Taking apart a suspiciously light AA Ni-Mh battery - Page 1
Forum section: electronics / general

author: kioan
author_rank: Newbie
timestamp: April 01, 2013, 11:12:13 am
content: I took apart one of those LED lamps that have a tiny solar panel (and are usually paced in gardens etc) to see why it stopped working.Inside it I found an AA Ni-Mh battery labeled as 400mAh. I haven't measured the actual capacity, but it couldn't keep a single 5mm LED lit for more than 5-6 hours (even when new, after a whole summer day under direct sunlight) so I assume that it was not even close to 400mAh.When I took it in my hand it felt strange... It was too light and the center of mass was almost 1/3 closer to the positive pole.After all thosefake capacitorswe have seen so far, I decided to take it apart. I would expect to find an AAAA cell, likethose in the 9V batteries.I started cutting using a saw but after hitting a plastic tube I continued using a pipe cutter. After removing the metal casing I found an empty plastic tube.The tube was almost 3.5cm deep so I made a second cut to the end of this tube.So, where is the goddamn electrochemical cell? Right behind the positive pole measuring under 1.5cmA few more photos arehere.

author: Magicmushroom666
author_rank: Contributor
timestamp: April 01, 2013, 11:14:39 am
content: Yikes!

author: orbiter
author_rank: Frequent Contributor
timestamp: April 01, 2013, 11:17:51 am
content: Didn't you know that when you buy cheap.. You only get half of what you pay for

author: grumpydoc
author_rank: Super Contributor
timestamp: April 01, 2013, 11:22:34 am
content: The only thing I don't understand is why there wasn't just a small cell inside anyway, since the whole thing was packaged so the consumer wouldn't see the AA cell.400mAh is about a quarter of a typical AA Ni-MH capacity so it's not surprising the actual cell is a quarter of the size.Maybe the original had Ni-Cd and they couldn't be bothered to change the design. Even then 400mAh is feeble capacity for an AA sized Ni-Cd.Edit:I see you canbuy these fairly readilyalthough even the £0.89 each in 10x or more is poor value compared with "normal" higher capacity Ni-MH in terms of pence per milli-amp hour.They do look like an excellent starting point for anyone who wants to fake higher capacity batteries

author: kioan
author_rank: Newbie
timestamp: April 01, 2013, 11:40:48 am
content: Quote from: grumpydoc on April 01, 2013, 11:22:34 amIt seems that someone stole your idea: theebay is full of cheap 3000mAh Ni-Mhbatteries...

author: AlphZeta
author_rank: Regular Contributor
timestamp: April 01, 2013, 06:12:01 pm
content: One has to admire the amount of effort put into creating these fake stuff. Sigh...

author: staxquad
author_rank: Frequent Contributor
timestamp: April 01, 2013, 07:57:04 pm
content: Quote from: AlphZeta on April 01, 2013, 06:12:01 pmSigh, we did it first (specify to low price/performance standard)I've been keeping around some old Dynacharge NiCad batteries that had to be replaced years ago. They were suspiciously light (67g/ea even though NiCad batteries are heavier than NiMH) and out of balance, one end weighing more than the other, and under performing due to age and low spec. Should chuck them away now that I unearthed them again.Took one apart. Something sized like a "C" cell inside.U.S.A. materials, assembled in MexicoDynacharge is featured in department stores. Specified to a price/performance level.These batteries are ~ 25 years old, inherited them inside a radio. Replaced the cheap fake American batteries with high end Chinese batteries that are extremely heavy (164g/ea) and feel balanced with a higher spec at 9Ah compared to 1.2Ah. Those high quality Chinese batteries last, and last, and last in my big Grundig Satellit 3400 radio. That high end Chinese battery purchase was quite a few years ago. Nowadays, 10Ah can be had.Which reminds me of these crap Duracell AA 2650mAh rechargeable NiMH batteries made in Japan that would drop to .85v in a matter of days and did not perform anywhere near 2650mAh, complete duds, worst batteries ever purchased, while my older Duracell AA 2300mAh rechargeable NiMH batteries made in Singapore worked nicely, using the same charger.

author: westfw
author_rank: Super Contributor
timestamp: April 01, 2013, 11:10:02 pm
content: Consumer reports mentioned ages ago that most consumer NiCd batteries (THE rechargeable battery in those days) larger than AA-sized (C, D) in fact had the same capacity as AA cells, because they were just AA internals in a bigger package (like the Eneloop adaptors now make very obvious.)Of course, as a consumer, these "fake AA" batteries might be useful sources of cheap small rechargeable cells, since those are normally "specialty items" commanding specialty prices...