Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[Evan Tuer via EV]

On Wed, Aug 8, 2018 at 6:38 AM David Nelson via EV 
wrote:

> On Mon, Aug 6, 2018 at 7:51 PM, Alan Arrison via EV 
> wrote:
> > I guarantee that the inferior Chinese cells will change capacity as they
> are
> > cycled and not by just a few percent.
> >
> > Running them without a BMS is a recipe for disaster. Damaged cells at
> best,
> > a fire at worst.
> >
> > All the Chinese cells are junk, especially the CALBS.
> >
> > Al
>
> I'm so glad my cells didn't talk to you! Manufactured 11/2009,
> installed and on the road 1/2010. No attached BMS other than split
> pack voltage monitor since 7/2011 and all 40 cells are doing just fine
> when checked in 3/2018. End of charge voltage 3.465V held for 45 min
> during the CV stage with current tapering to 0A.
>
> Clearly your abslolute about Chinese cells doesn't fit. Sorry you had
> a bad experience.
>
>
>
I have a lot of miles on CALBs too, probably 100k in total on personal
vehicles. One still in use with 50k miles and no BMS.  I dismantled a car
with a CALB pack recently too - somewhere around 9 year old cells, they
still had 90% of rated capacity.

I also sent around half a ton of CALB cells to be analysed / recycled by a
university research team.  Those had been run dead flat by a badly designed
BMS in a commercial conversion.

They're rather low power density but in my experience very reliable and
will last a long time if not abused.

 YMMV!
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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[David Nelson via EV]

On Mon, Aug 6, 2018 at 7:51 PM, Alan Arrison via EV  wrote:
> I guarantee that the inferior Chinese cells will change capacity as they are
> cycled and not by just a few percent.
>
> Running them without a BMS is a recipe for disaster. Damaged cells at best,
> a fire at worst.
>
> All the Chinese cells are junk, especially the CALBS.
>
> Al

I'm so glad my cells didn't talk to you! Manufactured 11/2009,
installed and on the road 1/2010. No attached BMS other than split
pack voltage monitor since 7/2011 and all 40 cells are doing just fine
when checked in 3/2018. End of charge voltage 3.465V held for 45 min
during the CV stage with current tapering to 0A.

Clearly your abslolute about Chinese cells doesn't fit. Sorry you had
a bad experience.


-- 
David D. Nelson
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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[Lee Hart via EV]

Alan Arrison via EV wrote:

All the Chinese cells are junk, especially the CALBS.


I would not go so far as to call them "junk", though I too have bought 
examples that were certainly of very poor quality.


Chinese business practices also leave a lot to be desired. The specs 
aren't honest, and warranty and support are nonexistent.


You get what you pay for (and DON'T get what you DIDN'T pay for). :-(
--
There is hardly anything in the world that someone cannot make a
little worse and sell a little cheaper. Those who consider price
alone are that person's lawful prey. -- John Ruskin
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[Rick Beebe via EV]

I have 48 CALB CA100's in my truck, also 5 years old. I've never even 
had to top off any. I checked them in the Spring and they were all 
within 2 thousandths of a volt of each other. In July I had one of those 
*doh* events and drained the *entire* pack to 9 volts. I recharged the 
pack and they were all within 2 thousandths of a volt of each 
other...except for 1 which read 0 volts. I had a spare which I charged 
externally to the same voltage as those in the pack. Two charge cycles 
and I checked again this weekend. All the same still. So I'm with Tom. 
CALBs are magic.


--Rick


On 8/7/2018 6:48 PM, Tom Jones via EV wrote:

I really have to beg to differ about CALBs.
My Focus has 45 CA180 cells that have been on the road for about five 
years without BMS. Once a year, sometimes twice, I pump a few amp 
hours into the lowest cells with with a radio control type charger.

That usually involves about five cells.
I do have a homemade battery monitor with a display, expanded voltage 
scale, that I use to keep a eye on the pack while driving. And, I do 
datalog each cell all the time while driving and charging. In the 
charging sweet spot, about 3.4 volts, all 45 cells are in a tight 
range of about 25 mV. I consider that basically magic!
My battery monitor also will stop the J1772 if any single cell voltage 
gets too high.

So, that my experience with CALB cells,

Tom



On 8/6/2018 7:51 PM, Alan Arrison via EV wrote:
I guarantee that the inferior Chinese cells will change capacity as 
they are cycled and not by just a few percent.


Running them without a BMS is a recipe for disaster. Damaged cells at 
best, a fire at worst.


All the Chinese cells are junk, especially the CALBS.

Al


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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[Tom Jones via EV]

I really have to beg to differ about CALBs.
My Focus has 45 CA180 cells that have been on the road for about five 
years without BMS. Once a year, sometimes twice, I pump a few amp hours 
into the lowest cells with with a radio control type charger.

That usually involves about five cells.
I do have a homemade battery monitor with a display, expanded voltage 
scale, that I use to keep a eye on the pack while driving. And, I do 
datalog each cell all the time while driving and charging. In the 
charging sweet spot, about 3.4 volts, all 45 cells are in a tight range 
of about 25 mV. I consider that basically magic!
My battery monitor also will stop the J1772 if any single cell voltage 
gets too high.

So, that my experience with CALB cells,

Tom



On 8/6/2018 7:51 PM, Alan Arrison via EV wrote:
I guarantee that the inferior Chinese cells will change capacity as 
they are cycled and not by just a few percent.


Running them without a BMS is a recipe for disaster. Damaged cells at 
best, a fire at worst.


All the Chinese cells are junk, especially the CALBS.

Al




On 8/6/2018 7:48 PM, David Nelson via EV wrote:
On Tue, Jul 31, 2018 at 9:25 PM, Tom Hudson via EV 
 wrote:

Those two were ZERO VOLTS, and show ZERO OHMS resistance.

Is this a common failure mode of lithium-ions (or the CALB 
modules)?  I'm
thinking that I'd better set up some kind of fusing between the 
buddy pairs
because if one of the pair fails in this way, it's going to present 
a dead

short to its buddy -- and nothing good is going to come of that.

I don't know how common of a failure mode that is but I suspect it
could happen. If they were placed upside down (terminals facing down)
there is evidence that that has corroded the internal contacts to the
terminal bolts but that caused an open circuit situation, not a dead
short.

Internally the cells are made up of several layers which are
"buddy-paired" at the terminals. I put 20 buddy pairs of TS-LFP100AHA
cells in my Gizmo back in January 2010 and they are still going
strong. While the probability of any given cell failing goes up with
the number of cells I claim that a 200Ah cell made up of the same size
materials as the 100Ah cells would also have a higher probability of
failure. Definitely give each cell a cycle test and if you have the
time a capacity test. I would recommend that you then pair them up
where the capacity of the pairs ends up being nearly identical. I did
a rudimentary version of this for my Gizmo and it has worked out just
fine.

Some claim that you have to have the cells at exactly the same SOC
before connecting the buddy pairs. Theoretically this doesn't make
sense and I have also tested it and practice shows it really doesn't
matter. As long as their voltages are similar the initial current
isn't that great. Somewhere in the EVDL archives I posted the numbers
from one of my tests of this. IIRC it maxed at ~100A for a second or
so and quickly dropped to below 20A or so. Charging the cell pair to
3.4V or discharging to 2.8V or so brings the two cells in line with
each other.

The 100% SOC resting voltage of LFP cells from CALB and TS is 3.38V.
Make sure you aren't hammering the cells with 3.6+V on every charge
trying to equalize them. A good set of cells doesn't drift that fast.
I have been running my pack top balanced without attached BMS boards
for several years with no issues. I recently sold the Gizmo and I
don't trust the new owner to be able to be the "human BMS" so I am
going to be reinstalling the BMS boards I have. Furthermore, it is an
unknown how much the cells will drift as they age. They have been fine
so far but I'm not driving it now so can't do my annual voltage check.
I've been charging to 3.465V/cell with my Zivan chargers and the
resting voltage with no load after 12hours has been 3.36V so I know
I'm not overcharging them.

HTH,



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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[EVDL Administrator via EV]

On 6 Aug 2018 at 22:51, Alan Arrison via EV wrote:

> All the Chinese cells are junk, especially the CALBS.

I know about the used and new OEM EV (Leaf, Volt, etc) cells, but are there 
ANY LiFePO4 cells available to the hobbyist (especially at a more or less 
affordable price) that aren't Chinese?

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[Alan Arrison via EV]

I guarantee that the inferior Chinese cells will change capacity as they 
are cycled and not by just a few percent.


Running them without a BMS is a recipe for disaster. Damaged cells at 
best, a fire at worst.


All the Chinese cells are junk, especially the CALBS.

Al




On 8/6/2018 7:48 PM, David Nelson via EV wrote:

On Tue, Jul 31, 2018 at 9:25 PM, Tom Hudson via EV  wrote:

Those two were ZERO VOLTS, and show ZERO OHMS resistance.

Is this a common failure mode of lithium-ions (or the CALB modules)?  I'm
thinking that I'd better set up some kind of fusing between the buddy pairs
because if one of the pair fails in this way, it's going to present a dead
short to its buddy -- and nothing good is going to come of that.

I don't know how common of a failure mode that is but I suspect it
could happen. If they were placed upside down (terminals facing down)
there is evidence that that has corroded the internal contacts to the
terminal bolts but that caused an open circuit situation, not a dead
short.

Internally the cells are made up of several layers which are
"buddy-paired" at the terminals. I put 20 buddy pairs of TS-LFP100AHA
cells in my Gizmo back in January 2010 and they are still going
strong. While the probability of any given cell failing goes up with
the number of cells I claim that a 200Ah cell made up of the same size
materials as the 100Ah cells would also have a higher probability of
failure. Definitely give each cell a cycle test and if you have the
time a capacity test. I would recommend that you then pair them up
where the capacity of the pairs ends up being nearly identical. I did
a rudimentary version of this for my Gizmo and it has worked out just
fine.

Some claim that you have to have the cells at exactly the same SOC
before connecting the buddy pairs. Theoretically this doesn't make
sense and I have also tested it and practice shows it really doesn't
matter. As long as their voltages are similar the initial current
isn't that great. Somewhere in the EVDL archives I posted the numbers
from one of my tests of this. IIRC it maxed at ~100A for a second or
so and quickly dropped to below 20A or so. Charging the cell pair to
3.4V or discharging to 2.8V or so brings the two cells in line with
each other.

The 100% SOC resting voltage of LFP cells from CALB and TS is 3.38V.
Make sure you aren't hammering the cells with 3.6+V on every charge
trying to equalize them. A good set of cells doesn't drift that fast.
I have been running my pack top balanced without attached BMS boards
for several years with no issues. I recently sold the Gizmo and I
don't trust the new owner to be able to be the "human BMS" so I am
going to be reinstalling the BMS boards I have. Furthermore, it is an
unknown how much the cells will drift as they age. They have been fine
so far but I'm not driving it now so can't do my annual voltage check.
I've been charging to 3.465V/cell with my Zivan chargers and the
resting voltage with no load after 12hours has been 3.36V so I know
I'm not overcharging them.

HTH,



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Re: [EVDL] Lithium Ion buddy pairing? (Was electriccarpartscompany.com?)

[David Nelson via EV]

On Tue, Jul 31, 2018 at 9:25 PM, Tom Hudson via EV  wrote:
>
> Those two were ZERO VOLTS, and show ZERO OHMS resistance.
>
> Is this a common failure mode of lithium-ions (or the CALB modules)?  I'm
> thinking that I'd better set up some kind of fusing between the buddy pairs
> because if one of the pair fails in this way, it's going to present a dead
> short to its buddy -- and nothing good is going to come of that.

I don't know how common of a failure mode that is but I suspect it
could happen. If they were placed upside down (terminals facing down)
there is evidence that that has corroded the internal contacts to the
terminal bolts but that caused an open circuit situation, not a dead
short.

Internally the cells are made up of several layers which are
"buddy-paired" at the terminals. I put 20 buddy pairs of TS-LFP100AHA
cells in my Gizmo back in January 2010 and they are still going
strong. While the probability of any given cell failing goes up with
the number of cells I claim that a 200Ah cell made up of the same size
materials as the 100Ah cells would also have a higher probability of
failure. Definitely give each cell a cycle test and if you have the
time a capacity test. I would recommend that you then pair them up
where the capacity of the pairs ends up being nearly identical. I did
a rudimentary version of this for my Gizmo and it has worked out just
fine.

Some claim that you have to have the cells at exactly the same SOC
before connecting the buddy pairs. Theoretically this doesn't make
sense and I have also tested it and practice shows it really doesn't
matter. As long as their voltages are similar the initial current
isn't that great. Somewhere in the EVDL archives I posted the numbers
from one of my tests of this. IIRC it maxed at ~100A for a second or
so and quickly dropped to below 20A or so. Charging the cell pair to
3.4V or discharging to 2.8V or so brings the two cells in line with
each other.

The 100% SOC resting voltage of LFP cells from CALB and TS is 3.38V.
Make sure you aren't hammering the cells with 3.6+V on every charge
trying to equalize them. A good set of cells doesn't drift that fast.
I have been running my pack top balanced without attached BMS boards
for several years with no issues. I recently sold the Gizmo and I
don't trust the new owner to be able to be the "human BMS" so I am
going to be reinstalling the BMS boards I have. Furthermore, it is an
unknown how much the cells will drift as they age. They have been fine
so far but I'm not driving it now so can't do my annual voltage check.
I've been charging to 3.465V/cell with my Zivan chargers and the
resting voltage with no load after 12hours has been 3.36V so I know
I'm not overcharging them.

HTH,

-- 
David D. Nelson
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