sealed (air tight) rechargable battery technology

[Ken Smith]

In article <pan.2005.04.27.02.08.47.328368@att.bizzzz>,
keith <krw@att.bizzzz> wrote:
[... SLA in tough environment lasting a year ...]

I'm really surprised they lasted that long. ...though low temperature
doesn't tend to ruin L-A batteries (unless they freeze). They *couldn't*
have had much capacity at those temperatures (-40C, or worse?)

The most common failure was due to the plates being mechanically weak. In
some versions of the battery, the plates are held in place only by the
lead joint that also serves to hook the cells together. In the better
ones, the plastic case has a tight fit on the plates holding them firmly
in place.

We developed a simple test. You hold the battery in your hand and shake
it. If the insides rattle, the battery is no good for the purpose.

It seems that, there are two factories in China that make all the SLAs in
the world regardless of the makers labels. One factory makes good ones,
the other makes bad ones. The various labels contract with which ever
offers the lower price. The result is that the exact same part number
from a given maker can suddenly be a totally different battery inside. A
competing brand could then suddenly be the former version.

At low temperatures, a 3AH SLA can still make a few hundred mA when
charged. When they run they tend to warm up a bit. At cold temperatures,
the batteries can't ever be fully discharged for fear of raising the
freeze point too high. As a battery discharges, the electrolyte becomes
more like just water. The gelling agent, I believe, makes the ice
crystals tend to be small and isolated but does not prevent the eventual
freeze up.

"D") Cyclons we used were mounted vertically, in a "bullet-proof",
nickel-plated, vented case that went for $1500 (blush).

Good price, if you can get it

No, it was rather embarrasing when I found this out. I had to snake out of
a design probem by telling field-service to replace the batteries
every one to three years insted of eight (which would have meant that they
never would have been replaced). "Come on! The damned bateries are worth
$15!" :-(

I've had to face the same embarrasement. The numbers in my case are $6
and $150.

How about captuing the energy from the people shivering? ;-)

When you are just about to freeze to death, you stop shivering, so we had
to reject that idea.


--
--
kensmith@rahul.net forging knowledge

 

[keith]

On Tue, 26 Apr 2005 14:03:09 +0000, Ken Smith wrote:

In article <pan.2005.04.26.02.08.04.675306@att.bizzzz>,
keith <krw@att.bizzzz> wrote:
[...]
Ok, your environment is a *little* more extreme than my Class-A computer
room. I don't think your batteries are going to last 10 years either. ;-)

If they make it through more than a year, customers will be somewhere in
the happy-delighted span of the scale so I was not too bothered by the
shortened life I expected.

I'm really surprised they lasted that long. ...though low temperature
doesn't tend to ruin L-A batteries (unless they freeze). They *couldn't*
have had much capacity at those temperatures (-40C, or worse?)

"D") Cyclons we used were mounted vertically, in a "bullet-proof",
nickel-plated, vented case that went for $1500 (blush).

Good price, if you can get it

No, it was rather embarrasing when I found this out. I had to snake out of
a design probem by telling field-service to replace the batteries
every one to three years insted of eight (which would have meant that they
never would have been replaced). "Come on! The damned bateries are worth
$15!" :-(

SLACs sound like the right solution. Maybe Peltiers with one side in
your arm pit? ;-)


There were several ideas like that rejected for reasons of cost and not
making enough current. The best second option we had was the "hamster
wheel" generator. PETA[1] got in a complete uproar over the abuse of
the poor animal being forced to work in the same environment as the
human.

How about captuing the energy from the people shivering? ;-)

PETA does not stand for People Eating Tasty Animals

So says Network Solutions, anyway. ;-)

--
Keith

 

[Ian Stirling]

Ken Smith <kensmith@green.rahul.net> wrote:

In article <426e9d1f$0$83051$ed2619ec@ptn-nntp-reader01.plus.net>,
Ian Stirling <root@mauve.demon.co.uk> wrote:
[... batteries in nasty environment ...]

Actually, lithium works quite well for this.
The lower the average charge state is, the greater the cells life.
As long as you have proper control, and don't overdischarge (under 3V)
or overcharge (more than 4.2/43V), and match the cells right, lithium
could be a fairly good match.

Cost is of course a problem.

The Lithiums I was looking at didn't like the cold and yes were very
costly.

AIUI, only charging at very low temps is a problem.

I could also never get it on paper that they had solved the "exploding in
flames" problem on the higher power ones. I could for the smaller ones
though.

As long as you don't screw up on the charge control, or overheat
them by packing too densely, or not taking care of temperature
and charging, or discharging, they are fine.

In the end SLAs just looked like the right one to pick.

Still good, in many cases.
Annoyingly heavy in many others though.

 

[Ken Smith]

In article <4275f3d5$0$559$ed2e19e4@ptn-nntp-reader04.plus.net>,
Ian Stirling <root@mauve.demon.co.uk> wrote:

Ken Smith <kensmith@green.rahul.net> wrote:
In article <426e9d1f$0$83051$ed2619ec@ptn-nntp-reader01.plus.net>,
[...]
I could also never get it on paper that they had solved the "exploding in
flames" problem on the higher power ones. I could for the smaller ones
though.

As long as you don't screw up on the charge control, or overheat
them by packing too densely, or not taking care of temperature
and charging, or discharging, they are fine.

I had no control over the temperature of the environment. I could control
the charging but I did have to charge them in any temperature.

In the end SLAs just looked like the right one to pick.

Still good, in many cases.
Annoyingly heavy in many others though.

Yes they ended up being most of the weight of the product. That was
considered OK. If they had more energy per unit volume, it would be
better. Zinc-air would be a lot better from that point of view but they
can't be sealed in use.


--
--
kensmith@rahul.net forging knowledge

 

[Ian Stirling]

Ken Smith <kensmith@green.rahul.net> wrote:

In article <4275f3d5$0$559$ed2e19e4@ptn-nntp-reader04.plus.net>,
Ian Stirling <root@mauve.demon.co.uk> wrote:
Ken Smith <kensmith@green.rahul.net> wrote:
In article <426e9d1f$0$83051$ed2619ec@ptn-nntp-reader01.plus.net>,
[...]
I could also never get it on paper that they had solved the "exploding in
flames" problem on the higher power ones. I could for the smaller ones
though.

As long as you don't screw up on the charge control, or overheat
them by packing too densely, or not taking care of temperature
and charging, or discharging, they are fine.

I had no control over the temperature of the environment. I could control
the charging but I did have to charge them in any temperature.

IIRC, it is only in very low temps, -20C?
A small heater is an obvious solution.
However, if SLA works.

In the end SLAs just looked like the right one to pick.

Still good, in many cases.
Annoyingly heavy in many others though.

Yes they ended up being most of the weight of the product. That was
considered OK. If they had more energy per unit volume, it would be
better. Zinc-air would be a lot better from that point of view but they
can't be sealed in use.

In theory they can, but then you need a source of oxygen, which gets messy,
and is almost certainly not worth it.

 

[Ken Smith]

In article <427694f1$0$567$ed2619ec@ptn-nntp-reader03.plus.net>,
Ian Stirling <root@mauve.demon.co.uk> wrote:
[....]

Yes they ended up being most of the weight of the product. That was
considered OK. If they had more energy per unit volume, it would be
better. Zinc-air would be a lot better from that point of view but they
can't be sealed in use.

In theory they can, but then you need a source of oxygen, which gets messy,
and is almost certainly not worth it.

One of the other engineers suggested a SNAP unit. This met all the
requirements but there were some minor problems with the regulations so I
went with SLA.


--
--
kensmith@rahul.net forging knowledge

 

[keith]

On Tue, 03 May 2005 00:09:32 +0000, Ken Smith wrote:

In article <427694f1$0$567$ed2619ec@ptn-nntp-reader03.plus.net>,
Ian Stirling <root@mauve.demon.co.uk> wrote:
[....]
Yes they ended up being most of the weight of the product. That was
considered OK. If they had more energy per unit volume, it would be
better. Zinc-air would be a lot better from that point of view but they
can't be sealed in use.

In theory they can, but then you need a source of oxygen, which gets messy,
and is almost certainly not worth it.


One of the other engineers suggested a SNAP unit. This met all the
requirements but there were some minor problems with the regulations so I
went with SLA.

Ah yes, your comment about the Peltier under the armpit. ;-)

--
Keith

 

[Mark W. Lund, PhD]

Ian Stirling wrote:

Ken Smith <kensmith@green.rahul.net> wrote:

....

The Lithiums I was looking at didn't like the cold and yes were very
costly.


AIUI, only charging at very low temps is a problem.

It is bad to charge a lithium-ion or lithium-polymer battery below
zero degrees C. The graphite can't absorb the ions and you start
plating out lithium metal. More details on this are at
http://www.powerstream.com/blog.htm

--
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PowerStream Technology ** Custom Power Supplies
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