How To Test a AA battery, Easiest Way For Any Battery Fast, Easy!

[capncarl]

I don't think that it is as much about the good battery standing up when dropped as the sound and bounce is.

[JimD]

A fresh duracell I tested wouldn't hardly stand up. If didn't bounce as much or fall over quite as easily as a depleted duracell but there was no dramatic difference like there is a fresh ever ready versus a depleted duracell.

[LCHIEN]

If you look on google for battery bounce test you'll find about 5 references that apply, one is this thread at BT3central, and a few others including the youtube. Most of the others refer to people passing on or asking if this works, the original story always goes back to some inmate in a jail who has no money but a lot of used batteries and a lot of time. That should be the first alarm bell. I always trust inmates in jail for my technical information.

The answers to these questions always get variations of it is total BS to it probably works because... loss of material due to outgassing. loss of material due to e=mC-squared(watch out nuclear reaction in progress!), liquid phase vs solid phase like spinning a raw egg vs a hard-boiled egg, distortion of the case due to gas release...

According to Wikipedia on alkaline batteries, the chemical reaction involves no outgassing. I'm pretty sure the checmicals are all solids - I've seen opened batteries before. they are not liquid tight so any liquids would run out.

The problem with the test is that its mostly subjective. You need a good battery to test against (subjectively), differences from test to test depend upon the height (not well controled) the angle at release (not well controlled - one finger can be a little more moist or stickey than the other), or whatever.

you need some apparatus to make a objective measurement of coefficient of resititution ( which is engineergspeak of how high will it bounce as a percentage of the height dropped from).

This can all be done is a short matter of time using some simple home built fixtures and tools and using a set of controlled batteries that have known charge levels. So you'd have to invest in maybe a dozen batteries each of three different name brands. Energizer, duracell and ray-o-vac are most commonly sold.

you need to mark them randomly with numbers so you have no idea which you are testing while doing the drop so it won't affect any judgements you make on the readngs.

You need a scale. They sell jewelers scales on ebay for under $20 that can measure down to like .01 or .05 gram. You will need to weigh all batteries before and after discharge to see if any mass is lost.
You need calipers. Harbor freight $16. you need to measure all batteries before and after discharge. To see if there's any case distortion. Measure the length and the diameter top bottom and middle.
You will need a fixture. I'd take a clean 2x4 with no knots and put a 45 degree groove down the length of a 2 foot board. THe top of the groove about .5" wide, a bit smaller than the diameter of a A cell.
Mark a scale on the 2x4, zero at the bottom end. Arrage to tilt the 2x4 a few degrees and hold securely. Place a 4x4 tile at the base of the two by four, square to the end of the 2x4.
Now you can hold a battery against the inclined groove with the end at the 12" mark, drop it with one finger release so as not to impart spin, angle or extra velocity to it. Adjust the incline for the most vertical that keeps the battery in the groove as it drops.
Observe how high the end bounces. You may need to use a PC and web cam or a video cam to record and playback in slo-mo. If the bounce is too low you can increase the intial drop height, but once chosen use the same hieght for all tests.

c.r = Coefficient of restitution = max bounce height/drop height

Now that you have a MEANs TO MEASURE,
deplete each of 4 batts of each brand to zero
deplete each of 4 batts of each to 1/2 (since a AA alkaline holds 2800 mAH, you'd need to run it about 10 hours on a 10 ohm 1/2 W resistor. Be careful the resistor will be hot.)
keep four fully charged batts.

Weigh them again. Measure with calipers again. We do this to see if there is any physical change that might correlate to bouncing characteristics.

Again, you can plot the physical changes against the list of charged partially charged, and discharged batteries to see if there's any correlation.

DO a minimum of four drops each and average the results.
If this works as promised the you can sort the C.R. and see three distinct groups. These should correlate with the state of charge.
Then repeat for the other two brands. and see if this holds for most battery brands or just one.





Linux R is right, I'll just use my voltmeter.

[LinuxRandal]

Seems easier just to grab the multimeter then argue over this.
Multimeter is quick, it keeps its use in your mind, it lets you know you have working batteries in it (so they don't sit, and corrode after death), etc.

[jdon]

I always trust inmates in jail for my technical information.

Words to live by

[capncarl]

This kind of discussion is always good for a chuckle. Kinda like digging a hole on a certain phase of the moon and not being able to get all of the dirt back in the hole, and dig the same hole later and not having enough dirt to fill the hole up. Lots of theories on compaction, soil moisture levels etc.
capncarl

[annunaki]

capncarl -


Forgot the Vampires & Werewolves.

[gsmittle]

you need some apparatus to make a objective measurement of coefficient of resititution ( which is engineergspeak of how high will it bounce as a percentage of the height dropped from).

This can all be done is a short matter of time using some simple home built fixtures and tools and using a set of controlled batteries that have known charge levels. [snip]

DO a minimum of four drops each and average the results.
If this works as promised the you can sort the C.R. and see three distinct groups. These should correlate with the state of charge.
Then repeat for the other two brands. and see if this holds for most battery brands or just one.

What the heck, I've nothing to do Saturday…

g.

[LCHIEN]

FWIW, in the background I have been collecting and measuring batteries, since I don't normally keep discharged primary batteries around.
I measured brand new, mid-level and totally discharged batteries I ran all the way dead with a flashlight (non electronics item that wouldn't disconnect itself upon low battery warning).
New batteries showed 1.6V, mid-life batteries that tripped some low batt warnings were around 1.35 and dead battieries were at 1.1V and 0 volts (internally open apparently.)
That is by far and away the best indication you will have.

I weighed them to .01 gram. I measured length and dia. to .01mm. I calulated the equivalent density (weight per volume).

Within a single brand, new mid, and dead batteries were all within about a percent on weight, dimensions and density, with no particular distrubution showing correlation of loss of any value with age/use.

Between brands there was a slight difference is weight, not much in dimensions. and no apparent correlation of a change with respect to useage.

THerefore there's no discernable external measured change that would lead to bouncing. Also all the speculation on loss of material leading to swelling and or density change is sheer nonsense. Furthermore, looking at the chemistry in the Wiki article, connfirms there's no outgassing or loss of material or mass.

I had a piece of 30" long 3x3 "L" angle of wood and fastened a 4x4 piece of polished granite sample to the end. By inclining it a few degrees (maybe 5 or so, I didn't get out my wixey to check the absolute angle) I could hold the battery at the top of the groove and release it with one finger so it hit the granite end first with no spin or additional imparted speed or rotation. Being a very shallow angle or about 5 degrees allows 92% of the gravity force and velocity to work with low friction losses on the supporting side, giving a consistent result.
What I found was that they all bounced less than an inch probably closer to 1/2", without a discernable difference. And pretty much no second bounces were measureable. I'd have to get a videocamera with macro and slow motion replay to do an actual measurement but it sure is not something you can see by eye. The video shown on youtube was dropping from much less and saying you could easily distinguish the differences.


So my conclusion is, if you want to check a battery get a $10 HF voltmeter. Or heck just put it in a flashlight and see how bright it is.