Are they size D cells? I could probably drop them in my battery charger. It could get tedious since it can only charge 8 at a time.

They could have D cells, I think the Ford Escape uses them. I don't want to add batteries though, just wanted to use what I have.

Ag4ever, from what I've been reading I don't see why your car wouldn't go 200,000 before the batteries are gone. I'm hoping for that myself. From what I've read (I could be wrong though), age is affecting the batteries as much or more than the number of recharge cycles. That's part of why I think a charger would help.

I was told the cells are the AA size. The cells are arranged in a pack or a plug in module. That way if a cell ever gets low they can replace that single pack and not the whole hv battery.

My guess is they may have a special voltmeter that plugs into a connector to show which module may read low.

From what I have read, this is extremely rare. I have heard of many Prius that have went over 200K miles with no battery problems.

I have wondered as well how long these batteries will last. Found a very interesting article on the subject. Go here. He claims he spoke with a gentleman from Toyota and says the batteries should have no problem going for 15 years at 12k mi/yr (20k km/yr).

Life is like a box of chocolates...you never know what you're gonna get.

The traction battery is warranted in US for 100k miles, 150k in CA, NY and some other states, or 10 years whichever comes first, therefore if they break before warranty runs out, they will be replaced for free. After that it's any one's guess, but normally the battery should not fail right away, but gradually, therefore 200k should be reasonable assumption. As far as I know if the battery pack is faulty, it is replaced as a whole and never repaired at least at the dealer level due to high voltages inside. Toyota sold tens of thousands of TCH in US, so junk yards should have steady supply of used parts even after warranty expires. I think using external charger would be bad idea, if nothing else it could affect warranty if it wasn't Toyota approved, especially that Toyota keeps the battery charged at 40%-80% full at all times and it would be difficult to monitor the charge and keep it inside this range without some sophisticated, computerized monitoring system.