# [EVDL] Active vs passive balancing



## EVDL List (Jul 27, 2007)

How much current does an active balancer typically use? The only ones that
I'm familiar with are for were the battery is actively being unbalanced as
well (center tapping to get 12 volts from a 24volt bank), and those are
pretty efficient... a few mA quiescent draw at most. Not enough to be
concerned about the draw on low power PV systems, so I would think they'd be
okay on an EV. However, I've never seen one that can handle more than two
batteries (usually 12 to 24 volts, or 24 to 48 volts)

Z



> Elithion <[email protected]> wrote:
> 
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

> shred wrote:
> > I believe a shunt (passive) balancing BMS system [wastes] too much
> > energy, making an expensive active BMS the only practical choice for me.
> 
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >
> > Badicheq: 0ma idle (but 35-60ma on 12v system), 0.5a balancing
> > Zivan Smoother: 12-20ma idle, 2a balancing
> ...


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## EVDL List (Jul 27, 2007)

>
>
>Unfortunately it does voltage based balancing all the time, which is
>actually counterproductive (long story). I am afraid that other active
>balancers out there suffer from the same limitation.


I'd be quite interested in hearing that long story. Why would 
voltage-based balancing all the time be counterproductive? Once the 
target voltage is achieved, they would just monitor, wouldn't they?

Bill D.


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## EVDL List (Jul 27, 2007)

> Bill Dube wrote:
> >
> > I'd be quite interested in hearing that long story.
> > Why would
> ...


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## EVDL List (Jul 27, 2007)

By the way, after a phone call with someone who found the terms "Active
balancing" and "Passive balancing" confusing, I feel we should start using
different terms, terms that would be more accurate: 

"Dissipative balancing"
"Non-dissipative balancing".

They are a mouthful, I know, but their meaning is clearer.
I think I'll start using them and see.

-----
Davide Andrea
http://liionbms.com/php/index.php Elithion 
-- 
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Active-vs-passive-balancing-tp2305641p2308382.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

With dissipative balancing meaning continuing to charge the battery bank
after some of the cells get full, and just dissapating the extra energy on
those cells, while the less-full ones continue to charge.. untill they are
all charged. An equalizing charge on flooded lead acid batteries would
actually fall under this... it's just dissipating the extra energy in the
full cells by electrolyzing water instead of with an electronic device.

And non-dissipative balancing meaning taking energy from the full cells, and
moving it over to the less full cells.

Z



> Lee Hart <[email protected]> wrote:
> 
> > On 7/30/2010 2:19 PM, Elithion wrote:
> > > By the way, after a phone call with someone who found the terms "Active
> ...


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## EVDL List (Jul 27, 2007)

I've always used the "active" balancing on systems which actively
reads cells and does balancing decisions on-the-fly. No fixed voltage,
temperature, current or SOC limits to stare at but more heuristic way
to get cells in the wanted alignment.

Passive systems are preset systems with hard values. With shunts or
DC/DCs on each cell or fewer switchable ones on main board. Or
something similar.

Active system makes preemptive thingies to get cells right. Passive
starts when it's already too "late".

Shunting systems limits the charge by transforming some of the
chargers output to heat.

Boosting systems shuffle the energy among cells with DC/DCs. So this
method actually "boosts" individual cells at need.

BMS was used with Battery Monitoring Systems too and I think BMS
should not be used on smarter active systems to avoid confusion. I
refer usually BMS as BS. I started using CCS on the active systems
years ago.

At best Active cell manipulating systems know how much Ah's are left
on each cell at any time. It can also tell to the used exactly how
much energy is available from the pack at any given power demand. I
believe any system tampering with customer cells should actually know
what the heck they are doing. Unfortunately there is none at the
markets even today (prove me wrong, please !) We might just have the
OS approach left to do it. Commercial approach seems to be failing
badly.

I was forced to stop doing anything at the field for many years. CCS
is there but made unavailable for anyone due perhaps just plain
greediness.

We've had plenty of "BMS" talks with Victor, Bill and others at here
EVDL, EVS-exhibitions and Nedra EVents. We should have our terms right
by now and also try to go even deeper to the cell behavior mechanisms.
Variation of cells is huge and the amount of information is crushing.

Just to be even more vaque hereI have to say that I'm not so convinced
anymore that connecting small cells in parallel/series -alignment is
the way to go with Lithiums anymore. One big single cell can do it too
and perhaps even with higher efficiency (measuring over lifetime). I'm
working on this approach now since it effectively takes the BMSes out
of the equation. But.. there's a LOT to do before even one prototype
exists. The whole cell mechanics has to be reengineered and foils
should be ditched as current collectors.

-Jukka

http://www.google.com/profiles/jarviju#about



2010/7/30 Zeke Yewdall <[email protected]>:
> With dissipative balancing meaning continuing to charge the battery bank
> after some of the cells get full, and just dissapating the extra energy on
> those cells, while the less-full ones continue to charge.. untill they are
> all charged. An equalizing charge on flooded lead acid batteries would
> actually fall under this... it's just dissipating the extra energy in the
> full cells by electrolyzing water instead of with an electronic device.
>
> And non-dissipative balancing meaning taking energy from the full cells, =
and
> moving it over to the less full cells.
>
> Z
>
>


> Lee Hart <[email protected]> wrote:
> >
> >> On 7/30/2010 2:19 PM, Elithion wrote:
> >> > By the way, after a phone call with someone who found the terms "Active
> ...


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## EVDL List (Jul 27, 2007)

> By the way, after a phone call with someone who found the terms "Active
> balancing" and "Passive balancing" confusing, I feel we should start using
> different terms, terms that would be more accurate: 
> 
> "Dissipative balancing"
> "Non-dissipative balancing".
> 
> They are a mouthful, I know, but their meaning is clearer.
> I think I'll start using them and see.

Id like to see even more accurate descriptions but keep Dissipative and non-disipative as classes. Some standard would be great.

Passive Shunt - zeners
Intelligent shunt	- regulators that feedback to charger
Flying capacitor	- Often meant when someone says non-disipative and in my mind the worst type.
dc-dc charge shuttleing - Often called non-disipative (but dc-dc's are not That eff.) In my opinion probably the best possible.

I could need some help with these clasifications
dissipative vs non
bottom vs top
columb counting vs voltage cutoff
series vs parallel (one module at a time vs all modules at once)
inteligent vs passive

Perhaps we can have types and classes and every term is
(classes)* type

like

passive shunt
managed shunt
managed series charge shuttleing.
etc?



> 
> -----
> Davide Andrea
> http://liionbms.com/php/index.php Elithion 
> -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Active-vs-passive-balancing-tp2305641p2308382.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.


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## EVDL List (Jul 27, 2007)

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