Re: (ET) battery drainage question

["David Roden" <etpost drmm net>]

Again, I'm no expert - but from what I've read, the lifespan issue with 
lithium secondary batteries is not so much cycle life, it's calendar life. 
They reportedly depreciate just sitting!  You might indeed get 7000 
cycles, 
but probably only if you cycle them that many times in less than, say, 5 
years.  

This is especially significant for ETs, which most people probably don't 
often use more than weekly.  Five years would be only 250-300 cycles.    

Even if they lasted 10 years in an ET, they stll couldn't match the cost- 
effectiveness of golf car batteries, which cost less than a third as much, 
and usually last about that long in ET service.  (They'd probably last 
even 
longer if the charger weren't such a blunderbuss.)   

Besides, the lead helps ballast the tractor.  I'd hate to see what a 
tiller 
or snowthrower would do to a tractor fitted with a lithium battery of 
comparable capacity.  It's tough to throw snow when the back wheels are up 
in the air.  

Lithium makes more sense for road EVs, IMO.  Of course if you need to 
drive 
your tractor halfway across the state, I guess a lithium battery the size 
of 
the original lead battery would get you a lot further than the lead. ;-)  

Lithium is the clear winner for ultra-compact electronic devices, at least 
for now.  I use lithium ion batteries in my laptop computers and a cell 
phone. For those gadgets they're great, though I can clearly see the 
calendar life issue developing on the computers.  

BTW, I've seen some mention of LionEV on the EVDL (Electric Vehicle List). 
You might want to search their archive for the comments :  

http://www.evdl.org/archive/

I got the impression from the discussion there that while LionEV may 
assemble cells into packs, they don't manufacture the cells.  I believe 
they 
import the cells from China.  I could be wrong about that, though.  



David Roden - Akron, Ohio, USA

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