# [EVDL] KOH for NiFe Batteries



## EVDL List (Jul 27, 2007)

Guys, I am now looking to source KOH (potassium hydroxide) for the Nickel
Iron batteries that I found.
Please look at this link and tell me if this is what I need?
And if it isn't, please tell me what to look for.

http://www.canadacolors.com/canadacolors/docs/spec/295404.pdf

Werner



> Joe <[email protected]> wrote:
> 
> > So very simple,
> >
> ...


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## EVDL List (Jul 27, 2007)

I am no chemist either. Do I just continue to dilute it with distilled water
until I get the desired hydrometer reading?

Werner



> Jeff Major <[email protected]> wrote:
> 
> >
> > --- Werner Peters <[email protected]> wrote:
> ...


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## EVDL List (Jul 27, 2007)

> --- Werner Peters <[email protected]> wrote:
> 
> > Guys, I am now looking to source KOH (potassium
> > hydroxide) for the Nickel
> ...


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## EVDL List (Jul 27, 2007)

This is for the SAFT - STM-180 battery, which I think
has the same specific gravity as the NiFe?
I'm not even 90% sure it's the same, but here's the
description,
The alkaline electrolyt in a nickel-cadmium battery is
a solution of potassium hydroxide (KOH), lithium
hydroxide (LiOH), sodium hydroxide (NaOH) and
distilled or demineralized water. During the
electrochemical reaction, its specific gravity remains
essentially constant and can thus not be used as an
indicator of state of charge. The specific gravity
however, varies due to the normal water consumption
during overcharges. The gravity is low when the cells
are topped up to their maximum, it is high when the
electrolyte reserve is all consumed. The electrolyte
used in STM blocks has a specific gravity of 1.21.

Rod



> --- Werner Peters <[email protected]> wrote:
> 
> > I am no chemist either. Do I just continue to dilute
> > it with distilled water
> ...


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## EVDL List (Jul 27, 2007)

That assay is for 45% KOH, which will not need dilution if the battery
calls for 45%. If it's 31% you want then you will need to make a
dilution with distilled water ... You can try the dilution by trial
and error but best to calculate the dilution rate and then adjust the
specific gravity by either adding water (to lower the S.G.) or
additional 45%KOH (to increase the S.G.). If you don't have a
hygrometer then you can do the measurement with some analytical scales
and a volumetric pipet and calculating the density of the solution.

If you want to do the dilution (which is simpler) take 0.688 L (or 688
mL) of the 45% solution and add enough distilled water to make 1 L (or
1000 mL). Mix well (exothermic reaction), then check the density of
the resultant solution (should be in the ball park of 1.3 g/mL). I'm
fairly certain of the calculation off the top of my head.

Please note this is a battery so if your off by a few percent it will
be ok. The redox chemistry of a NiFe battery is such that the plates
aren't reduced but rather the electrolyte. Worse case scenario is
you'd merely have to redo the KOH solution. If you get too much KOH
the cell will become less responsive due to an increase in the
concentration gradient as the ions build up at the interface of the
plates. Too low of a concentration ... well ... it simply won't
produce the power/capacity your expecting. Evaporation will be your
enemy as water is produced, top off with additional KOH solution (31%
or 45% depending upon which one is intended for the battery).

Hope this helps,

Ralph.





> Werner Peters <[email protected]> wrote:
> > Guys, I am now looking to source KOH (potassium hydroxide) for the Nickel
> > Iron batteries that I found.
> > Please look at this link and tell me if this is what I need?
> ...


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## EVDL List (Jul 27, 2007)

mmm ... NiCd and NiFe electrolytes are not the same; NiFe's only
require KOH (trace amounts of other compounds and metals are most
probable ... but only "trace" amounts). The iron would probably
reduce in the electrolyte of a NiCd battery leaving you with a chunk
of metal encased in plastic - good only as a very impractical giant
paper weight ...





> Rod Hower <[email protected]> wrote:
> > This is for the SAFT - STM-180 battery, which I think
> > has the same specific gravity as the NiFe?
> > I'm not even 90% sure it's the same, but here's the
> ...


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## EVDL List (Jul 27, 2007)

>From what I understand, the electrolyte for the Eagle-Picher NiFe batteries 
is straight dilute KOH. The Saft formula is not. 

NiCd and NiFe have some general characteristics in common, but the 
implementation details appear to be quite different.

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


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## EVDL List (Jul 27, 2007)

I am not a chemist, but I took a chemistry class last term.

The equation for calculating concentration is:

C(1) * V(1) = C(2) * V(2)

where C is concentration and V is volume.

So if you start with one liter of 45% solution and you want 31% 
solution:

0.45 * 1 = 0.31 * V(2)

V(2) = 0.45 / 0.31 = about 1.45

So if you add about 0.45 liters of water to one liter of 45% solution 
you should have 1.45 liters of 31% solution.

The units are unimportant. You can use cups, gallons, liters, gills, 
firkins, etc. as long as you stay consistent.

Stir it well then check it with the hydrometer to be sure 



> Werner Peters wrote:
> 
> > I am no chemist either. Do I just continue to dilute it with distilled
> > water
> ...


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## EVDL List (Jul 27, 2007)

This is only correct if it's 45% by volume. However, I'm pretty sure
it's 45% by mass, which will lead to a different result. (There's also
45% by molarity, but that's just ugly.)

-Morgan LaMoore



> Doug Weathers <[email protected]> wrote:
> > I am not a chemist, but I took a chemistry class last term.
> >
> > The equation for calculating concentration is:
> ...


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## EVDL List (Jul 27, 2007)

Either method will work - this is a dilution; set the molar (M)
equation up and solve for V1 (your wanting to make a known amount of a
31% solution using the 45% soulution) ... so you need to know the
amount of 45% to dilute.

Your equation would look like: M1 * V1 = M2 * V2
45% * X = 31% * 1L
X = 31% * 1L / 45%
X = 0.689 L of the 45%
solution diluted to 1 L
to make 1 L of a 31% KOH solution.


Ralph.





> Doug Weathers <[email protected]> wrote:
> > I am not a chemist, but I took a chemistry class last term.
> >
> > The equation for calculating concentration is:
> ...


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## EVDL List (Jul 27, 2007)

I believe that the alkali (whether solid or liquid) should be added to the water
and not the otherway around ( i.e., adding water to the alkali). The reaction is
exothermic and there could be rather unpleasant comsequences...

regards
hg.

R Patterson wrote:
> 
> That assay is for 45% KOH, which will not need dilution if the battery
> calls for 45%. If it's 31% you want then you will need to make a
> dilution with distilled water ... You can try the dilution by trial
> and error but best to calculate the dilution rate and then adjust the
> specific gravity by either adding water (to lower the S.G.) or
> additional 45%KOH (to increase the S.G.). If you don't have a
> hygrometer then you can do the measurement with some analytical scales
> and a volumetric pipet and calculating the density of the solution.
> 
> If you want to do the dilution (which is simpler) take 0.688 L (or 688
> mL) of the 45% solution and add enough distilled water to make 1 L (or
> 1000 mL). Mix well (exothermic reaction), then check the density of
> the resultant solution (should be in the ball park of 1.3 g/mL). I'm
> fairly certain of the calculation off the top of my head.
> 
> Please note this is a battery so if your off by a few percent it will
> be ok. The redox chemistry of a NiFe battery is such that the plates
> aren't reduced but rather the electrolyte. Worse case scenario is
> you'd merely have to redo the KOH solution. If you get too much KOH
> the cell will become less responsive due to an increase in the
> concentration gradient as the ions build up at the interface of the
> plates. Too low of a concentration ... well ... it simply won't
> produce the power/capacity your expecting. Evaporation will be your
> enemy as water is produced, top off with additional KOH solution (31%
> or 45% depending upon which one is intended for the battery).
> 
> Hope this helps,
> 
> Ralph.
> 
>


> Werner Peters <[email protected]> wrote:
> > > Guys, I am now looking to source KOH (potassium hydroxide) for the Nickel
> > > Iron batteries that I found.
> > > Please look at this link and tell me if this is what I need?
> ...


----------



## EVDL List (Jul 27, 2007)

OK ... it doesn't doesn't matter:

45% KOH * 56.11 g KOH/L = 25.25 g KOH / L = 0.45M KOH
31% KOH * 56.11 g KOH/L = 17.394 g KOH / L = 0.31M KOH

So now we have:
0.45M KOH * X L = 0.31M KOH * 1L

Solve for X = 0.689 L of 0.45M KOH diluted to the 1 L mark.

Total alkalinity as KOH by mass is given as 45% - 46% per the assay pdf.

No I didn't stay at a Holiday Inn Express last night ... I'm a chemist.





> Morgan LaMoore <[email protected]> wrote:
> > This is only correct if it's 45% by volume. However, I'm pretty sure
> > it's 45% by mass, which will lead to a different result. (There's also
> > 45% by molarity, but that's just ugly.)
> ...


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## EVDL List (Jul 27, 2007)

Thanks guys.. I will save these emails.. and when I get the stuff, I will
study these formulas carefully.

Werner



> R Patterson <[email protected]> wrote:
> 
> > OK ... it doesn't doesn't matter:
> >
> ...


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## EVDL List (Jul 27, 2007)

Disclaimer, I don't know Sh*t about the requirements
are for NiFe batteries, I was just quoting a passage
out of the SAFT STM-180 batteries manual. If NiFE
requires only KOH, I got some from Jim Wierick, who
purchased my electric 1984 fiero and used STM-180's
for awhile. The KOH I have is from T.S.C.C, 1024 S.
Victoria, Corona, CA 92879,
909-817-1962.
Thomas Schuster




> --- R Patterson <[email protected]> wrote:
> 
> > mmm ... NiCd and NiFe electrolytes are not the same;
> > NiFe's only
> ...


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## EVDL List (Jul 27, 2007)

Crud ... need to get my money back on that Holiday Express room.

percent composition = (msolute / msolution) x 100
percent composition = 45% =( 45 g KOH/ 100 g Solution) x 100
--> m of solvent = 55g for H20 1g = 1mL
percent compostion = 45%
so that now 45% KOH =

45g KOH * (1mole KOH / 56.11g KOH) = 0.802 moles of KOH in 55mL of H20
= 14.582 M KOH

Likewise 31% KOH = 31g KOH + 69 g H20 = 31 g KOH / 100 g solution

31g KOH * (1mole KOH / 56.11g KOH) = 0.553 moles of KOH in 69mL of H20
= ~8 M KOH

(Now this is starting to sound correct.)

So ... using (M1)(V1) = (M2)(V2)

(14.582M KOH) ( X L) = (8M KOH) (1 L)
X = 0.549 L of 45% (which is 14.582M) diluted to 1 L will give you 31%
KOH (which is 8M)

There.

I'll sleep outside by the pool for that one.

Ralph.






> R Patterson <[email protected]> wrote:
> > OK ... it doesn't doesn't matter:
> >
> > 45% KOH * 56.11 g KOH/L = 25.25 g KOH / L = 0.45M KOH
> ...


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## EVDL List (Jul 27, 2007)

And one more comment,
Chemcat wrote,
"No I didn't stay at a Holiday Inn Express last night
... I'm a chemist."
That's good, thanks for the smile 
Rod


> --- Rod Hower <[email protected]> wrote:
> 
> > Disclaimer, I don't know Sh*t about the requirements
> > are for NiFe batteries, I was just quoting a passage
> ...


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## EVDL List (Jul 27, 2007)

On Wed, 4 Jun 2008 10:01:24 -0400, "Werner Peters" <[email protected]>


> wrote:
> 
> >Guys, I am now looking to source KOH (potassium hydroxide) for the Nickel
> >Iron batteries that I found.
> ...


----------



## EVDL List (Jul 27, 2007)

I'm beginning to feel like th guy who has 10 clocks, and they all agree
except one or two. Now he never knows what the real time is.

I was doing fine until this last post..

One dissenting voice in that whoile bunch. Shall I order the KoH as found in
the link?

http://www.canadacolors.com/canadacolors/docs/spec/295404.pdf

Werner



> Neon John <[email protected]> wrote:
> 
> > On Wed, 4 Jun 2008 10:01:24 -0400, "Werner Peters" <[email protected]>
> > wrote:
> ...


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## EVDL List (Jul 27, 2007)

I personally would get the pellets from Fisher Scientific. ACS
standards of purity vs. industrial batches that can vary ... go with
ACS (Fisher). The pellets store nicely and are easy to work with
(just remember to never leave the container open very long as the
pellets will absorb water).

The ACS grade pellets would additionally reduce the interference from
the additional ions found in the SODROX product. Otherwise I don't
see any reason why the SODROX KOH wouldn't work ... and at the onset I
don't see any contaminant that would greatly interfere with it as an
electrolyte. Electrolytes are most commonly technical grade
chemicals, meaning they are not as refined as reagent grade chemicals.

I knew I had read something somewhere ... try this article:

http://www.homepower.com/article/?file=HP90_pg156_QandA_1

Just make sure you get KOH and not NaOH. With the homebrew of
biodiesel, don't let anyone convience you that NaOH is a substitute
for KOH (for biodiesel yes, for a NiFe battery no).


Ralph.




> Werner Peters <[email protected]> wrote:
> > I'm beginning to feel like th guy who has 10 clocks, and they all agree
> > except one or two. Now he never knows what the real time is.
> >
> ...


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