EEVblog #140 - Battery Capacity Tutorial

Ever wanted to know what battery capacity is? Dave takes you through everything you need to know about amp-hours, mAh, watt hours, internal or series resistance, temperature effects, battery cutoff voltages, and characteristic curves.
Part 2 coming soon.

[MichaelFJ]

Great video. This is batteries 101 and should be mandatory for any electronics student.

[zhuzzir]

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.

[arthurdragon]

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:)

[Afrotechmods]

@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.

[jawojnicki]

LOVE THE BTTF LICENSE PLATE IN THE BACKGROUND. SWEET DUDE!

[salomonjedidias]

i've never worried about the cut off voltage, thanks again Dave you are the best.

[jakeschur]

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.

[PICingfun]

WOW 300 thumbs up and only 1 downer! Dave you always do a great job and this Battery vid is no exception to the rule. Well done.

[EEVblog]

@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.

[Satchmoeddie]

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.

[linksmith]

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.

[Paulo-pymm]

youre so into this its making me excited about electricity. you get a sub my man.

[JonnyFlash]

This is the best video I've ever seen in my life.

[mukb]

In the cheat sheet you show that wasted power is IR which is not corrent. It is I squared R (I^2.R)

[telict]

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

[Afrotechmods]

@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.

[EEVblog]

@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.

[davidchen]

6:46 1J=1W.S=1W.H/3600, not the others way around.

[xDRTeK]

Very well rounded Hands-on. I can now do some starting research knowing more from this video.

[EEVblog]

@Certifiedfunds They will have a lower self discharge rate when colder, and hence a longer shelf life in theory.