the REAL problem with my Dustbuster...

[William Sommerwerck]

The actual problem was not an intermittent switch. It was the last thing I'd
have expected -- one of the welds on the battery pack had come loose!

Without turning this into a megillah... Any suggestions on repairing it
without damaging the cell? I don't have welding equipment. I do have an
EDSYN pencil iron, and a 100W RadioShack gun.

Please don't turn a straightforward question into a tsimmes. (But you will.)

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land

 

[Smitty Two]

In article <il6p15$q6k$4@news.eternal-september.org>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

The actual problem was not an intermittent switch. It was the last thing I'd
have expected -- one of the welds on the battery pack had come loose!

Without turning this into a megillah... Any suggestions on repairing it
without damaging the cell? I don't have welding equipment. I do have an
EDSYN pencil iron, and a 100W RadioShack gun.

Please don't turn a straightforward question into a tsimmes. (But you will.)

The Edsyn will work. Didn't we just have a thread on soldering to
batteries? Maybe that was on a.h.r. Clean surfaces. Scuff with
sandpaper. Use liquid flux. Crank Edsyn up to 800F. Tin wire. Tin
battery. Use more flux and reflow wire to battery.

 

[Jeff Liebermann]

On Tue, 8 Mar 2011 18:34:44 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

The actual problem was not an intermittent switch. It was the last thing I'd
have expected -- one of the welds on the battery pack had come loose!

It happens. Spot welding takes practice.

Without turning this into a megillah... Any suggestions on repairing it
without damaging the cell? I don't have welding equipment. I do have an
EDSYN pencil iron, and a 100W RadioShack gun.

Test the broken flat wire to see if it can be soldered. Keep the
battery as cold as possible (i.e. wet sponge). Plenty of liquid flux
and heat. Work fast to keep the heat affected zone to a minimum.

Please don't turn a straightforward question into a tsimmes. (But you will.)

Mazel Tov. You can also build your own spot welder with a big fat
cazapitor. Search Google and YouTube for "capacitor discharge spot
welder". For example:
<http://forum.allaboutcircuits.com/showthread.php?t=24385>
If you don't want to build the entire circuit, just charge up the
biggest capacitor bank you can throw together. One lead goes to the
battery terminal. The flat wire goes is placed on top of the
terminal. The electrode is some kind of heavy (#10 awg) solid copper
wire. Compress this sandwich together, and apply power at the
capacitor bank. Hopefully, it will weld the flat wire, and not the
capacitor terminals. In theory, the stainless leads with have a
higher resistance than the copper electrodes, so the stainless will
heat up, not the copper.

Last resort is to drag it down to Batteries Plus or some similar
vendor that has the proper spot welder.

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

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

 

[John Robertson]

Jeff Liebermann wrote:

On Tue, 8 Mar 2011 18:34:44 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

The actual problem was not an intermittent switch. It was the last thing I'd
have expected -- one of the welds on the battery pack had come loose!

It happens. Spot welding takes practice.

Without turning this into a megillah... Any suggestions on repairing it
without damaging the cell? I don't have welding equipment. I do have an
EDSYN pencil iron, and a 100W RadioShack gun.

....

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

There is a conductive epoxy that can be used to fix this sort of thing...

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[William Sommerwerck]

The Edsyn will work. Didn't we just have a thread
on soldering to batteries?

Yes. But I like to double-check.

Maybe that was on a.h.r. Clean surfaces. Scuff with
sandpaper. Use liquid flux. Crank Edsyn up to 800F.
Tin wire. Tin battery. Use more flux and reflow wire
to battery.

Pretty much what I thought. Thanks.

 

[William Sommerwerck]

Keep the battery as cold as possible (i.e. wet sponge).

Hadn't thought of that. I could stick it in the refrigerator for a while,
too.l

You can also build your own spot welder with a big fat
cazapitor.

Great! A man after my intellectual heart.

Search Google and YouTube for "capacitor discharge spot
welder". For example:
http://forum.allaboutcircuits.com/showthread.php?t=24385
If you don't want to build the entire circuit, just charge up the
biggest capacitor bank you can throw together.

I've got some electronic-flash caps lying around.

Last resort is to drag it down to Batteries Plus or some similar
vendor that has the proper spot welder.

I never thought of that! It might be worth a coupla bucks!

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

 

[William Sommerwerck]

There is a conductive epoxy that can be used
to fix this sort of thing...

I invented conductive epoxy 50+ years ago. I didn't patent it, though. And
probably someone else had beaten me to it.

 

[mike]

Jeff Liebermann wrote:

On Tue, 8 Mar 2011 18:34:44 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

The actual problem was not an intermittent switch. It was the last thing I'd
have expected -- one of the welds on the battery pack had come loose!

It happens. Spot welding takes practice.

Without turning this into a megillah... Any suggestions on repairing it
without damaging the cell? I don't have welding equipment. I do have an
EDSYN pencil iron, and a 100W RadioShack gun.

Test the broken flat wire to see if it can be soldered. Keep the
battery as cold as possible (i.e. wet sponge). Plenty of liquid flux
and heat. Work fast to keep the heat affected zone to a minimum.

Please don't turn a straightforward question into a tsimmes. (But you will.)

Mazel Tov. You can also build your own spot welder with a big fat
cazapitor. Search Google and YouTube for "capacitor discharge spot
welder". For example:
http://forum.allaboutcircuits.com/showthread.php?t=24385
If you don't want to build the entire circuit, just charge up the
biggest capacitor bank you can throw together. One lead goes to the
battery terminal. The flat wire goes is placed on top of the
terminal. The electrode is some kind of heavy (#10 awg) solid copper
wire. Compress this sandwich together, and apply power at the
capacitor bank. Hopefully, it will weld the flat wire, and not the
capacitor terminals. In theory, the stainless leads with have a
higher resistance than the copper electrodes, so the stainless will
heat up, not the copper.

Spot welding is a LOT harder than it sounds.
Just to use some round numbers that you can scale for your application...
If you expect to get 10,000 amps out of 10V, you can't have more than
a milliohm of resistance. That's the cap esr + the switch + the wire +
the contacts
+ the contact resistance at the weld. And the only thing that does much
good is the amps x volts x time at the junction between the two parts
being welded plus a little in the weld material itself.

An extra couple of milliohms in the system will render the welder impotent.
And the weld will be extremely sensitive to the contact resistance
between the weldments and thus the pressure applied and the contact area
and, and , and. With a low-voltage AC welder made from a microwave oven
transformer, I was getting about 20% good welds. The commercial CD
welder with the same homebrew weld head was closer to 100% good.

You really want something that controls current rather than voltage.
Then, most of the variables end up in one place, the weld.
Using a higher voltage and some intentional, controlled series
resistance can make it much more reliable.

Many battery tabs are made of zinc. Easier to weld than stainless.
Hobby-Store 5mil brass is very easy to weld, but may be too high
resistance for a dust buster.

Having said that, you can, with practice, make usable battery tab welds
with a capacitor bank, a pressure controlled contact system and a switch
made out of a nail. Charge the caps, apply weld pressure, slam the nail
across two BIG wires. I was using 4/0 wire. You get one weld per nail,
but nails are cheap.

You didn't say which wire. if it's the negative, you may be able to fix it
by hose-clamping the wire to the battery case.

I'm gonna get yelled at, but I would not solder a battery.
Can be done with practice. Trying it for the first time on the only
battery you have is fraught with risk. Separator material inside
melts pretty easily. I wouldn't try with a gun. I'd use a 50W pencil
with a MASSIVE 1000F tip and very short heat application. You're heating
a lot of mass quickly. Gun can't hack it.
YMMV

Last resort is to drag it down to Batteries Plus or some similar
vendor that has the proper spot welder.

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

 

[William Sommerwerck]

I'm gonna get yelled at, but I would not solder a battery.
Can be done with practice.

I remember successfully doing it once or twice before. But you're right --
it's not a good idea. Solder doesn't bond well with most battery cases, and
the case is huge heat sink that makes it hard to make a quick solder joint.

Trying it for the first time on the only
battery you have is fraught with risk.

Charlie Fraught and Joe Risk?

Last resort is to drag it down to Batteries Plus or some similar
vendor that has the proper spot welder.

I lucked out. The guy at the local B+ store said he'd do it for free if I
came in early tomorrow morning.

 

[Jeff Liebermann]

On Wed, 9 Mar 2011 03:58:33 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

I don't mean slopping the epoxy in between the battery terminal and
the flat wire. I mean push the two wires together, and slop some
epoxy on top in order to just hold them together. The Dustbuster
doesn't draw all that much current so I suspect a simple mechanical
connection will work. Kinda like the contacts for D cell batteries in
kids toys, flashlights, games, etc, where a welded contact isn't
necessary. If you're not sure if it will work, and don't want to deal
with permanent epoxy, use Duct Tape to hold the flat wire in place.

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

 

[Jeff Liebermann]

On Wed, 09 Mar 2011 08:16:00 -0800, mike <spamme9@gmail.com> wrote:

Spot welding is a LOT harder than it sounds.

I agree. I spent about 5 days tinkering with mine trying to get it
right. Every time I added more capacitance, things improved. The
basic trick is to make sure the resistance of the joint to be welded,
is higher than all the other resistances (and ESR of the capacitor).
Mine currently has two 3F 20v caps in parallel. Something like this:
<http://ledhacks.com/power/battery_tab_welder.htm>

Just to use some round numbers that you can scale for your application...
If you expect to get 10,000 amps out of 10V, you can't have more than
a milliohm of resistance. That's the cap esr + the switch + the wire +
the contacts
+ the contact resistance at the weld. And the only thing that does much
good is the amps x volts x time at the junction between the two parts
being welded plus a little in the weld material itself.

Good point. However, I have no way to measure the peak current or the
current necessary to do the weld. I just kept adding capacitance
until it worked.

An extra couple of milliohms in the system will render the welder impotent.
And the weld will be extremely sensitive to the contact resistance
between the weldments and thus the pressure applied and the contact area
and, and , and.

Well, the idea is to dissipate the power in the connection, not in the
capacitors, SCR, or contacts. As long as the capacitor is huge, the
SCR oversized, wires beefy, and the contacts can handle both the
current and the heat, it should work.

With a low-voltage AC welder made from a microwave oven
transformer, I was getting about 20% good welds. The commercial CD
welder with the same homebrew weld head was closer to 100% good.

Apples and oranges. There's enough resistance in the transformer
winding to probably make the welder useless. If the primary winding
was made from copper buss bars, it might have a chance, but not a
copper wire wound xformer. A big capacitor has an internal
resistance, but that's MUCH less than the resistance of a wired
transformer winding.

You really want something that controls current rather than voltage.
Then, most of the variables end up in one place, the weld.
Using a higher voltage and some intentional, controlled series
resistance can make it much more reliable.

Agreed. Voltage doesn't matter. It's the current that does the
heating. If you shove XX Amps through YY ohms of resistance, it's
going to heat I^2*R (Ohms Law). Whatever voltage it took to deliver
that much current is largely irrelivent.

Many battery tabs are made of zinc. Easier to weld than stainless.
Hobby-Store 5mil brass is very easy to weld, but may be too high
resistance for a dust buster.

I haven't seen any zinc tabs yet. I've seen tin plated steel and
stainless. Brass should work for a Dustbuster as they don't draw all
that much current.

Having said that, you can, with practice, make usable battery tab welds
with a capacitor bank, a pressure controlled contact system and a switch
made out of a nail. Charge the caps, apply weld pressure, slam the nail
across two BIG wires. I was using 4/0 wire. You get one weld per nail,
but nails are cheap.

I used a copper contact knife switch. I welded the contacts a few
times, but was able to break it apart, file it clean, and do it again.

One more idea. Single sided resitance spot welder as used in auto
body shops.
<http://www.jcwhitney.com/spot-welder/p2007539.jcwx>
However, you'll need an arc welder for this to work.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Wed, 09 Mar 2011 16:42:48 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

I haven't seen any zinc tabs yet. I've seen tin plated steel and
stainless.

Also flat wire made from nickel or various nickel alloys, which is
difficult, but not impossible to solder.

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

 

[William Sommerwerck]

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

I don't mean slopping the epoxy in between the battery terminal and
the flat wire. I mean push the two wires together, and slop some
epoxy on top in order to just hold them together. The Dustbuster
doesn't draw all that much current so I suspect a simple mechanical
connection will work. Kinda like the contacts for D cell batteries in
kids toys, flashlights, games, etc, where a welded contact isn't
necessary.

But there's a spring applying pressure.

If you're not sure if it will work, and don't want to deal with
permanent epoxy, use Duct Tape to hold the flat wire in place.

The problem (from my point of view) is oxidation. I figure the Dustbuster
draws ~1amp, so I need a clean, tight, connection.

Regardless, I'm going to have it welded tomorrow morning.

 

[Shaun]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:si5gn6l975binpornel9emp4a4aa61i6oo@4ax.com...

On Wed, 9 Mar 2011 03:58:33 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

I don't mean slopping the epoxy in between the battery terminal and
the flat wire. I mean push the two wires together, and slop some
epoxy on top in order to just hold them together. The Dustbuster
doesn't draw all that much current so I suspect a simple mechanical
connection will work. Kinda like the contacts for D cell batteries in
kids toys, flashlights, games, etc, where a welded contact isn't
necessary. If you're not sure if it will work, and don't want to deal
with permanent epoxy, use Duct Tape to hold the flat wire in place.

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

You're an idiot to suggest epoxy. The contacts will oxidize and then there
will be no connection, might take a couple of months before this happens,
but it will happen.

 

[mike]

William Sommerwerck wrote:

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

I don't mean slopping the epoxy in between the battery terminal and
the flat wire. I mean push the two wires together, and slop some
epoxy on top in order to just hold them together. The Dustbuster
doesn't draw all that much current so I suspect a simple mechanical
connection will work. Kinda like the contacts for D cell batteries in
kids toys, flashlights, games, etc, where a welded contact isn't
necessary.

But there's a spring applying pressure.


If you're not sure if it will work, and don't want to deal with
permanent epoxy, use Duct Tape to hold the flat wire in place.

The problem (from my point of view) is oxidation. I figure the Dustbuster
draws ~1amp, so I need a clean, tight, connection.

You should measure it. I was too lazy to get out the big power supply,
but 3A would hardly get mine started.
I've replaced the batteries in mine twice and finally gave up.
The load current is very hard on batteries. Especially since people
don't stop when it slows down. They just keep on trucking pumping
5A backwards into the weakest cell. And the constant current
charge 24/7 is also very hard on the battery. Bad design.

Regardless, I'm going to have it welded tomorrow morning.

 

[mike]

Jeff Liebermann wrote:

On Wed, 09 Mar 2011 08:16:00 -0800, mike <spamme9@gmail.com> wrote:

Spot welding is a LOT harder than it sounds.

I agree. I spent about 5 days tinkering with mine trying to get it
right. Every time I added more capacitance, things improved. The
basic trick is to make sure the resistance of the joint to be welded,
is higher than all the other resistances (and ESR of the capacitor).
Mine currently has two 3F 20v caps in parallel. Something like this:
http://ledhacks.com/power/battery_tab_welder.htm

Interesting. Those welds are way better than anything I could get using
a microwave transformer and handheld electrodes. Spring loaded parallel
electrodes jigged to an arbor press improved things dramatically.

Just to use some round numbers that you can scale for your application...
If you expect to get 10,000 amps out of 10V, you can't have more than
a milliohm of resistance. That's the cap esr + the switch + the wire +
the contacts
+ the contact resistance at the weld. And the only thing that does much
good is the amps x volts x time at the junction between the two parts
being welded plus a little in the weld material itself.

Good point. However, I have no way to measure the peak current or the
current necessary to do the weld. I just kept adding capacitance
until it worked.

Yep, at the time I did the experiments, I didn't have a digital storage
scope
or anything that could measure 10,000 amps. My welds got dramatically
better about 10 minutes after I got the DSO and could study what was
happening.

An extra couple of milliohms in the system will render the welder impotent.
And the weld will be extremely sensitive to the contact resistance
between the weldments and thus the pressure applied and the contact area
and, and , and.

Well, the idea is to dissipate the power in the connection, not in the
capacitors, SCR, or contacts. As long as the capacitor is huge, the
SCR oversized, wires beefy, and the contacts can handle both the
current and the heat, it should work.

Yes, but...
CONTROL is critical. Some tiny resistance in the path makes the current
in the weld slightly less dependent on the contact resistance.
When dumping a cap into the weld, I found that the a small difference in
electrode pressure made the difference between no weld at all and a hole
in the tab...and no weld at all. Keeping it in the sweet spot was tough.

With a low-voltage AC welder made from a microwave oven
transformer, I was getting about 20% good welds. The commercial CD
welder with the same homebrew weld head was closer to 100% good.

Apples and oranges. There's enough resistance in the transformer
winding to probably make the welder useless. If the primary winding
was made from copper buss bars, it might have a chance, but not a
copper wire wound xformer. A big capacitor has an internal
resistance, but that's MUCH less than the resistance of a wired
transformer winding.

Your apples must be different from my apples.
My transformer had a two turn secondary of copper wire an inch in
diameter...4/0 wire if I remember correctly. I carefully controlled an
integral number of full cycles of 120VAC
into the primary. Took about six cycles to weld. Primary current
was about 30A and made the house hum on a 15A breaker.

I'd like to measure the current profile of some of the homebrew
welders linked from this thread. No way a 50 amps is gonna be useful.
People get away with a 50A SCR in the secondary only because the
single-pulse
peak current rating is WAY bigger than 50A. I've been using a 40A
SSR on the primary side.

You really want something that controls current rather than voltage.
Then, most of the variables end up in one place, the weld.
Using a higher voltage and some intentional, controlled series
resistance can make it much more reliable.

Agreed. Voltage doesn't matter. It's the current that does the
heating. If you shove XX Amps through YY ohms of resistance, it's
going to heat I^2*R (Ohms Law). Whatever voltage it took to deliver
that much current is largely irrelivent.

Yes, as long as you can control the current. Some resistance in the path
makes the current less dependent on the resistance at the weld.
You trade significant wasted energy for repeatability.

Many battery tabs are made of zinc. Easier to weld than stainless.
Hobby-Store 5mil brass is very easy to weld, but may be too high
resistance for a dust buster.

I haven't seen any zinc tabs yet. I've seen tin plated steel and
stainless. Brass should work for a Dustbuster as they don't draw all
that much current.

Might want to measure that current. As I recall, mine was over 5A.

The weld current profile can also be important. You need to match the
energy in with the thermal time constant. A capacitor has peak
current at the time the contact resistance is highest.

The advantage of a dual-pulse welder is that the first pulse normalizes
the contact resistance somewhat. And with some effort, you can use the
voltage/current profile of the first pulse to match the characteristics
of the second pulse to a specific weld instance.

My CD welder claims to be able to put 7V into a milliohm. They dump
the cap into the primary of a transformer. That inductance gives the
current profile a softer start and spreads the energy out over a few
milliseconds.

Having said that, you can, with practice, make usable battery tab welds
with a capacitor bank, a pressure controlled contact system and a switch
made out of a nail. Charge the caps, apply weld pressure, slam the nail
across two BIG wires. I was using 4/0 wire. You get one weld per nail,
but nails are cheap.

I used a copper contact knife switch. I welded the contacts a few
times, but was able to break it apart, file it clean, and do it again.

One more idea. Single sided resitance spot welder as used in auto
body shops.
http://www.jcwhitney.com/spot-welder/p2007539.jcwx
However, you'll need an arc welder for this to work.
That ain't gonna work. The manual says hold it for 2 seconds.

the battery will be toast by then. And you have zero control
over what's happening. You can't wait for a battery weld to turn red.

 

[Jeff Liebermann]

On Wed, 9 Mar 2011 17:03:31 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

Very last resort is to just slop some epoxy on the flat wire and
battery terminal, and hope that it holds.

Unless it's silver-filled epoxy, no way.

I don't mean slopping the epoxy in between the battery terminal and
the flat wire. I mean push the two wires together, and slop some
epoxy on top in order to just hold them together. The Dustbuster
doesn't draw all that much current so I suspect a simple mechanical
connection will work. Kinda like the contacts for D cell batteries in
kids toys, flashlights, games, etc, where a welded contact isn't
necessary.

But there's a spring applying pressure.

Bend the flat wire over a few times and you'll get some spring
pressure.

If you're not sure if it will work, and don't want to deal with
permanent epoxy, use Duct Tape to hold the flat wire in place.

The problem (from my point of view) is oxidation. I figure the Dustbuster
draws ~1amp, so I need a clean, tight, connection.

Apply duct tape for contact pressure. Bury the battery pack in
cellophane wrap for water, dust, and debris proofing.

Regardless, I'm going to have it welded tomorrow morning.

Too easy but good luck anyway.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[William Sommerwerck]

You really want something that controls current rather than
voltage. Then, most of the variables end up in one place, the
weld. Using a higher voltage and some intentional, controlled
series resistance can make it much more reliable.

Agreed. Voltage doesn't matter. It's the current that does the
heating. If you shove XX Amps through YY ohms of resistance,
it's going to heat I^2*R (Ohms Law). Whatever voltage it took to
deliver that much current is largely irrelivent.

Same basic principle as electrocution.

 

[William Sommerwerck]

The problem (from my point of view) is oxidation. I figure the Dustbuster
draws ~1amp, so I need a clean, tight, connection.

You should measure it. I was too lazy to get out the big power supply,
but 3A would hardly get mine started.
I've replaced the batteries in mine twice and finally gave up.
The load current is very hard on batteries. Especially since people
don't stop when it slows down. They just keep on trucking pumping
5A backwards into the weakest cell. And the constant current
charge 24/7 is also very hard on the battery. Bad design.

This is why I always run it at High (which uses all the cells), and stop a
bit after the motor starts to slow down. As a result, the battery pack is in
excellent condition.

 

[Jeff Liebermann]

On Wed, 9 Mar 2011 20:49:02 -0600, "Shaun" <rowl@nomail.com> wrote:

You're an idiot to suggest epoxy. The contacts will oxidize and then there
will be no connection, might take a couple of months before this happens,
but it will happen.

Ok, I'll bite. Stainless or Nickel oxidize? What electrolyte is in
epoxy that will attack stainless steel or nickel? Meanwhile, I can
buy epoxy paint, epoxy coated rebar, conductive (Aluminum doped)
epoxy, epoxy covering junction coating for cheap PCB packaging, etc. I
can also buy quite a few fiberglass marine hulls and decks, which are
held together by epoxy and have stainless deck fittings. No corrosion
warnings on any of the epoxy cans, bottles, and tubes that I can find.
It's certainly not hydroscopic so there's no electrolytic action. The
stainless and nickel are fairly close on the galvanic series:
<http://www.corrosionist.com/galvanic_corrosion_chart.htm>

Sigh. Where is Dr. Barry L. Ornitz when we need him?


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