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.

[fred.nestler]

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

[chanceisom]

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

[topperdude]

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! 👍

[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).

[lupillos]

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 👍🏻

[kidulkono]

Nice to see tear down sessions, thx sir for the share

[ericklein]

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.

[englishrupe]

Great job, there. Many thanks for the video.

[LimbaZero]

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

[troyguererro]

Anyone knows the data sheet for these cells? I can't find it on the internet. Can they handle 2A charge/discharge current?

[MontanaBoy]

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

[jonleone]

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

[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...

[elvisclement]

After charging it. It stop charging my phone

[skyforce]

Just use a different bmu and those cells will do great

[felipehcraftgamer]

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

[lleworgaming]

Guys madami issue tonv powerbank. Meron ako nito, naglobo agad sya kahit bihira gamitin. Tas minsan nasa 30% nqmamatay na lang bigla. Misan naman bigla mag fufullcharge

[alexandercamacho]

The way he said "stubborn" 😂😂

[CapApollo]

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