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linuxslate.com|Post time:8-12-2017 10:06:59 View:1654|Reply:25

deejay1963| Post time 3-28-2017 17:30:12 From the mobile phone | Show all posts
good info provided here by @linuxslate.com and @technisol. we have 2 great masters here regarding power supply fundamentals. i bow to your knowledge and wisdom.
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technisol| Post time 3-30-2017 19:16:05 | Show all posts
Edited by technisol at 3-30-2017 19:50

Zen, we can spend all day doing math, and get nowhere because we are working from assumptions...  You're assuming the specs given by Gearbest are accurate, and I'm thinking that 24W in terms of 12Vdc @ 2Amps seems a little high on the voltage end of things if they're charging a 7.4Vdc pack...  Maybe we're both wrong and they have a 10.8 nominal battery pack built from three series connected cells, but it'd start getting rather large and heavy.  I hope they have the 7.4VDC pack at 10A/hr that you want, but it's going to require some room and add some weight.

PS.  I don't believe any math mistakes were made, I assumed a 5Vdc charger @ 2amps charging a 3.6-4.2Vdc battery, but have no idea off hand whether a dc-dc converter is used in the Hi12 to drop voltage (which would likely have inherent losses of 10-20%) or whether a resistor is used...  I recall the protective device on the battery which allows charging when the device is powered off may employ a resistor in series with a MOSFET from the schematics I looked up many moons ago.  The real world and simple math do not always mirror each other perfectly and in the absence of a schematic or tracing one out from circuitry one is often left to conjecture and approximation.  Futher muddying the simple math, in reality as the battery voltage rises during charging the differential between charging voltage and battery voltage decreases as does current unless one designs a constant current source which is generally achieved by raising the supplied charging voltage to maintain current -though highly unlikely in the case of a simple 5Vdc source supplied by a USB adapter.
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technisol| Post time 3-30-2017 19:28:39 | Show all posts
Edited by technisol at 3-30-2017 19:31

Thanks deejay, but any possible correctness displayed currently(not a pun) likely comes at the expense of mistakes made earlier...  ;-)  I'm not saying I'm right, or Zen is wrong, merely discussing possibilities... ultimately, I'm sure we'd all generally be happy to see a larger pack.  I'm just advising caution accepting specs.  Sure would be nice if the manufacturer would just release specs directly to the forum or on their web pages...   In all fairness, I was more than surprised the Hi12 has the battery life it does even with the 3.7Vdc @ 11A/hr specs that were provided.  Before I got mine I was pretty sure it'd arrive with about a 5-6A/hr pack.
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ZenBalancer| Post time 3-31-2017 03:26:14 From the mobile phone | Show all posts
Edited by ZenBalancer at 3-31-2017 03:55

FWIW, Emily updated: http://forum.chuwi.com/forum.php?mod=viewthread&tid=3653

Sorry @linuxslate.com, that was the thread I replied with in #4, that started the mixing..

@everyone, aside my nonsensical pseudonym (ZenBS is just my "online history") I'm not yet looking to become good at the intricacies of electrical power conversions within a device, especially in interaction between the charger and internals (battery etc..).

I simply applied basic arithmatics based on the available information that hadn't been confirmed by anyone, and what I understood from conversion between units of electrical measurement without deeper or relevant insights into understanding electrical engineering. Any speculations without feedback from relevant device holders (the Hi13 compared battery and charger wise to Hi12) , would have been a waste. No one has their Hi13 yet, aside rare but only usage impressions reviewer in the Video reviews subforum.

I assumed wrongly, that @technisol had assumed a 5V battery for the Hi12. I should have not posted here.

My involvement in this thread is offtopic on too many counts. For that, I apologize.

Edit: removed mobile URL parameter + fail recovery.
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technisol| Post time 3-31-2017 12:40:49 | Show all posts
Zen, your intentions were good.  The specs you were presented with were not.  Period.  End of discussion.  I can't begin to elaborate on how many times I would have been screwed if I didn't insist on building prototypes and seeing for myself rather than trusting specs or manufacturer's reference designs, etc.  You merely lack experience, of which you have now gained.  The thing they never tell you, is that the person who dares to be wrong is right more often than those who dare not.
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Rain44| Post time 8-12-2017 10:06:59 From the mobile phone | Show all posts
The 2 amp limit is governed by the OS. You can remove that limit through terminal emulator or changing some code. I saw it before but can't remember the link.
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