How to check battery capacity

[@guillep2k]

That's wrong. The curve is specified at a given drain current, while you're meassuring it without a load. You must connect a load drawing that specified current and *then* meassure the voltage. If you do that quickly, it won't make a dent on the battery's charge.

[@ZLau13]

Always measure voltage under load! This is incorrect, even a dead battery can show voltages like 1.5V if it's been idle for a while.

[@keithfreeman5204]

I use a flashlight bulb with a couple of wires soldered to it. This is used to test D cells down to AAA cells. Depending on the brightness of the bulb tells me how much juice the cell has in it. I admit that this isn't really as accurate as a meter but it works, and it is very, very cheap to make. Yes, I do have a Multi-Meter.

[@xdominion330]

How do you check a battery which is not fully charged or a running battery

[@bobl703]

You should rename this video to "voltage" as you are not actually testing the capacity. I was looking for a way to check the battery capacity (which is in milliamps). mA or mAh

[@JohnMSawyer]

As some commenters have already mentioned, sometimes a used battery's voltage will measure fairly high even when its capacity is mostly drained--they just become big resistors. So, my simple way to check remaining battery capacity is to use the current-measuring setting on a multimeter (I usually use a Fluke 77). I touch the leads briefly to the battery so I don't drain it very much, and see how much the digital display "deflects". I don't keep figures in my head for how much current a fully charged battery is able to deliver, but I go by rough memory, so that if I see little deflection, then I know the battery doesn't have much juice left.

[@robertjusic9097]

What's deflection?

[@VaughanMcCue]

I missed the rationale for 1.1 for 1.5 cells and 3.3 for 9 v cells. What formula do we use for button batteries and the small 12v used in car remote key fobs? AND what about lead-acid 6 and 2 volts. This was a great video and I got a real "kick" out of it and it brightened my day.

[@Beauchot78]

This was the video I needed to see, thank you. Most people don't realize voltage doesn't tell you much about the charge level of a battery. Unless you do this math.

[@tarstarkusz]

That discharge curve is under ideal very low load conditions. ONLY rechargeable batteries have anything like that flat curve. The complexities of primary cells is the reason they do not ever advertise the capacity of a primary cell.

[@EWOverland]

Thanks for the video, but I dont understand the multiplying numbers to get the percentange

[@frv6610]

Why is not Wh (battery capacity?) calculated with max full charged voltage? For example if an electric kickbike's (Sealup Q8) battery (38km range on a good day) is rated as 48V21Ah (48x21=1008Wh) but it's full charge voltage is 54.6, so why not calculate it as 54.6V x 21Ah = 1147 Wh? I have a kickbike Q8 battery (Samsung cells purportedly) rated as 48v21ah but it soaks only 877Wh according to power outlet meter. Should it be soaking 1008Wh or 1147Wh, or is 877Wh correct? I also have another battery from (Aliexpress) Liitokala (tested 27km range) rated as 48V20Ah (48x20=960Wh or 54.6x20=1092Wh) but it soaks only 698Wh (it's more like 15 or 17Ah?). So am I scammed or it is normal? I complained to Aliexpress about it LiitoKala battery, that it should be at least 835Wh in it if it is 20Ah but they ask for more proof. I already proved with power outlet meter how much it soaks, it is 698Wh and showed my other battery soaks 877Wh (for comparison). Aliexpress supports vendors lying about real capacity of battery. Idk how I can prove to them that LiitoKala is not 20Ah battery (more like 16Ah). I also bought on Aliexpress a 48v24ah battery called Aimjin but it only charged to 53v (not 54.6v) and from empty to full only soaked 340Wh which indicates its capacity is 7Ah. It also became warm when I used it which indicates it is an old tired battery. But I paid for it near same price as for new battery. Scammed.

[@arnoldtarbooz1420]

Old video - but I need to find the capacity of a Prius Lithium battery brick/cell. How do it do that?

[@blaizebunny7482]

Personally, I toss a battery when it hits 1.4V (or 7.something V)as some devices don't like the lower voltages and they consequently get weird about their behavior. I could try to figure out which devices can still function correctly down to 1.1V and which don't, but life is life. This video was a good explanation of how to use a VOM to test batteries though. Lots of people don't know that, and they should learn.

[@bitTorrenter]

So, 1.6V measures full. 1.1V measures the minimum useful voltage. The difference (x 100) gives the capacity. According to this method.

[@abjurian]

I was wondering at the beginning of this video you showed a load tester, Do you know where I can get one of those? Even a DIY kit would be nice. Thanks and thanks for the video.

[@mikerama4724]

David Galloway check out Amazon they have an assortment to chose from

[@nnejiamaechi9385]

Good. What if it's a 12v lead or litum battery pack

[@tonyotieno8192]

Misleading title. This is measuring state of charge (%), not capacity (mAh).

[@tarstarkusz]

Open readings are useless. You need a resister to find the voltage under load. Batteries are generally dead at about .9V under load for anything but the smallest of loads. A very small load, like a small LED can work down to like .6V

[@pofrani]

Awesome!! Thank you!

[@pavan7653]

Sir, I liked the video. What about 18650 batteries? How to measure the capacity of 18650?

[@zeshanrasheed5977]

and what multiplier do you suggest for 12 volt car battery or 12 volt 140 A lead acid battery

[@retrosteve2732]

Where would one get such a thing as the Electronic load with built in mah please?

[@BobCampbell530]

www.amazon.com/gp/product/B07VB4NTK8/ref=ox_sc_act_title_1?smid=A9JWJVEJFYCB1&psc=1 This one says it uses 120 Ohm load. MAH would depend on the battery style, it's not something that can be measured without draining the battery.

[@Fluffythecatmouse]

@@BobCampbell530 that's not accurate link, just battery tester, not an accurate load/drain device as in the video.

[@buddyboy4x44]

Very useful. Surely there are tables showing percentages for various batteries? Check voltage, check table, know capacity?

[@crazytom]

The graph showing linear voltage drop makes this approach uniquely useful to Alkaline cells (similar approaches also work for li-ion which exhibit similar linear behaviour)

[@BufordPusser582]

Thank you for this vid.

[@MrTedMcForehead]

does this work for 18650's as well?

[@crazytom]

Yes. Straight line from 4.2V to 3.0V with 3.6V = 50%.

[@vlad8614]

Capacity is measured in Ah, not in voltage!

[@rominhawk3949]

Mr. Donnelly, Thank you for sharing this informative article. I know it was 3+ years ago; but, I'd like to know why did you multiply times 200 for the 1.5/1.6 batteries, and times 33.34 for the 9V ones? Thanks for anyone who can answer.

[@82ryno]

You mean divide not multiply. Thanks for the vid

[@zarakatchi9191]

how did i get here?

[@XempireX18]

what is a bah-tree

[@balasikoutdoor1594]

Nice video, new friend here!

[@dimosthenisiasonidis5697]

With this method, you can measure the sod and dod not the capacity !!

[@vincent.416]

2:15 popointfour

[@vinitrajput6554]

What if battery shows 3.4v

[@crazytom]

Possible Li-ion (33% remaining) or LiFePO4 (75% remaining).

[@vinitrajput6554]

@@crazytom what method u used for this? Thank you!

[@crazytom]

Same method. Linear extrapolation. Li-ion useful range: 3.0V-4.2V. LiFePO4: 2.8V-3.6V.

[@sniffcardozo1970]

math is hard

[@danielg818]

My battery is 3.7v how much do I subtract?

[@bitTorrenter]

Depends on the lowest useful voltage for that battery type.

[@jameszcurtis]

How can you check your cell phone battery? The s7 edge

[@crazytom]

The S7 (and many other late-model 'phones) doesn't have a removable battery. What you could do instead, is fully discharge the 'phones battery and then charge via a USB inline mAh or Wh meter. This would measure how much capacity it takes to fully charge the 'phones battery. Search for "Keweisi USB battery capacity meter" and you'll see what I'm talking about.. about the size of a mini cigarette lighter.

[@MTBIKEXC]

SO USEFUL! Thank you!

[@davidgoodwin6522]

What are you talking about

[@StiloNautica]

i found this useful

[@ubbe1089]

;-);-);-)

[@whisperingblues9887]

Utter bollocks this stuff.

[@waynekendall6196]

I came here expecting to watch a video about checking battery capacity, not battery voltage.

[@oross99]

Well... you didn't understand then.

[@mhz2562]

@@oross99 ok you understand can you tell me how much mA? how many hour that battery can use?

[@robertjusic9097]

@BigBrain Time that will fry the fuse on the multimeter since the ampermeter gets connected on a battery in series and there is no load on it.

[@danielwatson7764]

Then you should have kept watching. He covered Capacity and % of charge remaining. And showed the math in easy to understand language.

[@jeremyblandford7669]

​@@danielwatson7764 Seconded

[@jaremaw2368]

You assume, that eg AA battery's internal resistance is the same for all types/manufactures. That's wrong.

[@noweare1]

As long as put a small load on the battery you can use the voltage to figure out if it's worth keeping or not.

[@MrExtremehustler]

Easier if you just take the ratio between remaining useful voltage and total useful voltage. Like this, ((measured voltage-lower range)/Useful)*100... For example, ((8.79-6.6)/3)*100=73% for the 9V...By the way the Math in this video is off, 8.79-6.6 is not 2.13 and 1.58-1.1 is not 0.47.

[@JasonTN]

why we subtract 1.1v not 1.2 or 1.0?

[@clm0208]

I think you are checking the voltage not capacity.

[@1uP-v2]

How to you calculate nimh with 1.2v?

[@Damian83z]

error: 1,58 -1,1= 0,48v (not 0,47v)

[@theyjustwantyourmoney4539]

I have a whole bunch of so called dead cells in the house awaiting disposal, I'm glad this will give me a job of screening them all. thanks

[@belowmars]

So how do you test battery capacity of a Zinc Chloride battery, or NIMH battery or lithium ion battery? Apply the same voltage upper and lower limits and calculate the percentage the same way?

[@informing_]

That's a great video, although my intention was to to check how many mah a battery has, like, not the percentage but the actually mah number

[@crazytom]

Try this kzbin.info/www/bejne/bIO9k5tneN6WpLs

[@crazytom]

Or this..

[@crazytom]

kzbin.info/www/bejne/nojQqmCDjLeNkMU

[@crazytom]

Or this .. kzbin.info/www/bejne/lYOuoIaiaLSDq8k

[@informing_]

@@crazytom Thank you I'll take a look

[@murtazamustafa579]

5v 1600mA How can i get which bateery is suitable 3000mah or 2300mah or 2800mah

[@chimerabxb]

this person probably seen a lot of batteriser bateroo bulshit videos .. :D

[@ericgeorge5483]

I really enjoyed this, thank you.

[@vmilovanovic]

Battery capacity is measured in Ah (Ampere hours), not Volts (actually, the capacity is properly expressed in Coulombs, but for the batteries Ah is more often used) . Therefore, this video should be named "How to check battery voltage", which is a different thing from the capacity. Two cells can have same voltage, but wildly different capacity. In order for capacity to be measured, you'd have to take the rate of voltage drop under load into account. Measuring just nominal voltage without any load will often give you skewed picture of the state of the battery.

[@alsemi-back-up579]

Very Useful in Testing . Thanks. Great Video

[@CuriousPoints]

How to test my cell phone bl5c battery capacity or how much % left for example output voltage of battery is 3.7v

[@larsonfam3861]

A Chaturvedi look at the battery gauge the phone provides....

[@CuriousPoints]

Larson Fam how