USB power packs - general thread - Page 1
Forum section: electronics / general

author: rr100
author_rank: Frequent Contributor
timestamp: January 28, 2013, 07:34:51 am
content: With the rise of non-removable batteries a new type of accessory is found everywhere: USB power packs (or whatever the appropriate name is for the devices that have some - usually - LiIon batteries inside and can charge a phone/tablet or even sometimes a small notebook).Most reviews on the net are quite shallow and of course almost nobody ever speaks about safety or true performance of those devices. I think many of us, on this forum, would do a good job of evaluating those.I'll start by posting the results of a test with a resistive load on (still in progress):Anker 10000 mAh(not my video).

author: baoshi
author_rank: Regular Contributor
timestamp: January 28, 2013, 08:40:23 am
content: I did some limited review last year.http://www.ba0sh1.com/mobile-charger-review/Forgive my poor English though

author: Balaur
author_rank: Unknown
timestamp: January 28, 2013, 08:52:40 am
content: Hey, that's actually a good idea.I may contribute later with a more in-depth analysis of theTenergy 8000 mAh External EnergyAs a quick review, I would like to say that I'm rather unimpressed by the device:2 Amp capability on the high current port is a joke. The voltage drops to some 3.6 volts!Slow recharge. The power input connector is a jack, not USB, and the device doesn't draw too much power, making recharge times on the order of some 10+ hoursThe power indication/power on circuitry is very sensitive, it sometimes starts when just touching the portsOn the "not good for me, but it was expected" side, the 2 amp port is configured for Apple products only. This is the intended design, and it's not a negative comment on the product, of course. I had to remove the existing resistors on the USB DP, DM lines and connect them together in order to be able to quickly charge my Android tablet. The interesting part that originally, my Nexus 7 tablet didn't wanted to recharge on either low or high current port when using a standard USB cable. The provided (male Jack to male USB cable) + a (female Jack to micro USB) combination was OK, but come on!On the good side, it provides (at least on paper) a lot of capacity for the money. I would have to check that through some measurements though.Cheers,Dan

author: amyk
author_rank: Super Contributor
timestamp: January 28, 2013, 09:09:48 am
content: Quote from: Balaur on January 28, 2013, 08:52:40 amIf it's really 8000mAh then at the 500mA USB default it'll take ~16h to charge, probably closer to 20h if counting the long "soak" phase for lion charging.

author: Balaur
author_rank: Unknown
timestamp: January 28, 2013, 09:23:37 am
content: Quote from: amyk on January 28, 2013, 09:09:48 amYes, I'm aware of this. I don't have a definitive measurement, and I haven't gone through a full cycle yet.I'll be happy to get back with some more detailed data.Cheers,Dan

author: rr100
author_rank: Frequent Contributor
timestamp: January 28, 2013, 11:41:48 am
content: Be aware that 2A is rather high for usb cables and while they won't burn the voltage drop is probably quite significant (in other words it is crucial where you take the voltage reading).I have the results for mine:Anker 10000 mAh7 months old, rarely used, except for a couple trips and I had to leave it for 3 week plugged-in used as a permanent 5V power supply (I don't know how happy it was about that as it would not stay in a stable state, it would start discharging, charging, etc)results on resistive load 2x4.7 ohm series attached (be aware the header of the file is shifted, 2.59 for example is VxA.Total results based on VxA readings:33.28 Whthat equals:6.67 Ah at 5V9.24 Ah at 3.6VI added an attachment with the charging log from empty. Charging is at 12V (variations in voltage are at first because my power supply probably takes some time to worm up and then I was trying to fiddle with it to compensate for the voltage drop on the ampermeter).43.43 Wh go incharging goes for 212 minutes with 0.9-1A then it starts to drop offit takes about 277 minutes total to finish the charge, including those 212 above

author: mianchen
author_rank: Regular Contributor
timestamp: January 28, 2013, 01:59:02 pm
content: I've cracked one open in this thread:https://www.eevblog.com/forum/reviews/'power-bank'-tear-down/

author: icpart
author_rank: Regular Contributor
timestamp: January 28, 2013, 07:05:37 pm
content: Quote from: baoshi on January 28, 2013, 08:40:23 amThanks a lot for this great review. For a long time I was wondering what have is inside of those chargers.