# Re: [EVDL] Li Ion Batteries



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

The link you provided is the original thundersky. Everyone else selling them
are resellers. You can buy direct from them or from a reseller like
Everspring.net. You can also contact Sky Energy who make cells with the
same specs as Thundersky, and may have been connected to Thundersky at one
time. http://skyenergy.en.alibaba.com/



> indiantuktuk wrote:
> >
> > Hi,
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Why do not consider Hipower lifepo4 battery? Compared with our competitors,
we have better quality control, 2 years warranty, as well as fantastic BMS
system. Now from 10ah to 600ah single cells are available. Pls contact me
for the data of our cells. [email protected]
Milo





> indiantuktuk wrote:
> >
> > Hi,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> milo0105 wrote:
> > Why do not consider Hipower lifepo4 battery? Compared with our competitors,
> > we have better quality control, 2 years warranty, as well as fantastic BMS
> > system.
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> milo0105 wrote:
> > Why do not consider Hipower lifepo4 battery? Compared with our competitors,
> > we have better quality control, 2 years warranty, as well as fantastic BMS
> > system. Now from 10ah to 600ah single cells are available. Pls contact me
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

My (and few others') experience is known on the list, but for
newcomers: the company has shady business practices and if management is 
the same as few years ago, will take advantage of you at the first 
opportunity. Some may doubt it, but I have NO indication of otherwise.

They knowingly sold to few first adopters total crap meant for
recycling and still did not rectify the situation.

Would you deal with the company that screwed you in the past?
No.

Would you deal with and support the company that didn't screw you 
personally but screwed other your fellow EVers (many on this list)?

You might, it's up to your moral standards.

Personally, I wouldn't take their product even for free.

Some others don't care and will support them as long as it's cheap,
giving them the message that what they've done is OK.

Some people can sell their mother if price is right. Money
talk. But ask others on the list what they think though.

Bottom line:
If *all* you care about is amp-hours per dollar right now, go right
ahead and buy TS stuff and feel good. Just don't complain about
anything few months from now in case something goes wrong.

Victor




> indiantuktuk wrote:
> > Hi,
> >
> > I would wish to secure TS LFP60AHA batteries from
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> milo0105 wrote:
> > Our fantastic BEST quality Charger (new invention ) and BMS
> >
> ... [more bullshit] ...
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> milo0105 wrote:
> > Our fantastic BEST quality Charger (new invention ) and BMS
> >
> > 1. Several models of charger available
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Milo

I followed the links but could find a site about your LiFePO4 cells. Where
can I find out about Hipower cells and associated BMS?

Thanks

Dave Cover



> milo0105 <[email protected]> wrote:
> 
> >
> > Why do not consider Hipower lifepo4 battery? Compared with our competitors,
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Victor Tikhonov <[email protected]> wrote:
> 
> >
> > Lastly, you still did not describe principle of the operation of
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Cory Cross <[email protected]> wrote:
> > milo0105 wrote:
> >> Why do not consider Hipower lifepo4 battery? Compared with our competitors,
> >> we have better quality control, 2 years warranty, as well as fantastic BMS
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

I should add, for clarity, it's not clear what caused the fire (I
heard about it 3rd hand). Quite worrying though.



> Evan Tuer <[email protected]> wrote:
> > On Wed, Mar 4, 2009 at 4:42 AM, Cory Cross <[email protected]> wrote:
> >> milo0105 wrote:
> >>> Why do not consider Hipower lifepo4 battery? Compared with our competitors,
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Roger Heuckeroth wrote:
> > So it sounds like they have a modular charger that has individual
> > isolated chargers that will balance charge the pack. That is a good
> > idea in my opinion, and beats shunting current. You can put two 72V
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Cory,

It sounds like you have had personal experiences with their 
equipment? If so, please tell.

Roger



> Cory Cross wrote:
> 
> > Roger Heuckeroth wrote:
> >> So it sounds like they have a modular charger that has individual
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Zeke Yewdall wrote:
>


> Victor Tikhonov <[email protected]> wrote:
> >
> >> Lastly, you still did not describe principle of the operation of
> >> your BMS. Claiming that you develop a charger (single unit) that
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Roger Heuckeroth wrote:
> > It sounds like you have had personal experiences with their
> > equipment? If so, please tell.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Victor Tikhonov <[email protected]> wrote:
> 
> > Zeke Yewdall wrote:
> > > On Wed, Mar 4, 2009 at 4:26 AM, Victor Tikhonov <[email protected]>
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> I was under the impression that those small wires might be doing diversion
> or shunting or balancing between the cells that get to full voltage sooner
> and those that don't, not just sensing. Kind of like the Rudman regulators,
> I think. But... it sounds like Cory might have a better idea of what they
> really do for the "bms" in question for this thread since he's taken one
> apart.
> 
Yes, shunting, for both "china hipower" and R/C chargers -- there are 
wires to each cell and a bulk charger.

Cory

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

The charge can indicate every cell if the cell is charged fully or not. We
can also provide 144v, 288v chargers etc. And yes, till now you will need to
prepare a good indicater to control the discharging. But Our onboard BMS
will be available soon. 

-----
China Hipower, best lifepo4 producer in China.
www.haiba.net.cn
[email protected]
-- 
View this message in context: http://www.nabble.com/Li-Ion-Batteries-tp22313031p22343835.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Can some one pls tell me the principles that a BMS stops fire in an EV
accident. And which BMS has this function? and Lifepo4 battery can be fired,
which company's lifepo4 battery catched fire before? 

-----
China Hipower, best lifepo4 producer in China.
www.haiba.net.cn
[email protected]
-- 
View this message in context: http://www.nabble.com/Li-Ion-Batteries-tp22313031p22343862.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

A123 batteries have caught fire in PHEV Toyota Prius Conversions. The 
cause was bad terminal connections. I believe the electrolyte that 
A123 uses is flammable

See http://www.autobloggreen.com/2008/06/18/converted-plug-in-prius-destroyed-by-fire/

and

http://theeestory.com/files/toyota-prius-a123-car-fire-investigation-report-2008-1.pdf

If a BMS monitored temperature of each cell it could have prevented 
this incident, by disconnecting the pack upon recognition of the 
thermal event.



> milo0105 wrote:
> 
> >
> > Can some one pls tell me the principles that a BMS stops fire in an EV
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Milo,

It sounds like your BMS is not as advanced as some of the BMS systems 
discussed on this list. It may handle charge balancing, but it does 
not do any of the following:

Monitor cell voltage during discharge
Monitor cell temperature
Determine and display Ah used
Provide a warning to the driver when the SOC is nearing depletion.
Prevent against over current draw.
Able to identify weakest cell(s) in battery pack

Ideally the BMS should do all of the above and perhaps even perform 
energy transfer during discharge to make sure all of the cells reach 
depletion at the same time. It also needs to communicate to the 
driver through at minimum a gauge, or preferably an LCD display.

I may have left some things out from the above, but it sounds like 
your company still has some work to do.

Roger




> milo0105 wrote:
> 
> >
> > The charge can indicate every cell if the cell is charged fully or
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Indeed,we have lots of work to do, I learned a lot of this forum, and will
share the information with our technicians. 

Roger Heuckeroth wrote:
> 
> Milo,
> 
> It sounds like your BMS is not as advanced as some of the BMS systems 
> discussed on this list. It may handle charge balancing, but it does 
> not do any of the following:
> 
> Monitor cell voltage during discharge
> Monitor cell temperature
> Determine and display Ah used
> Provide a warning to the driver when the SOC is nearing depletion.
> Prevent against over current draw.
> Able to identify weakest cell(s) in battery pack
> 
> Ideally the BMS should do all of the above and perhaps even perform 
> energy transfer during discharge to make sure all of the cells reach 
> depletion at the same time. It also needs to communicate to the 
> driver through at minimum a gauge, or preferably an LCD display.
> 
> I may have left some things out from the above, but it sounds like 
> your company still has some work to do.
> 
> Roger
> 
> 
>


> milo0105 wrote:
> >
> >>
> >> The charge can indicate every cell if the cell is charged fully or
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Roger

I'm very interested in getting a lithium pack in my car. The list of
features you've presented is pretty good, but is there anyone out there
doing this now? If you are running LiFePO4 cells, is thermal run away still
a problem like Lithium cobalt? I don't know, that's why I'm asking.

Not to defend Milo, he needs to do that, but one point he makes is that if
their BMS keeps the pack in good order (balanced and well charged) and the
driver monitors the pack to know when it's near discharged, (AHs in and out
with an EVision or Emeter) won't the pack survive pretty well? Monitor temp
to know when it's getting hot. Don't hot rod all the time. And an occasional
quarter mile run is within their parameters.

Their charging/BMS scheme with a conscientious EV owner might work well.
Maybe not good enough for the general public, but....

And it needs to be affordable. I'm not here to answer for Milo, but some of
what he says (and their documents state) sound reasonable to a non-EE like
me. I do rely on the more experienced people on this list, so correct me
where I'm wrong. I'm here to learn, and I don't have deep pockets.

Dave Cover, longing for lithium



> Roger Heuckeroth <[email protected]>wrote:
> 
> > Milo,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> Milo,
>
> It sounds like your BMS is not as advanced as some of the BMS systems 
> discussed on this list. It may handle charge balancing, but it does 
> not do any of the following:
>
> Monitor cell voltage during discharge
> Monitor cell temperature
> Determine and display Ah used
> Provide a warning to the driver when the SOC is nearing depletion.
> Prevent against over current draw.
> Able to identify weakest cell(s) in battery pack
>
> Ideally the BMS should do all of the above and perhaps even perform 
> energy transfer during discharge to make sure all of the cells reach 
> depletion at the same time. It also needs to communicate to the 
> driver through at minimum a gauge, or preferably an LCD display.
>
> I may have left some things out from the above, but it sounds like 
> your company still has some work to do.
>
> Roger

BMS's come in lots of flavors.

overcharge-works for floodies, we have heard some folks claim works 
with LiFePo4, they are being irresponsible spreading this.

Bybass regs - Balancing only at end of charge, prevents overcharge, 
interacts with charge to work (BTW love lee's lightbuld trick!), no ah 
feedback usually, but avilable (MK3)

Charge shuttleing
Flying capacitor - not practical, especially with lifepo4 where 
voltage is so stable.
Rotating charging - this can measure voltage at each and balance at 
end of charge and during discharge and keep track of individual module 
SOC. This SOC monitoring can only be accurate if it is the only charger, 
no bulk, but that can make it too slow depending on pack size.

Distributed chargeing - A smart charger for each. Best theoretical, but 
practically problematic especially for lots of small cells.

So we have to compromise.
Use bypass regs with LV monitoring and charger throttleing to balance 
at end of charge.
Use an Evision or emeter for SOC and fully charge once every 10 20-80 
charges to increase cycle life.

We are back to the capacity of the pack is equal to the capacity of the 
lowest capacity cell.
I think when calender life is rated 2x-3x longer than the cycle life for 
our applications, the next advancement in BMS will come.

I think the "perform energy transfer during discharge to make sure all 
of the cells reach depletion at the same time." is a lot harder with 
LiFePo4 that say lead. It would have to be inferred from a calculated 
and historical value since the voltage, as victor stated, is not a good 
indicator.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> dave cover wrote:
> 
> > Roger
> >
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

if you guys can give me a little time i am in the
process of negotiating with several companies for
prices. i am hoping i can organize enough of us that
want the li-ion to get a better price. i live in
Guangzhou, China and can go to visit the factories
before i purchase. 

(I am from the US and have lived here 3 years so far.
This place is insane. Something new everyday....)
feel free to contact me directly. 

Thanks,
Rick Randazzo
msn: [email protected]



--- dale henderson <[email protected]>


> wrote:
> 
> >
> > i appreciate the knowledge about a company's shady
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> if you guys can give me a little time i am in the
> process of negotiating with several companies for
> prices. i am hoping i can organize enough of us that
> want the li-ion to get a better price. i live in
> Guangzhou, China and can go to visit the factories
> before i purchase.

Hey, Rick, what kind of response do you get when you ask about 
guarantees, warranties, or any kind of assurance of quality? Telling a 
prospective buyer "we make the most super-fine best-ever battery in 
the world" won't fly with most of us, and even a product with good 
performance numbers can have a certain amount of failures. Will they 
cover replacements and they put that in writing?

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> dale henderson wrote:
> > i appreciate the knowledge about a company's shady history, but your
> > warning might have more weight if you offered some alternatives at
> > the same time. because of your warnings i've been hesitant to order
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> Not to defend Milo, he needs to do that, but one point he makes is that if
> their BMS keeps the pack in good order (balanced and well charged) and the
> driver monitors the pack to know when it's near discharged, (AHs in and out
> with an EVision or Emeter) won't the pack survive pretty well? Monitor temp
> to know when it's getting hot. Don't hot rod all the time. And an occasional
> quarter mile run is within their parameters.

No; you need to monitor every cell for undervoltage as you drive.

No matter how well you balance, the cells won't be all identical. At
the end of discharge, the internal resistance rises quite a bit,
leading to lots of voltage sag.

When one cell empties first and you don't realize it, it will sag to
very low voltage, damaging it. However, this has only a small effect
on overall pack voltage, so you probably won't notice and will just
keep driving, killing the cell.

I've watched data from an actual Lithium pack. If we hadn't had
individual cell voltage measurement, we would have had no idea that
the battery was empty and would have kept driving, killing that
battery.

-Morgan LaMoore

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> I've watched data from an actual Lithium pack. If we hadn't had
> individual cell voltage measurement, we would have had no idea that
> the battery was empty and would have kept driving, killing that
> battery.

Is there some kind of "fuzzy logic" you can use to alert the driver 
when any one cell gets a certain voltage below the rest?

Think more
Talk less
Become wise

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

There is the circuit that Lee proposed to build a "bridge"
which compares the center of the pack with the pack
voltage divided in two.
It is extremely simple and elegant and will warn you if
one battery (or cell) gets low, but it is fuzzy in the
sense that if in each pack half the voltage is balanced
and for example two cells go out at the same time, then
you won't be warned,
so I think this satisfies you requirement for fuzzy.
Not sure that it is a benefit though...

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Saturday, March 07, 2009 2:13 AM
To: [email protected]
Subject: Re: [EVDL] Li Ion Batteries

> I've watched data from an actual Lithium pack. If we hadn't had
> individual cell voltage measurement, we would have had no idea that
> the battery was empty and would have kept driving, killing that
> battery.

Is there some kind of "fuzzy logic" you can use to alert the driver 
when any one cell gets a certain voltage below the rest?

Think more
Talk less
Become wise

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> so I think this satisfies you requirement for fuzzy.
> Not sure that it is a benefit though...

Not the kind of "fuzzy" (whether warm or not) I was thinking about ;p
More like keeping track of all the cell voltages individually and 
warning when one gets a certain standard deviation from the average.

Maybe fuzzy logic isn't the right term...?


Think more
Talk less
Become wise

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> Is there some kind of "fuzzy logic" you can use to alert the driver
> when any one cell gets a certain voltage below the rest?

Yes, if you have a circuit measuring all of the voltages, it is easy.

A basic method is to use a voltage display that shows the lowest
cell's voltage. That way, you can drive based on voltage like normal,
but based on the weakest cell instead of the pack average.

If you took the time, you could develop a better algorithm.

-Morgan LaMoore

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Cor van de Water wrote:
> > There is the circuit that Lee proposed to build a "bridge"
> > which compares the center of the pack with the pack
> > voltage divided in two.
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Morgan LaMoore wrote:
> 
> >> Not to defend Milo, he needs to do that, but one point he makes is
> >> that if
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

> That got me thinking... what if you designed your BMS to essentially
> remove the cell from the pack once it gets to its low limit?
> Basically, just disconnect and bypass. You would need two high
> current switches to do that per cell. One to bypass and one to
> disconnect.

I don't think it's worth the cost of two high-current switches per
cell. As long as your pack is reasonably balanced, once one cell is
empty, the others should be almost empty.

That many high-current switches is pretty expensive for such a small benefit.

-Morgan LaMoore

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

Sent from my iPhone



> Morgan LaMoore <[email protected]> wrote:
> 
> >> That got me thinking... what if you designed your BMS to essentially
> >> remove the cell from the pack once it gets to its low limit?
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Morgan LaMoore <[email protected]> wrote:
> >> That got me thinking... what if you designed your BMS to essentially
> >> remove the cell from the pack once it gets to its low limit?
> >> Basically, just disconnect and bypass. You would need two high
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*

>
>> > That got me thinking... what if you designed your BMS to essentially
>> > remove the cell from the pack once it gets to its low limit?
>> > Basically, just disconnect and bypass. You would need two high
>> > current switches to do that per cell. One to bypass and one to
>> > disconnect.
>> 
>
> I don't think it's worth the cost of two high-current switches per
> cell. As long as your pack is reasonably balanced, once one cell is
> empty, the others should be almost empty.
>
> That many high-current switches is pretty expensive for such a small benefit.
>
> -Morgan LaMoore
> 

But...
If a bms can be designed to scale down, and you are using small 
format cells, like 10ah, perhaps 10 strings in series(100ah pack) each 
with their own bms could be used.
So now we can have only 10 high current switches and if one cell goes 
bad, you can disconnect the string, dropping the pack capacity by 10% 
but not the voltage.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Lee Hart <[email protected]> wrote:
> 
> > Morgan LaMoore <[email protected]> wrote:
> >>> That got me thinking... what if you designed your BMS to essentially
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Roger Heuckeroth wrote:
> > What is the volate drop in the ON state of a MOSFET? I thought it is
> > normally about 0.7 V. If so, that's a pretty sustantial loss. I was
> > thinking more in the line of a SPDT relay.
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Li Ion Batteries*



> Zeke Yewdall wrote:
> ...
> >> Because each cell must be treated individually. I don't know how RC
> >> models' chargers ate built, but if they have only sense wires
> ...


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