EEVblog #865 - How To Increase Alkaline Battery Capacity

[SeanB]

I did recharge non alkaline zinc carbon cells using rough AC, it did work to extend battery lifetime around 10 times, as the charging extended battery life. Never was a full run time after use, but in place of buying new batteries every week for the radio ( 4 C cells) this allowed them to last around 6 months before they were totally dead. Worked best on the white Everready non alkaline cells, was so so on the black heavy duty ones, and was a definite no go on alkaline cells, as I found out when the first one vented.

Basically a half wave rectifier of a 3VAC transformer secondary, with a series charge limiting resistor, and a resistor of around 10-15 times the value across the diode, so it would plate the Zinc case back evenly.

[mahwe]

Hi Dave,
i build radio controlled airplanes.
Some years ago in the time before Lithium Polymer Akkumulators, we used NiCd akkus.
There were two big firmes, who build the best Akkus Sanyo and Panasonic.
To reduce the battery resistance we pushed them with the help of a big capacity and a hammer.
We called it Hammerschlagmethode, it reduced the inner resistor from 8mOhm to nearly nothing.
At the end you were able to get 200A out of a 2000mAh Sub C cell  .

[MartinX]

I think the squeezing work because it redistributes the material inside allowing some unused material in the cell to get into contact with the electrodes, squeezing it in the middle is probably even better than doing it axially, squeeze it rotate it 90 degrees squeeze again and repeat a couple of times to squish around the material inside, you would have to take care not to break the battery or puncture it.

Elektor had a long article about their charger design recharging standard alkaline batteries, recharging a fully discharged battery does not work very well because the electrodes are largely consumed, but if you only discharged the batteries to about half their capacity recharging worked very well and it was possible to do this 4-5 times reliably and still have almost full capacity every time, but you could only use half of it every time of course. To be safe charging had to be slow and monitored it took 15 hours or so for a AA battery. Keeping track of the battery status and recharging at he half way point was probably more of a hassle than most people was prepared to endure to save not so much money on batteries.

[ez24]

This news will probably delay the delivery of the Batterizer, because now they will know to make their device a little shorter to "squeeze" the battery.  So they have another excuse for delays.

My suggestion is to design in set screws so the screws can be tightened as the battery loses power.  It seems carrying around a vise or hammer is a little too much.  A small screwdriver would take up much less space.

It also seems a good idea for a IG project to make a "battery vise" 

[Fungus]

I'm not an expert in battery chemistry, but this may have to do with ion diffusion.  When you deplete the battery so fast, the ions don't have time to diffuse to the electrodes.  Squeezing the batteries causes convection (liquid mixing) that stirs the liquid, quickly moving the ions around and replenishing the battery.  You might do better by alternately squeezing and releasing the battery several times.

Maybe a motorized battery spinner would work even better. Spin it up to 10,000rpm a couple of times in each direction.

[Don Hills]

The problem with squeezing it from the ends is that it can damage the seal and cause leakage. As others have pointed out, squeezing it around the middle is just as effective and safer.

[ftonello]

Very interesting!!! Will try this here...
But after you posted your video, Batteriser went ahead in a new project to take advantage of this phenomenon....





 

Att

[kodi]

I bought 8 of these when they came out.  Six have been thrown away (bad) but I still have 2 in a lantern that I do not use.  Once a year and take them out and the two always have a near full charge.  I discharge them and recharge until the next year.

 If they all lasted list these two they would have become the miracle battery.

DON'T! If you have RAMs they are very sensitive to deep discharge. Idea of those rechargeables  was sound, their weakness lays in their inability to full recovery from deep discharge. Basically - if you let them discharge up to 60% of original charge, you can recharge them hundreds of times. If you let the charge go lower then we are talking dozens. Full discharge - you can recharge it to full 10/15 maybe 20 times tops.
I'm using them mostly in weather stations/sensors as they can really hold the charge for a long time.

[lwatts666]

OK, No one else has asked, so: How flat do I have to squash my AA's to get 800% more energy out?

[Little Brutus]

Discharge B (1 hr), Discharge A (1 hr), wait for recovery, Re-discharge A (17 min), Squeeze B in Vice, Re-discharge B.

Hmmm, could it be B had at least 1h17m more time to recover than A?

[Little Brutus]

OK, No one else has asked, so: How flat do I have to squash my AA's to get 800% more energy out?

Bet due to laws of diminishing returns, probably as flat as needed to make it as wide as "Probe's" butt.

[ez24]

OK, No one else has asked, so: How flat do I have to squash my AA's to get 800% more energy out?

How big is your sledge hammer?  A regular hammer surface area is too small.  A hard rubber mallet works best.  A 90 degree swing should work with a rubber mallet.  A 3 lb sledge hammer should have no more than 45 degrees because the weight of the hammer does the work.  You may have to practice on several batteries to get the right results.  Be careful not to smash the battery too much because it may not fit.

I also suggest running over them with your car.  You will need to place a board on them to have enough force.  It is best if you cut a V slot in the wood to distribute the force.  If you can router a U shape that fits the battery then you should be able to get the 800 % increase (you have to run over them at least 8 times).

[MK14]

In Dave's video, towards the end, the battery voltage was far too high, for a run down battery (approx 1.25V at about 1800 Sec into test). I.e. I smell a rat. (Tomfoolery/trickery).

No trickery, the electronic load had switched off because the battery voltage dropped to 0.1V. What you saw was the battery voltage recovering under no load.

The voltage seemed/seems too high, to recover that much, from being forced down to 0.1V, for a while.
But you could be right and/or maybe Dave took a break or something, giving it time to recover.

Also the second battery (B ?), had much more time to recover (maybe not, I could be getting confused, because of the sudden time jumps in the video), than the first (A ?). That could also be the main factor in why we got the results shown.
Really, both experiments, should occur at exactly the same time, to be fair/accurate. (If you only have one of each of the test items, it is harder to do it at the same time, But still can be (done, by using the wall clock, and doing 2 passes of the experiments), by recording the physical time, and keeping the relative times, about the same, between both batteries. I was not sure, if that was or was not done, for this experiment).

BUT I could be misunderstanding the timings, from watching the video. Maybe the timings were NOT that far apart. It is NOT very clear, what the overall timings were (to me, at least).

[MK14]

What you and no one else it seems has realised is that there is no joke. It's not a trick. THAT'S the joke.

What makes you think I have been fooled ?

If you search on this subject area (which I did earlier in this thread, but decided NOT to post the results). There are indeed, others, a number of years ago, who discovered similar things. Since their reports are independent and from some time ago, they would appear to at least partially collaborate with some of Dave's findings.

My concern, is not so much if it was a trick or NOT. But if you had merely let the "other" (non-physically "squeezed") battery, recover naturally, by just leaving it to rest, for however long that takes. I DON'T know how long it takes, maybe it is 30 minutes or an hour, but could be a completely different time range. It also would have been able to deliver more power.

[Fungus]

My concern, is not so much if it was a trick or NOT. But if you had merely let the "other" (non-physically "squeezed") battery, recover naturally, by just leaving it to rest, for however long that takes. I DON'T know how long it takes, maybe it is 30 minutes or an hour, but could be a completely different time range. It also would have been able to deliver more power.

I'd say the opposite was true. "A" had a least an hour to recover before retesting (while "b" was being drained). "B" had much less time to recover before being squeezed ("A" took only 15 minutes or so to discharge the second time around).

nb. This assumes Dave didn't go for lunch between the two re-drains.

[MK14]

My concern, is not so much if it was a trick or NOT. But if you had merely let the "other" (non-physically "squeezed") battery, recover naturally, by just leaving it to rest, for however long that takes. I DON'T know how long it takes, maybe it is 30 minutes or an hour, but could be a completely different time range. It also would have been able to deliver more power.

I'd say the opposite was true. "A" had a least an hour to recover before retesting (while "b" was being drained). "B" had much less time to recover before being squeezed ("A" took only 15 minutes or so to discharge the second time around).

nb. This assumes Dave didn't go for lunch between the two re-drains.

The camera angle, suddenly "JUMPS" (so who knows how long, the time delay could be, while the camera was stopped), soon after about 7 minutes in to the video, which is when the batteries are swapped for the second drain test. This is NOT scientific. We (ideally) should know the wall clock time and/or how much time has elapsed for each battery. OR test them simultaneously.

Approx 100mA (if I remember correctly from the video, pity it is NOT in text format. It makes it much harder to quickly scan through the details. Sorry) or so apparent capacity change, between the batteries, could just be random variation between them and/or because of timing differences.

There is lots of stuff about partially revitalizing spent/used batteries, on the internet, including "SQUEEZING THEM".

Example from around 2011 (but there seem to be MANY others):

Title: "Why do 'dead' batteries work again after exchanging the places of the batteries in an electronic device?"

   
I have also read that squeezing them with pliers works, but neither of these cases is relevant to my situation.

http://physics.stackexchange.com/questions/9887/why-do-dead-batteries-work-again-after-exchanging-the-places-of-the-batteries

[Little Brutus]

"A" had a least an hour to recover before retesting (while "b" was being drained).

B was drained first, and had at least an hour to recover while A was drained.

In the 2nd pass, re-draining, A was done first.

[apis]

Well, I don't know how/if this really works, but I'm going to guess any way:
I suspect it has to do with the structure of the electrodes/electrolyte changing during discharge (becomes grainy or something is forming dendritic structures, etc) this increase internal resistance and prevent free flow of the electrolyte and kills the batteries prematurely. By applying mechanical stress to the battery you might be able to break up the structures somewhat making it possible to extract a few more mA from the battery.

[jesuscf]

If you take a barrel of non-BS and add 0.5% BS to it, it will make the 99.5% non-BS stink like BS.  By the way, in many parts of the world there is no such thing as April fools day.  Just my 2 cents.

[SL4P]

New Batteriser!

I like this idea, as it applies pressure around the electrolyte - rather than at the end caps.
The end caps of the battery may not compress the chemistry all the way through, and possibly crack or damage the central core electrode.
Perhaps a better (one time only) approach could be to 'roll' the battery between three cylinders, increasing the inward pressure slightly over the 'recharging' period - without distorting the original cylindrical profile of the cell.

Just a thought.

[nctnico]

Just wondering how much energy it takes to put pressure onto the battery versus the amount of energy you get in return.

[Smokey]

OK, No one else has asked, so: How flat do I have to squash my AA's to get 800% more energy out?

How big is your sledge hammer?  .....

[Fungus]

How big is your sledge hammer? 

http://www.amazon.com/Ampco-Safety-Tools-H-74FG-Non-Sparking/dp/B000WTPXKQ

[AndyC_772]

Non-Magnetic for use near highly sensitive magnetic equipment; MRI and Clean Room environments; Corrosion Resistant even in the most severe environments

MRI system misbehaving? Not a problem... 

[Fungus]

Non-Magnetic for use near highly sensitive magnetic equipment; MRI and Clean Room environments; Corrosion Resistant even in the most severe environments

MRI system misbehaving? Not a problem... 

I'm trying to imagine a scenario where you'd want to use a sledgehammer right next to a live MRI machine.