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Hello Jim
I am also a member of this list. The packs are NiMH cells but they are a
totally different animal. As David pointed out these cells are intended for
high energy use in and out. They were not engineered to be a deep cycle cell. If
you try to deep cycle them they will very quickly be destroyed. As an example it
would be like using a lead acid starting battery in place of a deep cycle
battery. Both are lead acid batteries but they were engineered to be
used under different conditions.
You would need to vastly over size the pack to be able to handle sustained
heavy amp loads. You could still not go below 50 percent DOD or charge over 80
percent SOC for long cycle life. Going above or below these percentages will
create heat and NiMH cells if heated will quickly be damaged. They will if
over heated lose capacity and become a fire hazard.
The Prius cells don't make any sense in an EV as the energy
density is about the same a lead acid when sized correctly. I would assume these
Ovonic cells would be very similar to the Prius NiMH cells. In a
tractor weight is not an issue but you would still need to make a very large
pack. If you did this and kept the SOC between 50 to 80 percent they actually
would last a very long time. The problem is keeping them in balance so cells
don't stray out of the 50 to 80 percent range. This would require a very good
BMS and temperatures would need to be controlled. They need to be charged in
series and cell balancing would require a very sophisticated system.
I talked to Ovonic around four years ago. At that time they have
zero interest in any fully electric vehicles. We had a long talk he was a nice
guy but the company was only looking at Hybrids. If your a large manufacturer
looking to build hybrids they are more then happy to work with you. They would
not even provide replacements for the OEM electric vehicles that
had their modules. I can guarantee Ovonic will not provide you any
help.
Others have tried in an EV using as many as five packs of
the Prius cells and after destroying several packs of the
five gave up. I wish anyone trying to use these the best of luck.
Don Blazer
In a message dated 6/4/2011 8:21:35 P.M. Pacific Daylight Time,
jbc_lists_NO_REPLY coate org writes:
David may be thinking of EV Bones in Arizona. However Jeff got out of |