Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).

I went grep-ing Digikey and all I found were "lithium"
batteries but I suspect these are intended for use in
"nonvolatile (data) backup" (i.e., low current rates)
and not actually used to *power* something. (I think
the battery is intended to last about 8 hours so I'm
guessing the load to be about 250mA?).

Can someone clarify what I need to go looking for?
And/or a pointer to a source for same (qty 1).

Thanks!

D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).

I went grep-ing Digikey and all I found were "lithium"
batteries but I suspect these are intended for use in
"nonvolatile (data) backup" (i.e., low current rates)
and not actually used to *power* something. (I think
the battery is intended to last about 8 hours so I'm
guessing the load to be about 250mA?).

Can someone clarify what I need to go looking for?
And/or a pointer to a source for same (qty 1).

Thanks!
google 18650.

spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).

google 18650.

Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

On Thu, 30 Jul 2009 08:13:41 -0700, D Yuniskis
wrote:

spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).

google 18650.

Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

Ummm.... Find a picture of a pig. Note the tail. There's no
semblance to a battery tab.

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

Ummm.... Google for "18650 tabs". There are also a mess of cells
available on Ebay using the same search key.

I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In article ,
Jeff Liebermann wrote:
I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.

I usually cut off the spot welded tabs from the old ones and solder these.
But don't know how LiIon react to heat. You've got to solder quickly with
other types to avoid damage.

--
*All men are idiots, and I married their King.

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 30 Jul 2009 19:01:04 +0100, "Dave Plowman (News)"
wrote:

In article ,
Jeff Liebermann wrote:
I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.

I usually cut off the spot welded tabs from the old ones and solder these.

Yep. Same here. I inherited a large box of Metricom battery packs.
When I ripped them apart for the cells, I kept all the tabs. They
solver very easily and are quite handy. They're also quite sharp. I
have the blood stains to prove it.

But don't know how LiIon react to heat. You've got to solder quickly with
other types to avoid damage.

Dunno. I killed a few NiCads from overheating until I learned the
trick. I have a glass of water handy when soldering on the tabs. As
soon as the solder even looks like it's about to harden, I dump the
battery in the water. That keeps things quite cool and prevents the
heat affected zone from spreading.

D Yuniskis wrote:
spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).

google 18650.

Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

buy cells with tabs.
do not solder to lithium cells!!!!! unless you have very good fire
insurance, medical insurance and a death wish.
Your wife will be very angry six months later when the GPS
sets her car on fire. So, if the battery doesn't hurt you, she will.

Just in case you missed it....DO NOT SOLDER DIRECTLY TO ANY BATTERY,
ESPECIALLY LITHIUMS. People will tell you they do it.
Are you feeling lucky?

You need a battery tab welder if you try to use non-tabbed cells.

Virtually every lithium ion laptop battery pack
ever made contains tabbed 18650 cells. Buy an old battery pack
and take it apart...carefully.
Sometimes, you can talk the radio shack guy to give you one from his
recycle bin. Or ask the IT guy at work.

Cut the tabs. You can (carefully) solder to the remaining part of the
tabs if they're 1/4 inch or more without overheating the cell.


Your gps (probably) takes significantly less peak current
than a laptop, so a weak laptop pack that's not completely dead
may provide useful cells for your application.

On Fri, 31 Jul 2009 00:37:21 -0700, spamme0
wrote:

buy cells with tabs.
do not solder to lithium cells!!!!! unless you have very good fire
insurance, medical insurance and a death wish.

Well, you're right. Heat will cause a Li-Ion battery pack to
deteriorate rather rapidly. There's also the fire danger. Several
web sites recommend against soldering directly to the can on Li-Ion
cells. For example:
http://www.electronics-lab.com/articles/Li_Ion_reconstruct/
http://www.panasonic.com/industrial/battery/oem/images/pdf/panasonic_liion_precautions.pdf
"Do not short circuit, overcharge, crush, mutilate, nail penetrate,
incinerate, reverse polarity, heat above 100 degrees Celsius, solder
directly on the metal can."

I guess I've been lucky as my method of dunking the battery into water
after soldering seems to have prevented any problems. However, in the
future, I probably won't take the chance. It's too risky.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

On Fri, 31 Jul 2009 00:37:21 -0700, spamme0
wrote:

buy cells with tabs.
do not solder to lithium cells!!!!! unless you have very good fire
insurance, medical insurance and a death wish.

Well, you're right. Heat will cause a Li-Ion battery pack to
deteriorate rather rapidly. There's also the fire danger. Several
web sites recommend against soldering directly to the can on Li-Ion
cells. For example:
http://www.electronics-lab.com/articles/Li_Ion_reconstruct/

http://www.panasonic.com/industrial/battery/oem/images/pdf/panasonic_liion_precautions.pdf
"Do not short circuit, overcharge, crush, mutilate, nail penetrate,
incinerate, reverse polarity, heat above 100 degrees Celsius, solder
directly on the metal can."

I guess I've been lucky as my method of dunking the battery into water
after soldering seems to have prevented any problems. However, in the
future, I probably won't take the chance. It's too risky.

Especially once you know what happens when you mix lithium and water - the
lithium catches fire.

Especially once you know what happens when you mix
lithium and water -- the lithium catches fire.

And we all know such batteries are so poorly sealed that water pours into
them the moment they're dunked in water...

On Sat, 01 Aug 2009 12:52:39 +0100, Nigel Feltham
wrote:

Jeff Liebermann wrote:

On Fri, 31 Jul 2009 00:37:21 -0700, spamme0
wrote:

buy cells with tabs.
do not solder to lithium cells!!!!! unless you have very good fire
insurance, medical insurance and a death wish.

Well, you're right. Heat will cause a Li-Ion battery pack to
deteriorate rather rapidly. There's also the fire danger. Several
web sites recommend against soldering directly to the can on Li-Ion
cells. For example:
http://www.electronics-lab.com/articles/Li_Ion_reconstruct/

http://www.panasonic.com/industrial/battery/oem/images/pdf/panasonic_liion_precautions.pdf
"Do not short circuit, overcharge, crush, mutilate, nail penetrate,
incinerate, reverse polarity, heat above 100 degrees Celsius, solder
directly on the metal can."

I guess I've been lucky as my method of dunking the battery into water
after soldering seems to have prevented any problems. However, in the
future, I probably won't take the chance. It's too risky.

Especially once you know what happens when you mix lithium and water - the
lithium catches fire.

Yep. That happens with metallic lithium. Li-Ion and LiPo batteries
use Lithium salts. These will oxidize violently if heated
sufficiently, such as when the battery is overcharged or rapidly self
discharged by pounding a nail into it. Lots of nice fires and
explosions on YouTube. For example:
http://www.youtube.com/watch?v=YCWdnjLqVWw

However, water incursion is a problem in that it causes the battery to
swell:
http://www.electronicsweekly.com/blogs/engineering-design-problems/2009/04/li-ion-battery-bloat-moisture.html
The plastic encased cell phone batteries seem to be fairly well
sealed. The tape wrapped variety found inside PDA's and iPod's are
not so well sealed. I tried dunking a dead battery I pulled from an
Palm something PDA in a class of water. It took about a week to
swell. The LG cell phone battery did not swell after about 2 weeks.
My guess(tm) is that the inside variety rely on the PDA, iPod, or
phone to provide the water proofing.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 02 Aug 2009 11:36:33 -0400, Meat Plow
wrote:

The Lithium Polymer battery is the most dangerous battery of its genre
on the planet.

Probably, but a Sodium Sulfur battery is more fun because it runs at
300C:
http://en.wikipedia.org/wiki/Sodium-sulfur_battery
Molten Salt batteries, which run at about the same temperature, are
also fun:
http://en.wikipedia.org/wiki/Molten_salt_battery


Not to mention a great source of lithium to aid in the manufacturing
of Meth.

Yech. I guess you're trying to reduce pseudo ephedrine cold pills
with thionyl chloride. To remove the alpha-hydroxy group to produce
N-methyl-alpha-chloroamphetamine you can hydrogenate that with lithium
aluminum hydride, but it's easier to just use pure hydrogen gas and a
platinum or nickel catalyst. Paint thinner, acetone, or kitchen drain
cleaner will also work. The result is N-methylamphetamine and
hydrochloric acid. Evaporate off the water and you have your
methamphetamine hydrochloride.

There was a semi-abandoned shack near my house that was used for a
meth lab. We didn't have a clue until we smelled the ether. One of
the neighbors bought the house from the now impoverished aspiring drug
manufacturer and discovered that the house was irrecoverably saturated
with meth in the drywall and wood. They tried ripping out the drywall
ceilings, but that didn't work. They eventually had to reduce the
house to a shell, rebuild everything inside, in order to recover.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
On Thu, 30 Jul 2009 08:13:41 -0700, D Yuniskis

spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).
google 18650.
Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

Ummm.... Find a picture of a pig. Note the tail. There's no
semblance to a battery tab.

Note the following: ;-)

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

Ummm.... Google for "18650 tabs". There are also a mess of cells
available on Ebay using the same search key.

Thanks. When I saw these were commonly used in laptop battery
packs, I just fished a couple of laptops out of the trash and
cannabilized the battery packs until I found cells with "decent"
open circuit voltages. Made sure I cut the tabs that connected
them to their neighbors so I would have a fair bit to work
with. Soldered some pigtails on and was able to replace the dead
battery in the GPS unit easily!

Rescued GPS unit: $0
Rescued Li Ion cell: $0
Working GPS unit: priceless

wink

I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.

I've never had luck trying to solder to these cans
(partly out of fear of letting the can get too hot!).

I've a friend who will make me a little welder but I
would have to fetch it from him (out of state) -- its
just not worth the effort for something I do so rarely!

Thanks, all, for the pointers!

Jeff Liebermann wrote:
On Thu, 30 Jul 2009 08:13:41 -0700, D Yuniskis

spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).
google 18650.
Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

Ummm.... Find a picture of a pig. Note the tail. There's no
semblance to a battery tab.

Note the following: ;-)

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

Ummm.... Google for "18650 tabs". There are also a mess of cells
available on Ebay using the same search key.

Thanks. When I saw these were commonly used in laptop battery
packs, I just fished a couple of laptops out of the trash and
cannabilized the battery packs until I found cells with "decent"
open circuit voltages. Made sure I cut the tabs that connected
them to their neighbors so I would have a fair bit to work
with. Soldered some pigtails on and was able to replace the dead
battery in the GPS unit easily!

Rescued GPS unit: $0
Rescued Li Ion cell: $0
Working GPS unit: priceless

wink

I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.

I've never had luck trying to solder to these cans
(partly out of fear of letting the can get too hot!).

I've a friend who will make me a little welder but I
would have to fetch it from him (out of state) -- its
just not worth the effort for something I do so rarely!

Thanks, all, for the pointers!

On Mon, 03 Aug 2009 14:15:05 -0400, Meat Plow
wrote:

On Sun, 02 Aug 2009 16:41:55 -0700, Jeff Liebermann
wrote:

On Sun, 02 Aug 2009 11:36:33 -0400, Meat Plow
wrote:

The Lithium Polymer battery is the most dangerous battery of its genre
on the planet.

Probably, but a Sodium Sulfur battery is more fun because it runs at
300C:
http://en.wikipedia.org/wiki/Sodium-sulfur_battery
Molten Salt batteries, which run at about the same temperature, are
also fun:
http://en.wikipedia.org/wiki/Molten_salt_battery

Yeah don't they use those for solar mirror array storage?

The sodium sulfur batteries are used in wind farms and solar
plantations for storing energy. Nothing like a few megawatts stored
in a small space. The molten salt batteries are used mostly in
missiles, artillery shells, bombs, and other places where you really
don't care about the condition of the battery near its end of life.
Add a little water to the metallic sodium, and you have a lovely
hydrogen-oxygen seperator, which at 350C, will merrily burn the
battery to the ground.

Note that the 1992 Ford Ecostar vehicle used a sodium sulfur battery.
http://www.greencar.com/articles/ford-ecostar-ev.php

Acetone and Camp Stove fuel are the staple reducers for Meth cookers
but they are looking for ways to use less volatile formulas. I guess
from what I saw lithium conversion is stable but doesn't produce as
pure of product but when you're hooked on that **** it doesn't really
matter what you jam in your arm as long as you get a buzz.

Bringing topic drift to a new all time low for sci.electronics.repair.

It's all probably a government conspiracy to kill off the meth addicts
by giving them a bad recipe and bad cooking instructions. Think of it
as accelerated evolution and saving tax dollars. The good may die
young, but so do the idiots.

Yeah contamination is a BIG deal. Just because the meth heads left
doesn't mean the meth and byproducts left too.

What I find disgusting is that most of the building contamination
problems are from the drug maker being in a hurry. Methamphetamine
hydrochloride isn't carried by the water evaporation process unless it
gets rapidly boiled off, which is often the case when the drug maker
is in a hurry. If they took their time, it wouldn't make as big a
mess. Kinda reminds me of my mis-spent youth making explosives. The
survivors were the slow and careful ones. Those in a hurry checked
out early.

People hooked un that
crap store it in the fridge right beside food, baby bottles
etc....It's a horrible chemical and after years of use it absolutely
destroys your nervous system.

Yeah, I've seen the results. Kinda messy. Standard procedure used to
be to give the newly arrested drug user a tour of the local neuro
rehab facility. That worked well for the recreational users, but not
for those that were physically addicted. However, the courts banned
this practice (possibly only in California) because it constituted
"cruel and unusual punishment".

snip

I've a friend who will make me a little welder but I
would have to fetch it from him (out of state) -- its
just not worth the effort for something I do so rarely!


I'd like to hear more about the welder design.

I messed around with low-voltage transformers, but never
got consistent welds. Was VERY sensitive to contact
resistance. About half the welds didn't stick.
The other half blew thru the tab.

Gave all that up when a CD welder
showed up on ebay for $15. It'll put 7000Amps into a milliohm.
Get MUCH more consistent tab welds.

If you have a chance to get an affordable tab welder,
you'll find other uses for it. And you'll have a lot of new
friends in need of tab welding ;-)

mike

In article ,
spamme0 wrote:
I'd like to hear more about the welder design.

I messed around with low-voltage transformers, but never
got consistent welds. Was VERY sensitive to contact
resistance. About half the welds didn't stick.
The other half blew thru the tab.

Think like all spot welds you need the correct current for the correct
time.

--
*Don't sweat the petty things and don't pet the sweaty things.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
spamme0 wrote:
I'd like to hear more about the welder design.

I messed around with low-voltage transformers, but never
got consistent welds. Was VERY sensitive to contact
resistance. About half the welds didn't stick.
The other half blew thru the tab.

Think like all spot welds you need the correct current for the correct
time.

I flat-out disagree with that statement.
Sure, you can play semantics with the words and claim it means anything
you want...but current/time control doesn't solve the repeatability
problem in the face of process variation.

If your resistance is zero, all the current in the world won't make a weld.
If your resistance is high, low current will blast holes thru the medium.

What you need is local temperature rise to fuse the metal together.

A current/time controlled weld is VERY sensitive to resistance.
If you have repeatable resistance and machine enforced pressure, you can
set the current/time
for the particular setup and make good welds...until something changes.

If you raise the minimum resistance, the variable portion becomes a smaller
percentage and welds get more repeatable. .005" sheet brass that you get
at the hobby store makes tabs that are much easier to weld.
I never used it in a battery pack because I didn't want that added
resistance and I was too lazy to look up the corrosion effects due to
the dissimilar metals.

A CD welder delivers energy and is much more forgiving of process
variations, ie pressure and resistance changes in a hand-operated
homebrew setup making welds on old used batteries.

A REAL battery tab welder hits it twice. The first shot stabilizes the
contact area and measures the resistance. The second shot uses results
from the first measurement to optimize the weld energy.

Re the discussion on making connections to battery cells: the summary
of the content so far is that soldering is dangerous, weldingis the
way to go, but is not trivial.

There's another possibility that I've seen read about but have no
experience with: conductive glue. From a commercial battery website I
saw (http://www.smallbattery.company.org....ire-glue.htm):

"Wire Glue - electrically conductive adhesive

Wire Glue utilizes the latest advances in microcarbon technology to
bring you a highly conductive glue at a fraction the price of
competitive products which use precious metals such as silver.

Wire Glue allows you to make low voltage AC and DC electrical
connections without soldering or heating.

There is no requirement to measure out and mix hardeners. Simply stir
and apply the glue to your surface and let it cure overnight. By
morning, you will have a reliable, permanent and electrically
conductive bond!

Cost-effective replacement for silver-loaded epoxies.

This lead free formulation is ideal for bonding all types of low
voltage electrical connections.

Wire Glue is not intended for high voltage or high current
applications. In high power circuits Wire Glue may become hot and give
off burning smells."

From another page on the same site:

"Can you make the tabbed cell I require?

We do not add tabs to order... Order a bare, untagged cell from us and
then carefully remove the existing tags from your dead cell. Apply the
Wire Glue to your cell's surface and to the tag, pop them together and
let it all cure overnight. By the morning your problems will be
solved."

This also suggests that you should be able to get similar but more
expensive silver-based glue. What current either will handle sensibly
I don't know - a data sheet would help.

HTH

In article
,
pol098 wrote:
Wire Glue is not intended for high voltage or high current
applications. In high power circuits Wire Glue may become hot and give
off burning smells."

Be nice if there was some guidance there. Most rechargeables can supply
very high current.

--
*Experience is something you don't get until just after you need it.*

Dave Plowman London SW
To e-mail, change noise into sound.