The AM Forum

THE AM BULLETIN BOARD => QSO => Topic started by: W1RKW on January 27, 2023, 03:47:18 PM

Title: battery spot welder
Post by: W1RKW on January 27, 2023, 03:47:18 PM

I purchased one of these mini spot welders for rebuilding a bunch of battery packs. did my 1st batt pack this afternoon.  Works quite well. Learning curve is very small. Perfect for rebuilding battery packs for cordless tools and HTs and whatever else. Very cost effective tool.  Almost paid for the welder with the first pack. Plenty of Youtube videos on it too. 

Title: Re: battery spot welder
Post by: WA2TTP Steve on February 05, 2023, 12:19:55 PM
Where have you gotten new cells from? Iíve read that theyíre a lot of poor quality cells on the market that donít perform very well.


Title: Re: battery spot welder
Post by: AL7FS on February 06, 2023, 02:13:58 AM
Which welder did you buy?  I have been looking at a few of them. 

Jim, AL7FS

Title: Re: battery spot welder
Post by: W1RKW on February 06, 2023, 06:17:57 AM
Steve, I get them from a local place called Battery Junction.

Jim, See the link in my first post.

Title: Re: battery spot welder
Post by: WA2TTP Steve on February 06, 2023, 03:38:07 PM
Thanks Bob

Title: Re: battery spot welder
Post by: W1RKW on February 07, 2023, 06:37:12 AM
Just a quick run down on rebuilding my first battery pack.  

I've rebuilt a couple of old battery packs for drills in the past but soldering wire to a cell in my opinion just shortens the life of the cell and if the internal space in the pack is very tight with very little margin, solder blobs can quickly use up the space making fit very difficult. So the solution was to duplicate the battery configuration as best as possible which includes duplicating fit tolerances as best as possible.

My first test of the welder:  Had a device that had 14 NiCd cells in it, 2 stacks of 7 all wired in series, self contained (not a removeable pack).  1 or 2 cells went bad giving a real short run time. Internal space was very tight so soldering wire and getting a good fit at the same time would not be possible.  

So off I go to Youtube about spot welding battery tabs.  I tried a homebrew welder without much success even after 2 or 3 iterations with varying thickness of battery tab material.  So much for trial and error.  

So back to Youtube.  The most promising spot welder seemed to be the Seesii welder shown in the link in my first post.  So off to  Amazon and purchased the spot welder.  

On my first try and I had a good weld.  I did the happy dance.

So onto my first battery pack. I replaced the 14 NiCd cells with 14 NiMH cells. Didn't want to deal with potential premature failure of the NiCd.   I use a lot of rechargeable NiMH batteries throughout the household so invested in smart charger a long time ago.  I charged all 14 of the new cells so they would start off on a somewhat equal footing.  I did not match them or test them for equal charge and discharge rates.

I disassembled the old pack to understand how it was wired and saved all insulating materials.  As mentioned earlier, there were 2 packs of 7 cells which were stacked. In order to ensure the new pack would fit I had to make sure all the cells were tightly packed together. So before welding the tab material, I taped up 2 packs of 7 cells. Tested them for fit.  The  pack fit with just enough space to fit an extra bit of insulating material.

Now it was time to weld the tab material.  Carefully duplicating the connections of the old pack for the new pack I proceeded to weld the tabs.  I used a setting of 40 which is about midway between max and min on the welder.  I did 3 shots per tab end which is 2 spot welds per shot for a total of 6 welds per tab end. All gave consistent strong welds. I was happy all was going well.  Before bonding the 2  packs to make the final pack, I tested fit again.  All going good.  Now time to make the final welds and put the full pack back together.  I did the final welds, put the insulating materials in place and put it back in the device and gave it a test run.   We'll see how it goes in the coming weeks and months.

I've ordered cells to rebuild 2 battery packs for a cordless drill.  I'll report back in the days ahead on that. Stay tuned.

One final note on the welder.  This can be used as an external battery pack for USB devices such as cell phones.  can be used as a cordless charger for those devices.

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands