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70 Posts
Discussion Starter #1
Howdy,
=

I was thinking (it can happen) that I should shut off the charger when elec=
trolyte starts spitting out of my STM5-180 ni-cads on my E-Porsche. By pla=
cing two 2" long stainless or nickel plated probes on the exit tube and tyi=
ng to the A/D converter on my uP (MC68HC908QY4) that should do it (with a 1=
0k pull up resistor, one probe in and the other tied to GND). Since potass=
ium hydroxide is fairly conductive, the uP sees this line go low when spitt=
ing starts. It occurs (I get about a quart of electrolyte) on the subseque=
nt charge cycle after watering on the tail end of the previous cycle (charg=
e to 7A 1.73V per cell per saft manual). A spit detector/charge shut off s=
hould fix this problem as this is the "dirty little secret" of these ni-cad=
s. Is this true with all ni-cads? =

=

I've tried the recommended Saft manual of waiting 1 hour, Rod's 20 minutes =
and right at the tail end with no wait and I get the same spitting on the n=
ext cycle regardless. Some people use catch tanks but I have 3 watering ci=
rcuits so I have to put small plastic containers under each drain tube whil=
e charging and dunp back into a main container for the next water cycle, a =
PITA. =

=

Others have limited their final charge to 2-3A to reduce spitting at the ex=
pense of equalization. I could also put a switch on for a lower/higher cha=
rge finish rate, do 7A final when watering and 2-3A other times although I =
found a low battery or two when I finished at the lower rate.
=

Have a renewable energy day,
Mark in Ronaoke, VA
_________________________________________________________________
Climb to the top of the charts! Play Star Shuffle: the word scramble =
challenge with star power.
http://club.live.com/star_shuffle.aspx?icid=3Dstarshuffle_wlmailtextlink_oct
_______________________________________________
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Registered
Joined
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70 Posts
Discussion Starter #2
Mark,

I think there a couple of possible causes for the 'spitting'. The most
likely is that the water doesn't completely drain out from the tubing
when you do the watering cycle. When you charge the modules again and
they start their normal venting, the gas then pushes the remaining water
out.

You might try gently purging the tubing with air after the watering cycle.

Another possible cause of the 'spitting' problem is that you have too
much pressure on the watering system. This might cause the modules to
get overfilled. When they are charged again, this might vent out at
that point. The SAFT manual has specific limits on water pressure and
flow rate. Have you made sure that you're not exceeding these limits?

Ralph


Mark Hanson writes:
> =

> =

> Howdy,
> =

> I was thinking (it can happen) that I should shut off the charger when el=
ectrolyte starts spitting out of my STM5-180 ni-cads on my E-Porsche. By p=
lacing two 2" long stainless or nickel plated probes on the exit tube and t=
ying to the A/D converter on my uP (MC68HC908QY4) that should do it (with a=
10k pull up resistor, one probe in and the other tied to GND). Since pota=
ssium hydroxide is fairly conductive, the uP sees this line go low when spi=
tting starts. It occurs (I get about a quart of electrolyte) on the subseq=
uent charge cycle after watering on the tail end of the previous cycle (cha=
rge to 7A 1.73V per cell per saft manual). A spit detector/charge shut off=
should fix this problem as this is the "dirty little secret" of these ni-c=
ads. Is this true with all ni-cads? =

> =

> I've tried the recommended Saft manual of waiting 1 hour, Rod's 20 minute=
s and right at the tail end with no wait and I get the same spitting on the=
next cycle regardless. Some people use catch tanks but I have 3 watering =
circuits so I have to put small plastic containers under each drain tube wh=
ile charging and dunp back into a main container for the next water cycle, =
a PITA. =

> =

> Others have limited their final charge to 2-3A to reduce spitting at the =
expense of equalization. I could also put a switch on for a lower/higher c=
harge finish rate, do 7A final when watering and 2-3A other times although =
I found a low battery or two when I finished at the lower rate.
> =

> Have a renewable energy day,
> Mark in Ronaoke, VA
> _________________________________________________________________
> Climb to the top of the charts! Play Star Shuffle: the word scrambl=
e challenge with star power.
> http://club.live.com/star_shuffle.aspx?icid=3Dstarshuffle_wlmailtextlink_=
oct
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
> =


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Registered
Joined
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70 Posts
Discussion Starter #3
When I was using 8 of these on my motorcycle I just watered them manually w=
ith a funnel and piece of tubing. It only took a few minutes to do all 8. =
Depending on how accessible all your modules are you may want to remove th=
e tubing between the modules and just do them one at a time manually.

damon

> From: [email protected]
> To: [email protected]
> Date: Fri, 12 Oct 2007 06:50:46 -0700
> Subject: Re: [EVDL] Spit Detector
>
>
> Mark,
>
> I think there a couple of possible causes for the 'spitting'. The most
> likely is that the water doesn't completely drain out from the tubing
> when you do the watering cycle. When you charge the modules again and
> they start their normal venting, the gas then pushes the remaining water
> out.
>
> You might try gently purging the tubing with air after the watering cycle.
>
> Another possible cause of the 'spitting' problem is that you have too
> much pressure on the watering system. This might cause the modules to
> get overfilled. When they are charged again, this might vent out at
> that point. The SAFT manual has specific limits on water pressure and
> flow rate. Have you made sure that you're not exceeding these limits?
>
> Ralph
>
>
> Mark Hanson writes:
>>
>>
>> Howdy,
>>
>> I was thinking (it can happen) that I should shut off the charger when e=
lectrolyte starts spitting out of my STM5-180 ni-cads on my E-Porsche. By p=
lacing two 2" long stainless or nickel plated probes on the exit tube and t=
ying to the A/D converter on my uP (MC68HC908QY4) that should do it (with a=
10k pull up resistor, one probe in and the other tied to GND). Since potas=
sium hydroxide is fairly conductive, the uP sees this line go low when spit=
ting starts. It occurs (I get about a quart of electrolyte) on the subseque=
nt charge cycle after watering on the tail end of the previous cycle (charg=
e to 7A 1.73V per cell per saft manual). A spit detector/charge shut off sh=
ould fix this problem as this is the "dirty little secret" of these ni-cads=
. Is this true with all ni-cads?
>>
>> I've tried the recommended Saft manual of waiting 1 hour, Rod's 20 minut=
es and right at the tail end with no wait and I get the same spitting on th=
e next cycle regardless. Some people use catch tanks but I have 3 watering =
circuits so I have to put small plastic containers under each drain tube wh=
ile charging and dunp back into a main container for the next water cycle, =
a PITA.
>>
>> Others have limited their final charge to 2-3A to reduce spitting at the=
expense of equalization. I could also put a switch on for a lower/higher c=
harge finish rate, do 7A final when watering and 2-3A other times although =
I found a low battery or two when I finished at the lower rate.
>>
>> Have a renewable energy day,
>> Mark in Ronaoke, VA
>> _________________________________________________________________
>> Climb to the top of the charts! Play Star Shuffle: the word scramble c=
hallenge with star power.
>> http://club.live.com/star_shuffle.aspx?icid=3Dstarshuffle_wlmailtextlink=
_oct
>> _______________________________________________
>> For subscription options, see
>> http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_________________________________________________________________
Help yourself to FREE treats served up daily at the Messenger Caf=E9. Stop =
by today.
http://www.cafemessenger.com/info/info_sweetstuff2.html?ocid=3DTXT_TAGLM_Oc=
tWLtagline

_______________________________________________
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Registered
Joined
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70 Posts
Discussion Starter #4
Mark,
We used systolic pumps on the TEVan. At the end of a
water cycle we ran them in reverse for a few minutes
to purge the lines (this also prevented the excess
water from freezing).
Rod
--- Ralph Merwin <[email protected]> wrote:

>
> Mark,
>
> I think there a couple of possible causes for the
> 'spitting'. The most
> likely is that the water doesn't completely drain
> out from the tubing
> when you do the watering cycle. When you charge the
> modules again and
> they start their normal venting, the gas then pushes
> the remaining water
> out.
>
> You might try gently purging the tubing with air
> after the watering cycle.
>
> Another possible cause of the 'spitting' problem is
> that you have too
> much pressure on the watering system. This might
> cause the modules to
> get overfilled. When they are charged again, this
> might vent out at
> that point. The SAFT manual has specific limits on
> water pressure and
> flow rate. Have you made sure that you're not
> exceeding these limits?
>
> Ralph
>
>
> Mark Hanson writes:
> >
> >
> > Howdy,
> >
> > I was thinking (it can happen) that I should shut
> off the charger when electrolyte starts spitting out
> of my STM5-180 ni-cads on my E-Porsche. By placing
> two 2" long stainless or nickel plated probes on the
> exit tube and tying to the A/D converter on my uP
> (MC68HC908QY4) that should do it (with a 10k pull up
> resistor, one probe in and the other tied to GND).
> Since potassium hydroxide is fairly conductive, the
> uP sees this line go low when spitting starts. It
> occurs (I get about a quart of electrolyte) on the
> subsequent charge cycle after watering on the tail
> end of the previous cycle (charge to 7A 1.73V per
> cell per saft manual). A spit detector/charge shut
> off should fix this problem as this is the "dirty
> little secret" of these ni-cads. Is this true with
> all ni-cads?
> >
> > I've tried the recommended Saft manual of waiting
> 1 hour, Rod's 20 minutes and right at the tail end
> with no wait and I get the same spitting on the next
> cycle regardless. Some people use catch tanks but I
> have 3 watering circuits so I have to put small
> plastic containers under each drain tube while
> charging and dunp back into a main container for the
> next water cycle, a PITA.
> >
> > Others have limited their final charge to 2-3A to
> reduce spitting at the expense of equalization. I
> could also put a switch on for a lower/higher charge
> finish rate, do 7A final when watering and 2-3A
> other times although I found a low battery or two
> when I finished at the lower rate.
> >
> > Have a renewable energy day,
> > Mark in Ronaoke, VA
> >
>
_________________________________________________________________
> > Climb to the top of the charts! Play Star
> Shuffle: the word scramble challenge with star
> power.
> >
>
http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
For subscription options, see
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Discussion Starter #5
On 12 Oct 2007 at 8:35, Mark Hanson wrote:

> Is this true with all ni-cads?

What Ralph said.

Also, wild guess - could it be that one of your cells has a funny cap and is
getting overfilled when you water? They don't have any moving parts but if
one of the passages got plugged or something I suppose that might cause
problems.

http://www2.ald.net/~roden/ev/images/saft_wtr.jpg

David Roden - Akron, Ohio, USA
EVDL Administrator

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