Re: (ET) Retofit a moderm Electric riding mower Battery pack to fit an ET

["David Roden" <etpost drmm net>]

For those who've done this, it would be interesting to hear what 
advantages 
a lithium conversion confers.  I can see some advantage, but not nearly as 
much as in a road EV, and some possible negatives.

I guess you'd get significantly more running time for a given battery 
volume, if that's something you need.   

In exchange you get a battery that requires a much more sophisticated 
charger and cell-level management - not just for cycle life, but for 
*safety*.  All that gear is pricey.  

You also have to pay more attention to temperature.  Lithium batteries 
degrade faster at full charge than when they're around 50% charge or less. 
And the higher the temperature, the worse this effect.   

So you want to charge just before using the tractor, rather than just 
after.  And what's the summer temperature in your garage?  

Lithium will also degrade, maybe be damaged, if it's charged when it's 
below freezing.  That's not such good news for winter snow moving.  A 
battery that's been used hard will be warm internally -  but if you charge 
it right after plowing or snow throwing, then you have to store it at or 
near full charge, also not so good for it.  

Factory EVs handle the temperature restrictions with micro-controlled 
thermal management systems, many times using liquid coolant.  What 
equivalent are you going to build for your ET?  

IMO, lithium in an ET would be a better choice in a temperate region - 
that 
is, one with winters that seldom get below freezing, and summers that 
don't 
often exceed 80 deg F or so.  

Finally, you *want* weight in a tractor, n'est-ce pas?  So the weight 
reduction would actually be another downside.

My lithium info is a few years old, so maybe modern batteries have fewer 
restrictions.  But I would suggest doing some further research and 
consideration.


David Roden - Akron, Ohio, USA

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