[RE-wrenches] Lithium-ion battery charging

[Dan Fink]

I am *almost* convinced that rating energy storage in kilowatt-hours is 
a benevolent attempt by the EV industry to make things more simple for 
consumers. kWh on my power bill vs. kWh stored in my new Tesla...it even 
fits into a news bite! Anything that has math in it? You can forget the 
news bite.

In my off-grid intro classes I explain amp-hours as a way for renewable 
energy consultants and writers to keep their jobs, and I immediately 
move the entire discussion to kWh of battery storage. Charge/discharge 
rates vs. capacity are not a relevant factor in such basic-level 
discussions with the general public, and as soon as you mention 
multiplying by system voltage or how series increases voltage but not 
amp-hours, and parallel increases amp-hours but not voltage, it's 
zzzzzzzz lights out.

We RE Wrenches will always be talking in amp-hours, as will our battery 
companies, the engineers at EV companies, and the rest of the tech 
community. We can define performance in detail that way.

But perhaps rating battery storage in kWh is a neat way to serve up a 
plate of real understanding to the general public, sans math? If it 
works, I'm all for it.


Dan Fink
Executive Director;
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC / ISPQ accredited Continuing Education Providers
http://www.buckville.com/
info at buckville.com
970.672.4342 (voicemail)
970.373.1311 (fax)




>     Wrenches
>     I am researching a GT PV installation to power an EV charging
>     station at a new car dealership nearby. After researching l-ion
>     technology and charging information on the www, I see that most
>     references to l-ion and EVs in general refer to battery capacity in
>     kWh instead of Ah.
>     Is kWh the new standard for battery propulsion in cars or is it used
>     muddy the conversion from Ah similar to the cold-cranking amps
>     standard for starter batteries?
>     I know kWh battery capacity could be calculated assuming a constant
>     charge/discharge rate but cars will seldom be operated at a constant
>     discharge rate.
>     Thanks for some clues
>      
>     *Jim Duncan*
>     *North Texas Renewable Energy*
>     *NABCEP Certified Solar PV*
>     *Installer No.031310-57*
>     *TECL 27398*
>     *ntrei at 1scom.net* <mailto:ntrei at 1scom.net>* *
>     *817.917.0527*
>     *www.ntrei.com* <http://www.ntrei.com/>
>     ** 
> 
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