The reason for the condecending tones is quite justified. anyone with basic electronics understanding will know that you cannot charge a AA in 15 Minutes. Well you can a couple of times and then you can throw the fucking things in the bin cause they will be cooked and will hold bugger all charge.
@GTXAbunada Like Dave said, 1 joule = 1 watt.second. If you haven't done calculus yet look up integration and integrals, and you will learn that the area under the curve equals the number of joules given up during the discharge cycle. Khan academy would probably have some good videos on basic calculus.
It is true that 1 joule = 1 watt.second It is also true that 1 watt.hour = 3600 joules, so that 1 joule = (1/3600) watt.hours What he is trying to say in the video is that if you have a value expressed in watt.hours you need to multiply that value by 3600 to get the value in joules, and that is exactly what he does for the AAA and AA cells. I agree that the presentation is a bit off in his 'equation'.
this very excited man doesn't mean here that 1J = 1Ws = 1/3600Wh instead he says that because 1J = 1Ws , so energy of battery in J can be calculated as Wh*3600
This whole Amp hours and Watt hours debate is why deep cycle batteries often use reserve capacity as a measurement because it's a good apples to apples comparison between the same kind of battery. I'll explain. A 12 volt nominal battery with 60 minutes reserve capacity. That means that this battery will stay above its depleted voltage (if memory serves the industry uses 9 volts as dead) for 60 minutes at an industry standard 20 amp draw. Basically at an average draw of 240 watts (12 volts nominal times 20 amps) the battery will run for 60 minutes till it's depleted.
@ryanstewart86 Probably because the capability of the battery to deliver current is dependent on a chemical reaction, and normally chemical reaction rates increase as temperature increases.
That curve looks suspiciously familiar. A RCA document was recently released that showed vacuum tube life. It was about the same curve. I am guessing the battery's chemical use/depletion and the valve's chemical depletion are much alike. I use Tenergy NiMh and had great luck with them. Some were 2500mAH and some were 2750-2900 for AAs. I factor in the dollars I save buying the Tennergy over some fancy retail crap, and the no name works fine. Energizers died long ago, but my no names still work.
Coming back here for the n-th times, these never gets old. A good refreshment course even if u wont need it 😅 it still fun (and soothing, probably 😅) to watch Dave face n voice with loads of info on the subject.
@Orthosonic Actually it's not a constant current (although you could assume that). You have to log the cell current as well when calculating power. This is shown in my next video on measurement, but I decided not to include it in this one.
@kd5gua It depends entirely on how you define the battery capacity and it's end use into a particular load type. By the very definition, mAh or Wh capacities are implying a constant current or power discharge rate.
I'm still debating if mA.h is the shittiest non-imperial unit in engineering world (the contender is the mm of water for pressure, used in the air filtering industry). Please use Coulombs and joules as much as you can.
Naa constant resistance would be like good for lamps (bicycle or so). I think thats why they got that types in there. There are batteries "specialised" for light/lamps. I dont think that it has any or much effekt on lamps what battery you use but well thats marketing xD
Good video. I didn't really understand milliampHours. Totally off topic, does anyone know what this 30-pin video connector I have is called? It only uses 16 of the pins. It came out of an old (the oldest) Gateway Profile.
English is not my first language, so it's somewhat difficult for me to understand some things, but all in all, this is the best video about batteries that i've found thank you very much, this video has been (and will be) a lot of help in my schoolwork:)
The total energy of any maximized chemical storage is roughly equivalent to the same mass of common explosives like flash powder or dynamite. So if you measure that a battery has around 5 grams worth of chemicals in it, if the energy was released at the same speed as a plastic explosive by a capacitor, the damage would be roughly the same as detonating 5 grams of TNT or C4 or RDX, whatever.
A very good video. I've been doing a bit of hobbyist testing of CR2032 batteries and this is very useful in covering the finer points of capacity and battery performance. For the discussion at 12:30, as per the added caption at 13:24 about rechargeable batteries, isn't there a dilemma here about product design vs a 0.8V cutoff as users are likely to try rechargeable batteries even if the product says not to use them? Some products have a user-specified setting for battery type but I've always assumed this is just used for battery level indication and is unlikely to be perfectly trustworthy?
You're saying that the mAh definition assumes a certain voltage, but you're making that assumption yourself. You would need to assume some voltage level if you want to calculate energy with a simple multiplication, but that's not the fault of the definition of Ah. Neither does it call for keeping the current constant. For example, 1h of 200mA + 1h of 400mA usage equals 600mAh, no matter what the voltages are. What is capacity? Does that mean energy or Ah capacity or something else? I don't know.
Think about this: an average person needs around 9000 kJ a day (not talking about manual labor or athletes here; they can easily use tripple the amount). That's equivalent to the energy stored in 1000 AA batteries or a cube a little larger than 21x21x21cm³ stuffed with batteries. Running a human on batteries wouldn't be cheap ;-) . And if you have rechargeables: even with those 4x15min quick chargers you'd need 3 of these charges stuffed 24/7 to have enough energy.
i really should have watched this video first before commenting on the other one and i would have answered my own question... so it's true that these numbers really are just consummer nonsence. now lts talk about getting the 9000 joules our of a AA.. theoretically speaking*wink wink* whats the formula to determine that in farads? =]
I have a 3.3V MCU wondering what sort of battery to use. 9V - buck converter, or 3x1.5V to regulator. I think did some rough calculations and could get 10 days of use putting the MCU to sleep 9/10 of the time.
hey expert...just want to ask what should be the delta peak and Amp set on a charger for a 7cell 3300mah nimh bat for RC car? 5mv/cell at 3A ok? the battery got very warm..
The old adage could be applicable... Those that can, do. Those that can't, teach. Probably not really fair but I have had put up with my share of bad teachers.
@GTXAbunada Because of the assumption of constant current load. So the actual area is in 'volt hours'. But multiplied by a constant current you get watt hours.
Dear Sir As a school project I built a very simple lead-acid battery to investigate cycle fade. The capacity of my lead-acid battery decreased as the number of cycles increased, as expected. Surprisingly enough, the capacity increased after a 24 day period of deep discharge. I did the same thing three more times (so a couple of cycles followed by a long period of deep discharge) and every time the capacity had increased after the period of deep discharge. The battery did become more difficult to charge (to induce current flow a voltage of about 10 to 16 volts was necessary, just for a few seconds) and eventually it stopped working. However, I was very surprised to see that the capacity loss after a few cycles, and I was wondering whether you could enlighten me. I assume you will not have time to answer my question, but I'd greatly appreciate if you could shed some light on this issue. I can send you my results, in case you are willing to take a look. Thanks in advance, Nol Duindam
It sounds like sulfation. It's when the sulfur dioxide in the battery acid breaks loose and sticks to the lead plates. Sulfur dioxide is a good insulator. As the sulfur coats the plates, you have less area to charge. If it fully covers the plates but in a really thin layer, a higher than normal voltage will start charging. This current flow will help put the sulfur back into battery acid (sulfuric acid) and you have to add water (the sulfur steals parts of the water to make acid again. Leftover hydrogen "boils" off). If it gets too thick, the charging voltage can be very high with little to none current flow, and the battery stops charging. Oddly enough the plates are holding a full charge, but you can't "reach" it through the sulfur on the plates.
about capacity ... well, i have never seen a single-use battery with its capacity written on it. its only written on rechargable batteries. what's the easiest and quickedst way to measure the capacity of single-use batteries when it's not written on the battery or the box?
Looked up for Peukert's Law, i noticed something else in other formulas being t = H[(C/H*currentdrawn)^k]. H being discharge rate, quite confused. Is it written in the battery's specs? what is it really? :\ THANKYOU!
I've been saying this for some time also. Ah is the wrong way. People think "My 15,600mAh (5V) battery is better than my 5Ah (18V) battery" which is bullshit.
I am back watching your vids Dave - great work. You are worth a trip to the "top paddock" - no knackery or mackers for you . comment all positive so fear not>>As I done Mech.Eng before Elec.Eng . Battery and nonlinear (eg. milliwave 18GHz and above) circuits never bothered me, but working with elec. techos I spent many hours explained non-linear behaviour and "capacity". Mech.Eng is about laws of Thermodynamics ( that's proper Mech eng science - more like physics or theoretical mech as opposed to quantum mechanics ). I had fun times explaining concepts to techos and I can tell you they hated anything that involves math let alone opening the mouth and sounding out word like "Integral" of "Differentiation" and Fourier was some French guy. Best example of non-electrical circuits involving sink-source ops are pneumatic-air or fluid circuit and "load-matching" all fun stuff. Keep up a good work Dave, I will see all of your blogs in no time - thumbs up on all of the ones I watched so far. ( Ps I did learn from them also how to ...:-)
At 13:00 -> If I would run a LED with 3 cells at 2.4 I'll get the most out of a battery? N how do I make shure that the LED is staying at 2.4V? A resistor is for the current, but what restricts the Voltage? Please help me I have to deliver the atomic bomb by Monday next week. thanks I will mention your name.
One of the best quick battery videos on YT, though most of what was said would apply more to primary cells. Unless you go nuts, you should get 3WH out of a 2500mAH NiMH cell at the same temperature (though most good quality NIMH cells will work at low temps). While it's nice to lower the draw by adding cells, there's a tradeoff on that too. Never underestimate the stupidity of the person who will use your product and go mixing cells and the more cells there are, the more opportunity there is for a mismatch.
Hello Dave, I find that when you try to charge your Batteries too fast, you end up killing the cells.they buckle and once you get them hot, they will never be the same again. The best way to charge Nicads and nimh is with a workshop power supply and when your current drops to close to zero, battery should be charged. If battery always draws current, usually means Battery is rooted. I have tried all the different tricks years ago when cell phones hust came out and phone batteries were worth a couple of hundred Dollars. We used to charge people to recondition their Nicads. All we would do is zap the batteries with 240V just for a laugh and the fucking stooges would think they were all reconditioned. It's basic Ohms law
GREAT job, Dave. I would consider this a video for intermediate level students of electricity. But, if I were to study electricity for a working knowledge of it, you would be my first choice as an instructor.
You've putted you finger in the wound, the capacity of the batteries still the most difficult thing to calculate as the technology of batteries still almost the same for decades. personally i've suffered alot with the lead-acid batteries for PV powered standalone systems. there are many factors affects the performance of the battery bank, so no way to get an optimum battery bank design. it will be always over sized. and if we can put finger on all effective factors on the battery performance. you can't make sure that the load will perform as u expected. for me i was using LED luminaries as a load which has alot of effective factors on the performance, the temperature is the most annoying thing about it.
hello, i am trying to create a circuit to charge a car battery could you make a video about that or point me to link based on your profesional opinion? it might be used to charge from a pv cell. thank you
I built the SC idea of a capacity tester. At a $2 shop type place and buy a cheapo analogue travel alarm clock powered by typically an AA cell. Bridge it with a load 15 ohm for a 100 mA load. set the clock to midnight, insert battery and it will tick away until the voltage is about 1.1 V when the clock will stop. Read the time in hrs and mins this gives fair comparative capacity time . I built a four unit tester, and the results are quite informative.and reliably indicative of capacity
can you help me with this? i have something like a charger.. it says like this: INPUT 100-240 V 50/60 HZ 0.3 A OUTPUT 12 V;;; 0.5 A how can i get more ams then taking? i dont get this.. this is the first charger i have seen like this.. taking 0.3 A OUTPUT 0.5 A what is this about? and can i compare batterie and electricity with pool and water? for ex.. pool is the battery.. voltage is the pressure i have on the hose.. if i can,, then what are the the amps and wats?. thank you .
Just been looking at the discharge curve for duracell batteries... i dont think its a coincidence, but they mostly show a sharp drop off at 1.1v... coincidence that the drop out voltage for a linear 3.3v regulator is 1.1v, so its almost as if 4 aa batteries were made for them ;P
Greetings from Bulgaria, Dave. I have a question. Well, for example AA battery is 1.4v fully charged and 1.0v fully discharged. From what I know, a battery rated at 2800mAh means you can draw for example 2800 miliamps for an hour and the voltage will drop from 1.4 to 1.0 in that time. So the voltage is actualy not ignored (or assumed constant). Am I wrong?
Awesome stuff.. maybe you can clear what I think is a misconception. If I store my standard AA or AAA cells in a fridge at 1- 5 deg C, will increase battery shelf life?
A non rechargable battery out of a high power device is kept here for the clocks. Clocks are really low power devices that can go years on a battery. The battery probably loses more through discharge then through what the clock needs. So after a big power drain is done here with a non rechargable they are simply demoted. Still I hardly use non rechargables these days. A good rechargable is worth its price ;) But not for clocks...
tarstarkusz I wouldn't know. I never seen them myself yet or tested them. I guess for one off high drain uses like cameras, drones and the likes it will have a use. Still rather go for Low Discharge NiMh if possible. Not that well suited for super low drain but medium and high drain they are just fine. And there always is lithium for the specific machines that can handle them.
I think Dyson hand vacuums pretend to be an ideal battery (I know it's just theoretical) we have a small Dyson vacuum at work that even new out of the box and even in the instructions says the battery will only last 7 minutes. And it literally does from a full charge you get 7 minutes and then it stops no slow down no way to get a bit more out of it the vacuum will just stop working at 7 minutes, bam, done!
David Hughes They've achieved that with power filtering. It's a good idea though, because nobody really wants a product that starts out tough and then wusses out after a few minutes (I'm looking at you, cordless drills.)
Lithium Ion Batteries will hit a certain Voltage and then just cut out. They have electronics in the cells to do this. I think It's because Lithium Ion Batteries don't like to be totally drained
