# [EVDL] How much for a Li-ion pack?



## EVDL List (Jul 27, 2007)

Today, when I was out and about getting some much needed exercise, a
Ford nev pulled into the parking lot. Before the driver and his young
daughter could get away, I let him know of a need for a couple nevs
at September 24th's eaasv.org rally at Palo Alto High School 10a-4p.

I asked him to whip out his web enabled phone and bookmark the URL.
I told them about how we have a good time and their is plenty of 
e-bikes and scooter for the kids to ride (his daughter's eyes lit up),
and everyone can get rides in personal EVs, driver's bring in to
give free rides to the public.

Reading his body language as he was interested but needed to head 
toward getting done what he came for, I finished with asking if he 
could make the 10 miles to this free EVent?

He said he only had a 30 mile range. Then, I told him there would
be free charging at there (his eyes lit up too). He could bring his
family, plug in, and enjoy the Rally.

We parted with him stating he usually finds out about these shows
after the fact. So, of course I felt my EVangel efforts had just 
made both our days.

...
OK, having said all that, a little history on the nevs. They were a
way for Ford, Chrysler (GEM), and GM to give-away or sell below cost
to meet the CARB mandated quota of EVs. These are costly, but 
inexpensively designed/made 72V PbSO4 pack 25mph Electric LSVs. These
usually have a light-short-lived 12V battery pack and a crummy 
inefficient low pfc 120VAC-only level1 on-board charger.

So on to the question ...
Though I know the nev costs less than the Li-ion pack, 
-how much would a 50mile Li-ion pack for this nev cost?

-and what dual input voltage (120 & 240VAC) charger would you
buy to replace the on-board pos? 1kW at level 1, and at least 3kW
off level2, with a 6kW charging ability preferred. 

http://www.motorcraftservice.com/vdirs/quickref/think/tsb/tsb02-13-03.pdf
says the 12V PbSO4 wet-cell batteries used are 130AH. Because you
can not discharge them as deeply as a 6V PbSO4 wet-cell 
golf-cart/traction battery, lets figure you can get about half the
deep-cycle's capacity without prematurely aging it.

That would mean the man's Ford nev uses 65AH at 72V, or a 4.68kW
pack for a 30 mile range. Extrapolating, a 50 mile range pack would
have about 7800kW. Lets round up to give the pack some head room and
call it a 8kW pack at 72V.

Forget whether it is worth it or not, think of it as an exercise.

Anybody got any ideas, comments, prices for a 8kW pack at 72V?


...
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{brucedp.150m.com}

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## EVDL List (Jul 27, 2007)

Bruce,

I would replace a 72V lead pack with 24 LiFePO4 cells for a nominal
voltage of 24x3.2V=3D76.8V. This may be too high of a voltage for the
rest of the components so you might go with 22 cells. 3.2vpc is a
realistic number to use for capacity calculations for a LiFePO4 pack.
At least it is close to what I get when I divide the Wh by the Ah that
my CycleAnalyst reports after a drive. Going with a 24 cell 100Ah pack
gives a 7.68kWh pack, a 22 cell pack would only be 7.04kWh. ThunderSky
sells 40, 60, 90, 100, 160 and up Ah cells. To give a little buffer
but buy the smallest pack I would go with buddy paired 60Ah cells for
a 120Ah pack. LiFePO4 cells are basically made up of many cells in
parallel so paralleling two just gives an external parallel
connection. Besides, the charge/discharge curves are perfect for
paralleling. A 22 cell 120Ah pack would be an 8.448kWh pack. 80% of
that is about 6.8kWh. A 24 cell pack would be 9.2kWh for an 80%
capacity of 7.4kWh. This is close to what you are wanting.

A better match might be CALB since they have a 130Ah cell. A 24 cell
pack of these would be 9.984kWh for an 80% capacity of just under 8kWh
which was your target. The internal resistance on these cells is so
low that for all practical purposes you can ignore the current draw.
Essentially an Ah is an Ah regardless of the current as long as it
isn't too high. I'd find out what the maximum current draw is on the
NEV and select the Ah capacity to be such that max draw isn't over 3C.
This will make the batteries last longer than under sizing the pack.

The cells will cost on the order of $1.25/Ah so a 130Ah cell will be
$162.50 or about $4000 for a 10kWh pack.

HTH,

On Sun, Jul 31, 2011 at 9:51 PM, bruce parmenter <[email protected]> w=
rote:
>
> Today, when I was out and about getting some much needed exercise, a
> Ford nev pulled into the parking lot. Before the driver and his young
> daughter could get away, I let him know of a need for a couple nevs
> at September 24th's eaasv.org rally at Palo Alto High School 10a-4p.
>
> I asked him to whip out his web enabled phone and bookmark the URL.
> I told them about how we have a good time and their is plenty of
> e-bikes and scooter for the kids to ride (his daughter's eyes lit up),
> and everyone can get rides in personal EVs, driver's bring in to
> give free rides to the public.
>
> Reading his body language as he was interested but needed to head
> toward getting done what he came for, I finished with asking if he
> could make the 10 miles to this free EVent?
>
> He said he only had a 30 mile range. Then, I told him there would
> be free charging at there (his eyes lit up too). He could bring his
> family, plug in, and enjoy the Rally.
>
> We parted with him stating he usually finds out about these shows
> after the fact. So, of course I felt my EVangel efforts had just
> made both our days.
>
> ...
> OK, having said all that, a little history on the nevs. They were a
> way for Ford, Chrysler (GEM), and GM to give-away or sell below cost
> to meet the CARB mandated quota of EVs. These are costly, but
> inexpensively designed/made 72V PbSO4 pack 25mph Electric LSVs. These
> usually have a light-short-lived 12V battery pack and a crummy
> inefficient low pfc 120VAC-only level1 on-board charger.
>
> So on to the question ...
> Though I know the nev costs less than the Li-ion pack,
> -how much would a 50mile Li-ion pack for this nev cost?
>
> -and what dual input voltage (120 & 240VAC) charger would you
> buy to replace the on-board pos? 1kW at level 1, and at least 3kW
> off level2, with a 6kW charging ability preferred.
>
> http://www.motorcraftservice.com/vdirs/quickref/think/tsb/tsb02-13-03.pdf
> says the 12V PbSO4 wet-cell batteries used are 130AH. Because you
> can not discharge them as deeply as a 6V PbSO4 wet-cell
> golf-cart/traction battery, lets figure you can get about half the
> deep-cycle's capacity without prematurely aging it.
>
> That would mean the man's Ford nev uses 65AH at 72V, or a 4.68kW
> pack for a 30 mile range. Extrapolating, a 50 mile range pack would
> have about 7800kW. Lets round up to give the pack some head room and
> call it a 8kW pack at 72V.
>
> Forget whether it is worth it or not, think of it as an exercise.
>
> Anybody got any ideas, comments, prices for a 8kW pack at 72V?
>
>
> ...
> http://www.urbandictionary.com/define.php?term=3DP.O.S.
>
> {brucedp.150m.com}
>
> --
> http://www.fastmail.fm - A fast, anti-spam email service.
>
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http://evalbum.com/1328

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## EVDL List (Jul 27, 2007)

2011/8/1 David Nelson <[email protected]>:

> I would go with buddy paired 60Ah cells for
> a 120Ah pack. LiFePO4 cells are basically made up of many cells in
> parallel so paralleling two just gives an external parallel
> connection.

Hmm... Could you please provide the facts how this conclusion would be true=
?

Are you absolutely sure there is no other means to flatten the
potential differences than just the electrical connection ?

If there would have been 'IMHO' in the the claim I would have let it go by.=
.. 

Thanks.
-akkuJukka


http://www.google.com/profiles/jarviju#about

> The cells will cost on the order of $1.25/Ah so a 130Ah cell will be
> $162.50 or about $4000 for a 10kWh pack.
>
> HTH,
>
> On Sun, Jul 31, 2011 at 9:51 PM, bruce parmenter <[email protected]>=


> wrote:
> >>
> >> Today, when I was out and about getting some much needed exercise, a
> >> Ford nev pulled into the parking lot. Before the driver and his young
> ...


----------



## EVDL List (Jul 27, 2007)

*****Hmm... Could you please provide the facts how this conclusion would be
true ?****

How would it not be true. Each 100 ah cell is actually two 50ah cells within
the case. Your only adding more packs separated by the plastic case. Within
the case each section is separated by a paper barrier and each pack is
wrapped in paper. So do you need photos of the inside of a cell to believe?

-----
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## EVDL List (Jul 27, 2007)

Ok. So the electrolyte is not physically the same liquid around the
separate cell structures inside the case ?

Is the amount of Ions constant in the electrolyte ?

In one cell you could have 100 pairs of electrodes.

Have you opened the 12v (common electrolyte) batteries ?

Separate cells in separate electrolyte are very different than
paralled pairs inside the common electrolyte.

-akkuJukka


http://www.google.com/profiles/jarviju#about



2011/8/1 gottdi <[email protected]>:
> *****Hmm... Could you please provide the facts how this conclusion would =
be
> true ?****
>
> How would it not be true. Each 100 ah cell is actually two 50ah cells wit=
hin
> the case. Your only adding more packs separated by the plastic case. With=
in
> the case each section is separated by a paper barrier and each pack is
> wrapped in paper. So do you need photos of the inside of a cell to believ=
e?
>
> -----
> If you don't understand, be patient, you will. Now I understand. 
> --
> View this message in context: http://electric-vehicle-discussion-list.413=
529.n4.nabble.com/How-much-for-a-Li-ion-pack-tp3708893p3710769.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Na=
bble.com.
>
> _______________________________________________
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## EVDL List (Jul 27, 2007)

You have parallel plates within each cell of the lead acid battery too. The
12volt battery is 6 cells within one case. With lithium you have single
cells of varying ah and size. Like a lead acid cell you can parallel them
through external connections. Each parallelled group of cells acts as one
cell. 

-----
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## EVDL List (Jul 27, 2007)

I have been trying to research the same type of question--but don't have
enough knowledge to know how to get answers.
I would like to get "ballpark" numbers to change my lead acid pack in my
Escort Wagon EV to 120 volt LiFePO4; batteries, charger(s) and BMS.
Any direction, experience, or advice welcome!
Michael B



> David Nelson <[email protected]> wrote:
> 
> > Bruce,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Only thing common for Lions and Lead is that they are both batteries.

I can see how this might seem to be a trivial thing but it's far from
it. LiFePO4 is kinda forgiving but the very same effects will come
just later compared to LiMn2O4 or LiNiMnCoO....

I know you can get very different opinions from batter chemists on
this... I observe and try to understand how and why. Equations do not
support the methods of Lion transport.. but it's there...

-akkuJukka


http://www.google.com/profiles/jarviju#about



2011/8/2 gottdi <[email protected]>:
> You have parallel plates within each cell of the lead acid battery too. T=
he
> 12volt battery is 6 cells within one case. With lithium you have single
> cells of varying ah and size. Like a lead acid cell you can parallel them
> through external connections. Each parallelled group of cells acts as one
> cell.
>
> -----
> If you don't understand, be patient, you will. Now I understand. 
> --
> View this message in context: http://electric-vehicle-discussion-list.413=
529.n4.nabble.com/How-much-for-a-Li-ion-pack-tp3708893p3710840.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Na=
bble.com.
>
> _______________________________________________
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## EVDL List (Jul 27, 2007)

> Mike Beem wrote:
> > I have been trying to research the same type of question--but don't have
> > enough knowledge to know how to get answers.
> > I would like to get "ballpark" numbers to change my lead acid pack in my
> ...


----------



## EVDL List (Jul 27, 2007)

Not from the pictures you've linked previously, as I've pointed out
previously. It's actually a large number of smaller cells in parallel that
they happened to physically bundled into two 50ah groups and then connect
those two groups. It could also have been 5 20ah groups, or 10 10ah groups,
but ultimately it's a higher number of cells in parallel.



> gottdi wrote:
> >
> >
> > Each 100 ah cell is actually two 50ah cells within the case.
> ...


----------



## EVDL List (Jul 27, 2007)

Wow, lots of muckin in the mud and fog here. Why make it harder than it is.
First off you can't compare LiFePO4 Cells with lead in how they will provide
power compared to the lead. Just the discharge curve alone is way different.
So if you want decent power and distance you need a decent sized pack. 120
volts of 160 AH cells or maybe just 120 volts of 140 AH cells you will be
doing better than with lead. Bottom balance your pack and set your charger
and controller to do your cut off and cutback. Be sure your pack is near
identical in capacity first. If you don't you may need to configure in a BS
system. Be smart from the start. 

Now for buddy pairing the cells. I have opened a 100 AH cell and found two
separate packs of 50 ah cells paralleled in side. Each is separate and the
minute amount of wetness in side does not interact the both cell packs. The
packs are separated within the plastic block. You could remove each set of
packs and make 50 ah cells and not affect the performance of the cell. Add
two packs within and you effectively increase the AH rating but not the
voltage. Add two more and you have a 200 AH cell with for separate packs
within the casing. OR you could buddy pair two 100 AH cells via your
external electrical connection and have what would be considered a 200 AH
cell. Even the charger will consider it that. No different than with a lead
acid cell. 

LiFePO4 is kinda forgiving but the very same effects will come 
just later compared to LiMn2O4 or LiNiMnCoO.... 

Not sure where you got this from. Do you have any thing that supports this
claim? 


LiFePO4 cells do very well if you parallel them like the lead cells do. I
have no interest in LiMn2O4 or LiNiMnCoO cells. The chemistry is not the
same as with LiFePO4. They are totally different beasts. 



-----
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## EVDL List (Jul 27, 2007)

> gottdi wrote:
> > Wow, lots of muckin in the mud and fog here. Why make it harder than it is.
> > First off you can't compare LiFePO4 Cells with lead in how they will provide
> > power compared to the lead. Just the discharge curve alone is way different.
> ...


----------



## EVDL List (Jul 27, 2007)

Sure...
2011/8/1 Jukka J=E4rvinen <[email protected]>:
> 2011/8/1 David Nelson <[email protected]>:
>
>> I would go with buddy paired 60Ah cells for
>> a 120Ah pack. LiFePO4 cells are basically made up of many cells in
>> parallel so paralleling two just gives an external parallel
>> connection.
>
> Hmm... Could you please provide the facts how this conclusion would be tr=
ue ?

Sure, just open one up and look. Several layers of alternating Cu and
AL foils separated by a separating film. The foils are electrically
connected just under the terminals. The electrolyte is just an ion
carrier and doesn't easily migrate around and through the plates.
Surely you have opened up some cells. There are several pictures
online where people have done just that. This is different than in
cell phone batteries and the pouch cells I opened up yesterday that
came out of a Mac laptop battery pack. The battery pack was made up of
a 2p3s pack of pouch cells. The two "plates" were wrapped around in a
rectangular spiral rather than the separate foils like in a TS
battery.

> Are you absolutely sure there is no other means to flatten the
> potential differences than just the electrical connection ?

I assume you mean besides the electrical connection at the top of the
plates where they are connected to the terminals. No I'm not sure.
That is why I said that, " LiFePO4 cells are basically made up of many
cells in parallel" and didn't leave out the word basically.

> If there would have been 'IMHO' in the the claim I would have let it go b=
y... 

See the word "basically" in my statement above. Also, look at the
charge and discharge curves. While it is possible for the electrolyte
to dry out in one cell and not the other in a buddy pair, this is and
exception and not the rule to normal operation. This would likely kill
both cells. No different than a cell of twice the capacity which has
the same electrolyte loss.


2011/8/1 Jukka J=E4rvinen <[email protected]>:
> Ok. So the electrolyte is not physically the same liquid around the
> separate cell structures inside the case ?
>
> Is the amount of Ions constant in the electrolyte ?

I don't know. They move to fast for me to count. 

> In one cell you could have 100 pairs of electrodes.
>
> Have you opened the 12v (common electrolyte) batteries ?

We are talking about paralleling cells not batteries. Show me a 12V
cell and I can show you one with a common electrolyte. If you are
talking about the 2V lead acid cells, then yes, every one I've taken
apart and/or looked inside of had a common electrolyte.

>
> Separate cells in separate electrolyte are very different than
> paralled pairs inside the common electrolyte.

So is this where you need to say, "IMHO"? 

At this point in my understanding, cell SOC can only be determined
reasonably accurately at the top or bottom voltage of the cell since
this is where the voltage changes the most for a given change in SOC.
If I take two LiFePO4 cells and parallel them there terminal voltage
will be forced to be the same. If one cell has a lower capacity than
the other and or is at a higher SOC than the other, under charge, it
will attempt to "climb" the upper knee of the voltage curve before the
other cell but since they are in parallel the lower SOC cell will
accept more of the charge and hold the higher SOC cell where it is
until they both reach the same SOC. A similar thing happens on
discharge. How do I know, that is how I balanced my cell pairs in my
pack and it works. I even had a situation where I had missed
tightening one of the terminal bolts on a cell pair and it didn't
accept a charge like the other one, due to the high resistance
connection. I simply hooked up a PS to that cell pair, after
tightening the bolt of course, and charged it up. Even though the one
cell had reached top the pair took several more Ah. That pair has been
working just fine, like the other 19 pairs have been working.


-- =

David D. Nelson
http://evalbum.com/1328

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## EVDL List (Jul 27, 2007)

I use the web for this forum anymore. Sorry if it was put in your part of the
thread. My view it does not matter. It just comes as listed. 


*LiFePO4 is kinda forgiving but the very same effects will come just later
compared to LiMn2O4 or LiNiMnCoO....*


This quote is what I am asking about and you must also include everyone else
in the context to and not just yours. So the person who wrote this knows who
they are and they can respond. I don't expect you to respond if you did not
write it. But since is came in a format that links my response to your
portion of the thread I can see the confusion. For that I am sorry. 




-----
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## EVDL List (Jul 27, 2007)

Thank you for the response, Willie! I have put questions in between the
information you provided

>
> I think there is a business opportunity here for someone to configure
> GC2 size cell blocks along with the necessary BMS. I think 4
> TS-LFP100s might fit in the space of a GC2. 2S2P would give you near
> the same voltage as a GC2. I believe a lead charger can be used if you
> depend on high single cell BMS detection to shut the charger off
> through a relay. Around $500 to replace each GC2 battery. To cut cost and
> halve

capacity, you could go 4S1P and populate half the GC2 spaces.

So, GC2 is two 6 volt golf cart batteries? +/- 12.8v? Which would cost
around $500?
4 Series, 1 parallel?



>
> The numbers I have indicate a GC2 is 7.2"x 10.6" and 10.4" high
> TS-LFP100s are 7.04"x2.44" and 8.66" high. So a block of 4 LFP100s
> would be 7.04"x9.76". That would leave .8" for the clamping mechanism
> which is probably enough. Of course, all those numbers need to be
> confirmed.
>
> The 2S2P would give you 200 ah or ~160 ah useable. How many ah can one
> take out of a flooded lead GC2? I would guess not much more than 50ah.
>
> 2 Series, 2 parallel?
Do you set up BMS on each LFP100? Does that require a compatible BMS
controlled charger?

I know I am asking a lot of questions, but I really need to be able to
estimate costs, as I am going to have to make a pack change soon, and I have
done enough lead/acid EV packs to have a really good understanding of what
each step in the process requires, and where to get what I need to make it
work. I am starting from no experience or knowledge with the LiFePo4
chemistry, and know I need to know a lot more before I can make a real
choice.
Once again, I am so grateful for all of the great EV creators on this
list--it makes it possible for people like me to be able to drive electric!!
Michael B
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----------



## EVDL List (Jul 27, 2007)

> On 1 Aug 2011 at 18:59, Willie McKemie wrote:
> 
> > I think there is a business opportunity here for someone to configure
> > GC2 size cell blocks along with the necessary BMS.
> ...


----------



## EVDL List (Jul 27, 2007)

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----------



## EVDL List (Jul 27, 2007)

I was thinking the same thing as Willie, a drop in replacement
with a group 24 footprint (has the same physical size as 
existing PbSO4 batteries we are quite familiar with).

Here are links to the aforementioned U-charge
http://www.valence.com/energy-storage/xp-12v-19v-lithium-phosphate-battery-module
http://www.e-traction.nl/downloads/Valence%20U-Charge%20XP%20Data%20Sheet.pdf

Yesterday, I found a page that seemed to be a similar package
that included a bms and charger. I did not see that page 
linked to their main page. Today, the URL is dead. The site
owner must have disabled it. Not for ordering purposes, but as 
an example of the product idea Willie had posted about, look 
at the cached page to see it:

http://webcache.googleusercontent.com/search?q=cache:ZRCjxpmdDWMJ:3xe-electric-cars.com/index.php%3F/virtuemart/Seiden/Seiden/Seiden-Battery-LiFePO4-72V-100Ah-with-BMS-and-Charger.html

This is quite an interesting thread.
Thank you all for your responses.

{brucedp.150m.com}



----- Original message -----
From: "EVDL Administrator" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Date: Tue, 02 Aug 2011 02:37:41 -0400
Subject: Re: [EVDL] How much for a Li-ion pack?



> On 1 Aug 2011 at 18:59, Willie McKemie wrote:
> 
> > I think there is a business opportunity here for someone to configure
> > GC2 size cell blocks along with the necessary BMS.
> ...


----------



## EVDL List (Jul 27, 2007)

> Mike Beem wrote:
> > Thank you for the response, Willie! I have put questions in between the
> > information you provided
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> > On 1 Aug 2011 at 18:59, Willie McKemie wrote:
> >
> > > I think there is a business opportunity here for someone to configure
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > I think there is a business opportunity here for someone to configure
> > GC2 size cell blocks along with the necessary BMS. I think 4
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> > Willie McKemie wrote:
> >
> > > I think there is a business opportunity here for someone to configure
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > I think this is an imagined problem. Any pack needs an initial
> > balance, either top or bottom. I haven't seen a lithium profile
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> >
> > I _know_ that it is not an imagined problem ;^>
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> > Just like all
> > conversions, worth far less than the cost of components.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > > I _know_ that it is not an imagined problem ;^>
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> > Willie McKemie wrote:
> >
> > > > I _know_ that it is not an imagined problem ;^>
> ...


----------



## EVDL List (Jul 27, 2007)

Some semi-hard data:

Yesterday's run was 137.1 "Hyundai miles" (1 Hyundai mile = 1.065 real 
miles due to larger tires) and took 216.3 ah. That indicates 270 ah 
would take me about 180 real miles. That's longer than a normal run; 
normal run is 60-90 miles. Needing to make another run this morning, I 
charged overnight with three 1500 watt chargers at 24.7 battery amps. 
Two of the chargers are configured for 45 cells or 165 volts; I now 
have 48 cells and one charger that goes up to 172 (174?) volts. This 
morning I reset the BMS at 22 minutes past 6am; didn't pay attention to 
seconds since I was doing other stuff. I was 6.2 ah short of a full 
charge. At 24 minutes, one charger shutdown; the other two going at 14 
battery amps. The BMS shut down at 29 minutes, still charging at 14 
amps. I was then 4.6 ah short of a full charge. I reset the BMS at 36 
minutes; I would normally wait at least 15 minutes. All three chargers 
charged for about a minute before the BMS shutdown again with 4.4 ah 
left to charge.

So, I got about 1.8 ah closer to balance in two BMS cycles and charging 
at twice or three times my normal charge rate. About 7 minutes and 
1.6 ah of charging the first cycle, about 7 minutes of wait, and then 
about 1 minute more of charging for .2 ah.

That well fits my previous description.

Looking at the cell module LEDs, there was one cell that was high. The 
same cell had been low in recent charges.

I feel confident that several of these 15-30 minute cycles would bring 
all cells up to the by-pass condition. But, I've got to hit the road 
and 4.4 is plenty close enough to a full charge.

-- 
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 42 days 23 hours 47 minutes

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> 
> > I develop charge algorithms for a living, and this specific issue is one I have worked on, so that is how I know it does exist ;^>
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> > ... how many people would be willing to pay what seems like a fairly
> > large premium to buy 4-packs of cells built into GC2-size modules
> > rather than buying naked cells (or pre-strapped into 4-packs) and
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > Yes, I knew you are a DeltaQ guy. My experience is that charge profile
> > is not crucial in charging lithium. I was just wondering what specific
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> > Since you had at least 2 chargers running when you reset the BMS, this means that the pack voltage had to be at or below 165V, which is 3.44V/cell for your 48-cell pack, when the BMS shuts things down. At what voltage does the BMS kill the charger(s)? 3.6V/cell or 3.8V/cell?
> 
> 3.6v. With my older 3.8+ set of modules, I was getting a distinctive
> ...


----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > On Fri, Aug 05, 2011 at 06:00:06PM -0700, Roger Stockton wrote:
> >> Since you had at least 2 chargers running when you reset the BMS, this m=
> ...


----------



## EVDL List (Jul 27, 2007)

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----------



## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> 
> > I don't normally use multiple chargers and I don't try to achieve
> > perfect balance on each charge.
> ...


----------



## EVDL List (Jul 27, 2007)

> Jeffrey Jenkins wrote:
> 
> > =
> 
> ...


----------



## EVDL List (Jul 27, 2007)

I've been following the thread regarding the move from lead to lithium base=
d batteries. I'm happy to see that the figure I used for lead acid battery =
capacity was correct when I had a lead-powered EV, that is, take half the l=
isted capacity as the real total capacity of the battery. The 98ah batterie=
s that were in place I rated to 49ah total capacity. =


With the help of my CycleAnalyst, I also made darn sure that of that 49ah c=
apacity, I never used more than 25 ampere-hours (approx 50% DOD) while driv=
ing. That part appears to be overlooked in some of the posted calculatio=
ns. I'd expect that few EV owners running lead-based batteries will pull ev=
ery last amp-hour from their pack, and conservative drivers should be looki=
ng for a charge at the fifty percent point, right?

Some of the numbers posted may need to be recalculated, in my opinion, base=
d on not exhausting the lead-based pack and perhaps adjusting for a conserv=
ative 75 percent depth of discharge on the lithium based pack.

If I ever complete my Gizmo re-work project, I expect that my previous 196 =
ah pack and 25 mile safe range (50% DOD) will be replaced nicely enough wit=
h the CALB 180 ah pack and 75 mile safe range along with a three hundred po=
und weight reduction.
-------------- next part --------------
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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| OTHER HELP: http://evdl.org/help/
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----------



## EVDL List (Jul 27, 2007)

> Fred wrote:
> 
> > I've been following the thread regarding the move from lead to lithium
> > based batteries. I'm happy to see that the figure I used for lead acid
> ...


----------



## EVDL List (Jul 27, 2007)

On Mon, Aug 8, 2011 at 2:24 PM, Roger Stockton <[email protected]> wrot=
e:
> The usable capacity of a lead acid battery is not, in general, 50% of its=
20hr rating.
>
> You really need to determine what your average discharge rate is (e.g. dr=
ive some distance and note how long it takes and how many Ah you actually r=
emove from the battery; from the Ah removed and the total elapsed duration =
of the trip you can compute the effective average discharge rate).
>
> Let's say you drive 10mi in 20min, and use 20Ah: 20Ah / (20min/60min) =3D=
60A average discharge rate.

That would be about 30mph. At that speed I consume 130-135Wh/mi which
is roughly 4000W. Assuming no voltage sag that is an average of ~83A
discharge rate. The T-875s I had have 109Ah at the 56A rate and 170Ah
at the 20hr rate. 80% of 109Ah is 87Ah which is really close to 50% of
the 20hr rating especially considering that the calculation is using
the 56A rate and not the 83A rate. This is where I came up with the
approximately 50% number for a Gizmo.

>> If I ever complete my Gizmo re-work project, I expect that my previous 1=
96
>> ah pack and 25 mile safe range (50% DOD) will be replaced nicely enough
>> with the CALB 180 ah pack and 75 mile safe range along with a three
>> hundred pound weight reduction.
>
> I've driven a Gizmo and have to wonder if a 75mi range might possibly be =
overkill? A pack of 100Ah CALB cells should handle your peak loads just =
fine and still provide a safe 75Ah usable capacity for about 40mi range. =
On the other hand, if you lighten the pack sufficiently, might you be at=
risk of the vehicle doing a faceplant in a panic stop situation?

Driving a Gizmo for over 60 miles with no stops, other than traffic
related ones, is definitely tiring on the trigger finger. Fred and I
have the same throttle trigger setup where only one finger fits on the
trigger. I think that 75mi is overkill for the way most people would
use a Gizmo. I use the range on average 2-3 times/month. With a 500A
controller I wanted to keep battery current peaks under 3C so I went
with a buddy pair pack of 40 TS-LFP100AHA cells. I can run full
throttle for a full 66 miles before reaching 80%DOD. Naturally at
30-35mph I could go a full 78 miles to 80%DOD. Just think, when I've
lost 50% of my battery capacity I'll still have a very usable vehicle
.

The other reason I went with 40 cells was for the CG height. I doubt
even with a light pack you could do a faceplant in a panic stop but it
could tip over on a quick turn. For a short time I had a 6V set of
flooded batteries while I waited for my TS cells to come in. Sitting
level, and empty, the Gizmo had 602 lbs on the front tires and 391 lbs
on the rear tire. This puts the CG 22.5 in behind the front axle. By
tilting, reweighing, and calculating I found the vertical CG to be 5
in above the axle plane or about 14.8" above ground.

With the 40 TS cells in I redid my CG calculations. Front weight was
now 524 lbs, rear 305 lbs. CG is now 21.1" behind the front axle and
6.6" above the axle plane or 16.3" above ground.

-- =

David D. Nelson
http://evalbum.com/1328

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## EVDL List (Jul 27, 2007)

> David Nelson wrote:
> 
> > On Mon, Aug 8, 2011 at 2:24 PM, Roger Stockton <[email protected]>
> > wrote:
> ...


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