I dont know about Tom , but what i do is to use a very small piece of sandpaper to clean the surface i’ll solden on .
It is really quite easy on the top of cells, the bottom is harder.
The only trick is to turn the soldering iron up very hot, ~450C or so. That way it heats the metal to the point the solder can wet it before it heats the cell under it.
Also, make sure you have good solder and possibly add some extra flux if you still have issues.
I generally am done soldering the top before the cell itself has even gotten warm, aka, I can still hold it indefinitely.
giorgoskok,
There must be some other ways to make solder stick to nickel-plating.
I just clean the tops up with isop. alcohol first, then use my flux pen and dab the top good, then use my good Kester solder on the biggest iron tip I have, add a ton of solder to the tip, then with the tip loaded, hold the tip on the battery top for a couple secs, and swipe it a bit if it doesn't spread. I use my regular iron temp of about 370C (700F) though. Usually takes a second tip full of solder to build it up to the size/coverage that I want. If I can't get it to get a proper dome shape, I'll touch it up with a fine file. Some, like the VTC6's come out bout perfect. With practice it's better of course.
Then it all gets cleaned up with isop. alcohol, removing the excess flux.
Oh that’s the trick. Thanks. I thought there’s some magic flux or something.
I’m just considering making a super-high-capacity battery for a Ryobi drill, by dropping in 10x GA’s and making a 7.0 (okaaay, 6.7 
A*h battery.
Thanks, Tom!
You guys are awesome!
Why? Sandpaper prep before solder is a typical step with a lot of metals. It helps to ensure that the surface is completely clean. Plus, it makes it a bit rough so that the solder has something to grab to. But, even at that, you do need to make sure you’re dumping heat into it quickly enough so that it doesn’t have time to dissipate into the cell. I use a dab of ordinary liquid flux, a hot soldering iron (with a good tip) and the cell prepped with sandpaper. Also, I melt a drop of solder onto the tip of the soldering iron and use that to heat the cell top - the soldering tip doesn’t need to touch the cell.
I’ve already tried to solder a couple of older Sanyos, after some pain I succeeded, I was afraid I overheated the batteries, but that was like in 2013 and they are still fine.
Having built a few drill packs, don’t use GA cells for this. Drills and other tools use an amazing amount of power. Easily 30+ amps. You want the highest drain cells you can get.
If you want a really high capacity pack VTC6’s or 30Q’s would be the best bet. Pretty sure this is what those cells had in mind when they were made anyways.
Right, the latest Sony VUS18650VTC6 from Illumn has printed on the side of it, Do Not Use Outside of Battery Pack… this is written by Sony, along with the identification text. It’s the laser dot text on the cell casing itself, under the green wrapper.
Texas_Ace
I knew someone would say that.
I’ve just tried connecting the drill via an old analogue amp meter, pushing the button and holding the chuck firmly in glove to add more load. I couldn’t get over 7 Amps! And that’s with 45 N*m rated drill. Even considering the resistance of the amp meter and wires, let it even be three times more, 20 amps, that’s still good for 2P 5S (not just 1S) connection.
I tried the same with an old and pretty weak Bort drill (running now for over a year with thousands of screws driven on 4S 18650 PF’s), and couldn’t get it over 5 Amps.
I know Sony is the absolute winner here, but almost 10 bucks a piece - that’s killing me.
What drill do you have? Also were you running the full voltage? 5 amps is VERY low for a drill, to the point of my being surprised it can even do what it is supposed to.
Even under no load this older ni-cd drill is pulling almost 7 amps and upwards of 20 amps with some load with those really long wires:
This one got up to around 40 amps:
I would use 30Q’s personally, they are cheap on banggood.
$6.50 ea. I think, maybe at imrbatteries.com or illumn.com. imr is offering free shipping at the moment.
$6 for VTC5
$6 for the VTC5 20A and $8 for the VTC5A 25A, $9 for the VTC6 at imrbatteries.com
Texas_Ace,
It’s called Bort and is marketed by German SBM Group, I’m sure it is not marketed in the US, but that’s an old china-made 14.4V (formerly NiCd) 12 N*m (amazingly still running since 2009!) piece of junk. I moved to a detached house two years ago with permanent repairs and renovations and this thing is saving me.
The new one is a Ryobi 1802, the amp meter is a Soviet-era one that will last for ages with thick copper wires.
Did you note btw both are DeWalts, probably they have more powerful motors?
DB Custom
Thanks, that’s still a future build and I think we’ll see prices drop or new battery models next year
Btw you can find 30Q’s for as low as $4.2 (if 20 pcs) on aliexpress.
(upd: And 8 pcs for $33.5 on Gearbest)
If you buy 20 pcs, Nkon will deliver standard 30Q for EUR 3:00 a piece; and then you won’t have to worry about fakes.
RollerBoySE
And I can order them with tabs. That’s cool, thanks.
I’m yet to decide whether to go for Samsungs or Sonys (or GA’s)
Would like to get on the list——-
With the deal goin on at IMRBatteries, SONY VTC6's are listed at $9, but subtract 15% using code 'BLF15' and comes to $7.65 each, then free shipping. My last set of 4 I ordered from MtnE for $8.09 each, qty 4, which is fine considering I had to order other parts anyway. But the IMRBatteries is a pretty decent deal.
Just placed an order w/IMR for variety of cells, and 3 weeks ago I ordered and rcv'd qty 8 of the 30Q's from GearBest and paid $28.51 shipped from the US warehouse, not sure if was coupons or points, but US warehouse is free shipping, but that deal is gone now.
Back in September got qty 4 of the GA's from LiIonWarehouse.com for $5.87 each at qty 4, but plus shipping, but decent shipping costs. The protected GA's I ordered from there came to $34.39 shipped.
Lots of deals, worthwhile checking around - one source for batteries doesn't work out well between in-stock, deals, and selection.
Thanks for the links.
All these appear to be flat-tops. Don’t we need button-top batteries for the Q8? Maybe I’m not understanding something…