# [EVDL] Do LiFePO4 batteries need a break-in period like Pba?



## EVDL List (Jul 27, 2007)

Hi,

I was wondering if anyone knew if the LiFePO4 batteries need to be
broken in like lead acid batteries do. Gauging from the currents I
draw with my lead acid pack I draw about 250A climbing my hill and
generally not more than 350A for a brief moment on acceleration up a
hill. I'll be getting rid of about 250lbs of weight, out of the
current 993lbs, so I suspect my current draws will be somewhat lower.
I'm installing buddy paired TS-LFP100AHA so at 250A I'm only pulling
1.25C.

Thank you,

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

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## EVDL List (Jul 27, 2007)

Good question. I was advised to do a very careful break-in, not going
above 1C or below 60% SOC for the first 20 or so cycles. I have
absolutely no idea what the mechanism behind this is, but decided it
couldn't hurt. Can anyone explain?

BTW: removing weight doesn't reduce the current draws. It just makes
the car accelerate more quickly 




> David Nelson <[email protected]> wrote:
> > Hi,
> >
> > I was wondering if anyone knew if the LiFePO4 batteries need to be
> ...


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## EVDL List (Jul 27, 2007)

"BTW: removing weight doesn't reduce the current draws. It just makes
the car accelerate more quickly" >>>that's one way, but you could also back
off on the throttle and accelerate at the same rate using less current and
power or less work per unit time since the mass is smaller.


Evan Tuer wrote:
> 
> Good question. I was advised to do a very careful break-in, not going
> above 1C or below 60% SOC for the first 20 or so cycles. I have
> absolutely no idea what the mechanism behind this is, but decided it
> couldn't hurt. Can anyone explain?
> 
> BTW: removing weight doesn't reduce the current draws. It just makes
> the car accelerate more quickly 
> 
> 
>


> David Nelson <[email protected]> wrote:
> >> Hi,
> >>
> >> I was wondering if anyone knew if the LiFePO4 batteries need to be
> ...


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## EVDL List (Jul 27, 2007)

Thanks for the idea, Evan. Maybe someone knows the mechanism. Given
how packed the cell material is I doubt the "paste" is likely to blow
off.



> tomw <[email protected]> wrote:
> >
> > "BTW: removing weight doesn't reduce the current draws. It just makes
> > the car accelerate more quickly"
> ...


----------



## EVDL List (Jul 27, 2007)

Lithium cells are formatted in the factory. Which means cycling in certain =
way.

If cells have been in transit for a long time you might want to cycle
the cells few times before going for high currents. Just to allow some
refreshing.

Othervice these cells are ready to be used as they come.

Then the question is IF the cells were formatted correctly... If not..
then you might have an issue anyway. Being easy will just push the
unavoidable a bit further.

There are ways to use cells in more optimal way. It requires active
balancing and some understanding how cells behave.

-Jukka

2009/12/29 David Nelson <[email protected]>:
> Thanks for the idea, Evan. Maybe someone knows the mechanism. Given
> how packed the cell material is I doubt the "paste" is likely to blow
> off.
>
>


> tomw <[email protected]> wrote:
> >>
> >> "BTW: removing weight doesn't reduce the current draws. It just makes
> >> the car accelerate more quickly"
> ...


----------



## EVDL List (Jul 27, 2007)

Thanks, Jukka.

These are TS-LFP100AHA cells which have what I think is a date code of
091102 (2009 November 2) which would be about right. The TS
Documentation says, "The electricity is half loaded when the battery
produced, the battery cannot be discharged directly under any
condition, and must be charged before first use." I don't know if the
"electricity is half loaded" is the factory cycling you referred to. I
did the TS recommended 4.2V initial charge.

When you say, "There are ways to use cells in more optimal way. It
requires active balancing and some understanding how cells behave."
What do you mean by active balancing? Do you mean balancing during
both charge and discharge or just at end of charge? Do you mean energy
or SOC balancing or voltage balancing?

On a related note, I'm going to be doing buddy pairing. What is the
best way to choose the pairs? Do I pair by matching resting voltages?
Maybe if I could pair by cell capacity where each pair has the same
capacity as the next. For example, pair 100Ah with 100Ah, 99Ah with
101Ah, 98Ah with 102Ah, etc. The problem with capacity pairing is I
don't have any way to measure it.

Thanks again for the input.

David

2009/12/29 Jukka J=E4rvinen <[email protected]>:
> Lithium cells are formatted in the factory. Which means cycling in certai=
n way.
>
> If cells have been in transit for a long time you might want to cycle
> the cells few times before going for high currents. Just to allow some
> refreshing.
>
> Othervice these cells are ready to be used as they come.
>
> Then the question is IF the cells were formatted correctly... If not..
> then you might have an issue anyway. Being easy will just push the
> unavoidable a bit further.
>
> There are ways to use cells in more optimal way. It requires active
> balancing and some understanding how cells behave.
>
> -Jukka
>
> 2009/12/29 David Nelson <[email protected]>:
>> Thanks for the idea, Evan. Maybe someone knows the mechanism. Given
>> how packed the cell material is I doubt the "paste" is likely to blow
>> off.
>>
>>


> tomw <[email protected]> wrote:
> >>>
> >>> "BTW: removing weight doesn't reduce the current draws. It just makes
> >>> the car accelerate more quickly"
> ...


----------



## EVDL List (Jul 27, 2007)

"Half loaded" likely means that they ship the batteries with nom. 50%
charge.
This is a compromise between safety and shelf life concerns.
-MT

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of David Nelson
Sent: Tuesday, December 29, 2009 8:54 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Do LiFePO4 batteries need a break-in period like Pba?

Thanks, Jukka.

These are TS-LFP100AHA cells which have what I think is a date code of
091102 (2009 November 2) which would be about right. The TS
Documentation says, "The electricity is half loaded when the battery
produced, the battery cannot be discharged directly under any
condition, and must be charged before first use." I don't know if the
"electricity is half loaded" is the factory cycling you referred to. I
did the TS recommended 4.2V initial charge.

When you say, "There are ways to use cells in more optimal way. It
requires active balancing and some understanding how cells behave."
What do you mean by active balancing? Do you mean balancing during
both charge and discharge or just at end of charge? Do you mean energy
or SOC balancing or voltage balancing?

On a related note, I'm going to be doing buddy pairing. What is the
best way to choose the pairs? Do I pair by matching resting voltages?
Maybe if I could pair by cell capacity where each pair has the same
capacity as the next. For example, pair 100Ah with 100Ah, 99Ah with
101Ah, 98Ah with 102Ah, etc. The problem with capacity pairing is I
don't have any way to measure it.

Thanks again for the input.

David

2009/12/29 Jukka J=E4rvinen <[email protected]>:
> Lithium cells are formatted in the factory. Which means cycling in certain
way.
>
> If cells have been in transit for a long time you might want to cycle
> the cells few times before going for high currents. Just to allow some
> refreshing.
>
> Othervice these cells are ready to be used as they come.
>
> Then the question is IF the cells were formatted correctly... If not..
> then you might have an issue anyway. Being easy will just push the
> unavoidable a bit further.
>
> There are ways to use cells in more optimal way. It requires active
> balancing and some understanding how cells behave.
>
> -Jukka
>
> 2009/12/29 David Nelson <[email protected]>:
>> Thanks for the idea, Evan. Maybe someone knows the mechanism. Given
>> how packed the cell material is I doubt the "paste" is likely to blow
>> off.
>>
>>


> tomw <[email protected]> wrote:
> >>>
> >>> "BTW: removing weight doesn't reduce the current draws. It just makes
> >>> the car accelerate more quickly"
> ...


----------



## EVDL List (Jul 27, 2007)

2009/12/29 David Nelson <[email protected]>:
> Thanks, Jukka.
>
> These are TS-LFP100AHA cells which have what I think is a date code of
> 091102 (2009 November 2) which would be about right. The TS
> Documentation says, "The electricity is half loaded when the battery
> produced, the battery cannot be discharged directly under any
> condition, and must be charged before first use." I don't know if the
> "electricity is half loaded" is the factory cycling you referred to. I
> did the TS recommended 4.2V initial charge.

well... cells should be "initiated" and tested well. This is done in
TS facility. So cells are just charged at certain state for
transportation. It is good idea to charge your cells to 4,25V (or so)
every now and then (say every 100th cycle) IF you are looking for
optimal capacity from your cells. This seems to ahev refreshing effect
on cell capacity. Thou.. it also seems to add some internal
resistance.. effect is thou quite minimal. It's more of an problem
after 6000 cycles...


>
> When you say, "There are ways to use cells in more optimal way. It
> requires active balancing and some understanding how cells behave."
> What do you mean by active balancing?

Adjusting the cells in certain alingment by their properties. IE
capacity, internal resistance, temperature behaviour, location in the
pack.. etc.

> Do you mean balancing during
> both charge and discharge or just at end of charge?

Balancing during charge, idle and discharging.

> Do you mean energy
> or SOC balancing or voltage balancing?

By cell properties. As you know not most of us drain the cells to 0%
SOC everytime we drive. Minimizing the losses usually minimizes the
generated tempereature =3D> longer lifetime.


>
> On a related note, I'm going to be doing buddy pairing. What is the
> best way to choose the pairs? Do I pair by matching resting voltages?
> Maybe if I could pair by cell capacity where each pair has the same
> capacity as the next. For example, pair 100Ah with 100Ah, 99Ah with
> 101Ah, 98Ah with 102Ah, etc. The problem with capacity pairing is I
> don't have any way to measure it.

If you really, really have to buddy pair.. go with the internal
resistance. Try to match in the way that the cells contribute similar
current and losses (heat generation). Then you might get away.

-Jukka



> Thanks again for the input.
>
> David
>
> 2009/12/29 Jukka J=E4rvinen <[email protected]>:
>> Lithium cells are formatted in the factory. Which means cycling in certa=
in way.
>>
>> If cells have been in transit for a long time you might want to cycle
>> the cells few times before going for high currents. Just to allow some
>> refreshing.
>>
>> Othervice these cells are ready to be used as they come.
>>
>> Then the question is IF the cells were formatted correctly... If not..
>> then you might have an issue anyway. Being easy will just push the
>> unavoidable a bit further.
>>
>> There are ways to use cells in more optimal way. It requires active
>> balancing and some understanding how cells behave.
>>
>> -Jukka
>>
>> 2009/12/29 David Nelson <[email protected]>:
>>> Thanks for the idea, Evan. Maybe someone knows the mechanism. Given
>>> how packed the cell material is I doubt the "paste" is likely to blow
>>> off.
>>>
>>>


> tomw <[email protected]> wrote:
> >>>>
> >>>> "BTW: removing weight doesn't reduce the current draws. It just mak=
> es
> ...


----------



## EVDL List (Jul 27, 2007)

I don't think this is necessary, or even factory recommended. Since the
cells are charged and discharged at the factory in testing procedures
they've already had that initial 4.2V charge. I don't see anything being
gained by doing it again. Don't the cells last longer if they are not
charged to the maximum?



> David Nelson-5 wrote:
> >
> > I did the TS recommended 4.2V initial charge.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Here is what the TS documentation that came with the batteries says,
"Warning. Before first discharge the battery, please charge it to 4.2V
with the constant current of 0.1CA~0.5CA and stop until the charging
current falls to 1% of the original."

I assume that since they put this warning in every crate that it is
"factory recommended." I don't see why the manufacturer would go
through the trouble of printing a separate warning page to put with
the documentation if they did the initial 4.2V charge at the factory.
As far as my batteries are concerned I have done the 4.2V charge. What
I would like to know, however, is what happens if they are _never_
fully charged. What gains/losses are there in the overall performance
of the batteries? Does any one have any data to support the claims?
All I can guess is that maybe the 4.2V initial charge opens up more
"ion sites" on the plates. Beyond that, who knows?



> AMPhibian <[email protected]> wrote:
> >
> > I don't think this is necessary, or even factory recommended. Since the
> > cells are charged and discharged at the factory in testing procedures
> ...


----------



## EVDL List (Jul 27, 2007)

Others have suggested that this is something of a "lost in translation"
problem, and what is really being said is "Charge the battery before use, to
a maximum of no more than 4.2V", since that is the cell maximum. Since cell
capacity is tested at the factory I think it's safe to assume they have
already done a maximum charge cycle in the cell. Notice that Sky Energy
cells have not such recommendation for a max charge to 4.2 volts on first
use, or even a max charge to 3.8 volts, the SE max voltage.




> David Nelson-5 wrote:
> >
> > Here is what the TS documentation that came with the batteries says,
> > "Warning. Before first discharge the battery, please charge it to 4.2V
> ...


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