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70 Posts
Discussion Starter #1
Sitting here looking at my spreadsheets for the monthly hydrometer
readings. I alternate month to month, with one month taking hydrometer
readings before my monthly "equalization" charge, the next month taking
after (about 24 hours) the equalization charge. So for the last two months:

(date format: mm/dd/yy)
equalization before:
date: 10/03/10 min cell: 1273 max cell: 1299 spread: 26
avg: 1284 standard deviation: 6.16

equalization after:
date: 10/31/10 min cell: 1259 max cell: 1290 spread: 31
avg: 1277 standard deviation: 6.86

The max cell just about always seems to be battery 16 cell 3. Usually
the lowest cell is one in battery 9, but not always, although battery 9
took the longest to gas down to 1/2". Several months ago (maybe it's
been a year), I dropped the electrolyte level from 1/4" to 1/2" below
the filler well. I think things are happier down here at 1/2". But I
debate at times whether to hold 16/3 at a little higher electrolyte
level. It just gets a little more complicated, then remembering that
cell (and maybe some others almost as high sg) are to have, say, 1/3".
One reason I might want to move up is 1300sg is probably where grid
corrosion effects start to step it up.

I remember from an EAA CurrentEVents article back in the 90s that a 25pt
spread or less was considered a balanced pack. Of course, that may not
tell you everything, such as a pack load test @ 75A. But I can come
within a pt or two of that 25 after an equalization charge. Mike
Slominski and his amazing Rabbit was the one mentioned in that article
about <=25pts. I remember hearing about Clare Bell and how she would
run her pack "hot", with 1300sg cells; don't last as long, but more fun!

Any thoughts on moving up with the electrolyte or grid corrosion vs sg?

This is a pack of 16 US2200XCs in my Rabbit. Obtained pack in Jan.
2009. There are about 6000mi and about 500 discharge/charge cycles on
them. The phase 2 constant voltage (~US-recommended 2.58V/cell) stage
does seem to be taking a bit more current now, say up to 2.5-3A at the
minimum, whereas earlier it would zoom down below 2A. Also, the peak
voltage under equalization for the pack at my constant 6A is not quite
as high, down from 131-2V to 129-130V. So things are starting to age a
bit, as expected. So far I think this is my most stable pack of the
four I've had in the last 16 years, and I want to keep it that way.

Thanks,
Chuck

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70 Posts
Discussion Starter #2
Hello Chuck,

The term "1.300 sg hot" is from the initial mixing of 5 parts of water
(1.000 sg) with 3 parts of acid - H2SO4 (1.800 sg). I ran a military
battery shop back in the 50's where we mix these parts to make 1.300 sg hot.
When the electrolyte cool, the reading would come down to 1.277 sg if we mix
it right.

The 1.300 sg hot is also cause by over charging and/or letting the
electrolyte level drop which boils off the water.

We take a large glass jar which we first add 5 parts of distill water and
then slowly pour in 3 parts of the acid. Do not pour the water into the
acid.

This makes (5 x 1.000) + (3 x 1.800) = 10.4

Then the average of 8 parts = 10.4 / 8 = 1.300 sg hot which then cools down
to 1.277 SG.

To make 1.300 cold, you have increase the amount of acid where it will
become 1.325 hot and about 1.300 cold.

I first EV back in 75 had large 300 AH 2 volt cells which had 1.300 sg
electrolyte cold. I drove the EV for 10 years with only 3 cell
replacements. If the electrolyte was 1.300 hot, the cells would not last
that long.

It is common to run a higher specific gravity in colder climates. I have
read about readings up to the 1.420 range at temperatures in the -30 below.

Roland


----- Original Message -----
From: "Chuck Hursch" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, November 03, 2010 2:50 PM
Subject: [EVDL] Hmm, fine tuning those cells


> Sitting here looking at my spreadsheets for the monthly hydrometer
> readings. I alternate month to month, with one month taking hydrometer
> readings before my monthly "equalization" charge, the next month taking
> after (about 24 hours) the equalization charge. So for the last two
> months:
>
> (date format: mm/dd/yy)
> equalization before:
> date: 10/03/10 min cell: 1273 max cell: 1299 spread: 26
> avg: 1284 standard deviation: 6.16
>
> equalization after:
> date: 10/31/10 min cell: 1259 max cell: 1290 spread: 31
> avg: 1277 standard deviation: 6.86
>
> The max cell just about always seems to be battery 16 cell 3. Usually
> the lowest cell is one in battery 9, but not always, although battery 9
> took the longest to gas down to 1/2". Several months ago (maybe it's
> been a year), I dropped the electrolyte level from 1/4" to 1/2" below
> the filler well. I think things are happier down here at 1/2". But I
> debate at times whether to hold 16/3 at a little higher electrolyte
> level. It just gets a little more complicated, then remembering that
> cell (and maybe some others almost as high sg) are to have, say, 1/3".
> One reason I might want to move up is 1300sg is probably where grid
> corrosion effects start to step it up.
>
> I remember from an EAA CurrentEVents article back in the 90s that a 25pt
> spread or less was considered a balanced pack. Of course, that may not
> tell you everything, such as a pack load test @ 75A. But I can come
> within a pt or two of that 25 after an equalization charge. Mike
> Slominski and his amazing Rabbit was the one mentioned in that article
> about <=25pts. I remember hearing about Clare Bell and how she would
> run her pack "hot", with 1300sg cells; don't last as long, but more fun!
>
> Any thoughts on moving up with the electrolyte or grid corrosion vs sg?
>
> This is a pack of 16 US2200XCs in my Rabbit. Obtained pack in Jan.
> 2009. There are about 6000mi and about 500 discharge/charge cycles on
> them. The phase 2 constant voltage (~US-recommended 2.58V/cell) stage
> does seem to be taking a bit more current now, say up to 2.5-3A at the
> minimum, whereas earlier it would zoom down below 2A. Also, the peak
> voltage under equalization for the pack at my constant 6A is not quite
> as high, down from 131-2V to 129-130V. So things are starting to age a
> bit, as expected. So far I think this is my most stable pack of the
> four I've had in the last 16 years, and I want to keep it that way.
>
> Thanks,
> Chuck
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
 

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Registered
Joined
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70 Posts
Discussion Starter #3
Hi Roland,

I think, though, that Clare ran her electrolyte "strong" shall we say
(instead of "hot") for less internal resistance in the batteries. She
was one who liked performance in her Porsche 914, and wasn't above
trying and succeeding at such things as the 2000+' hill climb on Hi17
between Santa Cruz and San Jose. She had a 120V pack of 6V floodies.
She also liked to drive fast. Her exploits are well documented in the
CurrentEVent issues in the 90s as I remember them.

My own sg readings are temp compensated. I wonder if that's what you're
talking about when going from 1300 to 1277 in your first paragraph, and
also that 1420 reading in your last paragraph; off-hand I don't know
what the temp compensation would be for -30, but given that it's about 6
points for roughly 20 deg from 77 to 60, then say 4 of those * 6 or 24
point compensation, sooo, no I can't cover your 1420. Maybe it's not
linear, although it looks linear on my hydrometer scale. This cooling
down you talk about appears to be something else from my hydrometer
reading temperature compensation.

Thanks,
Chuck

Roland Wiench wrote:
> Hello Chuck,
>
> The term "1.300 sg hot" is from the initial mixing of 5 parts of water
> (1.000 sg) with 3 parts of acid - H2SO4 (1.800 sg). I ran a military
> battery shop back in the 50's where we mix these parts to make 1.300 sg hot.
> When the electrolyte cool, the reading would come down to 1.277 sg if we mix
> it right.
>
> The 1.300 sg hot is also cause by over charging and/or letting the
> electrolyte level drop which boils off the water.
>
> We take a large glass jar which we first add 5 parts of distill water and
> then slowly pour in 3 parts of the acid. Do not pour the water into the
> acid.
>
> This makes (5 x 1.000) + (3 x 1.800) = 10.4
>
> Then the average of 8 parts = 10.4 / 8 = 1.300 sg hot which then cools down
> to 1.277 SG.
>
> To make 1.300 cold, you have increase the amount of acid where it will
> become 1.325 hot and about 1.300 cold.
>
> I first EV back in 75 had large 300 AH 2 volt cells which had 1.300 sg
> electrolyte cold. I drove the EV for 10 years with only 3 cell
> replacements. If the electrolyte was 1.300 hot, the cells would not last
> that long.
>
> It is common to run a higher specific gravity in colder climates. I have
> read about readings up to the 1.420 range at temperatures in the -30 below.
>
> Roland
>
>
> ----- Original Message -----
> From: "Chuck Hursch" <[email protected]>
> To: "Electric Vehicle Discussion List" <[email protected]>
> Sent: Wednesday, November 03, 2010 2:50 PM
> Subject: [EVDL] Hmm, fine tuning those cells
>
>
>> Sitting here looking at my spreadsheets for the monthly hydrometer
>> readings. I alternate month to month, with one month taking hydrometer
>> readings before my monthly "equalization" charge, the next month taking
>> after (about 24 hours) the equalization charge. So for the last two
>> months:
>>
>> (date format: mm/dd/yy)
>> equalization before:
>> date: 10/03/10 min cell: 1273 max cell: 1299 spread: 26
>> avg: 1284 standard deviation: 6.16
>>
>> equalization after:
>> date: 10/31/10 min cell: 1259 max cell: 1290 spread: 31
>> avg: 1277 standard deviation: 6.86
>>
>> The max cell just about always seems to be battery 16 cell 3. Usually
>> the lowest cell is one in battery 9, but not always, although battery 9
>> took the longest to gas down to 1/2". Several months ago (maybe it's
>> been a year), I dropped the electrolyte level from 1/4" to 1/2" below
>> the filler well. I think things are happier down here at 1/2". But I
>> debate at times whether to hold 16/3 at a little higher electrolyte
>> level. It just gets a little more complicated, then remembering that
>> cell (and maybe some others almost as high sg) are to have, say, 1/3".
>> One reason I might want to move up is 1300sg is probably where grid
>> corrosion effects start to step it up.
>>
>> I remember from an EAA CurrentEVents article back in the 90s that a 25pt
>> spread or less was considered a balanced pack. Of course, that may not
>> tell you everything, such as a pack load test @ 75A. But I can come
>> within a pt or two of that 25 after an equalization charge. Mike
>> Slominski and his amazing Rabbit was the one mentioned in that article
>> about <=25pts. I remember hearing about Clare Bell and how she would
>> run her pack "hot", with 1300sg cells; don't last as long, but more fun!
>>
>> Any thoughts on moving up with the electrolyte or grid corrosion vs sg?
>>
>> This is a pack of 16 US2200XCs in my Rabbit. Obtained pack in Jan.
>> 2009. There are about 6000mi and about 500 discharge/charge cycles on
>> them. The phase 2 constant voltage (~US-recommended 2.58V/cell) stage
>> does seem to be taking a bit more current now, say up to 2.5-3A at the
>> minimum, whereas earlier it would zoom down below 2A. Also, the peak
>> voltage under equalization for the pack at my constant 6A is not quite
>> as high, down from 131-2V to 129-130V. So things are starting to age a
>> bit, as expected. So far I think this is my most stable pack of the
>> four I've had in the last 16 years, and I want to keep it that way.
>>
>> Thanks,
>> Chuck
>>
>> _______________________________________________
>> | REPLYING: address your message to [email protected] only.
>> | Multiple-address or CCed messages may be rejected.
>> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> | OTHER HELP: http://evdl.org/help/
>> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>


_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
 

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Registered
Joined
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70 Posts
Discussion Starter #4
Hello Chuck,

When initialing mixing the acid with a specific gravity of 1.800 to water,
the reaction cause the electrolyte temperature to increase to about 110 to
120 F which reads about 1.300 sg.

As the electrolyte cools down to about 78 to 80 F. the electrolyte should
read about 1.277 SG.

As the ambient drops, the specific gravity of the acid can be mix with water
until until there is no water which would be actually be 1.800 sg. According
to my electro chemical hand book the 1.800 sg acid has a freezing point at
about 115- below and will be frozen, so you will not be going any where.

Roland





----- Original Message -----
From: "Chuck Hursch" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, November 04, 2010 3:40 PM
Subject: Re: [EVDL] Hmm, fine tuning those cells


> Hi Roland,
>
> I think, though, that Clare ran her electrolyte "strong" shall we say
> (instead of "hot") for less internal resistance in the batteries. She
> was one who liked performance in her Porsche 914, and wasn't above
> trying and succeeding at such things as the 2000+' hill climb on Hi17
> between Santa Cruz and San Jose. She had a 120V pack of 6V floodies.
> She also liked to drive fast. Her exploits are well documented in the
> CurrentEVent issues in the 90s as I remember them.
>
> My own sg readings are temp compensated. I wonder if that's what you're
> talking about when going from 1300 to 1277 in your first paragraph, and
> also that 1420 reading in your last paragraph; off-hand I don't know
> what the temp compensation would be for -30, but given that it's about 6
> points for roughly 20 deg from 77 to 60, then say 4 of those * 6 or 24
> point compensation, sooo, no I can't cover your 1420. Maybe it's not
> linear, although it looks linear on my hydrometer scale. This cooling
> down you talk about appears to be something else from my hydrometer
> reading temperature compensation.
>
> Thanks,
> Chuck
>
> Roland Wiench wrote:
> > Hello Chuck,
> >
> > The term "1.300 sg hot" is from the initial mixing of 5 parts of water
> > (1.000 sg) with 3 parts of acid - H2SO4 (1.800 sg). I ran a military
> > battery shop back in the 50's where we mix these parts to make 1.300 sg
> > hot.
> > When the electrolyte cool, the reading would come down to 1.277 sg if we
> > mix
> > it right.
> >
> > The 1.300 sg hot is also cause by over charging and/or letting the
> > electrolyte level drop which boils off the water.
> >
> > We take a large glass jar which we first add 5 parts of distill water
> > and
> > then slowly pour in 3 parts of the acid. Do not pour the water into the
> > acid.
> >
> > This makes (5 x 1.000) + (3 x 1.800) = 10.4
> >
> > Then the average of 8 parts = 10.4 / 8 = 1.300 sg hot which then cools
> > down
> > to 1.277 SG.
> >
> > To make 1.300 cold, you have increase the amount of acid where it will
> > become 1.325 hot and about 1.300 cold.
> >
> > I first EV back in 75 had large 300 AH 2 volt cells which had 1.300 sg
> > electrolyte cold. I drove the EV for 10 years with only 3 cell
> > replacements. If the electrolyte was 1.300 hot, the cells would not
> > last
> > that long.
> >
> > It is common to run a higher specific gravity in colder climates. I
> > have
> > read about readings up to the 1.420 range at temperatures in the -30
> > below.
> >
> > Roland
> >
> >
> > ----- Original Message -----
> > From: "Chuck Hursch" <[email protected]>
> > To: "Electric Vehicle Discussion List" <[email protected]>
> > Sent: Wednesday, November 03, 2010 2:50 PM
> > Subject: [EVDL] Hmm, fine tuning those cells
> >
> >
> >> Sitting here looking at my spreadsheets for the monthly hydrometer
> >> readings. I alternate month to month, with one month taking hydrometer
> >> readings before my monthly "equalization" charge, the next month taking
> >> after (about 24 hours) the equalization charge. So for the last two
> >> months:
> >>
> >> (date format: mm/dd/yy)
> >> equalization before:
> >> date: 10/03/10 min cell: 1273 max cell: 1299 spread: 26
> >> avg: 1284 standard deviation: 6.16
> >>
> >> equalization after:
> >> date: 10/31/10 min cell: 1259 max cell: 1290 spread: 31
> >> avg: 1277 standard deviation: 6.86
> >>
> >> The max cell just about always seems to be battery 16 cell 3. Usually
> >> the lowest cell is one in battery 9, but not always, although battery 9
> >> took the longest to gas down to 1/2". Several months ago (maybe it's
> >> been a year), I dropped the electrolyte level from 1/4" to 1/2" below
> >> the filler well. I think things are happier down here at 1/2". But I
> >> debate at times whether to hold 16/3 at a little higher electrolyte
> >> level. It just gets a little more complicated, then remembering that
> >> cell (and maybe some others almost as high sg) are to have, say, 1/3".
> >> One reason I might want to move up is 1300sg is probably where grid
> >> corrosion effects start to step it up.
> >>
> >> I remember from an EAA CurrentEVents article back in the 90s that a
> >> 25pt
> >> spread or less was considered a balanced pack. Of course, that may not
> >> tell you everything, such as a pack load test @ 75A. But I can come
> >> within a pt or two of that 25 after an equalization charge. Mike
> >> Slominski and his amazing Rabbit was the one mentioned in that article
> >> about <=25pts. I remember hearing about Clare Bell and how she would
> >> run her pack "hot", with 1300sg cells; don't last as long, but more
> >> fun!
> >>
> >> Any thoughts on moving up with the electrolyte or grid corrosion vs sg?
> >>
> >> This is a pack of 16 US2200XCs in my Rabbit. Obtained pack in Jan.
> >> 2009. There are about 6000mi and about 500 discharge/charge cycles on
> >> them. The phase 2 constant voltage (~US-recommended 2.58V/cell) stage
> >> does seem to be taking a bit more current now, say up to 2.5-3A at the
> >> minimum, whereas earlier it would zoom down below 2A. Also, the peak
> >> voltage under equalization for the pack at my constant 6A is not quite
> >> as high, down from 131-2V to 129-130V. So things are starting to age a
> >> bit, as expected. So far I think this is my most stable pack of the
> >> four I've had in the last 16 years, and I want to keep it that way.
> >>
> >> Thanks,
> >> Chuck
> >>
> >> _______________________________________________
> >> | REPLYING: address your message to [email protected] only.
> >> | Multiple-address or CCed messages may be rejected.
> >> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> >> | OTHER HELP: http://evdl.org/help/
> >> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
> >>
> >
> > _______________________________________________
> > | REPLYING: address your message to [email protected] only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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