leading U.S. electric vehicle (EV) manufacturer Solectria Corporation announced today that its prototype Solectria Sunrise™ all-composite electric sedan successfully completed a trip from Boston to New York City, at normal highway speeds, on one charge of its state of the art nickel metal hydride (NiMH) batteries produced by Ovonic Battery Co., Inc., the originator of this battery technology.

 

[adric22]

If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

You can't be serious? The EV1 was a totally unmarketable car. Being a 2-seater immediately moves it to an extremely niche market. The car was ugly back then and in today's climate even worse. The Volt is 100 times the car the EV-1 ever was. The Leaf is a much better car too.

 

[TonyWilliams]

If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

GM doesn't need to serve the country... it's owned by the country (and a few other countries and provinces).

The EV1 was carbon fiber, I believe, and therefore is a non-starter for a "cheap" car. The BMW i3 will be carbon, but far from cheap.

 

[surfingslovak]

Interesting discussion. I don't have much time this week, but let me just note that we should not judge the potential of lithium-ion batteries on the performance we have seen from the Leaf. Although the final word has not been spoken yet, I suspect that the Leaf won't be a good benchmark for battery longevity.

 

[ENIAC]

If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

The EV1 was carbon fiber, I believe, and therefore is a non-starter for a "cheap" car. The BMW i3 will be carbon, but far from cheap.

The body panels were plastic. Recall Saturn's dent resistant plastic doors?

 

[TonyWilliams]

If GM wanted to serve the country, it would either build the EV1 again or sell the plans to another company that would. The EV1 was also a more beautiful car than most.

The EV1 was carbon fiber, I believe, and therefore is a non-starter for a "cheap" car. The BMW i3 will be carbon, but far from cheap.

The body panels were plastic. Recall Saturn's dent resistant plastic doors?

http://en.wikipedia.org/wiki/General_Motors_EV1" onclick="window.open(this.href);return false;

"The EV1 was among the first production vehicles to utilize aluminum in the construction of the frame. The car's body panels were made of plastic rather than metal, making the car lightweight and dent resistant... Super-light magnesium alloy wheels and seats provided strength despite their low weight."

 

[surfingslovak]

"Super-light magnesium alloy wheels and seats provided strength despite their low weight."

Crazy! Also this:

The EV1's drag coefficient of 0.19 was the lowest of any production automobile in history.

Magnesium wheels are light wheels, much lighter than steel or aluminum wheels. That means they will give better mileage for your car because there's less weight to move. The main factor weighing against magnesium wheels is the price. They're expensive.

 

[DaveinOlyWA]

Interesting discussion. I don't have much time this week, but let me just note that we should not judge the potential of lithium-ion batteries on the performance we have seen from the Leaf. Although the final word has not been spoken yet, I suspect that the Leaf won't be a good benchmark for battery longevity.

i suspect you will be proven wrong. i predict "some" LEAFs will see 120-150,000 miles by the time they reach 30% degradation. granted not all will, but then again, not all RAV 4 EV NiMH battery packs did well either

this makes me wonder if Nissan did not put in TMS because they didnt want a completely maintenance free car going 200,000+ miles?

a study http://www.evchargernews.com/miscfiles/sce-rav4ev-100k.pdf" onclick="window.open(this.href);return false;

with an "interesting" paragraph on one pack that did not perform well

CON 3 had a range of 54.1 miles when tested in December 2002. This was a concern but no problem
was detected by the diagnostic tester. It was suggested by service personnel that the SOC gage
should be reset. A reset is performed by using the diagnostic tester to “Auto-Discharge” the traction
battery until the controller automatically stops it at 0% SOC. The SOC gage is then reset to zero with
the tester and the vehicle is fully charged to achieve a normal reading of 100% SOC. After this
procedure, a UR1 range test was completed and yielded 54 miles. The project test protocol called for
a capacity test which showed that the battery pack still had 92% of nominal capacity. Since battery
capacity was still within specifications but the range had declined, an attempt was made to recover the
range. Figure 8 shows total range recovery. Toyota would like to keep details about the recovery
method employed confidential at this time.
The battery of CON 3 will be closely monitored during the remainder of the project.