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Tips for Fast Charging

[Copy link]|Post time:3-26-2017 07:49:59 View:2808|Reply:25

People have been complaining that it takes too long to charge the large battery in the Chuwi Hi12.

The Chuwi Hi12 actually does support fast charging over USB, but it takes the right combination of charger and cable to actually get fast charging to work.

Here are a few tips to make sure you are charging at the highest rate possibe:

1.  Charger
You must have a fast charger.  The tiny square ones from the dollar store will not work! Also, charging from a PC or other USB port is not likely to give you a good charge rate.

The included Chuwi Charger actually will supply well over 2A, but only under the conditions below. Note also that USB-c is becomming more common. This is both good and bad.  USB-c supports higher voltage charging, which the Hi12 does not, so a USB-c adapter may produce more voltage (and thus current), but only when used with a USB-c device. If it is rated at 3A (or more), but comes with a USB-c cable, it may or may not be capable of sourcing >2A at the normal 5V.

You need a *normal* USB adapter that is rated at at least 3A, and says it supports *normal* USB fast charging.

2. Cables
The cable is the most important part. The Chuwi Hi12 requires a special high charge rate USB cable. Again, those skinny brightly colored ones in the bins at the local discount store will not help you.

The included cable is pretty good, and much better than the average USB cable. It can consistently charge at 2A, but you can do even better:

If you want to buy another/additional USB cables, look for the following:

-- The package/advertising shows a specific current rating -- just saying "fast data transfer and charging" (note that terminology is ambiguous) is not good enough. Look for 2.1A or more. The cable will be obviously thicker than regular cables.
-- The package/advertising shows a specific wire guage (ga or awg).  Look for 18 awg.
-- Look for dedicated Charge-Only USB cables (will usually specify wire size as above).
Here is one on eBay found from a quick search. I do not know anything about this seller: ... ctor-/171699709183?
-- Fast charge cables will usually be short. 1m (3 ft) at most.
-- Shorter is better.  I was able to get over 2.25A with the Chuwi included charger and a short, high quality and obviously thicker cable even though I got the cable at a local flea market, and it had no packaging/specifications.
-- Make your own Charge-only cable. Get USB connectors from an old cable, or from a parts vendor, and obtain some 18 awg or even thicker wire.  The results may not be pretty, but if made correctly, it will work.  Be careful of polarity!  A charge only cable also has security benefits.

3.  USB tester or "USB Doctor"

Buy a USB Tester (often called a "USB Doctor") and carry it with you when you travel with your Chuwi Tablet.

Here is a basic example: ... -blue-silver-305545

-- Avoid ones that have a skinny wire of thier own. You can loose or degrade the high-current capability right there.
   Either look for one where all connectors are "hard soldered" to the device, the included cable is thicker, or replace the cable yourself.
-- Other features are nice -- such as OLED displays -- Watt/Amp-hour calculations, etc.  But you really only need a basic one.

Note also that there are chargers with built-in voltage/current monitoring.  I have several of these, and really like them: ... dapter-white-431312

These say they are rated at 3.5A for a single port, but I have never seen it charge my Chuwi at more than 2A.  I think it will go over 2A with a good charge only cable, but I have not tried this combination yet.

The nice thing is that it will happily charge my Chuwi Hi12, and several phones at the same time, and I know exactly how fast each one is charging.


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technisol| Post time 3-24-2017 15:41:15 | Show all posts
Edited by technisol at 3-24-2017 16:08

From what I've seen and a bunch of others have posted 1.8-2.0 Amps seems to be about the max rate anyone has achieved -with heavier cables 2+Amps/Hr may well be achievable.  (the best cables I found when I went looking last fall were 20 or 21 ga. and I didn't see the need to Frankenstein my own for the small increase when it's more than fully charged while I sleep.)  That's hardly the accepted definition of FAST charging as the term is used these days, as it does not employ a higher voltage to provide more overall power, the product of current times voltage...

That said, 2A/Hr is a pretty decent rate, it's just that with a large battery in the Hi12, 11,000 Mah or 11Amp/Hr, it's going to take 5+ hours at that rate for the hi12 to suck up 10AMPs and it's going to taper off a bit as the battery nears a full charge.  Live with it.  2Amps/Hr is pretty decent, all in all.  If most people would try getting by with a lower brightness setting, which is pretty acceptable in most conditions, I think they'd discover 25-50% is pretty bright and the Hi12 battery lasts quite a while, IMHO.
Back in the day, when I was but a "wee genius" -before I knew sh-t, think S-100 bus and then PC 386DX40 processors, I designed, built, programmed and troubleshot industrial controls and we found that after a while in the field two 18ga. wires in parallel(about 1/2 the resistance) with a connector at either end only about 24" long at 2amps draw could drop near a half a volt...  At that amperage rate it's more often the connector than the cabling, and micro-usb represents far less surface area than the connectors we used.  Food for thought.  In extreme cases I contemplated soldering the wires directly to the upper card rack's backplane and eliminating the molex connector being used, but that would have required a technician to make a backplane board swap should an individual board connector develop a bad solder joint over time.  I should mention we were in a high vibration, extremely dusty environment, so periodic maintainence was a reasonable requirement.

If that's not enough, pick up a lithium power pack.  I have a 20Amp unit and I've used it more this last week because the cell phone charger in my truck died and I'm waiting on the new one to arrive than I ever have for the Hi12...  $15 at Walmart on Black Friday!  

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deejay1963| Post time 3-24-2017 18:15:02 From the mobile phone | Show all posts
you are right technisol. microusb connector is the worst thing for high amp charging. its pins are too tiny for carrying sustained large loads, it gets too hot., actually microusb was not designed to carry such high currents, it was developed during the feature phone era when charging current was very less.
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ZenBalancer| Post time 3-25-2017 10:23:34 From the mobile phone | Show all posts
Edited by ZenBalancer at 3-25-2017 10:26

If I'm not misremembering, the charger and the battery have different volts. The Hi13 charger and its battery have also different volts than each other, and not the same as the Hi12 either. See the Hi13 battery uncertainty.. thread for some details if relevant to what you need to know also about the Hi12 (if I'm not wrong): ... ttery%2Buncertainty
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technisol| Post time 3-25-2017 21:01:14 | Show all posts
Edited by technisol at 3-25-2017 21:59

I'm just curious, where does the info regarding the Hi13 battery being 7.4VDC come from?  I see a lot of reports of 10AH, but I have yet to see any sites confirm 7.4Vdc...  It could well be, just have not seen it.
In the case of the Hi12 all it takes is a resistor or a switcher circuit basically with a transistor/MOSFET pulse width modulating the 5VDC onto a cap and a few support components to lower the voltage/vary the available current.  If the Hi13 has a 7.4Vdc battery either the two 3.7Vdc cells have to be charged separately(unlikely, I think in part because the voltage would be so much higher than current circuitry at 3.3-1.8Vdc and circuitry complexity would be higher) or they must have a step-up converter to charge a 7.4Vdc battery from a 5Vdc source and then a second internal step down converter to generate 3.3-1.8Vdc for the Z8300...  Highly unlikely as both are somewhat inefficient at best and it would be silly to convert both ways and double losses and components required.  I'd greatly prefer confirmation to conjecture, but my guess is both Hi12 and Hi13 have 3.7Vdc batteries and may employ relatively simple regulation to provide 3.3vdc and 1.8Vdc for the SOC and board components.
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ZenBalancer| Post time 3-26-2017 02:33:54 From the mobile phone | Show all posts
See references linked below the thread I posted.
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ZenBalancer| Post time 3-26-2017 02:37:18 From the mobile phone | Show all posts
And you will know for sure if you either ask Chuwi, or find out with the device via some software or physically thus maybe voiding warranty. So just ask.
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ZenBalancer| Post time 3-26-2017 02:39:35 From the mobile phone | Show all posts
I meant PM someone from Chuwi if you must, and state the answer in that thread too please.
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Hackerjac| Post time 3-26-2017 06:57:17 | Show all posts
ZenBalancer replied at 3-26-2017 11:39
I meant PM someone from Chuwi if you must, and state the answer in that thread too please.

Is it possible that you could use the edit button insted of alot of reply's in short time, for me it makes the trend confusing
I do NOT work for Chuwi. Please DO NOT pm or email me with problems you may have!
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ZenBalancer| Post time 3-26-2017 07:49:59 | Show all posts
Edited by ZenBalancer at 3-26-2017 07:52
Hackerjac replied at 3-26-2017 06:57
Is it possible that you could use the edit button insted of alot of reply's in short time, for me  ...

See many of my previous posts. I've edited silly. But when I'm in mobile-view/wap (automatically returns to it from time to time), there is no edit button, and the reply field is right there. So it's a laziness thing. Also could you imagine the other thread in which I accidentally overloaded with about 10 consequtive posts, if they were all one giant post? Sometimes it's unclear what's best. Maybe a thread in the general subforum about "guide lines" is needed to discuss various situations and "best practices". @Emily was contemplating the feasabilety of some "integral rules".
Edit: clarity.
Correct Reply button? Also lists for a response, @username doesn't.
Link: overview of replies to your username. They have to click for theirs.
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