Daniel A wrote:
> I recently read a post about some LIMNPO4 batteries and tried to post a query
> about them. I guess I did not edit the reply very successfully as I received
> one reply saying to edit my replies.
Sorry, the EVDL server will bounce your message back if you try to reply to
a digest and let your email program tack the entire digest onto the end of
it.
Regrettably, this is what many popular email systems do by default. I
suggest that, if possible, you turn off quoting in your email system's
configuration. Then, copy and paste the passage you want to reply to.
The reason the server is configured this way is to prevent annoyance and
inconvenience for your fellow EVDL members. For one thing, it's a matter of
"netiquette" to edit your reply and not include the entire message, much
less an entire digest. For another, it costs a few EVDL members real time
and money to download a large amount of irrelevant text.
Remember that we have members all over the world, and some of our members
still have to use slow dialup connections. Be nice to them. ;-)
> I am trying again to gain some info on the batteries and not include
> everything else in a paticular digest. Does anyone know anything about
> those batteries or are the same as the Lithium Phosphate batteries?
Here is a message from a couple of weeks ago which compares LiMnPO4 with
LiFePO4 batteries.
http://evdl.org/archive/#nabble-td2274441%7Ca2274441
My take on this - for what it's worth - is that using any kind of lithium
batteries makes for a more expensive and riskier project for an EV hobbyist.
Experience with lithium batteries is growing, but there are still many
things that can go wrong and damage an expensive battery pack - or the car,
or even you.
I may have missed something, but it appears to me that what's still missing
is an affordable, pre-engineered, drop-in solution.
Valence makes a lithium battery (LiMnPO4, I think) that emulates a 12 volt
lead-acid marine battery and is almost trivial to substitute for the latter.
It's pre-engineered and drop-in, and has a fairly long history now, but it's
hardly what I'd call affordable.
There are also several pre-configured lithium battery systems, aimed at
scooters and e-bikes. These are typically 24 to 48 volts and 10 to 20 amp
hours. They almost meet the qualifications above, but AFAIK none of them
is big enough and powerful enough for a 2500-3500lb, 4-wheel EV.
I sometimes wonder though if one could use several of these in a series-
parallel array. A 48 volt, 20 amp hour LiFePO4 battery from the most widely
recommended seller costs around $800, shipped from China (I know of no one
making these in the US), with a C/10 charger. Each of these little e-bike
batteries is good for nearly a kWh, so 8-10 of them might have enough energy
for respectable range with a car EV.
Other than this, nearly every lithium battery system for a car type EV
requires substantial engineering work. This is fine if you're an electrical
engineer with access to ample support and data, and plenty of time. For
many hobbyists, though, there's a substantial risk of financial loss. With
some types there are also physical dangers and risks.
Folks with lots of EV building experience and good electronics chops are the
ones who might want to forge ahead with lithium right now. However, if
you're an EV beginner or intermediate hobbyist, I'd recommend staying with a
more mature and less risky battery technology. That almost certainly means
lead-acid. NiCd is another possibliity; check out what some folks here have
done with BB-600 mil-surplus NiCd cells.
Others may have different views, so let's hear from you.
David Roden - Akron, Ohio, USA
EVDL Administrator
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EVDL Administrator wrote:
>
>
> My take on this - for what it's worth - is that using any kind of lithium
> batteries makes for a more expensive and riskier project for an EV
> hobbyist... nearly every lithium battery system for a car type EV
> requires substantial engineering work. This is fine if you're an
> electrical
> engineer with access to ample support and data, and plenty of time. For
> many hobbyists, though, there's a substantial risk of financial loss.
> With
> some types there are also physical dangers and risks.
>
> Folks with lots of EV building experience and good electronics chops are
> the
> ones who might want to forge ahead with lithium right now. However, if
> you're an EV beginner or intermediate hobbyist, I'd recommend staying with
> a
> more mature and less risky battery technology. That almost certainly
> means
> lead-acid.
>
I completely disagree with David's take.
I am a new EV hobbyist. I'm working out building my first EV right now, and
I will never build a lead-acid machine. While I agree that building packs of
cylindrical cells is beyond most of us, and I wouldn't do it for other
reasons as well, the same just isn't true of the prismatic (TS/CALB) cells.
First, the substantial engineering work and supposed electronics (BMS)
requirements are pretty much unnecessary. Several users are running
prismatics without BMS with no problems. Monitoring is good, and better
systems to do that are coming all the time. There is a rapidly accumulating
body of knowledge indicating these cells are quite docile and liveable if
always slightly undercharged, and never overdischarged. I can manage that
very easily, and monitor carefully.
Since I don't have any baggage from years of working with lead-acid, I have
no problems with the differences in care and feeding of prismatics. Sadly,
its almost like the more you know about lead-acid batteries, the less likely
you are to accommodate yourself quickly and effectively to a Lithium pack.
Newbies actually have it easier in this regard, and the knowledge base on
the cells is getting very deep very quickly, thanks largely to Jack Rickard.
The action on Lithium isn't here on the EVDL- its on EVTV.com.
I strongly recommend that anyone serious about an EV build think hard about
whether you really want to take on a "throw away" learning curve of Pb-based
batteries if it is avoidable. Sure, if you buy a used EV with lead, use 'em
up, but I wouldn't buy a new lead pack today, period. In fact, if you have
no EV experience, lead-acid batteries are actually harder to manage.
They leak corrosives, they vent explosive gases, they rust everything, they
cause ground faults, they don't last very long, can cost almost half as much
as Lithium, and- oh, yeah, they are four times heavier. Yes, the guys who
love and use them will dispute all of that, but who cares? Long term, lead
is dead.
If you aren't running them right now, my advice is there's no good reason to
buy lead acid batteries, except for extreme cheapness and a plan to keep
your car for no more than 200-300 charge cycles. That's a legitimate reason,
but not a particularly good one. Lithium has major advantages from range to
maintenance to ROI. Moreover, my build would not be possible with lead-acid,
as it is just too heavy for my plans.
There's a lot to say, but succinctly: I completely disagree that a new EV
hobbyist should start with lead.
Just my $.02...
TomA
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Tom Alvary wrote:
Mostly, I agree with you.
> First, the substantial engineering work and supposed electronics (BMS)
> requirements are pretty much unnecessary. Several users are running
> prismatics without BMS with no problems. Monitoring is good, and better
> systems to do that are coming all the time. There is a rapidly accumulating
> body of knowledge indicating these cells are quite docile and liveable if
> always slightly undercharged, and never overdischarged. I can manage that
> very easily, and monitor carefully.
I feel you at least need an automated way to shut down your charger
when a single cell goes over voltage. It is almost as crucial for the
driver to know when a single cell goes low on voltage. I believe
Jack's scheme depends on all cells being and remaining very close in
capacity.
--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 127 days 13 hours 20 minutes
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Tom Alvary <[email protected]> wrote:
> Newbies actually have it easier in this regard, and the knowledge base on
> the cells is getting very deep very quickly, thanks largely to Jack Rickard.
> The action on Lithium isn't here on the EVDL- its on EVTV.com.
Just a word of caution. When looking at Jack's info I recommend you
carefully look at his data, how he collected it, and form your own
conclusions. Some of Jack's conclusions tend to be a bit on the
sweeping generalization side of things.
--
David D. Nelson
http://evalbum.com/1328
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EVDL Administrator wrote:
> Others may have different views, so let's hear from you.
As I posted a few weeks ago:
>From my perspective the LFP technology seems far more mature than that
of other EV components. I have 92 LFP cells and three have failed;
those almost certainly due to failed balancer modules that allowed over
charging. The car has spent most of it's life in the shop undergoing
repairs, upgrades, and re-designs. It has left me stranded and
demanded towing at least three times. It has rolled about 8K miles
which is far less than hoped. All that, due to non LFP issues.
I initially chose lithium because lead just wouldn't give the range I
need. Our minimum trip is about 60 miles. Lithium was a good choice
and gave us the range we need. I just did not expect so much trouble
with the other components.
--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 127 days 8 hours 42 minutes
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Willie McKemie <[email protected]> wrote:
> On Fri, Jul 16, 2010 at 02:12:28PM -0400, EVDL Administrator wrote:
>
> > Others may have different views, so let's hear from you.
>
> As I posted a few weeks ago:
>
> >From my perspective the LFP technology seems far more mature than that
> of other EV components. I have 92 LFP cells and three have failed;
> those almost certainly due to failed balancer modules that allowed over
> charging. The car has spent most of it's life in the shop undergoing
> repairs, upgrades, and re-designs. It has left me stranded and
> demanded towing at least three times. It has rolled about 8K miles
> which is far less than hoped. All that, due to non LFP issues.
>
> I initially chose lithium because lead just wouldn't give the range I
> need. Our minimum trip is about 60 miles. Lithium was a good choice
> and gave us the range we need. I just did not expect so much trouble
> with the other components.
>
> --
> Willie, ONWARD! Through the fog!
> http://counter.li.org Linux registered user #228836 since 1995
> Debian3.1/GNU/Linux system uptime 127 days 8 hours 42 minutes
>
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>
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EVDL Administrator wrote:
>>
>> > Others may have different views, so let's hear from you.
>>
>> As I posted a few weeks ago:
>>
>> >From my perspective the LFP technology seems far more mature than that
>> of other EV components. I have 92 LFP cells and three have failed;
>> those almost certainly due to failed balancer modules that allowed over
>> charging. The car has spent most of it's life in the shop undergoing
>> repairs, upgrades, and re-designs. It has left me stranded and
>> demanded towing at least three times. It has rolled about 8K miles
>> which is far less than hoped. All that, due to non LFP issues.
>>
>> I initially chose lithium because lead just wouldn't give the range I
>> need. Our minimum trip is about 60 miles. Lithium was a good choice
>> and gave us the range we need. I just did not expect so much trouble
>> with the other components.
>>
>> --
>> Willie, ONWARD! Through the fog!
>> http://counter.li.org Linux registered user #228836 since 1995
>> Debian3.1/GNU/Linux system uptime 127 days 8 hours 42 minutes
>>
>> _______________________________________________
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>>
>>
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joe-22 wrote:
>
>>>>The action on Lithium isn't here on the EVDL- its on EVTV
>
> If you think that, you haven't been following the EVDL very closely for
> very
> long! The real action is HERE!
>
I'm guessing you're joking, but if just in case you're not...
I have read every single post to the EVDL for the past two years. I'm well
aware of the depth and breadth of this resource and its contributors.
I also read and participate at Endless Sphere and DIY Electric Car, I follow
EcoModder and the EVTech list, and I am a frequent contributor to the EVTV
discussion blog. I kinda know who is posting what and where.
Its really a matter of individuals and where they put their information.
There is some very good (early) prismatic cell information at DIY Electric
Car, much of it posted by individuals who also contribute here. It is
gradually getting out of date, primarily because:
In the last year, Jack Rickard has put out a ton of extremely valuable data
and debriefs of his considerable experience with these batteries. Not the
gospel, but clearly the best source of info to date. Its OK with me if you
don't think so or don't watch or read EVTV, but newbies who don't actually
know oughtn't be mislead about it. And no, I don't work there.
I only mentioned it because much of what I understand (and have seen
demonstrated) about these batteries came from EVTV, some more from DIYEC and
ES, but almost none of it from the EVDL. I think that's because the real
early EV adopters are here, and before a couple of years ago lead was the
thing. Also, ever since the TS group buy disaster with Victor a few years
ago, this population has been slow to warm up to the prismatic cells.
Whatever, either way, the ball moves forward.
So back to my point: Prismatic LiFePO4 cells aren't too difficult a
chemistry or format for a first time EVer- and if you want to study up on
them, go to EVTV.ME and dig right in.
TomA
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tomw wrote:
> This is a myth which continues to be propagated by some on this site.
I don't think it's a myth. Lithiums simply have not proven themselves
yet. They can certainly deliver the amphours and/or the peak currents
required for an EV. But, the cost is unquestionably high. And, there are
precious few examples of EVs (or anything else, for that matter) with
rechargeable lithium cells that are more than a few years and have in
fact delivered the promised cycle life.
> I think it stems partly from the early days (pre-2005) when Thundersky
>had quality problems
I was one of the ones burned by them. I would not characterize it as a
quality problem; it was a deliberately-cheat-the-customer problem!
, the fact that manganese-containing cells, as used in the
> Volt, require tighter temperature control, and cobalt-containing cells, as
> used in laptops catching fire in some cases. This is a real contrast to the
> diyelectriccar site where many conversions are with LiFePO4 cells.
Why is it that none of the hybrids use lithiums, even though using nimh
forces them to pay large amounts in royalties to Cobasys/Chevron?
Why are the Volt and Tesla using LiMn or LiCo lithiums instead of LiFe?
They have the money to do thorough testing and quality assurance.
> I don't have the shunts, and my cells, which are coming up on one year old,
> have remained balanced to within a few mV of each other.
Please keep us informed. I want to know how the pack works when it is a
few years old and has 30k miles on it.
Early adopters are willing to pay higher prices and take higher risks.
Personally, I'm not rich enough to pay the price, and not willing to
take the risk. With lead-acids, I know what it will cost initially, and
I know how long it will last.
> I used to log cell voltages, but it got really boring because they
> are always about the same.
Recognize that voltage is a bad indicator of the condition of a lithium
cell. The right way to do it is with a load test; measure the amphours
each cell can deliver to a defined cutoff voltage. Or, see how many
amphours you need to put in to bring each cell up to a defined "full"
voltage.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
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On 17 Jul 2010 at 10:27, Jack Murray wrote:
> The experience with LiFePO4 has not yet spanned the test of time... Now
> that the costs have (finally) come down significantly, it is a better
> time than ever to start.
Well said. Now, don't fall off your chair, but - as infamously cautious as
I am in these matters - I'm actually considering a lithium experiment.
I'll do something relatively small and inexpensive, though, where I won't
lose much more than a few hundred dollars if something goes wrong. I'll
probably try lithium batteries in a power mower.
Yet to be determined is whether I'll wuss out and buy a ready-made,
preconfigured battery and BMS "bundle," a relatively safe but slightly more
costly route; or whether I'll study up, choose a cell type, pick a BMS and
charger, and take take a few more chances on a little less money.
David Roden - Akron, Ohio, USA
EVDL Administrator
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