Help with PCBA - Page 1
Forum section: electronics / beginners

author: kadeez
author_rank: Newbie
timestamp: April 03, 2014, 02:07:02 pm
content: Hi Guys,I am a complete noob to electronics but I recently bought 2 power banks same model from aliexpress and found that they werent even near 80% of capacity so I decided to open them up because they were cheap anyway. How do I determine if the PCBA is good quality or not? What are things to look for? Heres some attached photos, ive removed the companys initials with paint (dont wana get in trouble)On my brief analysis the soldering is complete crap, I did soldering in high school and I thought I cuda done a better job and for the same product they seem to have small things missing from each one....

author: pa2ees
author_rank: Contributor
timestamp: April 03, 2014, 02:27:13 pm
content: I agree, the soldering looks pretty bad. There looks to be some gunk on the boards as well. They are cheap, and thus their components are probably sub-standard (the switch might only handle 5K cycles or something like that. However, if this isn't designed to be delivering much power (an amp or so), then there's not much that can go wrong with the board itself. The board looks fairly adequate, vias look decent (although I probably would have put more in some of the traces), space between traces is ok because you're dealing with lower power.All in all, they look decent, not top quality, but exactly what I would expect for a cheaper power bank.As far as the different components, you probably got 2 different revisions.- Erik

author: kadeez
author_rank: Newbie
timestamp: April 04, 2014, 04:38:13 am
content: Thanks for the reply pa2ees, after taking these apart I find them quite interesting. Judging by the pictures, do you think that these pcbas will fail within a year or shortcircuit? I might just invest in a jackery power bank!

author: pa2ees
author_rank: Contributor
timestamp: April 04, 2014, 04:51:06 am
content: Quote from: kadeez on April 04, 2014, 04:38:13 amNah, I would suspect the PCB would be the last thing to fail. Unless you're pulling quite a few amps, or high volages (which is not the case), then the chance of the board shorting is slim to none. Connectors will probably go first, ie the USB connector pins will go bad and not make good connection anymore. Solder joints might go also, cracking from the stress of plugging and unplugging devices. Buttons and such might go next. But I think it should last quite a while, as you are probably not connecting things very often (once a day or so), and you are not pushing buttons very often.The only thing I would be a little nervous about is those wires. If it's in a case, you should be fine, but if not, I would reinforce those wires (hot glue them to the board, or something like that). You don't want the wire breaking right above the solder joint and shorting to something. But again, that's IF they're not going to be in a case.With care, and a little luck, I wouldn't be surprised if you get several years out of it.- Erik

author: sleemanj
author_rank: Super Contributor
timestamp: April 04, 2014, 08:38:17 am
content: Quote from: kadeez on April 03, 2014, 02:07:02 pmNot unusual, 18650 cells (the battery cells in your device) from China are notorious for having "ambitious" capacity, or even just being recycled old cells from laptops.See this youtube channelhttps://www.youtube.com/channel/UCmHvGf00GDuPYG9DZqQKd9A

author: Zepnat
author_rank: Regular Contributor
timestamp: April 04, 2014, 09:46:56 am
content: Can we have a pic of the batteries? I have some LG and they are pink like yours, could be they just put a inflated number on the unit, as sleemanj says china are the worst for selling junk batteries, they sell the best batteries too you just have to get to know which to look for.

author: kadeez
author_rank: Newbie
timestamp: April 04, 2014, 10:21:52 am
content: Sure thing, They are just pink on both sides. I looked into it and normally Samsung has 18650 which are the same colour but these have no text at all. I peeled off the pink plastic aswell and there was no text at all, so I'm assuming they are just generic inhouse batteries, explaining the poor capacity.

author: AndyC_772
author_rank: Super Contributor
timestamp: April 04, 2014, 11:01:38 am
content: You got 80% of rated capacity from a no-name Chinese battery pack, AND your house hasn't gone up in smoke...... and you're complaining??

author: kadeez
author_rank: Newbie
timestamp: April 04, 2014, 11:19:05 am
content: Hi Andy,Sorry if I came off wrong, I didn't meant to complain. I was a bit curious what constitutes a good quality product and a bad quality one and what to look out for with regards to the PCBA, so I can compare with other products I get later on. I was expecting crap anyway with the price I paid.

author: Erickben
author_rank: Contributor
timestamp: June 29, 2016, 09:15:48 am
content: You got 80% of rated capacity from aliexpress, actually it's normal. Cause you should buy components from digi-key, Mouser like that original one to ensure the quality.Maybe better.