Review & teardown of a Romoss 40,000mAh USB power bank

How does it work and what's inside this power bank? Let's find out!

[@slepro]

Careful there, the capacity is 40Ah at the batteries. It's not 40Ah at the 5V output, it's less. You must use Wh instead.

[@Sylvan_dB]

Yes, this. The spec at 0:48 says it is 148Wh, which at 3.7v nominal battery voltage is indeed 40Ah.

[@fred.nestler814]

AS ALWAYS---A WORTHY VIDEO ANALYSIS! KEEP EM COMIN!

[@chanceisom]

Love your sense of humor you always make me laugh, keep up your videos

[@topperdude2007]

Wow! Two informational videos in two days! Look forward to projects where you will use these salvaged pouch cell batteries as well as the 14500 batteries from yesterday's video. Keep up the great work! 👍

[@englishrupe01]

Great job, there. Many thanks for the video.

[@TorbenRune]

When you use USB for charging, the USB interface uses the so calle USB PD (Power Delivery) protocol, to indicate how much voltage and current the recieving device requests. For some devices this will be a static ammount, but for modern phones, ipads and laptops, the PD protocol may change the supplied power during charging. Typically, when a device like that reaches 80% of charge, the PD protocol will reduce the power, so that the recieving battery will not heat up, when it is filled with the last 20% of charge. This means, that in order to judge how effecient a charger/battery bank is, you need to analyze a full charcing cycle form a few % up to 100%, with a device that can actually draw the full power that the supply is capable of (in this case up to 22,5 W).

[@lupillos7404]

Good videos like always, I always had seen this power banks but was thinking that 40k was all lie was surprised was very close to 10k on each battery 🔋 thanks for the video 👍🏻

[@LimbaZero]

Other to test for glue/tape is IPA. Should be little safer compared to hot air

[@ericklein5097]

Yep 99% IPA (or even the 90%+ stuff from the Walgreens/CVS/local grocery store...just DON'T even bother with the 70%) works wonders and is so useful when cleaning off flux and other crap on electronics.

[@ericklein5097]

Does that power adapter you attempted to charge with through the USB C port support 12V? 12V is technically not part of the PD 3.0 spec so companies like Anker do not include 12V on their power adapters...which is just silly all the way around though. Thankfully most companies do include a 12V PDO. I also would guess that the powerbank you chose as a load for the USB A ports wasn't the best choice for measuring the max output of the ports. The green port is likely the one that supports some fast charging protocols like Qualcomms QC 2.0/3.0. The best way to test the actual outputs of those ports is to use something like an FNB48/FNB58 or KM003C USB tester since they will run a protocol detection and show you every protocol supported and what voltages/power levels it supports. You could then buy the corresponding QC/PD/whatever protocol triggers off Aliexpress and trigger them on the powerbank and have the load running to a cheap Atorch DL24 electronic load (0-200V/0-20A/150W) that are only like $23 shipped.

[@BabaNamKevalamGames]

nice nice, just simply nice..

[@MontanaBoy93]

An adjustable load is a much better way of determining maximum output power. The bms in the charged devices are surely throttling the system,

[@nuclearthreat545]

Thanks bro

[@lmwlmw4468]

Nice.

[@jonleone777]

So what power bank would you recommend to power or charge a phone or laptop during a power outage.

[@skyforce1983]

Just use a different bmu and those cells will do great

[@jacquesb5248]

interesting

[@alexandercamacho3104]

The way he said "stubborn" 😂😂

[@felipehcraftgamer4193]

Can this batteries provide high current? Next video: how to build 40ah e bike battery Lol

[@Sylvan_dB]

0:48 - no. Remember Ah are almost meaningless. To have meaning, you need to know the voltage. For powerbanks like this, that is usually 3.7v (the nominal battery voltage). A better number is Wh (watthour). You'll notice on the specs, 148Wh. Power(watts) = Volts X Amps. So 3.7v X 40Ah = 148Wh. If your e-bike battery is nominally 36v, and had 148Wh, it would only be 4.1Ah at 36v. If it were 40Ah at 36v it would be 1440Wh - almost twice the size of the typical e-bike battery, but some are in this range.

[@felipehcraftgamer4193]

@@Sylvan_dB stack like 10 or 13 of theese to make a 40ah battery

[@Sylvan_dB]

@@felipehcraftgamer4193 This is already a 40Ah battery.

[@CapApollo]

those batteries dont have balance charging . a call for magic lights and smokes.

[@vuaeco]

4 cells in parallel doesn't need balance charging.

[@Rosstysh]

Holy Christ I tried to open this mf and completely destroyed this powerbank. don't repeat my mistakes. Literally was glued with 3M tape. Impossible to take it off...

[@lyleson]

the accent is so strong... it's sending me to the bed....