Alkaline Leakage & Battery Holder Design for Joule Thief Questions

[dlong]

This is kind of an odd question and the title isn't exactly correct. So here goes.

I have a few devices that refuses to use NiMH; they either do not work or shows low battery and stops working in a fairly short time. As such, I will have alkaline batteries that are as high as 1.3V down to about .9V. While I have LED flashlights, remotes, and other electronics that will use these 1.3V-1.2V alkaline batteries for a while, I would prefer not to have them leak in my electronics; as they have done in the past.

So several places states that the reason that alkaline leaks is from the hydrogen gas not properly being vented from the battery and so the battery seal/venting system breaks and the chemicals leak out. They also state that it leaks because the battery is "pushed too hard" which seems wrong because it seems like most of the time the leak doesn't happen during use but either from dis-use or regular "non-hard" use, i.e. electronics that sitting on the shelf or battery backup for digital clocks. So maybe I don't understand the reason and or the phrase "pushed too hard". I mean, using fresh alkaline and push them as hard, short of "shorting" them, and the battery just drains not rupture and leak, right? First: What causes batteries to leak? Is my understand somehow wrong?

So... with all of that. I'd like to build a joule thief (resistor, coil, NPN transistor) to run some decorative LED strings that uses these "dead" batteries. As I understand it, depending on the coil, I can drain the alkaline down to .4v, maybe lower, depending on the coil. Second: How can I design a battery compartment that would be resistant to alkaline leakage? While making it easy to clean, if (when?) it does?

Comments? Ideas? Suggestions? Thoughts?

Thanks!

 

[Katherine Alicia]

personally I`d use a plastic battery holder with leaf type "springs" (like a thin sheet of metal folded nearly in half) and replace these with pure silver (just cut a strip from some silver sheet metal). it`s completely immune to almost all corrosion and the oxide still conducts (yes, that black tarnish on silver is conductive too!).
Then keep the holder as the lowest part of the device so nothing can drip, and if there`s any holes in the plastic holder, fill them with potting compound (super glue and bicarb works well).

 

[archimedes]

Re: Alkaline Leakage & Battery Holder Design for Joule Thief Questions

I always wanted one of these ...

https://www.candlepowerforums.com/vb/showthread.php?382066-The-A-AA-an-alkaline-AA-battery-vampire

It is too bad the photos are partly obscured now

 

[Lynx_Arc]

Re: Alkaline Leakage & Battery Holder Design for Joule Thief Questions

One solution is to use magnets and to just place the battery in a plastic tray of sorts.
As far as reasons for alkaleakage, pushing them too hard IMO sometimes greatly heats up the batteries possibly warping the seals and when the battery cools the seals shrink back to normal size but end up damaged somehow.
Before there were battery vampire circuitry I would take cheap black plastic AA battery holders and gang them together to hold from 3-8 AAs in series and wire a variable resistor inline with an LED and starting at no light crank it up till I get some light and leave it running for weeks on end. When the light drops to nothing I would first reduce the resistance and when there was no resistance I would go and measure the individual battery voltages and pull out the ones that are below a certain point. I've drained AAs down to 0v even reverse charging them by doing this but typically once they go below 0.5V under a very light LED load the batteries have less 1 percent of power left IMO.
alkaleaks that measure 0.9v or less IMO are not worth messing with as they don't really have much power left especially when you have an excess of batteries measuring 1.2v or more.

 

[dlong]

Are sterling silver sheet metal, "springy" or does it just bend -- I have never worked with the material. How does it do in a high pH (base)?

I was thinking of some stainless steel nuts and bolts (inexpensive?) -- how are they vs battery acid and/or base?

I think this is correct? Please let me know if it's wrong:
--------------------------------------------------------------
Alkaline leaks Potassium hydroxide: pH of 12 to 14 (base)
Zinc Carbon leaks ammonium chloride: pH of 4.0 to 6.0 (acid)
Zinc Chloride "(Super) Heavy Duty" leaks zinc chloride: pH of 4 (acid)
Lithium Iron, if it leaks? Propylene carbonate, dioxolane, dimethoxyethane?: pH ? 7.0

 

[Katherine Alicia]

Are sterling silver sheet metal, "springy" or does it just bend -- I have never worked with the material. How does it do in a high pH (base)?

I was thinking of some stainless steel nuts and bolts (inexpensive?) -- how are they vs battery acid and/or base?

I think this is correct? Please let me know if it's wrong:
--------------------------------------------------------------
Alkaline leaks Potassium hydroxide: pH of 12 to 14 (base)
Zinc Carbon leaks ammonium chloride: pH of 4.0 to 6.0 (acid)
Zinc Chloride "(Super) Heavy Duty" leaks zinc chloride: pH of 4 (acid)
Lithium Iron, if it leaks? Propylene carbonate, dioxolane, dimethoxyethane?: pH ? 7.0

it`s quite springy, I use it myself to replace all sorts of flashlight parts (often springy parts), the Pure .999 silver is less springy though.
quite a few common metals will react with strong hydroxides forming things like, Cuprates, zincates, aluminates, ferrates etc... there`s no such for silver. interestingly silver will form a thin chloride layer (in certain circumstances) preventing any further reaction and it also conducts too, so no problem there either.
and although silver can for organometalic compounds, it wouldn`t react with any of those and certainly not in its elemental form.

 

[dlong]

Sounds like Silver is a winner, especially for repairing damaged contacts from battery leakage. Magnets is also a good idea.

Where you do get Sterling Silver Metal Sheets? I see amazon has them but Amazon has/becoming just has bad as (edit) eBay for selling fake/bad items and I'm not sure I trust trust them.

You said that .999 pure is less springy. What purity and gauge do you recommend for this particular use (springy battery contacts)?

 

[Katherine Alicia]

I used to make Silver jewelry, so I mixed my own alloys and rolled them into sheets or wires as I needed them, but I know you can buy the stuff, just not sure where? I used to buy the raw silver metal as grain and didn`t really spend much time looking at other things that were ready made. Sterling`s probably the best for springiness, I used to make my own sterling (92.5%) for ear ring hooks and it`s quite tough, Brittania silver (95-96%) is what I use in flashlights for replacement parts and I`v not had a problem with that either and it will work harden quite nicely too, so after you`ve cut what you want with scissors and shaped it, it`ll stay put.
as for guage, again I used to work by hand and the sheets were rolled until the they felt the right thickness, I rarely worked with numbers unless it was ring sizes, you just get a feel for the metal and what will work and what wont. but in sterling .3 to .5 mm thick would work for battery contacts no problem.