The NiMH batteries they used at first degrade relatively quickly if you keep charging and discharging them fully on a regular basis.
That's why the plug-in Prius uses lithium.
They did not change their mind, they changed the chemistry.
one advantage of the 2nd gen Insight is the lower voltage on the pack; see
http://avt.inel.gov/pdf/hev/batteryinsight1748.pdf.
A parallel pack of about 117 Volt would do, no DC-DC conversion needed just 36 LiFePO4 cells in series.
That could be split into 3 '36V' packs or 9 '12V' subpacks and have standard 36V or 12V chargers per subpack.
Using lithium, 32 cells would do too, which can be split into any power of 2 sized number of subpacks.
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.