Plug in Prius in 2010 model: Modular battery would make sense

I recently attended a Prius connection for the 2010 Prius and asked a few questions regarding plug-ins.

This year (2009) they will place about 150 of the 2010 model leased into fleet customers with plug-in battery and perhaps altered battery control module. It appears this is just exporatory.

In terms of future plug-in for commercial sale they still seem hesitant to enter that market, in part due to a question as to the limitations in the true market size. The idea is that maybe half the people can not park where they can plug it in (ex. live in the city without a personal garage - perhaps on street parking, etc.). Then, it takes a real behavior change to plug it in every day - most people probably won't do that. And, the expense of the large battery. So, the market is likely to be smaller than many imagine, and then only a certain market share would go to any single manufacturer.

To me, the point is we are heating ourselves off the planet. If we can use electricity for transport, that then could be from a renewable and non-polluting resource. So, it is a key requirement environmentally. Also, energy independence could help the economy and reduce geo-political tensions. Since those aspects might not be a prime motivator for many folks who need simply to make ends meet, it is exciting that this technology could also make sense from a $$$ perspective considering a gallon of gas equivalent in electricity is about $1.

To make the battery for a plug in more cost effective it would be key to allow people to purchase it by the battery module - perhaps 10 mile modules. So, a person who makes a 5 mile commute (one way) might only need a single module, whereas someone with a 20 mile (one way) commute might want four (ten mile) battery modules. Each module should be identical to the others with the management smarts being in the packaging/control system. Due to the current plug-in battery cost it would be uneconomical (per each purchaser's individual case) to purchase more modules than would be needed for a normal day's use. This could also reduce replacement costs, since only the failed module might be replaced in the case of an early failure.

So, the modular approach increases the cost/benefit analysis for each individual purchaser, and lowers the risk exposure to premature failure of an expensive component. This would help gain market acceptance and increase the pool of purchasers.

Eric