Xiaomi Mi 2 Powerbank 20,000mAh Review - New 20Ah King?

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R10500
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Sorry if this has been asked before, but has anybody observed unusually slow charging with this model? Mine has started to charge at 0.92A throughout the entire charge cycle and i’ve confirmed that it’s neither a charger nor cable problem, my 5000mAh Xiaomi charges consistently at 2A, while this 20000mAh always did 1.42A max.

d_t_a
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R10500 wrote:
Sorry if this has been asked before, but has anybody observed unusually slow charging with this model? Mine has started to charge at 0.92A throughout the entire charge cycle and i’ve confirmed that it’s neither a charger nor cable problem, my 5000mAh Xiaomi charges consistently at 2A, while this 20000mAh always did 1.42A max.

Not really, experience with my PLM05ZM.

Since I have a USB meter (actually I have several) I notice it usually registers 5.01v without any load (just USB meter), but when loaded a bit, the voltage can dip to say 4.94v, but at other times, just replugging the same device (smartphone), the voltage will instead go up with load.

My smartphone charges at max 1.74A (tested with several USB meters and using different power outlet chargers/powerbanks). But when display is ON, the max charge rate is 1.15A, again only when the smartphone is less than about 75% full (if more than 75% full, the charge rate will not reach 1.74A but will be lower).

Anyway, what I’m mentioning is that sometimes replugging the smartphone on the PLM05ZM, the voltage is up to 5.15v, then the charge rate can reach 1.74A. But when the voltage is around 4.94v, the charge rate is just up to 1.3-1.4A. I’m not very sure how to trigger the powerbank to have voltage go slightly up or down though…

The smartphone’s charge current DOES appear to correlate with the voltage it’s sensing (which can also be affected by the cable used — using a worse quality cable will have lower charge current)

madrian
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" voltage gets bumped from 5.0V to 5.2V. "

 

https://imgur.com/a/Z1sdYDN

 

This is why I see these spikes in the graph (USB24C USB meter)?

 

I am charging  with an Orico charger, which has max 2.4A/port, but it is only charging with ca. 2A. It is normal? 

BlueSwordM
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1. Yes this is normal. This is done because of the resistance of the cable, so the charger bumps the voltage to 5,2V so the phone/powerbank receives 5,0V.

2. It has 2,4A max output, but the device decides what current it is charging at. In this case, it is 2A. So, perfectly normal.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

madrian
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Cool, thanks for the answer. Smile

will34
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madrian wrote:

“ voltage gets bumped from 5.0V to 5.2V. “


 


https://imgur.com/a/Z1sdYDN


 


This is why I see these spikes in the graph (USB24C USB meter)?


 


I am charging  with an Orico charger, which has max 2.4A/port, but it is only charging with ca. 2A. It is normal? 

This powerbank will “boost” the output voltage when the current exceeds 1.5A, it is programmed to always do it because it has no way to detect cable resistance (for that you need feedback on the other end of the cable). but in your case the spikes are due to drops in the current draw.

Some manufacturers claim their powerbank being smart and will detect voltage drop across the cable/connectors and compensate for that, but they’re just being programmed to ramp up the voltage according to the current.

The Micro USB has an maximum rated current of 2.1A, and the 2.4A rating was designed for Apple which implemented 12W charging for their iPads. So even if your charger has a higher amp rating, no device with Micro-USB input should exceed 2.1A on the input side (in theory)

d_t_a
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will34 wrote:

This powerbank will “boost” the output voltage when the current exceeds 1.5A, it is programmed to always do it because it has no way to detect cable resistance (for that you need feedback on the other end of the cable). but in your case the spikes are due to drops in the current draw.

Some manufacturers claim their powerbank being smart and will detect voltage drop across the cable/connectors and compensate for that, but they’re just being programmed to ramp up the voltage according to the current.

Thanks for that explanation, I have also been wondering how “powerbanks” can really detect voltage drop since the drop is on the other end..

I do notice several such behaviors, USB voltage increases a bit when current increases, different chargers/powerbanks implement them slightly in diffferent ways at different voltage thresholds (I use EBD-USB+ to do a current load sweep and notice the voltage changes).

Quote:
The Micro USB has an maximum rated current of 2.1A, and the 2.4A rating was designed for Apple which implemented 12W charging for their iPads. So even if your charger has a higher amp rating, no device with Micro-USB input should exceed 2.1A on the input side (in theory)

For smartphones (mostly I’ve only checked a few older Samsung phones, and they typically charge to 1.8A max current at USB 5v. It’s only some powerbanks that I’ve noticed charging at 2.0A or sometimes spiking over 2.0A charging current)..

The Xiaomi powerbank in particular, seems to continuously “test” the charge current and voltage every now and then, at least that’s my understanding of the “spikes/dips” when I try to graph the Mi powerbank when it is getting charged…

HONDARIDER
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Looks like Banggood pulled the ol’ switcharoo. The link in the OP takes you to the old version. 3.7v (74wh) instead of the 3.85 (77wh). Didn’t notice it till I got mine today. Not a major deal for me but you all should be aware if you are looking for the one in the review.

DBSS
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Anyone know a place that will ship this to Canada?

prototype3a
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I would NOT want a lipo cell inside a power bank. This is not an upgrade to the design.

Also, the voltage spec is non-sense. The nominal voltage was listed as being higher to bump up the claimed capacity. Don’t fall for the obvious marketing.

FlashPilot
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HONDARIDER wrote:
Looks like Banggood pulled the ol’ switcharoo. The link in the OP takes you to the old version. 3.7v (74wh) instead of the 3.85 (77wh). Didn’t notice it till I got mine today. Not a major deal for me but you all should be aware if you are looking for the one in the review.

Well, thats very disappointing but very observant of you to catch. I wonder how old the cells are in the old pack they pawned off on you? Do you have a link for the new model?

Bangood also did the same blatant switcharoo on me with a cell phone I ordered from them. Of course, they tried to deny the claim and then ignored me… until I filed a PayPal dispute and kicked their crooked asses. Now I have a free phone, but turns out it was used and broken by someone before me! Yeah, they sent me a used broken phone and claimed it was new, then tried to stick me with it!

will34
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I think they fixed it now because it does indeed link to the new (2C) version. Or they just decided to send you the old one?

About Lithium Polymer it’s all about preference, if safety if your primary concern then definitely stick with 18650 versions, which are marketed 10,050 and 20,100mAh respectively and have sightly lower energy rating. They have light blue LG F1 cells inside which according to discharge tests yield approx 3,200mAh.

Xiaomi has now released a Mi powerbank 3, same capacity same form factor, but now supports Power Delivery output up to 45W and costs about $12 more.

Both banggood or gearbest pricing are not so worth it for me now that a official Xiaomi store has opened in my town. The updated 10,000mAh version with 2 USB ports sells for $16 and the 2C goes for $25. And all of the other accessories are also much cheaper by a considerable margin.

I have also found that many “Xiaomi” branded accessories are also sold under the ZMI name, some of them being just 1/3rd of the price of banggood. Search zmi on amazon or go directly to their homepage and you’ll find some great deals.

will34
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30-4-2019 Update

Almost 2 years after my initial review and regular use of about 100 full cycles my unit started to show signs of swelling. My power bank is fully charged and ready to go most of the time, which is not optimal for Li-Ion storage but otherwise defeats the purpose of a power bank. And that’s how most people who are not into batteries will use them anyways, so “real world results” nonetheless.

A bit of swelling in pouch batteries is not always dangerous but there is a chance it continues expanding, in which case I must dispose it. One more reason to go with 18650, they also degrade quicker when stored fully charged, but at least won’t became dangerous.

Spins on its belly

Vs flat surface

BlueSwordM
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By god.

This isn’t safe.

Due to how pouch cells are constructed, they tend to release much more gases during bad conditions compared to cylindrical cells.

This is also why powerbanks OEMs should implement an 80-90% storage charge and design it so it consumes as little power as possible.

My RavPower QC 3.0 20Ah has a standby drain of about 14,2uA, which is excellent, but some are 100uA, or even in the mA range in the worst of cases.

Therefore, a lithium-ion cell stored at say 60-80%+ with very little standby drain should have no problem not losing much power at all for a year, and not degrading.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

neBstress
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Agreed!

@will34, a puffed/swollen Lipo of any extent is dangerous, you need to dispose of that pack immediately!

I’ve used Lipos for many years mainly for RC hobby, Lithium polymer cells are not as stable as Lithium Ion and even a Lipo cell that is only slightly puffed can unexpectedly blow its load and with yours being contained in a hard case would make that more likely and more explosive if it did.

d_t_a
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BlueSwordM wrote:
By god.

This isn’t safe.

Due to how pouch cells are constructed, they tend to release much more gases during bad conditions compared to cylindrical cells.

This is also why powerbanks OEMs should implement an 80-90% storage charge and design it so it consumes as little power as possible.

My RavPower QC 3.0 20Ah has a standby drain of about 14,2uA, which is excellent, but some are 100uA, or even in the mA range in the worst of cases.

Therefore, a lithium-ion cell stored at say 60-80%+ with very little standby drain should have no problem not losing much power at all for a year, and not degrading.

Just curious, how do you test the standby drain of a powerbank?

varbos
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That swelling is troubling, stay safe.

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