They Lied about their 9V Battery Capacity 

thanks for the info You should make a new video with the current 9v batteries to know how much you get from a 600mah batt

Thank you that explanation was very clear and informative, I am about to buy a couple of these so now I know what to expect from them.

mAh is a stupid unit to measure battery capacity. We should use Wh or just J, since then you don't need to know what voltage is being used to know how much energy is actually stored

I have the TQTHL variants of this battery - same thing, of course.

which one would be the best to buy

Very nice ! Please please a new video with this time good surprises and great 9v rechargeable you could then advise.

I tested the same from and other supplier and also came out at about 400mAh @ 9V

ugh i hate these. the buck converter makes a 50 hertz garbage buzz that gets really bad at higher current draws so its useless for audio equipment/microphones. I also believe the poorly tuned oscilator voltage step thing messes with smoke detectors and even though it has capacity it will randomly wake u up at 2am with a fire alarm/low bat chirp. also, i presume because of how poorly tuned that buck converter is, it has a lot of loss of something like 15%. i dont think anyone has put one of these on a oscillaskope yet but im guessing it will look like a guangzhou sawtooth electrical grid frequency mismatch at 6pm on a monday

Is that battery several times better than a 250 rated version?

Wait till you discover the fake Ernie Ball Chinese strings

I bought one of these 9V 6900mAh, I wonder what is the true mAh of it. even if I divide it with 3.7 it still doesn't sound right. what kind of scam is this? I assume they measured it with 1.5v?

Very usefull video. Could I please kindly ask you what is total weight of this battery named "9V 1300mAh" incl. skeleton? I bought from Ali "DAWEIKALA 9V 28000mAh" weighting in total 20 grams (incl. skeleton, i.e. not disassembled). Apparently the Li-ion cell itself must be there even smaller..

It looks pretty good, but that type of batteries with a voltage booster circuit cannot be monitored on the device in use to indicate the charge level or when it is getting low, that is, you cannot see at what point the charge of the battery 🔋 is, but at a certain point without prior notice the device will turn off when the battery charge has dropped to the point where the internal electronics cut off the operation of the internal voltage booster, for a toy or a device such as a multimeter yes I would use it, but not on something critical like a fire alarm or smoke detector

great video, thanks for writing out the math, keep them coming !

Any chance of seeing the 9v output voltage sag, if any, under load?

Some of these "true" 9V batteries with booster circuits do not like high current loads (like 1A). I've seen a couple that claimed a limit of something like 300mA if I recall correctly...which is still pretty hefty for typical uses of a 9V battery in this small "6LR61" form factor. I've also seen a number of these batteries CLAIM they retain 75%-80% of their stored capacity after a year on the shelf. So their circuits must consume considerably less than 100uA when not connected to anything external (or they are lying, or using some non-standard testing protocols to bump up that percentage).

I have another brand that I use with a similar charger with alligator clips. These do not have a usb port. These do not advertise that they are True 9 volt. The voltage is max 8.4. I assume these are just 2 cell batteries which operated at a lower voltage. I set the charger to 2 cell, and charge them to only around 8.1 volts. The lower voltage doesn't seem to matter to my smoke detectors. I'm surprised you could even charge these batteries with alligator clips if the power coming out is running through a boost circuit! Perhaps you meant you charged around the USB connector. I like these other type so far and do a top off charge about every 3 months, the batteries in the smoke detectors are barely drained and only require maybe 20 mah each to top (and the capacity of these batteries is like 500+ mah). Thanks for letting me know that these true 9 volt batteries are not the way to go UNLESS your device is unhappy with top voltage under 9 volts. Incidentally, while it sounds like a ripoff that they advertise "deceptive" capacity based on true battery voltage, the manufacturers of USB Power Banks often do the same thing. That's why people complain about true use capacity vs advertised capacity of these power banks. They're advertising the capacity of the cells Before the voltage gets boosted.

AFAIK this battery would not be allowed to sell in the EU, because of intentionally misleading marking/marketing. And I noticed that it can't be found in any of the Amazon stores in the EU, so that may be why. 🙂

In the video on the Tenergy official channel, they claim to use 2 li-ion cells in their 9V battery and they say it's a nominal 7.4V, so apparently no boost converter involved.

4.837 wh Battery Output: "kwh or wh is correct power rating" (E x I = P) 9v (E) x 1.3 x 3.7 / 9 (I) = cancel the 9s and 1.3 x 3.7 = 4.837 wh (P) The electronic ckt onboard will maintain the 9v constant. The labe states 9v x 1.3ah false rating of 11.7 watts per hour. Note the battery of 3.7v @ 1.200 wh is the factor only, voltage is only the product of that with a loss. So fully charged is a joke due to 4.3 to 4.15 is minutes apart on any lipo or lion battery test if you ever did many tests I have. 550 alkaline to lion is okay. Maximum amperage rating should be included in sale. "9v 4.837wh 1.5amp(max amperage)" the output IC limits amperage usually by it's thermal internal ckt.

Better off using a DC load and actually measuring at the 9V output. Then you'll get a real reading. Your maths doesn't include the efficiency of the boost converter which is not going to be anywhere near 100%.

People expect 1300ma @9v. It's probably a 1300ma cell @4v. Somebody didn't do the conversion. I really wish they would state battery capacity in watt-hours..

If im not wrong, that aint an ion, its a li polymer

You be way better off to get a 9-volt battery holder that holds two double a batteries and put in the lithium 14500 battery cell those batteries are about 1,000 Ma and your project will last a lot longer

So we are not so advanced in battery technology after all lol

Rechargeable batteries: EXPOSED

at least it doent look LIPO !!

4.15 is not fully charged so your test is not good, bring it to 4.2 and do it again

Don’t say amperage. Say current.