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inconsistent charging current

asked 2014-10-06 20:23:17 +0200

chemist gravatar image

My 2A charger puts through 1A, my 2A charging port of my USB hub does 500mA but sometimes more (did not measure but it was like fully charged within 30min from 30% once or twice)

So how much can it actually do? Do others have measurements with different chargers? (I used readings from the internal csd tool)

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check the comment that I posted about charging of Li-Ion batteries.

https://together.jolla.com/question/55764/charging-limitation-for-enhanced-battery-life-feature-request/?comment=55979#comment-55979

Any kind of battery is easy to charge back to SOC 80%, but remaining 20% will take more time unless you are able to increase the charging voltage i.e. boost charging. Unfortunately that is seldomly possible with chargers we have available.

What was surprising to me is that avoiding the fullcharge seem to have big impact to the battery lifetime together with full discharge/charge cycles, which has been my operating mode until now.

Hopefully Jolla team will create those configurable charging level alarms for discharging and charging.

perhaps cycle count infirmation would be good for the users as well...

Kari ( 2014-10-06 23:02:08 +0200 )edit

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answered 2014-10-06 20:58:57 +0200

simo gravatar image

Too fast charging might reduce the battery capacity faster, so I'd recommend to use Jolla's own, similar, or slower than that (For example USB connection on computers) chargers only. Jolla's charger is 5V, 1A (1000mA)

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So-called chargers are just power supplies. The actual charger is inside the phone. Feel free to apply as much potential current as you want to your device, provided the voltage is within bounds. The phone will draw whatever current it needs to charge the battery.

Giacomo Di Giacomo ( 2014-10-06 23:37:00 +0200 )edit
1

Oh, by the way, I found out that the weak point of cheap chargers is actually the cable. Cheap, thin cables will show significant voltage drop and slow down charging. This is especially true for USB adapters where you plug your own USB cable to charge the phone.

Giacomo Di Giacomo ( 2014-10-06 23:38:52 +0200 )edit

I know that CSD can show current current (ha!) but what does it indicate? It can't be charging current, because using Huawei 5V 2A charger at 2% battery it said -975µA at most, which is roughly -1mA, which is far away from 2000mA, or even 1000mA... Units error or insufficient data?

Direc ( 2015-10-25 17:25:19 +0200 )edit

I believe it's a unit error. Considering that it's the net current flowing into the battery (if negative), and that the phone draws about 500 to 800 mA when the display is lit, it appears that it's not far from 2000 mA.

Giacomo Di Giacomo ( 2015-10-26 10:19:36 +0200 )edit
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answered 2014-10-06 22:10:36 +0200

Philippe De Swert gravatar image

updated 2014-10-06 22:36:22 +0200

Charging speed depends on a lot of factors. For example one of them is how much power the device is using at the time. So if you see about 1A, it could be the charger is actually outputting 1,5A but 0,5A is used to keep the device running for example. As this varies the whole time it is pretty hard to compare things. So in short the incosistency you see is the charging current fluctuating depending on the power usage of the device. And that can vary a lot depending on the moment when csd reads the value and when it updates it. In effect what you see is the inconsistent power drain of your Jolla ;)

And I almost forgot, the current you can stuff in a battery in a sane way also depends on how much charge it contains, temperature etc... So there is some variation on that side too.

Normally from dedicted charger it should be able to pull the announced power (depending on the quality of the power supply. It's not the first time I have seen a charger only being able to supply barely more than 50% of the announced chargin power). From USB normally it will pull a max of 500mA. If it might have charged seemingly faster that might be due to the battery hysteresis and the low end being a bit more innaccurate. And also if it is a dedicated charging port and the phone manages to recognize it as such it might pull more, but that is a bit hit and miss with most USB hubs as a lot of them do not follow the spec or have a bad implementation.

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Thanks, but, I am well aware that all depends on factors like built quality and actual charging capacity and stuff -> the dedicated USB charging port does supply 2A, it is a dumb socket without data wiring. , just to have another try I just hocked up my N900 to the same dumb USB port, as the chipset is known to be very restrictive in terms of wrong wireing, it charged to full capacity in <2h which means in this case that the actual power-draw was more than the Jolla but way less than 2A on average (the last 5% seem to take ages). The wall-charger is a 2A charger for my tablet (~2h from dead 4Ah including the trickle charging to full capacity, SGTab2). So what I am on about is, what is the actual chipset+battery in my jolla capable of? And why does it not draw more power (always) from my dumb USB charging port?

chemist ( 2014-10-07 00:15:57 +0200 )edit
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Asked: 2014-10-06 20:23:17 +0200

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Last updated: Oct 06 '14