# [EVDL] Zivan NG3 and NiMH Battery



## EVDL List (Jul 27, 2007)

Greetings,
I've got a Zivan NG3 (230V/19A) charger configured for a 144V/100Ah AGM
pack. I have since upgraded to a 144V/100Ah NiMH pack (120 cells @ 1.2V
each). The battery supplier (EVB Technology HK) recommends to end the
charge at 1.5V per cell or 180V per pack. Currently the charger is set to
taper at 171.6V. Is there anyway to reprogram the charger to work with the
NiMH pack. The documentation that came with the charger does not address
this and I'm still waiting for a response from the Zivan dealer. You can
see charge, discharge curves, and a photo at the most recent blog at
http://seaburyhall.org/engineering/blog/.
Thanks.
Martin
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## EVDL List (Jul 27, 2007)

> martin emde wrote:
> 
> > I've got a Zivan NG3 (230V/19A) charger configured for a
> > 144V/100Ah AGM pack. I have since upgraded to a 144V/100Ah
> ...


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## EVDL List (Jul 27, 2007)

Did anyone else on the list notice he said 144V 100Ah NICKEL METAL
batteries? I looked at their blog and they installed one string of 1.2V
100Ah NiMH cells. I would like to have a NiMH pack! Martin, can you give us
any details about how you bought the pack?


-- 
-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555



> martin emde <[email protected]> wrote:
> 
> > Greetings,
> > I've got a Zivan NG3 (230V/19A) charger configured for a 144V/100Ah AGM
> ...


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## EVDL List (Jul 27, 2007)

Jon,
The procurement of the pack was a long precess that began back in
September. As you may have gathered I teach an engineering course at
a local high school and this is our second year doing the EV
conversion. A parent of one of the students at our school is working
on the "one laptop per child" program and as such has dealt with a
couple of battery manufacturers in China. I contacted two companies,
BYD and Gold Peak and was originally hoping for a sponsorship of
lithium cells. I was informed that lithium chemistry was not mature
enough for the EV market, and even though they have lithium cells they
were not willing to sell or donate any. Instead, the engineers at
Gold Peak (EVB Technology) were able to locate a used NiMH pack for us
to purchase (unfortunately not donated). The cells are rated at 100Ah
when new and we were guaranteed 70Ah. We paid $430/kWhr plus $1200 in
shipping/handling/duty. The batteries were air freighted direct form
China to Hawaii. The individual cells are packaged in groups of 10
and weight 42lbs. I have also attached an excerpt from a recent
correspondence with EVB regarding some specific specifications on the
cells. We are in the process of installing the pack and I'll post
some performance data on our blog once it becomes available. Hope
this helps.
Martin



Regarding to your concerns, here are our reply.

1. The 70Ah is the result of 1C discharge. We have re-arranged the
unit cell and form the module again.
The average capacity of them is 75Ah.

2. The minimum safe voltage per cell for MiMH is depending on the
depth of discharge and its duration.
For your application, 400A (max) and 280A (average), the safe value
can be down to 0.9V/cell.

3. The cell reach to 0.9V is not means the cell come to 0% SOC since
we are using high current for discharging.
According to our study, there are still 20 - 30% energy here.

4. We always said micro-cycle (means not full cycle) is the best for
the life of rechargeable cell.
In order to fully utilize the cell capacity, the cycling can be
ranged between 100% and 10%, which means 90% DOD is still ok.



> Jon Glauser <[email protected]> wrote:
> > Did anyone else on the list notice he said 144V 100Ah NICKEL METAL
> > batteries? I looked at their blog and they installed one string of 1.2V
> > 100Ah NiMH cells. I would like to have a NiMH pack! Martin, can you give us
> ...


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## EVDL List (Jul 27, 2007)

Thank you very much for the info! I looked up what information I could on
the web about the company. It would be great if they hold up to the
ratings! A nice NiMH pack would be much better than lead!


-- 
-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555
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## EVDL List (Jul 27, 2007)

Gold Peak is one of the only, if not THE only, manufacturer whose NiMH 
license is old enough that it predates the AH restriction set by Cobasys to 
ensure that NiMH batteries can't be (readily) used for BEVs. 

I seem to recall that Solectria or Azure used GP's NiMH batteries for some 
kind of EV a few years back, but the details have escaped me now. Maybe 
someone else remembers. 

I don't know whether they (GP, I mean) are currently offering any EV-size 
NiMH batteries in the US. That would be tremendously helpful not just for 
hobbyists but for commercial builders and converters, since it's apparently 
becoming a challenge to find new NiCd batteries in EV size. I'm not sure 
whether GP's license to >manufacture< covers >sale< to consumers, however. 
If not, grey market importing, as referenced here, would most likely be 
possible - but I would think only for private use, not for commercial 
enterprises.

Cobasys has done quite the job of locking down NiMH, a proven and useful BEV 
battery technology. Now why do you suppose they would do such a thing? 
(Rhetorical question ;-)

Let's see, AA NiMH cells are now up to a claimed 2.9AH each. Now that 2.8AH 
cells (3.36Wh each) are "last year," they're down to about $2.50 each. So 
let's see. We could make a 15kWh pack with onlly 4,464 cells at about $11k.

I wonder where I can buy 8 gross of 4-cell AA battery holders. And about 
that many 4-cell wall chargers. Oops, there's where it gets expensive. 

Just kidding. ;-)

David Roden
EVDL Administrator
http://www.evdl.org/


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## EVDL List (Jul 27, 2007)

> EVDL Administrator <[email protected]> wrote:
> 
> > Let's see, AA NiMH cells are now up to a claimed 2.9AH each. Now that
> > 2.8AH
> ...


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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> > Gold Peak is one of the only, if not THE only, manufacturer whose NiMH
> > license is old enough that it predates the AH restriction set by Cobasys to
> > ensure that NiMH batteries can't be (readily) used for BEVs.
> ...


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## EVDL List (Jul 27, 2007)

Thanks for the rundown on availability. Any news on Firefly?
storm



> Haudy Kazemi <[email protected]> wrote:
> > EVDL Administrator wrote:
> >> Gold Peak is one of the only, if not THE only, manufacturer whose NiMH
> >> license is old enough that it predates the AH restriction set by Cobasys to
> ...


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## EVDL List (Jul 27, 2007)

I don't know if it has been pointed out already,
but you can't use a lead-acid charger for NiMH,
it will not stop charging them because they will
continue to draw amps until they explode, whereas
lead-acid will taper off its amp draw at constant
voltage. A simple patch would be to put a temp sensor
on the pack, and have it turn off the charger when the
batteries heat up.

I should also point out that charging more than a
12-24v string of NiMH is asking for trouble, because
the cells can vary such that overcharging one cell
buried in a long string is not hard to do.

Hope that helps.
Jack




> --- Haudy Kazemi <[email protected]> wrote:
> 
> > EVDL Administrator wrote:
> > > Gold Peak is one of the only, if not THE only,
> ...


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## EVDL List (Jul 27, 2007)

> Jack Murray wrote:
> > I don't know if it has been pointed out already,
> > but you can't use a lead-acid charger for NiMH,
> > it will not stop charging them because they will
> ...


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## EVDL List (Jul 27, 2007)

There is a recent Firefly battery discussion here: 
http://www.peakoil.com/fortopic8972-0-asc-150.html
That discussion says availability is unclear (although it looks like 
bulk purchases will be needed) and actual performance is also unclear.

Also see 
http://www.autobloggreen.com/2008/01/25/fireflys-oasis-group-31-batteries-getting-some-ev-fans-excited/

Firefly's website now says "Available Summer 2008". There are only ~3 
more weeks until the start of summer...and ~15 weeks to the end.
http://www.fireflyenergy.com/index.php?option=com_content&task=view&id=273&Itemid=100

The spec sheet: 
http://www.fireflyenergy.com/images/stories/pdfs/G31%20Specification%20Sheet%20012308.pdf
says: 12v 100ah (1200wh), with a 1C discharge time of 60 minutes. C/2 
discharge time of 120 minutes. Reserve capacity (RC, 25 amp) time 
listed at 215 minutes.
It also estimates 700 cycles to 100% DOD, and 800 cycles to 80% DOD.

storm connors wrote:
> Thanks for the rundown on availability. Any news on Firefly?
> storm
>
>


> Haudy Kazemi <[email protected]> wrote:
> >
> >> EVDL Administrator wrote:
> >>
> ...


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## EVDL List (Jul 27, 2007)

I don't know about that.
I've been charging a string of 5 24v modules of NiMH batteries with a 
Russco charger for months without any problems. 
I set the finish voltage for 145.5 volts it starts tapering the current from
about 140 volts 
down to 2 amps by 144 volts then shuts off shortly thereafter once it
reaches 145.5 volts.
Neal





> Jack Murray wrote:
> >
> > I don't know if it has been pointed out already,
> > but you can't use a lead-acid charger for NiMH,
> ...


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## EVDL List (Jul 27, 2007)

Here is the latest info I received from my contact at GP. They
recommend charging at .5C to 1C (50-100A). This is going to be a
problem for the Zivan which may reach 20A. I will upload the data
sheet to our blog page (www.seaburyhall.org/engineering) sometime
today.
Martin


"For charging the NiMH, it can be very simple.

As we told you before, you should charge up the cell by using 0.5C -
1.0C current.

The End voltage of batteries is depending on the temperature.
Higher the ambient temeprature, lower the voltage, implied lower
charging efficiency.
Lower the ambient temperature, higher the voltage, implied higher
charging efficiency.

Say, when you charge the batteries @25C, the end voltage of each cell
may only up to 1.4V - 1.45V.
Never allow the batteries temperature rise higher than 50C, so when
the batteries temperature rise as high as 45C, stop charging.

You are no need to measure every individual cell temperature, usually
we only measure the temperature of middle cell terminal.
It can be the representative of the batteries module.

The -dV/dt is the advance cutoff method for fast charging, it is not
necessary to employ in your system.

I attached the technical data sheet of our batteries module for your reference."




> shred <[email protected]> wrote:
> >
> > I don't know about that.
> > I've been charging a string of 5 24v modules of NiMH batteries with a
> ...


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