nickel metal hydride? is that really better. i never had good experience with those.
lifepo4 is where it's at.
lifepo4 is where it's at.
What's interesting is because Toyota has been developing the NiMH for so long, it has achieved densities of approx. 150Wh/kg, which actually makes it about as good as Lithium technology from 5 years ago, but without any of the stability problems.
The wikipedia page for NiMH also mentions things like venting hydrogen gas when overcharged...
Looking through the LiFePo4 pages on wikipedia the safety and durability profile seems superior to NiMH, but maybe the LiFePo4 pages there are just fixated on vs. other Li-Ion chemistries.
My impression ATM is if you've got LiFePo4 available it's preferable to NiMH. And my personal experience with a LiFePo4 portable battery booster for jumping cars and emergency charging stuff has been an incredibly positive one. The thing is like a tiny weightless magic box that tolerates incredible abuse without losing any charge even stored for a year in desert temps, and somehow manages to put out enough current to start large-displacement high-compression V8s.
This is an interesting point; why hasn't Toyota made longer-range plugin hybrids with these batteries, which would seem to be sensical? Looks like the largest battery in a plug-in Prius so far is just 8.8 kWh, according to Wikipedia.
Because even Toyota found the Lithium works better for that application.
So to start a plug-in hybrid program using that battery technology, could be very bad (outpriced, outperformed) if there was suddenly a huge leap forward in Li density and safety.