EEVblog #779 - How To Measure Product Battery Cutoff Voltage

[Muttley Snickers]

I haven't read every article or post in relation to the product but has there been any mention so far in regards to reverse polarity protection and if so would this then incur a voltage drop by the implementation of such a feature ?, ie diodes or are there other means without sacrifice.

Muttley

[Fungus]

I haven't read every article or post in relation to the product but has there been any mention so far in regards to reverse polarity protection and if so would this then incur a voltage drop by the implementation of such a feature ?, ie diodes or are there other means without sacrifice.

I think it's physical - it just doesn't fit if you put it on backwards.

[Muttley Snickers]

I think it's physical - it just doesn't fit if you put it on backwards.

 
Ah yes, I have a raincoat with a similar feature but what if you have a number of batteries in parallel and you put one in back to front, this could be destructive and might be worth testing should we ever see these things.

Muttley

[amyk]

I was looking around at the interesting side of this. I have never looked at the LTC3105 but a very interesting chip .25V startup is very impressive.

Anyway I wonder how much current they can deliver at the claimed dropout? If they have a real device, chip, whatever that can deliver the current then sell that. I guess if they did have such a thing then there would be no need for the batterizer.

The LTC3105 can startup at such a low voltage but from the first page of the datasheet doesn't look like it's designed to supply more than ~100mA and is usually down in the tens of mA; the amount of current also decreases with supply voltage.

TPS61200 is closer to this application, 0.5V startup and few hundred mA up to 1.4A output, but also decreases in current as voltage decreases. Highest efficiency of ~90% is achieved at 100mA output current, and drops sharply after that.

[edy]

If you set up your experiment just right, you can prove anything. You can see by the patent that a low voltage of 1.39 was used as a cutoff, which has plenty of current driving potential that you could easily boost it and keep drawing from it and achieve over 50 mA for a long time after. This is what Dave called "moving your goalposts".

Patent and figure 7 shown below:

FIG. 7 shows measurements that illustrate the advantages of the various embodiments. Three popular AA battery brands, Panasonic, Duracell and Sony were chosen for the measurements. Active load circuitry that drew a fixed 50 mA current was placed at the output of these batteries and the voltage of each battery was measured over time. The horizontal access shows time and the vertical access shows the battery voltage. The starting voltage for these fresh batteries was 1.6V. The amount of time it takes for the batteries to reach 1.39V, which is where a lot of electronic equipment stop operating, are listed. The Panasonic battery took 6.3 hours to reach that level, while it took 4.5 hours for the Sony battery. The Panasonic battery when used in conjunction with a regulator, according to embodiments of the invention, took 27.9 hours before it stopped providing 1.5V, and the Sony battery when used with a regulator took 32 hours before its stopped providing 1.5V. Thus, with the regulator, it takes 4.5 to 7 times longer before the battery needs to be replaced. Thus, the total number of batteries that need to be manufactured and consequently discarded would be reduced by 4 to 7 times. This would have a significant impact on our planet if one takes into account the carbon footprint for extracting all the battery material, their manufacturing, their transportation to stores, their packaging as well as all of the toxic material that end up in our landfills.

Can someone please explain the figure. It seems to make no sense and does not match up to the numbers they provided in the description. 

[P_Doped]

So this whole Batteriser concept got launched based on a completely errant assumption that a 1.5V battery is useless to consumer electronics below 1.39V? 

Either:
1) This is pretty sad for a set of experienced engineers to believe that end product manufacturers would design their equipment so mismatched to a power source's discharge curve.
2) They are completely scamming people.

Which would you rather have: smart, unethical people, or dumb professors?  Quite a dilemma...

[AF6LJ]

My money is on this being an intentional scam.

[jippie]

So this whole Batteriser concept got launched based on a completely errant assumption [...]

Which would you rather have: smart, unethical people, or dumb professors?  Quite a dilemma...

I think marketing people came into the mix somewhere along the line and they made the engineers say "mehh ... it kinda sorta works". I remember Dave has made a mention in one of his vlogs about how a product just works fine for a given goal, but then marketing comes in and thinks up all kinds of fantastic new ways to utilize it which just don't work. Unfortunately I can't recall what the subject was about.

The Dyson vlog http://www.eevblog.com/2010/12/13/eevblog-132-delusional-dyson-marketing/ is not the one I was thinking about, but it is about a similar mechanism with marketing.

[Delta]

As a pragmatist, I too think there could be some truth in the theory that the engineers came up with a working device that could be useful in certain applications, but then the marketeers got hold of it.

Engineers: "This device will keep an old incandescent torch (flashlight) nice and bright for longer before you need to change the batteries".

Marketeers: "That doesn't sound much of a sales pitch.  How about REVOLUTIONARY NEW INVENTIONS INCREASES BATTERY LIFE BY 800%!"

[tarheels100]

Probably the simplest counter-argument against Baterizer would be if you demonstrated how adding the battery's 100-300 mOhms of resistance to the output of the power supply makes no difference when measuring voltage at the product's battery terminals.  That would be apples-to-apples in terms of comparing the two, even helping to account for transient load issues, although I doubt you would see any difference in reality.  Sometimes you have to make the argument such that even a monkey clapping cymbals could understand.

[CHexclaim]

Dave, you should get hold of the SAME toy, the annoying Monkey thing, and do the test properly, with the DMM connected at the battery terminals in the monkey's ass and using similar flat batteries as in their video. Showing that the battery voltage under load drops.

[TheElectricChicken]

this thread become boring for me, so I play with monkey. have a monkey avatar anyone.

[edy]

NICE MONKEY!!! 




I still can't for the life of me understand Figure 7 from their patent.

The "Regulated" curves start off at 1.8 V and remain there and suddenly drop to 0 V.

The "Unregulated" curves start at 1.6 V and continue more like regular battery depletion curves.

1. Where did they get the numbers?
2. What does the description for Figure 7 and the actual diagram have to do with each other?
3. What do those multipliers mean?

        

Can anyone make sense of what this means? It almost looks like the Regulated curves are worse. And why show 1.6 and 1.8 V starting points? Since when is this a regular operating voltage for devices per cell?

[merlinb]

The quickest way to point out the fallacy in Batterizer's 'method' of measuring battery cutoff voltage is to note that, for a given product, every battery you try it with will give you a slightly different answer. Dave, be more concise! 

[Muttley Snickers]

I would love to know when that graph was done as I posted a while back in another thread about a Canon camera dropout at 1.42 volt per cell and new Energizer Ultimate Lithium batteries with an unloaded  voltage of 1.80 volt (non rechargeables), it may be related and perhaps they can read and whats with the vertical and horizontal access in the patent, yes it reads access and not axis.

Muttley

[edy]

I would love to know when that graph was done as I posted a while back in another thread about a Canon camera dropout at 1.42 volt per cell and new Energizer Ultimate Lithium batteries with an unloaded  voltage of 1.80 volt (non rechargeables), it may be related and perhaps they can read and whats with the vertical and horizontal access in the patent, yes it reads access and not axis.

Muttley

Well they are assuming a "load" of 50 mA in the patent as well. Since when do toys and cameras and most devices run on such a small current? Of course if you call 1.39 V threshold an "unusable" voltage, and then boost it back up to 1.5 V and keep measuring until your current drops below 50 mA you will last a long long time after your "so called dead" battery has run out.

Their definition of a useless battery (one below 1.39 V) and then assuming a paltry 50 mA "load" is how they can say they extend the battery so much further. It's the way they DEFINED things wrongly to begin with.

....And I still don't understand their graph. Surely someone must be able to explain it. Can we ask Batteriser to explain the graph in their patent?

AND I JUST NOTICED they did say "access" in their patent (not "axis"). Wow?   

@TheElectricChicken...  I propose a new emoticon to be added to the EEVBlog forums, it should be a cymbal monkey bent over with an oscilloscope probe up it's arse. Can you make one like that? 

[Pentium100]

Wouldn't the "bursty" devices that use high current when starting and then low average current benefit more from a capacitor and not a boost converter? For example, my portable tape player uses ~150mA (from a single cell) when playing, but changing modes (starting, stopping, reversing) requires 320mA or more for a second or so. If a battery is marginal and can only provide voltage above cutoff at 150mA then adding a capacitor would work better.

[LabSpokane]

In the interest of completeness, and since I still see an Apple Magic Trackpad shown on the Batteriser website as a device that stands to benefit, I am providing the testing data for this as well.  The test setup is identical to that of the Apple Wireless Keyboard I posted earlier.  The short answer is that the minimum device operating voltage is 0.95V per cell, and the cutout voltage is 0.925V per cell.  The same caveats of voltage drop at the terminals as before apply.  In short, the currents and ESR involved are low enough to be largely irrelevant to the result. 

In the end, the Magic Trackpad is even more efficient a battery consumer than the Apple Wireless Keyboard and leaves less than 5% of the battery's energy remaining when the device is run to the point it ceases function.

V   %   Notes
============
3.2   100   
3.1   100   
3.0   100   
2.9   93   
2.8   84   
2.7   76   
2.6   58   
2.5   42   
2.4   -----   no measurement taken
2.3   17   
2.2   13   
2.1   0   
2.0   0   
1.9   0   min startup voltage
1.85   0   Device ceases function

At this point, I feel that Batteroo and it's advisors, particularly one Dr. Kiumars Parvin, Professor of Physics at San Jose State University, need to demonstrate publicly how they have come to the conclusion that these devices leave 80% of the battery's energy left untapped, and that a boost converter can release it.  I am using what I feel are reasonable methods that are backed by standard calculations, and I am completely unable to reproduce Batteroo's results. 

My offer to reproduce these tests before an audience of qualified observers stands.  You come to me.  I only ask for reasonable time accommodations.

====================================
BTW, Dr. Parvin has a impressive CV and has authored nearly two dozen peer-reviewed publications: 
http://www.sjsu.edu/people/kiumars.parvin/
http://www.sjsu.edu/people/kiumars.parvin/CURRICULUM%20VITAE.pdf

[mikerj]

this thread become boring for me, so I play with monkey.

Jeez, that was more information than I wanted.

[TheElectricChicken]

@TheElectricChicken...  I propose a new emoticon to be added to the EEVBlog forums, it should be a cymbal monkey bent over with an oscilloscope probe up it's arse. Can you make one like that? 

[Hugoneus]

In the interest of completeness, and since I still see an Apple Magic Trackpad shown on the Batteriser website as a device that stands to benefit, I am providing the testing data for this as well.  The test setup is identical to that of the Apple Wireless Keyboard I posted earlier.  The short answer is that the minimum device operating voltage is 0.95V per cell, and the cutout voltage is 0.925V per cell.  The same caveats of voltage drop at the terminals as before apply.  In short, the currents and ESR involved are low enough to be largely irrelevant to the result. 

In the end, the Magic Trackpad is even more efficient a battery consumer than the Apple Wireless Keyboard and leaves less than 5% of the battery's energy remaining when the device is run to the point it ceases function.

V   %   Notes
============
3.2   100   
3.1   100   
3.0   100   
2.9   93   
2.8   84   
2.7   76   
2.6   58   
2.5   42   
2.4   -----   no measurement taken
2.3   17   
2.2   13   
2.1   0   
2.0   0   
1.9   0   min startup voltage
1.85   0   Device ceases function

At this point, I feel that Batteroo and it's advisors, particularly one Dr. Kiumars Parvin, Professor of Physics at San Jose State University, need to demonstrate publicly how they have come to the conclusion that these devices leave 80% of the battery's energy left untapped, and that a boost converter can release it.  I am using what I feel are reasonable methods that are backed by standard calculations, and I am completely unable to reproduce Batteroo's results. 

My offer to reproduce these tests before an audience of qualified observers stands.  You come to me.  I only ask for reasonable time accommodations.

====================================
BTW, Dr. Parvin has a impressive CV and has authored nearly two dozen peer-reviewed publications: 
http://www.sjsu.edu/people/kiumars.parvin/
http://www.sjsu.edu/people/kiumars.parvin/CURRICULUM%20VITAE.pdf

All of this publications seem to be in physics. I don't see anything in electronics.

[TheElectricChicken]

Jeez, that was more information than I wanted.

now you can play with monkey too. 

[TheAmmoniacal]

I just emailed Dr. Kiumars Parvin asking if he still stood by his quote in PCWorld and if he could explain which test he performed along with what battery cut-off voltage he used at which discharge rate.

Would be fun to get an answer!

[TheElectricChicken]

slower version, you choose or suggest.

Image of monkey copyright unless artist says otherwise, my part is PD, waveform I steal from the internet, but doesn't matter because too simple, it just describe sinewave.

[edy]

@TheElectricChicken

      

That's the funniest thing I've seen in a long time! Great work!

Every time there is some shady product or claim, this will be the "meme" that represents it! It will go viral! "Shove a probe up a monkey's arse!" has a good ring to it.