Has anyone heard anything about getting one of those aftermarket battery systems that need to be plugged in? I hear that it gets like 100mpg and costs like $5k. Any ideas?

It's still very early days for the aftermarket PHEV conversions, so early adopter prices are high. At least 3 companies are selling LiIon conversions around $10k, but a $3k DIY kit based on lead acid should soon be available from a group of hacker enthusiasts who are putting the kit together now.

May be cheaper just to wait for the first PHEV Prius direct from Toyota, it may be a factory option.

http://mysite.wanadoo-members.co.uk/ecotech/ecot.htm

My 2002 Prius hasn't needed the battery yet and it has 105,000 miles on it. If it needs another battery I'm thinking it'll be possible to get one from a junkyard which will be much cheaper.

Yes. Various companies are starting to do it. This table lists them all.
http://www.eaa-phev.org/wiki/Templaterius_PHEV_Options


You may find this FAQ helpful:
http://hybrids-plus.com/ht/faq.html

Better yet, get a new battery pack from companies that convert a Prius to Plug-in (PHEV). They replace the original Toyota pack with their own pack, so then the Toyota pack (usually in pristine conditions) is available!

Three companies are doing this today:
Hybrids Plus, http://hybrids-plus.com/
EnergyCS, http://energycs.com/
HyMotion, http://hymotion.com/

D'de

Which makes a lot of sense although I suspect we'll be over 250,000 miles before that day comes.

In my case, the first step would be to take my existing battery pack apart and diagnose the problem. Have you noticed there haven't been a lot of battery autopsies? Then seen if I could ressurect a little more life before whole battery replacement.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

FYI,
One of Toyota's service specification is attaching the S2000 scanner, then checking the delta-SOC.
If it was more than 20%, replace the battery.

Ken@Japan