Don't buy this travel router - Page 1
Forum section: electronics / general

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 23, 2014, 03:36:58 am
content: I bought this router a few months ago, used it a few times for a few minutes to a few hours at a time. (Not as a 3G router but just as a general purpose Ethernet/WiFi converter, mainly so I could use my tablet to configure various network equipment.)http://www.amazon.com/BrainyTrade-Mobile-Wireless-Hotspot-1800mAh/dp/B0093IPJKQ/ref=sr_1_1?s=pc&ie=UTF8&qid=1393122340&sr=1-1&keywords=3g+wifi+routerLately, I noticed that the battery seems to not work anywhere as well as it used to. It easily handled a few hours when new, now it's lucky to do 30 minutes. Charged it up, pulled the cover, and measured the battery voltage at 4.23V. (4.2V is max rating for a standard lithium ion.) I also noticed that when on, the board directly below the battery gets hot to the touch. Looks like the combination of excessive charging voltage, heat in direct contact with battery, and possibly a poor quality battery all combined to yield less than half a year of useful life. The form factor is such that it's difficult to find a replacement (at least not one that's a reasonable price) and in any case, unless I address the issues, the new battery will fail just like the old one.So now, it looks like I have a tiny router with a battery that is merely usable as a UPS, and probably become a worthless brick in not much more time. The only good news is that once it goes completely, there would be plenty of room for all sorts of mods and whatnot.

author: amyk
author_rank: Super Contributor
timestamp: February 23, 2014, 02:48:48 pm
content: 4.23Vis about rightif it's a standard lipo cell; the fact that there are varioussingle-chip chargers preset to 4.23Valso shows that this is likely intentional. Of course 4.20 or even 3.9 cutoff would make it last a lot longer, but that's what you get with these devices that will try to keep their batteries fully charged; lion chemistry degrades faster at high charge levels and high temperature.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 23, 2014, 04:39:36 pm
content: It's regular lithium ion, not lipo.

author: IanB
author_rank: Super Contributor
timestamp: February 23, 2014, 04:48:46 pm
content: Many modern lithium ion cells are designed to charge at higher voltages up to 4.3 V these days. Even if it is a 4.2 V cell, there is nothing magic about that figure of 4.20 for the maximum voltage. It's just a trade-off someone picked on a sliding scale of capacity and cycle life. More likely the trouble is the heat and/or the battery quality. Does the battery have a reputable brand name on it, or is it unbranded?

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 24, 2014, 01:26:34 am
content: It's just a generic shrink wrapped rectangular cell. So quality is probably (partly) to blame, but this is the first time I have had a lithium battery degrade that quickly. Not even the cheap Bluetooth headsets and toy helicopters have that problem.

author: amyk
author_rank: Super Contributor
timestamp: February 24, 2014, 12:43:50 pm
content: Quote from: NiHaoMike on February 24, 2014, 01:26:34 amUnless it has a metal casing, that's probably a lipo...

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 24, 2014, 02:33:59 pm
content: It is a metal casing.

author: brainwash
author_rank: Frequent Contributor
timestamp: February 26, 2014, 12:00:54 am
content: Maybe the inductor is getting saturated and lowering the efficiency. Nevertheless, it that battery has ~500 cycles on it is nearing its life end. But for 9$ I would just buy another one.I would measure battery drop under load, converter efficiency and charger cut-off voltage, if any. If it chargers via USB and has a charging chip that it's probably a proven design, but perhaps with poor parts.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 26, 2014, 12:50:06 am
content: Nowhere near 500 cycles. Maybe a dozen or so.

author: Rasz
author_rank: Super Contributor
timestamp: February 26, 2014, 01:36:28 am
content: http://wiki.openwrt.org/toh/hame/mpr-a1Its not a terrible productstandard chinese battery, replace it with original nokia cellphone one (obviously not from escambay)