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Discussion Starter #2
Re: [EVDL] Nimh battery packs.. go for lithiums

On 27 Aug 2007 at 8:18, Ian Hooper wrote:

> Even those cheap lead acids cost more in the long run ...
> much cheaper initially at $0.12/Wh. But they probably only give you
> 300 cycles in an EV ...

I'd say that's rather pessimistic.

Most golf car batteries are rated for 750 - 850 cycles. Careful,
experienced EVers can actually achieve this. Around 500 - 600 cycles is not
unusual.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Discussion Starter #3
Re: [EVDL] Nimh battery packs.. go for lithiums

Even when successfully charged, when two NiMH cells are put in parallel
one can discharge into the other, resulting in a damaging overcharge for
on cell and an unbalanced state for the pair.

Well, it's a generalization because there are definitely variations on
these cells out there, but AFAIK this is a persistent problem across the
board for them that prevents 2 cells from being put in parallel even if
they were charged separately.

Danny

----- Original Message -----
From: Ian Hooper <[email protected]>
Date: Sunday, August 26, 2007 7:20 pm
Subject: Re: [EVDL] Nimh battery packs.. go for lithiums
To: Electric Vehicle Discussion List <[email protected]>

> hit full charge and as such require peak detection cutoff when
> charging, which doesn't work with cells in parallel. (You'll never
> get perfectly matched cells - weaker cells hit their peak voltage
> earlier, then the stronger cells pump extra charge in and kill them.)

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Discussion Starter #4
Re: [EVDL] Nimh battery packs.. go for lithiums

How do they handle this in the Rav4 EV? You're telling me the Rav4 has one
huge battery?

-----Original Message-----
Even when successfully charged, when two NiMH cells are put in parallel one
can discharge into the other, resulting in a damaging overcharge for on cell
and an unbalanced state for the pair.

Well, it's a generalization because there are definitely variations on these
cells out there, but AFAIK this is a persistent problem across the board for
them that prevents 2 cells from being put in parallel even if they were
charged separately.


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Discussion Starter #6
Re: [EVDL] Nimh battery packs.. go for lithiums

Vectrix, just debuted in US, runs on NiMH as well
http://www.vectrix.com/Portal/1/Language/47/Page/63/Battery_Pack.aspx

3.7Kwh, 125V, 30Ah.
Looking at Gold Peak ( or Sanyo ) NiMH large-capacity battery prices
on mouser.com, they work out even more expensive than A123 for
example, per KwH. Thats just cell prices, of course.

-kert

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Discussion Starter #12
Re: [EVDL] Nimh battery packs.. go for lithiums

Obviously they don't wear out as quickly but can't NIMH packs be recycled just as lead acid batteries can?

Also, if nickel gets expensive enough, you'd think the US mint could replace nickels with some other base metal (if they haven't already). Same deal with copper.


----- Original Message ----
Well it's also worth noting that the price of nickel has skyrocketed
since then, even without a huge additional demand from an EV fleet.





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Discussion Starter #16
Re: [EVDL] Nimh battery packs.. go for lithiums

Ian Hooper wrote:

> Even if you work out a decent system to overcome the charging
> problems, the other consideration is long term cost. Direct from
> Chinese manufacturers (e.g unitechbatt.com), NiMHs cost about 40
> cents per watt hour. Decent NiMH cells are usually rated to
> about 500 cycles, which gives you long-term energy storage cost
> of 80 cents per kWh.

A Cobasys 9500 module is 85Ah @13.2V and runs US$1000; using a nominal
13V this gives a cost of $0.90/Wh and they are good for 1200-1500
cycles. Cheaper than building your own from lotts of small Chinese
cells...

> Lithium Iron Phosphate batteries are about 50% more expensive by
> capacity ($0.60/Wh), but they are usually rated to 2000-3000 cycles,
> which gives lifespan costs of ~$0.25 per kWh - the long term running
> costs are less than *one third* NiMH!
>
> Even those cheap lead acids cost more in the long run. Using Trojan
> T-105s for example ($110 for 6V, ~150Ah @ 1C rate), they seem to be
> much cheaper initially at $0.12/Wh. But they probably only give you
> 300 cycles in an EV, so you're looking at $0.40/kWh - half again as
> much as LiFePO4 lithiums. (Is 300 cycles an unreasonable figure for
> lead acid, anyone?)

I'd guess that someone who can't get more than 300 cycles from flooded
T105s certainly isn't going to get anything close to rated life from
either NiMH or Li either.

Flooded GC batteries should be good for 600-700 cycles if treated well;
if we're going to us rated life for the other chemistries we really
ought to use rated life for PbA.

Cheers,

Roger.

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Discussion Starter #17
Re: [EVDL] Nimh battery packs.. go for lithiums

----- Original Message -----
From: <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, August 27, 2007 12:48 PM
Subject: Re: [EVDL] Nimh battery packs.. go for lithiums


> Ovshinsky is 80+ years old.
> He's invented many things, and has no real need for money.
> now WHY would he go and sell something like this to an oil company??
> Hi EVerybody;

He DIDN'T sell the batteries(patents) to an Oil company. But to General
Murders FOR the EV-1! He, too, was enchanted with the EV-1, as it was the
Gold Standard EV 10 years ago. Youse guyz that have driven an EV-1 know what
I'm talking about? I think it probably Stan' s last harrah, as an' old
man?He felt,as we all did that THIS was the all conquring battery, and by
now A NMH powered EV would be in all our garages. You DID see "Who Killed
the Electric Car'??Right?If you didn't (Gasp!)don't watch it on a full
stomach!

Seeya

Bob

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Discussion Starter #18
Re: [EVDL] Nimh battery packs.. go for lithiums

And, by the way, don't forget which company bought transit systems in some
US cities and then shut them down...

----- Original Message -----
From: "Bob Rice" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: 27 August, 2007 9:27 PM
Subject: Re: [EVDL] Nimh battery packs.. go for lithiums


>
> ----- Original Message -----
> From: <[email protected]>
> To: "Electric Vehicle Discussion List" <[email protected]>
> Sent: Monday, August 27, 2007 12:48 PM
> Subject: Re: [EVDL] Nimh battery packs.. go for lithiums
>
>
>> Ovshinsky is 80+ years old.
>> He's invented many things, and has no real need for money.
>> now WHY would he go and sell something like this to an oil company??
>> Hi EVerybody;
>
> He DIDN'T sell the batteries(patents) to an Oil company. But to General
> Murders FOR the EV-1! He, too, was enchanted with the EV-1, as it was the
> Gold Standard EV 10 years ago. Youse guyz that have driven an EV-1 know
> what
> I'm talking about? I think it probably Stan' s last harrah, as an' old
> man?He felt,as we all did that THIS was the all conquring battery, and by
> now A NMH powered EV would be in all our garages. You DID see "Who Killed
> the Electric Car'??Right?If you didn't (Gasp!)don't watch it on a full
> stomach!
>
> Seeya
>
> Bob
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


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Discussion Starter #19
Re: [EVDL] Nimh battery packs.. go for lithiums

Indeed. If you had 8.5AH "D" cells aty $10/ea, you'd be at $1100 in
cells alone and yet you'd probably never be able to build them into a
batt, resolve the charge balance issues associated with paralleling
cells or strings, and frankly I expect these would be cheap-ass cells
that would either fail prematurely under high current service or you'd
have one out of the 110 cells go bad for no reason other than there's
110 of them.

We'd certainly LIKE for this to work, but the problem of using many
smaller NiMH cells has been brought up any number of times and the
problems are very high and the cost-effectiveness just isn't there.
Smart people have looked at it. At best there is a strategy to make
several long series strings and put them in parallel. That's still
difficult to manage the charge state, and the charge controller is quite
expensive, the cheap cells don't have the power density or reliability
and they're still too expensive per kwh.

Danny

Roger Stockton wrote:

>A Cobasys 9500 module is 85Ah @13.2V and runs US$1000; using a nominal
>13V this gives a cost of $0.90/Wh and they are good for 1200-1500
>cycles. Cheaper than building your own from lotts of small Chinese
>cells...
>
>
>
>
>

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Discussion Starter #20
Re: [EVDL] Nimh battery packs.. go for lithiums

My wife's sister worked for Ovshinsky in Detroit in the 90's, she says
the company was hurting until he sold that patent. Little things like
coffee, tea and even TP were just not available at that place, and
paychecks were getting rubbery before the deal...

MTS in SJ, CA


> He DIDN'T sell the batteries(patents) to an Oil company. But to General
> Murders FOR the EV-1! He, too, was enchanted with the EV-1, as it was the
> Gold Standard EV 10 years ago. Youse guyz that have driven an EV-1 know what
> I'm talking about? I think it probably Stan' s last harrah, as an' old
> man?He felt,as we all did that THIS was the all conquring battery, and by
> now A NMH powered EV would be in all our garages. You DID see "Who Killed
> the Electric Car'??Right?If you didn't (Gasp!)don't watch it on a full
> stomach!
>
> Seeya
>
> Bob


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