Extending the question a bit:
If I went the route of small cap cells, I would think about optimizing the
assembly. For example, I might design a parallel cell group to be comprised
of stacking 10 cells sideways and spot welding two appropriately heavy gage
copper strips to the cell ends with enough strip sticking above to be used a
lugs - this would amount to something looking like:
+ +
| |
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
|xxxx|
where "xxxx" are the cells and the + at the top are the lugs (or bolt holes,
perhaps).
Then these groups could be packed in U shaped troughs and wired togehher
with short bands of copper screwed to the lugs, and group bms' added.
Considering this kind of design, a lot of work could be optimized. I think
the assembly labor would be greatly reduced. It just might be enough
savings to justify using small lower cost cells.
Or maybe I'm just repeating the obvious :)
Peri
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Bruce EVangel Parmenter
Sent: 19 June, 2013 9:03 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Did Tesla steal my battery design?
I have been following this thread (as best I could), and thinking to ask
what hoegberg posted (see below). Your answer (in hindsight below) that
you would use larger capacity cells, gave me my answer. Please allow me
to ask other questions along the same lines.
After having gone through all the planning, designing, welding, and
implementation
? - At what point would the cost differential have to be between
deciding to
-pay a higher price for larger capacity cells,
-over using a lot of lower cost smaller capacity cells in a
series-parallel pack configuration?
[Picking an Ah number out of no where] I mean if four 10Ah cells cost
less than one 40Ah cell,
? how much less would it need to be to be worth all the additional cost
of connecting them, your time spent planning, designing, and welding
them all together ?
I ask this, because someone either lurking now, or reading this thread
later will have the thought of going cheap by using a lot of lower cost
cells over paying a high price for fewer larger capacity cells. Assume
pack space is not an issue, i.e. the converter has plenty of room
(underneath a truck bed?) for a large physical pack made up of several
small capacity cells.
Also, is there a disadvantage in maintaining the pack, i.e. is it harder
for the BMS to monitor all the additional smaller capacity cells, over
how much less the BMS has to work on a pack of fewer but larger capacity
cells?
If I understand correctly, a BMS would control the charger's charging
current, and monitoring temperatures as well.
I would assume one may be able to pay less for an off the self BMS if
there is less for it to monitor/keep healthy, right?
Please post your thoughts on these questions.
{brucedp.150m.com}
-
> From: hoegberg...
> Date: Wed, 19 Jun 2013 16:25:25 +0200
> ..[If].. you had to do it again today, would you go for less power and a
smaller pack?
-
-
On Wed, Jun 19, 2013, at 08:00 AM, Cruisin wrote:
> If I did it today, I would shoot for a larger pack using cells with more
> capacity that are now available, like Tesla uses. probably best to go
> with CALB and be done with it.
-
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