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Re: Battery thickness problems & Ebay sellers

PostPosted: November 6th, 2011, 1:19 am
by Coughinhk
Hi,

Well it seems I am Mr Unlucky eh ? One of the things that drives me crazy about HK is that every shop (and I do mean every shop) keeps the cheap copy crap rather than OEM.

Anyway, I'll try that other Ebay seller - thanks ! And in the meantime I'll see if grinding off does the job. It might be close but I doubt I'll need to go into the copper ground plane.

Did you guys try to fit the 900mah version ? Just a bit too long ?

http://www.ebay.co.uk/itm/2x-LiPo-7-4v- ... 570wt_1270

EDIT. That seller won't ship to Hong Kong. This is quite common for sellers just over the border in Shenzhen. They list as being in HK but aren't. Apparently posting from Shenzhen to HK costs more, and that's why.

Oh well.

Re: Battery thickness problems & Ebay sellers

PostPosted: November 6th, 2011, 4:01 am
by jtktam
lipos that are not in hard cases will have variations in the thickness and sometimes they might swell..

i think the outer plastic sleeve is there to prevent punctures, i have removed it before and it's not an issue but you are taking a risk

-joe

Re: Battery thickness problems & Ebay sellers

PostPosted: November 6th, 2011, 5:29 am
by MisterX
There is no "plastic sleeve" on these batteries. :x

The cell tabs/wires are covered with a piece of double sided foam tape (that is very much like servo tape), wrapped top to bottom with strapping tape and a piece of Kapton tape is wrapped across the width to secure the other tape layers if the cell's temp. rises high enough to compromise the adhesive.

Re: Battery thickness problems & Ebay sellers

PostPosted: November 6th, 2011, 7:16 pm
by MisterX
amb wrote:
Coughinhk wrote:
So, I think the best solution is going to be grinding off some of the mini3 board in the appropriate place if no-one can think of anything else ?

Note there are some traces on the bottom near the battery area.


He shouldn't have to cut that much off ...
(the centerline of the silkscreened polarity indicators should be enough)

:mrgreen:

Re: Battery thickness problems & Ebay sellers

PostPosted: November 6th, 2011, 10:53 pm
by Coughinhk
Hi,

Thanks for the help guys. I have ground off some of the board and now it fits just fine. It's no worse than filing down the battery contacts for the standard mini3 and actually would be easy if the board is unpopulated. This one was an upgrade so it was tricky avoiding the x7r caps with the grinder, and I am a little concerned the vibration and dust might have done some harm, but wait and see. I'm waiting for replacement caps before I can finish - found some Panasonic that are designed for audio....

http://au.element14.com/jsp/level5/modu ... 388706.xml
Image

Image
Image

Thanks again !

Tom

Re: Battery thickness problems & Ebay sellers

PostPosted: November 7th, 2011, 3:19 am
by jtktam
Nice!

Re: Battery thickness problems & Ebay sellers

PostPosted: November 7th, 2011, 6:25 pm
by Coughinhk
Thanks - I had to go down to the copper for the batteries' thickest area - about 1.5mm I guess.

I've ordered more batteries and specifically asked the sellers to check thickness; these two :

wi-model
http://myworld.ebay.co.uk/wi-model/?_trksid=p4340.l2559
http://www.ebay.co.uk/itm/250855188402? ... 275wt_1037

and abeyerr
http://myworld.ebay.co.uk/abeyerr/?_trksid=p4340.l2559
http://www.ebay.co.uk/itm/270818095850? ... 443wt_1270

fmt-model are no good.
http://myworld.ebay.co.uk/fmt-model

Wait and see how the others do.

EDIT Wi-model contacted me - their batteries are 9mm thick, so the order has been cancelled. So now trying ok-fly
http://www.ebay.co.uk/itm/250855711681? ... 530wt_1037
http://myworld.ebay.co.uk/ok-fly/?_trksid=p4340.l2559

Re: Battery thickness problems & Ebay sellers

PostPosted: November 28th, 2011, 8:25 am
by Coughinhk
After waiting 3 weeks, I contacted the sellers, who both say the items must be lost and they'll refund. Mainland China - what a nightmare. This is turning into a major pita.

Re: Battery thickness problems & Ebay sellers

PostPosted: November 28th, 2011, 8:37 am
by linux-works
look at that grinding job! whoa! ;)

I don't know how they can ship from china for pennies. they seem to, though. and they are 'happy' to reship again if the item does not get there. I suspect shipping is subsidized, somehow. I've had to return an item that was fake (sigh) and paypal insisted I return it to the shipper to get credit. my return shipping was half the price of the item, itself! we do not get cheap shipping overseas, no way!

Re: Battery thickness problems & Ebay sellers

PostPosted: November 28th, 2011, 10:00 pm
by Coughinhk
Hi,

Grinding works and is easy. If I can do it...anyone can !

Wages in mainland China for jobs like postmen are sickeningly low so postage is cheap, slow and unreliable. Most people use couriers to do the cross-border trade because there is a huge volume and it is same day, not 3 weeks, and doesn't cost that much - a fraction of what UPS and FedEx charge. Unfortunately the Ebay sellers won't use a courier.

I'm not willing to wait another 3 weeks to repeat the same problem, and there aren't any other Ebay sellers who will post to HK that I can try, so I'll just have to get over-sized batteries from a local shop and grind down the boards.

BTW, the alps pot now has some noise on it so if anyone is in the same situation as me, desolder and remove the volume pot before you grind.

Of course, better to get a full supply of the batteries in advance of building the boards. ;-)