18650/cellphone Lithium batteries off ebay - Page 1
Forum section: electronics / general

author: lk
author_rank: Regular Contributor
timestamp: July 31, 2013, 10:20:07 am
content: Greetings,has anyone at any time baught any rechargeable battery off ebay, that lived up to what it was specified at? I have tried mobile phone batteries, which where in general 1000 mah lower than what they were advertised at, eg items listed with 2900 mah end upwith 1800 mah, i discharge test with 250mah, which i see i fairly low for those large capacity batteries.and if looking at the 18650 batteries, everything with "fire" in the name is usually at between 600-900mah, where they advertise 2600 to 5000(3100 is max from the name brands)I have attached some discharge curves of different 2600mah+ batteries, the only one that was close supposedly had undercharge protection, but the first battery i tested, happily discharged to 1.9 volts, and now that is brokencomment for the picturesgalaxySVI:(i suppose that should have been IV), was sold as a 2900mah battery, that fell short, the protection seems to work on these.missing battery protection: this was sold as a battery with undervoltage cutout at 2.7, here you can see that i stopped the discharge at 2.5 volts (with sense directly at the battery), the first one went down to 1.9.http://www.aliexpress.com/item/2pcs-x-Julibao-2600-mAh-18650-Protected-battery-Li-ion-rechargeable-battery/1052214577.htmlQuoteFirepeak3, i knew when i bought these that they would never have 3000mah, i had hoped for 2000mah, but sadly, i ended up in the 600-900 range in the four batteries.-lk

author: Psi
author_rank: Super Contributor
timestamp: July 31, 2013, 10:25:23 am
content: I've found lithiums need to be discharged/charged maybe 2 times from new before you see their true capacity.This is flat pack lithiums though, ive never used 18650'sCharging and then discharging a new lithium out of the box may not be the best test.

author: amyk
author_rank: Super Contributor
timestamp: July 31, 2013, 11:31:18 am
content: Are you thesame guy who did this?The *fire seem to be used/recycled cells, which is why their capacity varies so much - if you're lucky you get 2200mAh, if you're not you get a complete dud.

author: lk
author_rank: Regular Contributor
timestamp: July 31, 2013, 01:04:26 pm
content: amyk,sadly no, but we are both from denmark i suspect-lk

author: lk
author_rank: Regular Contributor
timestamp: July 31, 2013, 01:07:22 pm
content: psy,yes, properly to get the last 10% out of the battery, but im sure it wont get me from 800mah to 2600mahi have had good experience with batteries from hobbyking, the type Dave uses in one of his videos, on his battery powered bench supply.-lk

author: peter.mitchell
author_rank: Super Contributor
timestamp: August 01, 2013, 01:00:09 pm
content: the person who made that site is a member here, i bumped into them in another thread, i'm sure if you search for that link you should be able to find them.Also, my experience with cellphone/18650 batteries from aliexpress/ebay? well it's a bit mixed, i have ordered bargain basement 18650s and cellphone batteries and gotten garbage, but i have also ordered some fairly cheap (cheaper than OEM, but not crazy cheap) cellphone replacement batteries that have exceeded OEM batteries. Then there are the samsung and panasonic 18650s I have bought, some were definitely OEM batteries, and I did buy many, others were not. Also, there are some A123 26650 cells out there which are legit, but you also have to watch out for the fakes.The hobbyking batteries are pretty good, i have to say, so are some of the others though. Here is somerthing I made a littlle while ago that may be useful to you:https://dl.dropboxusercontent.com/u/677635/Book1.xlsx

author: brainwash
author_rank: Frequent Contributor
timestamp: August 01, 2013, 09:56:22 pm
content: I hear the same thing about Singapore, but while I was there I did not find any good deals. Once the money is handed you are out of luck:http://www.tripadvisor.com/Attraction_Review-g294265-d1459192-Reviews-Sim_Lim_Square-Singapore.htmlBack on topic:I actually bought a new flashlight from the flea market here which came with two 18650 batteries, for 10E/12$. I never used the included charger, only Accucel-6. Battery life is on par with the tech specs, light intensity is higher than those expensive flashlights. Seeing this, a friend of mine went and bought 3 similar flashlights, at 2 months interval each. His ones have about half the light intensity and less battery life, even though they look identical. I suspect some of his batteries actually have sand inside to weigh them down.Oh, a few months later I took the included chargers apart: the mains one had an LM317 fixed at ~5V and the car one had a single resistor inside or maybe a resistor divider. They relied on the fact that slow charging batteries would be ok, which is obviously not.

author: brainwash
author_rank: Frequent Contributor
timestamp: August 02, 2013, 08:51:49 pm
content: Looks like I spoke too soon, I measured the batteries at ~750 mAh. The Accucel-6 might not be the best way to do this (I did two cycles though) but it's still a far cry from the 3800mAh marking.