Hi. Just a quick follow-up video to my previous video which is a response to the Batteries Up Monkey video where they tried to explain why power supplies are different to batteries and it's actually quite a misleading video and I went in detail and explained why they didn't actually measure it correctly and all sorts of stuff. So cliquey if you haven't seen that. I Just wanted to do another quick follow-up video because one of my viewers, Andrew, sent in the real Monkey.

It's the same one that Better Eyes are used in their video. thank you very much! Andrew So I wanted to repeat their test where they showed the monkey working down to our two volts on a power supply and why it didn't work with batteries measuring 1.25 volts per battery open circuit that we reproduce it and see what we get. The answer is pretty obvious to anyone who knows about batteries. Let's go! Ah, by the way, this is Probes The Monkey, so we'll call him Probes 2 and let's go probes.

So my test setup is very similar to before: I've got a beak, a precision 8500 electronic load I've got art double-a battery holder this time and I've got big high current leads leading to there. Not that that matters because this time I've actually got this extra since wire tapped off here going around to the back of the DK precision load. That's the sense import, so we're actually compensating for any loss whatsoever in any of those leads and that's soldered directly under the contact points here. the contact points also going over to the keysight 3 double, 4, 7, 0 a so we can actually log the discharge curve.

Now this what I didn't show last time is that the BK Precision 8500 electronic load actually has a battery test mode. If I actually go in there shift battery for example, I can go up there we go I can actually set a minimum voltage here of what I want this thing to cut out at so I can set my constant current out load so it'll just continue to do a draw constant current from the battery until it's whatever voltage we specify here and then it'll automatically cut out. So the plan is to discharge two brand-new batteries to until they get to about 1.25 volts open circuit voltage even though that's the wrong way to measure it and there's lots of traps in doing that. This is exactly what batteries I did in this video.

So we were all actually drain these things down using about a half an amp which is roughly what the monkey here we'll call him probes, probes, The monkey, um, what he actually takes, you know, roughly on average. Okay, what I've done with this first battery here is I've discharged it to one volt at half an amp. so it but it recovered to one point three eight volts. I Wasn't sure what and because you're never sure what voltage is actually going to recover - because that's due to the ionic resistance of the very battery which is extremely dynamic has to do with all sorts of factors.

So yeah, I Discharged it to one volt from fresh in the pack and well, we only got the 1.38 recovered and we actually extracted almost one amp out. You'll notice I just turned this back on. It's not in battery mode again. Once again, we're still drawing half an amp constant current and it was one point Three eight.

I Just switched it on then and it's slow. It's very quickly dropping so it doesn't immediately drop back to one volt. As I said, that ionic resistance of the battery. extremely dynamic chemistry at play inside this thing.

but as you can see, it'll it'll should very quickly in the scheme of things because it actually took like three hours to discharge this thing or whatever to evolved or two-and-a-half to three hours. So it's going to get back down to 1 volt pretty quickly. So what? I'll do so I'll discharge it down to 0.9 volts and you know, see if we can get around about that 1.25 volt open circuit voltage even though the open circuit voltage is not the right way to do it. I Want to reproduce what better eyes I did and Bingo! it's just finished discharging to 0.9 volts and we sucked out an extra 0.44 amp.

hours. There we go. from going from one volt to down to 0.9 volts I Cut off after that constant discharge curve and you can see it's jumped right back up to 1.2 volt and this second battery is finished and that took about two and a half hours I think or there abouts and it's jump back up to 1.2 volts actually. I'm not really happy with that at all.

As you can see, they're recovering to 1.32 volts. I think I'm going to discharge these down to Naught Point Eight Five Volts. Let's go. So shift battery 0.85 Go there we go.

Okay, discharging the second battery and we're going to log that one as well to 0.85 volts. And after that third discharge down to Naught Point Eight Five Volts, we drew a total of our point to another 0.2 to amp hours out of the thing. That's not too shabby, she's a can't be much juice left in it. Okay, discharging the second battery and we're going to log that one as well to 0.85 volts.

Alright, I've now got two batteries that have been discharged three times. so really, there's hardly any juice left in these things. We've got one point two, four volts there, and we've got one point two seven volts there. So just over two point Five volts.

Exactly the same open circuit voltage as batteries it used. So let's stick them in the Monkey. These are incredibly discharged batteries, but I think we'll find they'll still work because they've got still some energy left. Well, just a little bit should be enough to operate probes.

The Monkey. Let's have a look. Here we go. No problems at all.

They work just fine and dandy. Why is it so watch I'm pushing that finger I'm pushing it I'm Did you see Mr. Cork that the stick did not tip? So I call your attention to the title of all my shows. Why is it so? Why is it? So there you go.

So why did the monkey under test work with my batteries? At one point? two five volts each or a total voltage of 2.5 volts. Open circuit Just like batteries as one's It's very simple. the internal resistance of the battery. Everyone knows about this.

It is hobby level stuff as I've explained my batteries even though I brutally discharged them here. Yet three discharge curves. most of the energy is gone. There's still enough energy left in there to operate this monkey.

No problems at all. So the batteries that batteries used. Even though they measured exactly the same open circuit as the batteries I used here, there ones work. there was no energy left in and they must have discharged them down to Bloody Bugger All.

No wonder it didn't work. And ironically, this test the tests that they used in their video for this monkey that proved that batteries are different two power supplies. As if anyone didn't know about internal resistance. Ironically, the monkey is actually a very poor choice because this thing can extract virtually all the energy out of the batteries it doesn't need the batteries.

ER And the reason why they didn't actually put the baton, the dead batteries on the batteries er and put him in the Monkey because it wouldn't have worked. It doesn't matter how magic your boost converter is, they're not going to work because there was no energy left in the batteries. Ah goodness, how embarrassing. How could they put out a video like that? It's incredible.

So this is why the Batteries A Monkey video is not only wrong, but it's misleading because it's making out that the open circuit voltage of the battery showing that there 1.2 volts per cell implies that there's actually energy left in the battery. When in their case, there is not. There is clearly no energy left in the battery. That's why people do not measure the open circuit voltage of the battery.

It doesn't happen in history because it's a very, extremely poor indicator of whether or not there's energy left in this battery. Even better, Eise's own video showed that this monkey works down to naught point. 5 volts per cell extracts almost every drop of energy from the batteries. that with a power supply, the monkey will operate even when we bring the voltage down all the way to zero point: 9.

Boltz However, when using two batteries with a total voltage of 2.5 volts, the monkey will not operate. Of course, the monkey won't operate because those batteries aren't 1.25 volts per cell when you skip them back up the monkeys. but because you didn't do what? I Tried to explain in the previous video that you must probe right here and that is why using a power supply is exactly the same as using batteries when you actually measure the voltage where you should, which is right up the monkey's butt. And that's the trick.

which batteries a don't seem to understand is that one battery that measures 1.25 volts and another one that measures the same 1.25 volts open circuit When you actually put them in a product, one cannot work at all because it just plummets because of the internal resistance, the chemistry. There's no energy left in the battery, but the other battery that measures exactly the same opens open circuit may still have some energy left in it, do to help was discharged and all sorts of complex you know factors involved in the battery. The open circuit voltage doesn't tell you that Oh Everyone knows this except that ERISA So my batteries at one point two five volts open circuit still had a little bit not much, but a little bit of energy enough to make this monkey work because this monkey extracts practically all the energy from the battery. so the batteries they use clearly had zero energy left.

because batteries can recover to a high terminal voltage. That's how ionic resistance in the chemistry inside a battery works. That's why you never, ever measure the open circuit voltage. Ah, and here's an example of this.

In a previous video, you saw that I are very slowly discharged at a constant power. A couple of triple-a batteries, this one was discharged at a hundred milli watts continuous and I have to do a follow-up video showing the data for this and this one was. But here's a quick look at the data. This one was discharged at 50 milli watts and this one here was discharged at 20 milli watts.

Okay, so let's have a look at the voltage left in these batteries. Open circuit with no load: 1.2 volts, 1.15 volts I discharge these things right down to zero and they even oscillated down around zero. I left them there in continuous. you know, practically shorting the things and they still recovered to 1.2 volts.

That's what these the battery chemistry can do. but it doesn't mean there's much if any energy left in these. There is actually some due to the ionic resistance in the chemistry is a tiny little bit. Maybe 1% of the energy still left to these are discharged completely discharged batteries.

It could be less than 1% so it might operate. You know something? a low power device for another error or something like that, and that's what you can do. Of course, you can stick these batteries into some low power device like this for example and it will still operate. So here we go.

We'll measure that. 1.15 volts. There it is. We'll stick it in here and we'll find that this thing will still work.

It's a, you know, it's pretty dim. Okay, but it still works. It's still a tiny amount of energy left in there. And let's measure the voltage in there.

There we go. It's because this thing takes, you know, absolutely nothing at all. really. Except maybe when a beeps there.

we go just see a drop when it beeped. So look, you can even still put them in something like this multimeter and it will still work. Look at that. It's not even showing low battery.

That's because it hasn't dropped to a low enough voltage yet. Look, it's still there. You go. Two point, three, two.

Okay, it'll even have just enough energy left to still operate the backlight like that. Okay, however, you know it might be running at five milliamps or something which is not much power at all. But if you measure the voltage in there, you'll see it. It's dropping and it's going to continue to drop.

and it's going to drop off pretty quickly. There's you know, you might get another half an hour's use out of this multimeter out of the 300 odd hours that it normally operates. And no, don't jump to all the excitement that aha, that's a usage case for the battle riser. Well yeah, okay, it is right.

if your product doesn't extract all the or most of the energy from the battery, but it's how much do you get out of it An extra couple of percent and when you slap on the boost converter on this thing, it's going to be draining a lot more current than if you just put them in here like this Because you've not only got the efficiency of the converter, but you've also got the increased current of the product because it's operating at 1.5 volts per cell instead of you know, down around one volt per cell or whatever these happen to be at the time. So just be very careful when you get all excited about a boost converter. Like the batteries. er, it's not magic.

it's all to do with the amount of energy left in the battery. Physics 101 and this other battery I discharged at 20 millivolts. What happened to it? Well, let's take a look here. Why Point 1 1 volts? Why is it? So take a look at it.

It has leaked. Look, This is what can happen if you don't get the batteries out quick enough and you continue to drain them right down to zero. I Must I Might left this one in for an extra you know, couple of hours or a day or something like that to when compared to the other ones and it leaked. And this is one of these Duracell Dura lock ones that isn't not supposed to leak, they're supposed to have you know 10-year life and Blair there we go.

Got all that got a bloody leat? Unbelievable. That's a danger of discharging batteries right down to zero and not getting them out quick enough. So here's the discharge curve that I actually got from this thing and you can see that I did three discharges here from here to this point where then it recovered and then as part of the ionic resistance of the battery, it recovers very quickly and then a tapers off like that and slowly if you keep going, it actually recovers. You know, probably up to one point four volts eventually or maybe just a little bit under.

And then I started the discharge again and then right. It jumps down straight away, but due to the ionic resistance of the battery, it starts to slowly diss. show that it doesn't drop back to exactly this point because it's the dynamic electrochemistry of the battery. Okay, you're not gaining any extra energy by doing that.

The battery only has a fixed amount of energy in it, but the that's that's why the voltage really is not telling the whole story there. So it gets down and down. So we extracted some more energy from here and we turned it off. and then we extracted some more energy.

Three different periods and the battery tester measured point seven nine, seven, Npr's point Four Four, and Powers point two two amp hours for a total of about one point Six three amp hours 1630 milliamp hours. Now just to clarify something here, and Powers or Milliamp Hours is not the true measure of battery capacity because it's not taking into account the voltage. It's not power. The only true measure of energy in a battery.

either energy used or energy remaining in a battery is actually in watt hours. So that's why I've shown in previous videos how you can't just use the voltage. you've actually got to convert it to power. and it's the total integral under the under the power curve.

So if you do constant power discharge, you can actually just read off the percentage directly from the X-axis here. But we're not doing constant power discharge. We're doing constant current discharge Anyway, We've got. we extracted one Point Six Three and Powers out of the battery.

but clearly this could. These could still operate the Monkey, which is a fairly high drain device, so it still clearly had some energy left. It might have five or that, maybe even 10% left. And Giroux cell data for the milliamp hour capacity in this case, but energize I Do so energizes Alkaline.

Just as an example. here here we go out of 500 milliamp constant current discharge, which you did on the Jura cell. If you draw a line across there, it's around about 1,400 milliamp hours. and we extracted actually 1630 from it.

How we'll be able to do that walk? Because we actually because this is continuous discharge. Okay, just in one cycle, we did it in multiple cycles. You allowed it to recover so we can actually get just like you get increased capacity at lower currents. so lower average currents like this, so you don't necessarily have to discharge it at a lower current.

You can still discharge it at 500 milliamps as we did here here and here. But because we let it rest for sometime in between, this is not the true time. By the way, here and here this is I Just that's only where I stopped doing the data. so it actually had more time to recover than that.

So the average value is going to be better than this nominal 1400 in one continuous discharge. Anyway, that's just a quick little look at milliamp hour discharge. But yeah, like I said, there's probably not much left in this thing. The only way you can do it is to really time it in the monkey itself.

and I know what you're all saying Dave Probe the monkeys. But well, here it is the MU T the monkey under test. I've probed in there. These big probes here go into the banana plugs which you can hook up to the battery or a power supply here and then.

I've also got some leads. It was quite tricky, but I shoved them in the end of the probes right at the contact points right up in there. So I've set the power supply to 2 volts if I turn it on. There we go.

So one volt per cell, 2 volts total. As you see, it's not dropping much at all because there's not that much loss in these leads at all. So still on just fine. So now I'll do my two batteries and the open circuit voltage of these batteries is two point five.

Nine volts there. Okay, so this is going to be a little bit tricky, so bear with me for a second. I've got to sort of use all of my hands. Oh, hang on I Got to use my three free hands here.

and like that, can see it's dropped down to one volt, but it's not there. We go: two volts. Okay, so it's dropped from that two point five down to two volts because well, there's not much energy left in the battery. So the ionic resistance drops that terminal voltage by a fair amount and just like battery.

so let's wind the voltage down. Here we go: 1 point 7 volts. Let's take it yeah at a volt at a volt. So that's half a volt per cell.

the monkey is still working. This is an incredible probes. The monkey is absolutely amazing, but that's yeah, he's pretty much dead there. The torque from the motors just yeah.

can't do it. So that's why these ones still work because there's enough energy left. It can keep the terminal voltage up above that, 2 volts up above well double what is required to operate the monkey. So what I'm going to do is discharge these things even more until I get to a point where they weren't working the monkey and we'll see what happens.

Even though the terminal voltage you'll be high, they will drop. when you actually plug them in here. it'll just plummet and it'll go under that one volts. you bet your life on it and discharging to 0.6 volts, we're able as jump back up to one point one one way I would extract another point.

Three One our powers. Beauty All right. Here we go. I've drained them a bit more and put them in here.

There you go. Two point One volts. Okay, so should be enough to operate Probes the Monkey and I suspect we will get some juice out. Yes, I soldered some plugs onto there.

Here we go. let's have a look. Ah, just he's getting real slow. Look One point Four Eight.

but you put any resistance on there at all and he's just gone. You hold him, maybe up like that. The talk might be a bit more and he's oh yeah. You can see he's virtually dead.

Okay, just train a little bit more charge out of him by holding that and of course the resistance of the motor in that not look. He's gone, he's gone. Ah, poor probes. sorry probes.

You can see the batteries that Batter Riser must have used even though they are measuring that terminal voltage. Okay look, we've even get in that voltage under load. 1 volt. So half a volt per cell like he's dead.

Ok, he's gone. There was no more energy usable energy lifting those batteries. Take it off and here we go. It'll recover.

and if you leave them there long enough it'll probably recover up to a quite a reasonable quite a reservoir. You There we go. So one point seven, eight volts already and climb in. It'll probably get up to once again that tube easily that 2.5 volts at one point two five volts per cell which Batteries A showed in their video.

You can see that it's just ridiculous. And they made out that measuring the voltage of the batteries open circuit was exactly the same as the power supply here. And it's not. It is completely different.

Yes, batteries are different two power supplies. But you can see when we actually probe it in there. Even with the power supply, it won't work. It's the terminal voltage of the battery that is dropping due to the electrochemistry because there's no energy left in it.

So a power supply is equivalent to using the battery when you probe it properly like everyone in the bloody industry does. except better. Iser Oh Unbelievable. So you can clearly see with no doubt whatsoever that a power supply is equivalent for determining the cutoff voltage of battery because the cutoff voltage is probing right up the monkey's butt, right on the terminals.

That's all that matters, not the open circuit voltage of the battery. Of course, batteries are not the same as power supplies when you measure the damn things open circuit because this doesn't have any electrochemistry. this thing and does all that matters is the cutoff voltage at the terminals there. So they're very specific.

Claimed at the end of the video that me measuring the battery cutoff voltage with this is is wrong and misleading at best. That was their claim here. It is right in the video. To use a power supply to show a battery operated devices cut off voltage.

ignoring the battery's internal resistance is wrong and misleading at best. And you can see that's total rubbish because they didn't probe it properly. Unbelievable. It's such a misleading video.

this better eyes are one, it's completely busted. I don't know how I can bust it any more than that. So sorry. that video was a lot longer than I was expecting.

But as always I like to win clued detailed information exactly what I'm doing because people are learning a lot from these videos and that's the intention. So there you go I Hope you found that video useful. If you did, please give it a big thumbs up on YouTube And as always the link to the EEV blog forum down below for comments: leave them on Youtube blog side: All that sort of jazz and I've got a whole bunch of other battery videos not just on this batter. Iser I've had a whole bunch of videos for years.

I've got like 10 battery videos or something crazy so I'll link in the playlist the YouTube playlist here. We can go through and see them all, so just remember the moral of the story. Always probe the monkey's butt catch you next time you you.