Toyota Seeks Battery-Price `Sweet Spot' for Plug-Ins

Toyota looking for a 'sweet spot' is just a practical acknowledgement that different battery capacities is a bit more involved than having a couple of steering wheel covers available in the parts store.

For instance:
Space utilization
Safety Testing
Weight distribution
Battery related heat dissipation, supporting electronics

... and I'd guess another 100 other things an auto engineer could bring up. Fitting a battery size to a car is just not a trivial exercise in time and money for Toyota, and they want to find the capacity that the greatest number of people are going to want to buy, at the highest price Toyota can charge and watch the market grow.

The GM Volt spec has been a PR stunt from day #1. Toyota has different priorities, thankfully.

 

I think that this is a good SOTP matrix. It's about the same as my own estimates. I look at it differently using a % coefficient.

I drive 150 mi daily with an annual fuel bill of about $2700 based on 2.1 GPC ( 48 mpg ) and fuel at about $3.50/gal*. At current fuel prices a 'gas-free' capability of....
..5 mi would save me about 3.3% of my annual bill, or $90 / yr.
..10 mi would save me about 6.7% of my annual bill, or $180 / yr.
..20 mi would save me about 13% of my annual bill, or $360 / yr.
..40 mi would save me about 25% of my annual bill, or $720 / yr.

*If fuel prices continue to escalate at a nominal rate of $.50 / gal per year on average then over 7 yrs of ownership my average cost of fuel would not be $3.50 ( current ) but rather $5 / gal.

A realistic estimate is that I will drive 250,000 miles in a 7 yr period. At an average fuel cost of $5 a Gen 2 Prius would cost me about $24500 to buy and about $26000 to fuel up.
A 10 mi gas-free segment would save me about 6.7% of my total fuel bill or about $1750.
A 40 mi gas-free segment would save me about 25% of my total fuel bill or about $7000.
Thus I wouldn't want to pay any more than about $31000 for a PHEV that gives me a 40 mi gas-free segment each day.

However if the new Gen3 Prius has improved fuel economy of 10-15% at little or no increase in price of the vehicle, then neither of the two soon to be seen PHEVs have any economic value for me. OTOH my wife who drives 30 mi per day is a perfect candidate for one....as long as they are not priced near $40000.

 

A 30 to 40 mile EV range is what I need 75% of the times. Not sure yet how much I'd pay for it, but any range shorter that probably won't interest me at all.

A 60 mile range would serve my needs 90% of the times. If it could go for around $5K I think it'd sell like hot cakes.

 

Why do you say that fast charging is dicey? The A123 LiFePO4 battery used in the Phoenix Motorcars SUT can be charged in 10 minutes, given a sufficiently powerful charger and sufficient available electric power. Swapping would require the same overall available electric power, fed to a much larger number of chargers due to the (much) slower charge time for conventional charging.

Standardizing form factors among different auto makers is a pipe dream.

And paying for the battery on installments is lousy personal economics, as you pay an exorbitant interest rate whenever you buy anything on installments. You'd pay far more at the swapping station than you now pay in interest on your car loan because the swapping station would represent a humongous investment for the owner: Remember that swapping requires double the number of batteries: one in the car, and one waiting to be swapped in, and you'd never know when you're going to get a bad battery pack from the swapping station.

While your points about differing battery size are valid, there are conversion shops all over that will turn just about any car into an EV, and you can specify what range you want to pay for. If they can put different size packs into an existing car, Toyota could design a car from the ground up to accommodate different size packs.

Agreed, that the Volt is nothing but a PR scam.

 

Conversion shops do indeed exist, but they do not operate under the same constraints as Toyota. E.g., they typically do not certify the car for EPA or CARB, do not crash test the vehicle for safety, and do not concern themselves with altered driving mechanics due to a weight redistribution. In fact, in the best of cases all they offer is a working battery, usually with a short warranty.

I'm not trying to diss the independent shops, but the comparison isn't useful.

 

One wouldn't have to sit around and wait for the charging to happen. It would be done on racks. The customer won't care as long as they can swap packs and keep going to get a long effective range. Stopping for 15 minutes (10 of it actually charging) every 150 miles is NOT going to be very appealing to someone on a trip.

I seriously doubt that. Once the initial race is over and some battery tech takes the lead, I expect to see a major push for form factors. It will happen within car companies first, then across car companies. They aren't going to want to be in the business of producing, selling and servicing batteries. There will be advantage in shifting the overhead and infrastructure outside of their organization. It's a core competency issue as much as a customer convenience/range extending matter.

Another really big advantage I see for car manufacturers is that they might be able to remove much of the battery expense from the purchase price.

We already have battery form factors for other services, and a few of the many form factors tend to dominate.

Nope, I disagree entirely.
1. The installments don't have to be any worse than for purchasing and recharging. In fact, the battery should be far cheaper in a limited number of form factors/sizes across car manufacturers. While I tend to pay for things in cash upfront, most U.S. consumers prefer installments as it minimizes the initial outlay.
2. You also neglect that plug in stations will also have a similar infrastucuture cost. The same power has to be input after the same distance and you will need more parking space to sit around charging.
3. Swapping only requires a small increase in the number of batteries because the battery just removed goes on the rack and will be back in service later that same day (repeat for several cycles). It comes down to how many cycles can be done per day and how many days between charges for the average vehicle and driver. It wouldn't surprise me if the working ratio was 1 for 10.
4. Part of the form factor (and/or charging center, and possibly the car) will be the self-diagnostic capability of the batteries and probably some charge metering. It will be in the battery owner's economic interest (charging station or other lessor) to check batteries and recondition before batteries fail.

 

A few thoughts:

I agree, Hymotion is a better reference. Bear in mind that their 30-40 mile range is their mixed mode range, not their EV range. With a raw capacity of 5kWh, and a usable of ~3kWh, one would expect maybe 15 miles EV range from Hymotion. Its also worth noting that this is by far the best price going on a Li-ion pack from what I have seen. Not surprising since it is being developed and sold directly by the battery manufacturer. That would be about $7500 per 10 mile EV range, so Toyota's $5k/10 miles range number sounds reasonable in the next few years.

I've said it before, at those kinds of numbers ($5k/10 mile, $10k for 20 mile, $20 for 40 mile range) I think Toyota is being much more realistic talking about 8-20 mile PHEVs in the 2010-2012 timeframe, compared to GM's 40 mile in 2010. Keep in mind also that packs in the 8-15 mile range could be pretty readily implemented with NimH rather than Li-ion, cutting the cost in half.

I think people also vastly underestimate the benefit of lower range PHEVs. Here are a couple of rough estimates for a basic PHEV10 with a 50mpg charge sustain mode efficiency, and 100mpg hwy speed charge deplete mode efficiency:

20 mile commute, charge at work:
--INF MPG city, >100mpg hwy
20 mile commute, charge only at night:
--100mpg city, 100 mpg hwy
30 mile commute, charge at work:
--150mpg city, >100mpg hwy
30 mile commute, charge only at night:
--75mpg city, 83mpg hwy
40 mile commute, charge at work:
--100mpg city, 100mpg hwy
40 mile charge at night only:
--67mpg city, 75mpg hwy

Based on Toyota's number of $5k/10 mile Li-ion, and given that NimH is about 1/2 the cost of Li-ion, I would think a 10 mile PHEV with NimH for $2,500 extra would be a good place to start. If you drive 30 miles per day, you'd save about $300 in gas a year ($4/gal), paying for the system in about 8 years. Not hugely financially compelling, but not a loss which will be helpful for the first adopters who will mostly be motivated by factors other than gas money. Contrast that with a $15k Li-ion PHEV30, which for the same 30 mile per day would save between $400-900 per year. At that rate it takes 17-37 years to pay back. Not that payback is the bottom line, but it helps. Payback gets a little longer when you factor electricity in, but charging at night the cost should be small (<$100 per year). Obviously if the PHEV tax credits go through and are substantial it will make longer ranges in Li-ion practical sooner.

Rob

 

"Toyota's number of $5k/10 mile Li-ion"

Toyota are grossly overestimating the cost of lithium-ion. BYD and others are already selling LiFePO4 for $300 per kWh, which at 5 miles per kWh is just $60 per extra EV mile range. Assume $100 per EV mile to allow for shallow discharging.

What they mean is their lithium-ion (ie from Panasonic EV) is still uncompetitive in terms of cost.

 

I think thats a bit of an exaggeration. I agree BYDs pricing is impressive, but their reliability and life is a complete unknown. While I admit I am a bit out of date on the subject, the last threads I had seen on the EVDL regarding chinese Li-ion there were still major problems to overcome in the areas of manufacturing variation, cycle life, and reliability. I think Toyota's price is right on for tier one vendors like A123 or their own PanasonicEV. They are high priced, but top notch in quality. Even A123 is only guarantying their cells in the Hymotion L5 pack for 3 years, despite only using 60% of the packs capacity. Given that PHEV manufacturers are going to have to warranty their products for 8 years and 100-150,000 miles we're talking about an even bigger problem of quality, reliability, and battery management.

I think this is the exact problem GM is wrestling with right now. A123's solution for the Volt is robust and high quality but pushing the cost way over target. Their Chinese vendor can meet cost targets, but they open themselves to a huge potential liability and PR nightmare.

For an example of the kind of experiences EV converters were having with Chinese Li-ion cells, see the posts below:
ThunderSky Lithium-Ion Cells
YouTube - Thundersky battery failure in Bob Siebert's AC150 conversion

Here's a datasheet from one of the latest Thundersky batteries. They claim 2000 cycles at 80% DOD, 3000 at 70%. At 80%, that would be about 5.4 years charging once a day, or 2.7 years charging twice a day. At 70% its 8.2 and 4.1 years. PHEVs are probably much morel likely to be charged multiple times per day due to their reduced range. The Google PHEVs are often being charged 3 times a day, which manufacturers will have to account for in their designs. Also bear in mind this is probably only valid at the optimal discharge rate (0.3C) and temperature. Real world operating conditions will be much harsher. Prius NimH are routinely discharged at greater than 15C! PHEV current draw will be considerably higher, though may be a wash due to larger capacity.
http://www.thunder-sky.com/pdf/TS-LFP40.pdf

I'm sure the Chinese manufacturers will eventually get their act together and revolutionize the industry with low cost batteries. I'm not sure we're at that point yet though.

Rob

 

Sorry for the offtopic qs : but 15C? whats that

 

There may be more than one convention, but I believe 1C indicates a discharge in Amps equal to the capacity in Amphours. Ideally this would be the current draw required to fully discharge the battery in one hour, although that is not often the case in reality. You can think of it as a measure of how "hard" a battery is being worked. Putting out 100A might be no big deal for a 100Ah battery, as its only 1C, but a smaller battery will have to work harder to put out the same amount of current. The Prius batteries are rated at 6.5Ah capacity, and from what I have read a full electric drive acceleration can draw 100A or more. 100A/6.5Ah =~15.4C. 15C is considered quite a high rate of discharge. This would generally have a negative impact on battery life, but the PanasonicEV cells used have been specifically designed for these conditions.

To put that a little bit in perspective, consider a traditional lead acid starter battery. Most of us would think of these as very powerful batteries, optimized to deliver very high currents for a short period of time. These are often 40-50Ah in capacity, and capable of putting out short bursts of 400-500 Amps to start a cold car. So they would be running at around 10C (400-500/40-50).

Rob

 

but the prius 6.5ah are based on a 6h rating
for example a 12 volt lead acid battery is rated 20amp hours. ( 20h )
so where is this fitting in?

 

Yeah, thats where it gets complicated, and I'm not honestly what the proper convention is (or if there is one agreed upon). The 20 hour rate is where most PbA are specified, and this is often referred to as the C/20 (1/20*C) rate. As you rightly point out, under that definition a PbA battery will last much less than an hour at 1C (usually about 30 minutes) due to the non-linearity of the Peukert effect. If you are talking about capacity, I think most people do scale the current such that at 1C it really does last an hour. If you are just talking about discharge rate relative to capacity I think people often don't scale it, and just use the 20 hour capacity. Fortunately the whole thing gets simpler for Li-ion and NimH as they generally do not exhibit Peukert effect and are much more linear over discharge rate.

Rob

 

so a lead acid battery with a discharge rate of 12ah over 20h and 8ah over 6 hours = NiMh prius battery rated 6,5ah over 6 hours?

 

i wouldnt comment on this post with a 10 foot pole

 

Clett,

Don't be fooled by BYD's advertising hype.

The quoted price for raw cells is $1843/kWh delivered to US with only 1 yr warranty.

See quote below.