http://in.youtube.com/watch?v=s_8n2Qgguto

I guess not. But I think the fear-speak that you have to have an electrical technician replace the batteries is also a load of horse pucky. What is the battery pack for a Mercury Mariner / Ford Escape? Try about 120 d-cell size NiMH batteries, wired in series and parallel to generate something like 300VDC. While I agree it wouldn't be the easiest job out there, it IS possible to build your own packs, and any custom battery shop can do it for you too.

What is a battery pack? It is made up of 3 basic specifications - Output voltage, output amperage (either total or amp-hours) and physical form factor. In this case, each d-cell size battery would contain somewhere around 3 amps of power, at 1.2v. So it is simple math to match the desires of the car to the number of batteries. More amps (from the D, instead of like a C-cell) means more run time. Like a bigger fuel tank. Higher voltage means faster acceleration or a higher top speed. The battery controller has limits on what it can accept, and must be sized to the motor. Again, simple math.

The hardest part is wiring up each individual D-cell. Usually they are strung out inside lengths of heat-shrink tubing, and sealed together. Then the ends of each string are hardwired to the next one. The limitation in size of the battery bay determines the shape of the pack.

How do I know all this? I've been researching replacing the 240k mile old engine in my minivan with an electric powerplant, and possibly a smaller battery pack with a charging system connected to a diesel generator. A small diesel genset is available for about $2000 that I think would do nicely. Its a 5kw powerplant, so it can produce a fair bit of juice. In this case, the batteries would act as a short-term capacitor for the power, and the generator would almost directly power the wheels.

There's no definitive word on replacement costs because they are almost never replaced. According to Toyota, since the Prius first went on sale in 2000, they have not replaced a single battery for wear and tear.

Starting in 2004 to the current models, the standard Prius battery is a Panasonic Metal Case Prismatic Module. Prior to 2004 and as early as 2000 the battery used was a Panasonic Plastic Case Prismatic Module. The first generation was sold only in Japan. Of the 70,000 sold a small but significant number of vehicles had problems with the battery pack. Furthermore, the battery pack was so large it took up the entire space between the trunk and the cabin. This led to changes in the Generation II models whose stacks were significantly smaller and far more reliable.

Toyota Warns After Market Prius Battery May Void Warranty
Autos – Prius owners already enjoy fuel economy above the industry average, thanks to its rechargeable battery system. The Toyota Prius has long been considered the standard hybrid vehicle, but that isn't stopping owners from pursuing after market options which might have an unintended side effect: void the car's warranty.Prius owners already enjoy fuel economy above the industry average, thanks to its rechargeable battery system. The Toyota Prius has long been considered the standard hybrid vehicle, but that isn’t stopping owners from pursuing after market options to improve mileage including replacing the standard lithium battery with a $9995 battery from A123Systems, a move which could push fuel economy over 100 mpg.

Toyota, however, isn’t keen on the new battery as it could cause unforeseen consequences, namely the frying of the Prius’ electrical system which could void the car’s warranty.

A123Systems has already begun taking orders for the battery with expected delivery to begin in July. When driven in the 30-40 mile range, the battery should help Toyota Prius owners get over 100 mpg, more than doubling the car’s current limit. The new battery would be a plug-in model too.

“We don’t recommend customers modify our vehicles,” said Bill Kwong, a spokesman for Toyota’s U.S. sales unit in Torrance, California. “It wouldn’t automatically invalidate the warranty, but if they put this in and it fries the electrical system, for example, obviously that would not be covered.”

Prius Battery
In older Prius models there was a lot of concern about the viability of the Prius battery. They were often needing to be replaced and the replacement costs were extortionate and running into the thousands of dollars.

Newer Prius models (since 2005) have a vastly improved battery that comes with a 5 year warranty. The new Prius battery has also been designed to be cheaper than its predecessor thus bringing back trust for the Hybrid vehicle.

The Prius battery is designed to last the lifetime of the vehicle and given that Toyota cars are renowned for their durability and longevity then this could be a very long time. Toyota have lab data showing the Prius battery can do 290,000km of normal driving with no lessening of the battery’s performance.

Since 2001 I have participated in too many Prius internet groups. Therefore I claim to speak with some authority on the subject of HV battery life. If anyone on Earth has yet abandoned an otherwise functional Prius because of facing a $4000 battery replacement, that news has not reached me.

A number have been replaced under warranty by Toyota, but they have not said how many. Reports on the internet lead me to guess within the range of 1/1000 to 1/100. The new model Prius had a major battery redesign, and while it has not been flawless, its failure rate appears to be lower.

Might they start failing in droves tomorrow or next year? Yes, but it would come as a great surprise to many who follow the subject quite closely.

It is certainly true that the retail cost of the battery has not decreased since 2001 as many predicted at the time. A major factor in this is the 4-fold increase in the price of nickel metal since then. Sorry about that; but the demand for stainless steel has grown rapidly and this is a commodity in tight supply. We’ll see how lithium battery prices develop, in the next few years I suppose.

Toyota was reported in the media to be offering rebuilt batteries at discount (I linked that article here about last September?), but nothing heard from them about it since. Just a guess, but it may be that they have not had many takers.

Several people known to me have replaced their HV batteries with units recovered from crashed salvage Prius. As I have said too many times already, Prius crash out of the fleet faster than they fail. Thus used HV batteries are always available to those who search. Price $400-$1200, up to you to negotiate a warranty etc. But the excess availability actually means that many of them have gone into homebrew electric vehicles. This has become the Prius battery ‘daughter industry’, not pack rebuilding.

I believe that battery cell renovation was pioneered by Andy Roberts in Virgina, but he unfortunately died and we lost many of his skills. More recently Bob Wilson in Alabama has stepped up, and I have every reason to expect that he will be a leader in the ‘cottage industry’ of Prius battery renovation.

Toyota has the best Spin Control Department in the industry.

There's no definitive word on replacement costs because they are almost never replaced. According to Toyota, since the Prius first went on sale in 2000, they have not replaced a single battery for wear and tear.

Toyota has the best Spin Control Department in the industry. True they have been known to Take Care of Their Customers, but they are not perfect, there stuff does break and fail and they do their best to cover it up. I have coached friends and family to get satisfaction out of Toyota, but others have been left out to dry. They are banking a lot on the Prius, but as diesel owners we all knew their 65mpg was a total scam and in reality it was 42mpg. My Wife's 99TDI gets better mileage than that and it is a larger, roomier, safer car.
One reason the News Media does not rip Toyota is the same reason they don't expose the politicians they vote for for minor offenses, they voted for Toyota with their paychecks and a lot of them own Toyota. If the problems with an given Toyota were a major safety or reliability issue, they would cover it, but Toyota gets away with more than any of the U.S. car companies.
The one reason I don't own Toyota is that I have driven them and worked on them in the past. I find the rental units to be a disappointment to drive. When I was in the repair business, I was glad some one was paying me for my time to fix them.

it will all be moot anyhow, hybrid cars are just a bandaid fix until hydrogen technology advances....right now Honda is getting ready to release 500-1000 hydrogen cars only in southern california, the place with the most (if not all) the hydrogen refilling stations...no one else can pre-order one of these cars yet, but its only a matter of time until hybrids go by the wayside for the real alternative fuel cars. Once refueling stations can be built nationally, it will be a slow start, but in the end, hydrogen vehicles will replace the gasser/electric hybrid. my 2 cent prediction. LOL

You are kidding right? have you looked into the actual practicality of H2 as a fuel source? Here is a very good compare/contrast article on the concept.
http://en.wikipedia.org/wiki/Hydrogen_economy
There is an excellent graph halfway down the page showing the superiority of battery energy storage. This was an interesting quote "Currently it takes 2½ times as much energy to make a hydrogen fuel cell than is obtained from it during it's service life" The Honda hydrogen car is a masterpiece of engineering and gives a nice warm fuzzy feeling to the uneducated but is in the end pointless, as it would never make more sense than even current BEV technology.