Advice wanted on lithium battery choices - 914ev

Message from discussion Advice wanted on lithium battery choices
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Date: Sat, 13 Jun 2009 16:00:27 -0700
Message-ID: <6368e4f70906131600r731e4771v7c10b92d2a2cf...@mail.gmail.com>
Subject: Re: [914ev] Advice wanted on lithium battery choices
From: David Hale <astronomerd...@gmail.com>
To: 914ev@googlegroups.com

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Peter,
I know you have been considering this and my recent woes posted both here
and EVDL have swayed you into lithium. Li is going to give you less mass and
more voltage in the same space, so it's a great thing. And numbers I see
about FLA & LFP lifetimes suggest that LFPs may be cheaper to own over the
long run; of course, you have to pay substantially more for this up front.
If that is not a concern then that's great. But in light of the recent
responses I've gotten from EVDL and especially with Andy's car coming on
line and getting 0-60 in 20s, it is clear that my car has a unique problem.
So you shouldn't let my case be the sole decider for you.

Now, if you are sure about LFPs then you should talk to Electro Automotive
about it. Bill mentioned once that you should not use less than 160Ah cells,
although JungleMotors is using 90Ah units. I e-mailed Jungle about this and
they didn't respond. Dave @ evcomponents said he'd make some calculations.

Power is linear with voltage so in theory you want as high a voltage pack as
you can fit, but I've heard (or read) somewhere something to the effect of
the Azure motors having a certain range where voltage increases don't help
until you cross certain thresholds. You might want to try contacting them
about that.

Also, my figures are slightly different from yours. I determined the
following for SE cells in the ElectroAuto battery boxes:

180Ah: 59 batteries for 188V pack and 728 lb
120Ah: 76 batteries for 243V pack and 754 lb
100Ah: 86 batteries for 275V pack and 588 lb.


Anyway, now that it seems clear that my car has a unique problem I am no
longer pursuing the idea of LFPs -- at least not until the FLAs need to be
replaced (and assuming we've fixed the current problem).

--Dave

On Sat, Jun 13, 2009 at 1:48 PM, Peter Thompson <PThompson...@gmail.com>wrote:

>
> Hi Folks,
>
> I've figured out several different configurations of lithium batteries
> for the EA 914AC kit racks, and have come up with some interesting
> possibilities.
>
>        Individual Battery                              Battery Pack
> Battery         V       Ah      Weight  Cost            # of Batt
> Pack V  Avail Kw
> Pack Lb Cost
> SE120 min       3.2     120     9.9             $132.00         51
>      163             13,709
> 505             $6,732.00
> SE100 min       3.2     100     7.04            $110.00         52
>      166             11,648
> 366             $5,720.00
> TS90 min                3.2     90      7.04            $99.00  60
>      192
> 12,096  422             $5,940.00
> SE60 min                3.2     60      5.28            $66.00  72
>      230
> 9,677   380             $4,752.00
>
> SE120 max       3.2     120     9.9             $132.00         76
>      243            20,429
> 752             $10,032.00
> SE100 max       3.2     100     7.04            $110.00         63
>      202            14,112
> 444             $6,930.00
> TS90 max        3.2     90      7.04            $99.00  89              285
>            17,942
> 627             $8,811.00
> SE60 max        3.2     60      5.28            $66.00  109             349
>            14,650
> 576             $7,194.00
>
> All of the costs are based on the posted values on the
> evcomponents.com site.
>
> Assumptions:  cost is not a huge factor in this assessment.  Space has
> been predetermined by the battery racks from the kit. This is powering
> the AC24 / DMOC445 motor and controller.
>
> Questions:
> 1) should I go for max voltage?
> 2) or should I go for max
> 3) or should I try for a compromise.
>
> If there is a desire, I can post the spreadsheet used to calculate
> these values on the group list.
>
> Thanks in advance for any advice/suggestions.
>    Peter
> >
>

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Peter,<div><br></div><div>I know you have been considering this and my rece=
nt woes posted both here and EVDL have swayed you into lithium. Li is going=
 to give you less mass and more voltage in the same space, so it&#39;s a gr=
eat thing. And numbers I see about FLA &amp; LFP lifetimes suggest that LFP=
s may be cheaper to own over the long run; of course, you have to pay subst=
antially more for this up front. If that is not a concern then that&#39;s g=
reat. But in light of the recent responses I&#39;ve gotten from EVDL and es=
pecially with Andy&#39;s car coming on line and getting 0-60 in 20s, it is =
clear that my car has a unique problem. So you shouldn&#39;t let my case be=
 the sole decider for you.<br>

<br></div><div>Now, if you are sure about LFPs then you should talk to Elec=
tro Automotive about it. Bill mentioned once that you should not use less t=
han 160Ah cells, although JungleMotors is using 90Ah units. I e-mailed Jung=
le about this and they didn&#39;t respond. Dave @ evcomponents said he&#39;=
d make some calculations.=A0</div>

<div><br></div><div>Power is linear with voltage so in theory you want as h=
igh a voltage pack as you can fit, but I&#39;ve heard (or read) somewhere s=
omething to the effect of the Azure motors having a certain range where vol=
tage increases don&#39;t help until you cross certain thresholds. You might=
 want to try contacting them about that.</div>

<div><br></div><div>Also, my figures are slightly different from yours. I d=
etermined the following for SE cells in the ElectroAuto battery boxes:</div=
><div><br></div><div><span class=3D"Apple-style-span" style=3D"border-colla=
pse: collapse; "><div>
180Ah: 59 batteries for 188V pack and 728 lb</div><div>120Ah: 76 batteries =
for 243V pack and 754 lb</div><div>100Ah: 86 batteries for 275V pack and 58=
8 lb.</div><div><br></div></span></div>
<div><br></div><div>Anyway, now that it seems clear that my car has a uniqu=
e problem I am no longer pursuing the idea of LFPs -- at least not until th=
e FLAs need to be replaced (and assuming we&#39;ve fixed the current proble=
m).</div>

<div><br></div><div>--Dave</div><div><br><div class=3D"gmail_quote">On Sat,=
 Jun 13, 2009 at 1:48 PM, Peter Thompson <span dir=3D"ltr">&lt;<a href=3D"m=
ailto:PThompson...@gmail.com" target=3D"_blank">PThompson...@gmail.com</a>&=
gt;</span> wrote:<br>

<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><br>
Hi Folks,<br>
<br>
I&#39;ve figured out several different configurations of lithium batteries<=
br>
for the EA 914AC kit racks, and have come up with some interesting<br>
possibilities.<br>
<br>
 =A0 =A0 =A0 =A0Individual Battery =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0Battery Pack<br>
Battery =A0 =A0 =A0 =A0 V =A0 =A0 =A0 Ah =A0 =A0 =A0Weight =A0Cost =A0 =A0 =
=A0 =A0 =A0 =A0# of Batt =A0 =A0 =A0 Pack V =A0Avail Kw<br>
Pack Lb Cost<br>
SE120 min =A0 =A0 =A0 3.2 =A0 =A0 120 =A0 =A0 9.9 =A0 =A0 =A0 =A0 =A0 =A0 $=
132.00 =A0 =A0 =A0 =A0 51 =A0 =A0 =A0 =A0 =A0 =A0 =A0163 =A0 =A0 =A0 =A0 =
=A0 =A0 13,709<br>
505 =A0 =A0 =A0 =A0 =A0 =A0 $6,732.00<br>
SE100 min =A0 =A0 =A0 3.2 =A0 =A0 100 =A0 =A0 7.04 =A0 =A0 =A0 =A0 =A0 =A0$=
110.00 =A0 =A0 =A0 =A0 52 =A0 =A0 =A0 =A0 =A0 =A0 =A0166 =A0 =A0 =A0 =A0 =
=A0 =A0 11,648<br>
366 =A0 =A0 =A0 =A0 =A0 =A0 $5,720.00<br>
TS90 min =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A03.2 =A0 =A0 90 =A0 =A0 =A07.04 =A0 =
=A0 =A0 =A0 =A0 =A0$99.00 =A060 =A0 =A0 =A0 =A0 =A0 =A0 =A0192<br>
12,096 =A0422 =A0 =A0 =A0 =A0 =A0 =A0 $5,940.00<br>
SE60 min =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A03.2 =A0 =A0 60 =A0 =A0 =A05.28 =A0 =
=A0 =A0 =A0 =A0 =A0$66.00 =A072 =A0 =A0 =A0 =A0 =A0 =A0 =A0230<br>
9,677 =A0 380 =A0 =A0 =A0 =A0 =A0 =A0 $4,752.00<br>
<br>
SE120 max =A0 =A0 =A0 3.2 =A0 =A0 120 =A0 =A0 9.9 =A0 =A0 =A0 =A0 =A0 =A0 $=
132.00 =A0 =A0 =A0 =A0 76 =A0 =A0 =A0 =A0 =A0 =A0 =A0243 =A0 =A0 =A0 =A0 =
=A0 =A020,429<br>
752 =A0 =A0 =A0 =A0 =A0 =A0 $10,032.00<br>
SE100 max =A0 =A0 =A0 3.2 =A0 =A0 100 =A0 =A0 7.04 =A0 =A0 =A0 =A0 =A0 =A0$=
110.00 =A0 =A0 =A0 =A0 63 =A0 =A0 =A0 =A0 =A0 =A0 =A0202 =A0 =A0 =A0 =A0 =
=A0 =A014,112<br>
444 =A0 =A0 =A0 =A0 =A0 =A0 $6,930.00<br>
TS90 max =A0 =A0 =A0 =A03.2 =A0 =A0 90 =A0 =A0 =A07.04 =A0 =A0 =A0 =A0 =A0 =
=A0$99.00 =A089 =A0 =A0 =A0 =A0 =A0 =A0 =A0285 =A0 =A0 =A0 =A0 =A0 =A017,94=
2<br>
627 =A0 =A0 =A0 =A0 =A0 =A0 $8,811.00<br>
SE60 max =A0 =A0 =A0 =A03.2 =A0 =A0 60 =A0 =A0 =A05.28 =A0 =A0 =A0 =A0 =A0 =
=A0$66.00 =A0109 =A0 =A0 =A0 =A0 =A0 =A0 349 =A0 =A0 =A0 =A0 =A0 =A014,650<=
br>
576 =A0 =A0 =A0 =A0 =A0 =A0 $7,194.00<br>
<br>
All of the costs are based on the posted values on the<br>
<a href=3D"http://evcomponents.com" target=3D"_blank">evcomponents.com</a> =
site.<br>
<br>
Assumptions: =A0cost is not a huge factor in this assessment. =A0Space has<=
br>
been predetermined by the battery racks from the kit. This is powering<br>
the AC24 / DMOC445 motor and controller.<br>
<br>
Questions:<br>
1) should I go for max voltage?<br>
2) or should I go for max<br>
3) or should I try for a compromise.<br>
<br>
If there is a desire, I can post the spreadsheet used to calculate<br>
these values on the group list.<br>
<br>
Thanks in advance for any advice/suggestions.<br>
 =A0 =A0Peter<br>
<br>
</blockquote></div><br></div>

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