EEVblog #779 - How To Measure Product Battery Cutoff Voltage

[Fungus]

On a different note... When you boost voltage don't you get a drop in current? Power is VxI so wouldn't the current drop as a result?

Ohm's law...?

[AF6LJ]

This whole campaign is really frustrating to watch. There is clearly conflict of interest from people whom they interview.

Of course.
The Indiegogo video has the former CEO of K-Mart, because he's on the Batteriser board as the Chief Strategy Officer.
And it seems all the professors they are getting to support it are colleagues.
It's a big circle jerk thinking they have the greatest invention in history 

Does anyone know how much money is actually involved in this company?

No idea. But clearly they are not just relying on the Indiegogo money. The money they must have already spent on the professional videos and marketing must be a lot. I suspect they don't really need the Indiegogo money, it's probably just a big pre-sales marketing vehicle and looks good to future investors.

Clearly it looks like they are smoking their own Dope.

[amyk]

That patent is ridiculous!

If one were to assume that the time versus the voltage drop is a linear function

It is very much not.

The time it takes for the battery voltage to drop by 0.1V is longer at lower voltages versus at higher voltages.

...it is longer in the middle, conveniently ignoring the lower part of the discharge curve...

It is smarter to build the electronic into the battery: http://lygte-info.dk/review/batteries2012/Kentli%20AA%202800mWh%20%28Blue%29%20UK.html

Very interesting... so the Chinese have effectively already shown what a battery with a switching regulator behaves like. Possible prior art? A quick search shows these self-regulated AAs have been around since 2013.

[AF6LJ]

Yeah, that's certainly at the forefront of the controversy. I did find it interesting that they have considered that it could be added to a battery during manufacture. I assume if that were to happen it could be done very cheaply since it would be effectively disposable single use.

Never going to happen, even if it cost nothing to integrate into the battery, because of the simple fact that it would render all battery guages in every product non-functional. Actually worse than non-functional, it would show 100% all the time and then your product dies instantly. No one would buy such a battery that did this.

You also won't see this product incorporated directly into batteries due to environmental concerns.
Consider the number of batteries that are thrown out every hour in your country, let alone in the US..
Each of those batteries now contains materials that not only make them more difficult to recycle but pose an environmental hazard.

[AmmoJammo]

Why not build it into the device!

Oh, right, they already do...

[zapta]

I just watched the video. If I got it correctly, the argument is that the series resistance doesn't matter because the voltage is measured directly at the monkey's contacts. This assumes that the current consumption is steady right?

Consider this theoretical load. It alternates fast between two states with 50% duty cycle:

State A:   I = 1ua,  required min v = 1V
State B:   I = 1A,   required min v = 0.6V

With a zero ohm source resistance, the load will stop working at 1VDC measured at the load (it breaks state A requirement). 

With 0.4 ohm source resistance, the load stop working at 0.8V DC measured at the load (source is at 1V, load voltage alternates between 1V in state A and 0.6V in state B).

This shows that there are scenarios (possibly theoretical only) where the serial resistance does matter, even if we measure the voltage at the source.

Anything wrong with this analysis?

[WN1X]

The best strategy I think is to keep encouraging young and old people alike to foster an interest in basic science and electronics with places like EEVBLOG where people from all walks of life can learn. If anything, this Batteriser debate has done more to help promote EEVBlog than it has to market Batteriser. This is the best thing about having this open forum.

The more we discuss these and other projects, the more videos by Dave and others, the higher the search rank in Google, the word will get out to those who want to hear it. People have to want to hear it though. You can't force a fool to keep their money.

So very true! 

[EEVblog]

This shows that there are scenarios (possibly theoretical only) where the serial resistance does matter, even if we measure the voltage at the source.

Yes, because of the fact that the low battery voltage warning/cutoff/whatever in a product, is always taken form the battery terminals. So nothing else matters.
You can get into pulse loads etc, cold start and torque motor loads in the monkey etc, but that's essentially a red herring.
The tutorial was about how battery cutoff voltages are determined in a product. The low impedance PSU is used to determine the lowest cutout voltage that includes any dips on pulses. If whatever battery you use in your device can't maintain that cutout voltage with pulse loads, then that's an issue with the battery, not one of product cutout voltage.

[EEVblog]

Weirdly enough: Those are the exact same devices that EEVBLOG forum members predicted the batteriser might be worth using with.

I'm pretty sure they are mining this thread and my Youtube video comments for ideas. Give them an inch and they'll likely run a mile with it.

[Anders]

Dave!

Don't waste more energy on these obviously incompetent statements and video!
They have just made their own grave and I cannot see how they ever could be trusted again for even the simplest thing?
Their product is completely dead to everyone with minimum knowhow of batteries. And they brought it on themselves! 

[LabSpokane]

It would appear their 800% claim came from this video.



13% battery, being boosted to 1.5volts, so the indicator shows 100%...

I guess seeing as batteries store 1.5volts of energy, it all makes sense!

I tested the trackpad and found the cutout voltage to be 0.95V.  I posted that in another thread. If I need to buy a wireless keyboard and go through that too I will. Pretty sure I will get the same result since I doubt they use a different radio.

The Garmin Dakota is a pretty old GPS. It can be had off Amazon, but I'm not sure about local availability.
================

Dr. Bob,

Can you please retract your more, shall we say, "optimistic" claims?  That way we don't have to keep on going down this road. I will source these devices, and I'm fairly certain we both know what I'll find.

I want to think that you're a good person that has been trapped into this Silicon Valley startup lottery mania. I want to think that this marketing campaign has been hatched out of investors' needs for a miracle device, instead of a good device that solves a true problem for users of legacy or poorly engineered devices. And the latter is a FINE business model, and shame on the lottery culture for not supporting what could be a nice business. I would love to see you and your brother succeed and making such devices better.

We are engineers. We have a social responsibility to telling the truth. When we abandon the truth, society suffers, and we lose credibility. Will any great tragedy result from the mere doubling up of boost converters?  Almost certainly not. But the failed promise will simply bring discredit to the profession. It will be yet another opportunity for someone to sneer, "well that's what engineers said about <fill in the blank>."

That does not mean we don't make mistakes. We all do, and that's why we have peer review. This venture seems like more than a mistake. If I thought you were a fool, I would dismiss it as such. But, you are not a fool. You are a highly educated man and I'm sure you are aware that the truth is being substantially "bent."

Please reconsider what you're doing.

Thanks.

[vindoline]

I just took a look at the "batteriser" site. Wow, just wow! A group of apparently successful, educated people running this! An awful lot of money has been spent on marketing and production "values." I wonder what kind of insurance they have, it's a class-action lawsuit waiting to happen.

[boffin]

The Garmin Dakota is a pretty old GPS. It can be had off Amazon, but I'm not sure about local availability.

Dave's a geocacher, I'm pretty sure he probably has 10 friends with Dakotas if he doesn't already have one (or two).  In fact as a geocacher/electronics hoarder, I'm sure he has (pick at least four of the below):

• eTrex (Yellow)
• eTrex Legend
• Rino 120/130
• Garmin 73/76
• Dakota
• Oregon
• some Magellan (and then realized he really preferred Gamin)

The test would be valid against pretty much any of them.

[AF6LJ]

I just took a look at the "batteriser" site. Wow, just wow! A group of apparently successful, educated people running this! An awful lot of money has been spent on marketing and production "values." I wonder what kind of insurance they have, it's a class-action lawsuit waiting to happen.

Looks to me more like a conscious effort to promote a scam.
While the BS meter is not pinned against the stop is just off the scale at 80+ DB over S-9.

[Svuppe]

I just dug deep down in my pile of old gizmos, and I found an old Garmin eMap. It is so old that it does NOT have a setting for the battery type. Instead the manual states that when used with NiCd or NiMH, the battery status will not show full with fully charged batteries, and that this is not a defect 

Anyway, I think it is time to do some measuring on it.

[ogden]

Guys, did you see Batteroo comment below their video? 

"The best way to measure the cut of voltage of any battery operated device is not to use the bench power supply but instead use batteries. Then to get an accurate cut off voltage of the device; one should directly hook up it's battery terminals to a Data logger that is recording both voltage and current; and operate the device until it stops functioning. Using this technique one can determine the operating voltage of the device and take all guess work out of it!"

[Svuppe]

Garmin eMap has been tested. It's cutoff voltage is about 2.130V +/- a little (it uses 2 x AA batteries). 1.06-1.07 V/cell.
And sorry, but no I didn't use actual batteries. I used a power supply, and measured the voltage right on the battery terminals in the monk..... ehhh GPS.

I am tempted to run down a pair of actual batteries, while logging the voltage all the way. That will have to wait until the weekend though.

[fcb]

Following Daves #779 video I opened up an AA cell.

I couldn't find the resistor 'Rs' anywhere.  Please help..

[akshaykirti]

I'm not sure if anyone saw this but on the Batterizer video the dude has his oscilloscope hooked up to the test signal contacts on the oscilloscope which are used for probe compensation. The square wave looked pretty shitty.

 

Edit: Just read all the post comments.. Dave mentions it at sometime

[romelec]

I am tempted to run down a pair of actual batteries, while logging the voltage all the way. That will have to wait until the weekend though.

Can't you do it this evening ? It will just take you 2 hours 

[KedasProbe]

Way to long for such simple concept. (only watched the beginning so I know what it was about)
The key is to keep the battery properties, battery properties and product properties, product properties and not mix them up.

[AF6LJ]

I'm not sure if anyone saw this but on the Batterizer video the dude has his oscilloscope hooked up to the test signal contacts on the oscilloscope which are used for probe compensation. The square wave looked pretty shitty.

 

Edit: Just read all the post comments.. Dave mentions it at sometime

I saw that along with the never used soldering iron.

[RFZ]

Regarding the GPS test-setup... I guess by measuring current, those flimsy wires and connectors, they just added a significant voltage drop to the setup which lets the GPS think it drained the batteries way too early. Since the batteriser supplies a constant voltage, the voltage drop has no effect over time, it just has to be low enough to get the GPS running at all. You can actually see a bargraph indicator on the top left of the display, showing one red bar constantly on all scenes. Is that the battery indicator? Couldn't find a manual for that device... If it is: assumption confirmed

To measure the current, they use a Hantek 365A/B/C/D/E/F, I think. But it's manual doesn't say what internal shunt resistor is used...

They actually also measure the voltage of the battery with a DATAQ DI-145, but they don't give us the values
I'm curious why, they'd confirm that the GPS has a cutout voltage of ~1.3V 

[Falk]

Hello Dave,

you have my deepest respect for your endurance and power to bash this marketing bullshit.         
It's a tough job, but some got to do it! 

Keep on educating!

Regards
Falk

[apis]

Got this reply from Indiegogo:

Hi there,

Thank you for sharing your concern with us. At this time, the campaign is under review to ensure that it adheres to our Terms of Use (http://www.indiegogo.com/about/terms). We will follow up with you if we have any further questions.

So what happens now? We will include the information you have provided along with all other information at our disposal in our review of the campaign. In some cases, we will contact the campaign owner to have them edit their campaign and it will remain on our platform. If the project doesn't follow our rules, we may remove the campaign. We may also restrict the campaign owner's future activities on Indiegogo.

To protect our users' privacy, we're unable to share the action we take. At Indiegogo, we take the trust and safety of our community very seriously, and we greatly appreciate your patience and understanding throughout this review process. To learn more about Indiegogo’s Trust & Safety effort, please visit: www.indiegogo.com/trust

Please note that you do not need to contact us again. Doing so would create a new ticket and prolong the process. Thank you again for taking the time to get in touch with us and for helping to keep Indiegogo a safe and secure platform.

Sounds like a default reply to complaints. Maybe they'll do something if enough people report them...