Batteries of electric vehicles, Q for Darrell

I have read a few posts from Darrell and read on his website about electric cars, trucks, mail trucks, etc. OF all the types of vehicles, it seems after they are made, a decision is made to quit. I am sure we can think of various reasons such as the oil companies, unions, public demand, but what about the though of replacing the batteries?

I dont know about you guys, but I dred replacing the two deep cycle batteries that fit in the various wheelchairs I own and used the past few years. Its hard enough to find two the same age, I cant imagine the cost at finding 12 or so identical batteries and the hassle of installing, removing them and charging/cycle them.

I use to use an electrical scooter that uses two deep cycle u1 batteries or 35 amp hours hooked in series for 24 volts. Basically as they died the range was reduced per a charge. When in great shape it would run three days between charges. Then it got to the point it would go two days, then one day and finally a few hours. I would just head to walmart and look for two identical batteries and plop down 70 bucks for them, carry them home, swap them out, leave it on charge all afternoon and night and morning. Then at a later date carry them back for the core. After a week or so they seem to build up a longer range and charge faster each time. I did this every 6months, buying batteries.

I think the hybrids use a pack that contains 280 C cell nickle metal batteries. Last I heard on an auto show on NBC they are experiencing shortage of those cells. I can just imagine the nightmare of finding 280 matched cells and how one cell going bad could ruin the whole pack.

Hello, I am a mechanic at a Toyota dealership. I am also one of a few in the shop who have been to the Prius Hybrid training class (at least the first part anyway... /ubbthreads/images/graemlins/grin.gif ). The "battery" in this vehicle is composed of multiple packs, depends on model year, but somewhere around 30. If I recall correctly they are NiMH around 7v nominal. They are wired in series. The battery pack is able to be seperated into individual cells (taken apart), but it is not servicable ie if the battery is determined as defective or damaged in an accident, one cell or multiple, then it has to be replaced as a unit. The cost of this I'm told by the parts department is in the neighborhood of $4000+. Not a decent prospect for salvage imo, because if the vehicle is damaged enough to have an effect on the battery then it's pretty bad.

I've taken these batteries out of many of the first gen Prius. I'd not want to do this every 6 months /ubbthreads/images/graemlins/smile.gif

I'd have to check on the warrany period of the battery (maybe an owner would know, any out there?). I don't know the specifics of vehicle warranty, and they differ from year to year and model to model.

You're worried about the replacement of this battery due to normal wear. I don't think it will be replaced (paid for) by an owner. If it's not a warranty claim or insurance issue then imo the vehicle will be scrapped by the time the battery needs replaced for normal wear.

2 words: battery matcher

Not that it particularly matters in this case, but there are nicd/nimh cell matchers out there. They can determine cell characteristics so closely that you can assemble a pack that is exactly the same for each cell.

I've got one for my r/c car. It's handy for r/c use, and making packs for high power incan lights.

The battery modules (Six 1.2 volt cells in a plastic carrier) have electonics that allows it to isolate a bad cell so it does not hamper the operation. My understanding is that they don't have to be matched that closely.

There have been a lot of cases where the battery pack has been salvaged. The battery is not damaged in most accidents that might total the car. It's pretty well protected, being at the very back of the trunk. You might even find an occasional battery pack on e-bay.

The battery pack, BTW, has a 150,000 mile warranty.

I've not read of anyone paying for a replacement battery pack, though I'm sure it's happened by now. My toyota dealer did not have a price avaialable when I asked two years ago.

Bear in mind that 240 NiMh C cells are available for less than $4000, and that the modules can be rebuilt with a little work.


Daniel

[ QUOTE ]
cobb said:
but what about the though of replacing the batteries?

I dont know about you guys, but I dred replacing the two deep cycle batteries that fit in the various wheelchairs I own and used the past few years. Its hard enough to find two the same age, I cant imagine the cost at finding 12 or so identical batteries and the hassle of installing, removing them and charging/cycle them.



[/ QUOTE ]

The other point I forgot.....


You are using deep cycle lead acid batteries. They are not a 'battery pack' like the RAV EV or Prius uses. Battery packs are easier to replace as a whole.

You also run yours down pretty much all the way, whereas hybrids and EV town cars only discharge a little between charges. Long distance EVs may discharge much deeper if driven long distances, but hybrids do not. Hybrids are pretty much charged all the time (using Toyota's method).

You are probably right that the eventual cost of battery replacement is a deterant to purchasing EVs. It shouldn't be. People buy cars with $500 tires (look at the Jaguars and other high end cars), knowing that in 2 or 3 years they have to spend $2,000 or more to replace them. They pay 1,500 for the extra fancy sound system. $2,000 to $4,000 for battery replacement after 5 to 7 years does not seem too bad.

Daniel

"The battery modules (Six 1.2 volt cells in a plastic carrier) have electonics that allows it to isolate a bad cell so it does not hamper the operation. My understanding is that they don't have to be matched that closely."

If a cell is determined "bad", at least in the Prius, it sets off the master warning light and sets a code in the battery ECU. The battery packs are matched when they are assembled in Japan. If one cell goes bad, the whole pack must be replaced, this is just the policy I am told. I know that a match could be made and just one replaced, but Toyota is worried about technician level understanding of this technology.


"Bear in mind that 240 NiMh C cells are available for less than $4000, and that the modules can be rebuilt with a little work."

The Prius battery pack does not have C cells, if that is what you were meaning... Each cell is a rectangle, I would have to guess at the size, maybe 5.5"x9"x1/2". Next time I remove a pack for service I will measure it and take a few pictures...they may come out blurry as I'll be wearing my rubber gloves rated for 1k volts, they are pretty thick and hamper my manual dexterity /ubbthreads/images/graemlins/grin.gif

I'm glad those batteries have 150k mile warranty...that's about 10 years for an average drive.

The other thing to remember here is charge electronics. There's some money going into charging electronics, but not nearly as much as if you have the auto industry behind said electronics. The charge controller in a $20,000 car had better be smarter than the one in my $30 charger.

Late to the party. All the good parts have been covered already!

No actual "decision" was made to get out of the EV business. Every company jumped out when and because they COULD jump out.

The short answer about battery replacement: I worry about that as much as I worry about replacing the entire engine in my gasoline car. For all intents and purposes, the batteries in my Rav and the engine in my gas car should last the life of the vehicles.

Yes, these things are matched. Matched insanely well, in fact. Even under hard acceleration (taking better than 50kW out of the pack) at low SOC, there is never more than 0.2V difference between the 26 modules. When allowed to rest for a second, there is no detectable V difference (resolution is 0.1V).

Daniel made some great points on the cost of other products/consumables. Folks will gladly add $4000 DVD packages, $4000 GPS packages, $2,000 leather upgrades, $5000 wheel/tire upgrades.... It is all about the priorities I guess. In the grand scheme of things, batteries *could* be a bargain. All we have to do is make them in quantity. But the big battery makers are a bit shy since they've already been burned once for tooling up for the coming EV explosion that died an early death a few years ago.

C cell batteries? The car runs on C cells? I had thought that C cells where the last cells to benefit from any advances in battery technology. I see commercially available C cells starting about 2000mah and 1 model claiming 4500. What is the rating of the cells in the car? 2500mah AA's are regularly available now, along with high drain versions, and I'll bet that there are bigger ones that I just don't know about.

So how long before my car runs on AA's /ubbthreads/images/graemlins/smile.gif

or can we put in some AAA to C adaptors and give it more power /ubbthreads/images/graemlins/grin.gif

It doesn't run on C cells. It runs on rectangular 7.2V packs custom made by Panasonic. This is the page that I've been linked to in reference to the Prius batteries:

http://www.peve.panasonic.co.jp/catalog/e_kaku.html

and this document shows pictures of the battery modules:

www.ctts.nrel.gov/BTM/pdfs/2a_2002_01_1962.pdf

I am sorry about the C cell, that was my understanding that those packs used small cells of that nature. Maybe I am wrong?

Daniel/Darrel, you guys almost hit on something i missed. I bet the price of a battery pack is about that of what you would spend on gas if its an EV or half the gas for a hybrid.

I think we pretty well got the hybrids covered, but what about the other evs that use multiple lead acid batteries?

Just thinking......

The term C cell was used in several places for different reasons:

1) It gives an idea of the approximate volume if the individual cells

and

2) A company in Japan that makes NiMH actually rebuilt a Prius pack (model year 2000, Japan domestic) to use their cells. They claimed a performance increase in several ways. I seem to recall they used their C cells, they might have used D sized.

Daniel

[ QUOTE ]
cobb said:
I think we pretty well got the hybrids covered, but what about the other evs that use multiple lead acid batteries?

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Well, like the hybrids, any modern vehicle would be using something superior to Lead Acid. Only the very first EVs (EV1) used Lead Acid - and then NiMH became the standard. Today it would be Li-Ion. Lead Acid is by far the cheapest, but also the lowest energy density of the bunch.

I thought that lead-acid could handle steeper discharges than NiMH - its one advantage for EVs.

EV-size NiMH cells are costly and tough to find, however...

[ QUOTE ]
idleprocess said:
I thought that lead-acid could handle steeper discharges than NiMH - its one advantage for EVs.

EV-size NiMH cells are costly and tough to find, however...

[/ QUOTE ]
Couple of things...

1. Yes, Lead acid can offer up the power faster than NiMH... but if you size the pack correctly with the right V, then NiMH can provide what you need with no trouble at all. Let's face it, a typical EV can so easily have more torque than it needs, the amount of power instantly available is rarely a limiting factor.

2. NiMH packs cannot legally be made for EVs at this time. Costly and tough to find is an understatment! The patent is owned by Chevron-Texaco, and they have decided that NiMH should not be used in electric vehicles for some reason. /ubbthreads/images/graemlins/icon3.gif

I can verify that NiMH patents are indeed held by Chevron-Texaco, but haven't been able to find anything about said organization prohibiting their use in EVs.

It seems that they see a big business in supplying packs for hybrids judging by press releases of 1-2 years ago.

[ QUOTE ]
idleprocess said:
I can verify that NiMH patents are indeed held by Chevron-Texaco, but haven't been able to find anything about said organization prohibiting their use in EVs.

[/ QUOTE ]
I'll get you something on this in a bit. Google doesn't know everything, eh? /ubbthreads/images/graemlins/smile.gif I wonder how many people realize that one of the largest oil companies in the world owns the patent on what once was the ONLY chemistry to use for full-size BEVs?

[ QUOTE ]
It seems that they see a big business in supplying packs for hybrids judging by press releases of 1-2 years ago.

[/ QUOTE ]You sell oil, you own the patent for the battery chemisty... what's not to love about hybrids in that situation? /ubbthreads/images/graemlins/evilgrin07.gif

Idle -

If you want to dabble in some hands-on research into the "no NiMH batteries for EVs" business, look these guys up: http://www.cobasys.com/solutions/featured_solutions.htm#case2 and tell them you're starting an EV business and want some of those NiMH batteries that were in the EV1 and S10 vehicles.