Re: [Electric Boats] Battery specific energy and power in relation to volume and density

 

So question:

If you are planning  a light efficient catamaran  with 2000 or better watts.  It would be relatively unlikely that you would seriously deplete your battery often. Then lithium may not be the way to go because it would spend most of its life fully charged?  Is this correct?   If that is correct what would be the better type of battery for that situation?

Thanks

Nick

Sent from my Bell Samsung device over Canada's largest network.

-------- Original message --------
From: "Hannu Venermo gcode.fi@gmail.com [electricboats]" <electricboats@yahoogroups.com>
Date: 2017-06-26 5:33 PM (GMT-05:00)
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Battery specific energy and power in relation to volume and density

 

I do not know about enerdel.

We do know that Leafs are crap, in longevity, and volts are crap, in longevity.
Typical loss is 15-30% in 3-6 years use.
This does NOT necessarily mean the cells are bad.
On those; ...
The temp / thermal conditioning is missing or poor, ...
chemistry is not so good, ...
cells are not balanced/equal (absolutley critical ! THIS is how tesla made their first batteries last, by sorting the cells), ..
and most important they are not shallow-cycled !!!

ANY of the critical-path factors in lion cells will massively degrade their lifetime.
C-rates, as You said,
balance,
chemistry,
temp conditioning,
cycling.

The Tsla Lesson is this.
Big Battery.
(= low cycling)
Thermal conditioning.
=> good.

(Optimal cells etc .. critical but less so).

No-one else in the world, so far, has demonstrated 1/3 the lifetime capacity of tesla packs.

This is NOT just because tsla was so brilliant, but because
1. they picked the cells for balance,
2. they used BIG batteries for low-cycling,
3. they used thermal conditioning.

At less than 1/5th C rate no commercial batteries last in any use I know of.
Lack of BMS/thermal.
Chemistry/shelf life/use life.

On 26/06/2017 21:16, 'Myles Twete' matwete@comcast.net [electricboats] wrote:

It's always important to consider the Use-Case.  Tesla's batteries are great as are Enerdel's, Nissan Leaf's and Chevy Volt's.  They're all designed to handle regular safe usage at up to 1- and even 2-3C current rates especially if rated for fast charging---e.g. Tesla's.  At less than 1/5thC rate, ANY OF THE CAR BATTERIES will work fine and last for years for the typical E-boat.

--  -hanermo (cnc designs) 

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Posted by: 63urban <63urban@gmail.com>

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