12-05-2023, 10:44 AM
Wishing I did not properly recycle the dead LG 18650 pulled from the failed Ryobi, as i don't have a cell for practice welds unless i sacrifice an OK cell.
The dual battery trick for the spot welder seems so simple, in theory, one strong battery for the actual spot weld, one just to open and close the current gates.
To accomplish this both battery - are tied to BSW negative but red welding pen goes to strong battery instead of bsw input/output which are circutly the same. The second battery for gate opening positive goes to BSW +.
Luca's recommended 'gate decoupling modification' are all about insuring the gate trigger voltage does not drop too low during the weld, and on the Purple bsw requirez a capacitor resistor and a diode and the ability to solder to a 0.75mm trace on the circuit board.
He sets up and oscilliscope to measure the microseconds for the gates to fully open and close, wbich revalss the purple is 4 times faster than the red on both rise and fall times, and the purples infineon MOSFETs are supposedly far better tha those used on ole red.
But apparently if the mosfets are not reasonably well matched, then you are kinda screwed as the lowest resistance one will take a majority of the load and eject the magic smoke.
The purple one has room for 5 more mosfets on the bottom of circuit board, to share the load, but no point in adding more unless they are matched to original 5, which means ordering 10 matched mosfets, which with shipping will likely cost 2x as much as the spot welder itself.
So maybe just ordering a second purple for backup purposes is the call.
The 3S 5.2ah 80C lipo battery i ordered, has two plugs, an xt 60 on 12 awg leads, and a 4 pin connector, not sure what it is called, that is designed for charging and cell balancing via a 'hobby' charger.
I was using my dmm leads to check individuLcell voltage, but the test leads are basicaLly 0.5mm from a dead short, which would likely weld the test leads tigether frhing it and shorting the cells and cause them to catch fire. One can put negative on the one end, and measure 4.01 on cell 1, 8.02 on cell2, 12.03 on cell three. easy peasy but when they are at ~3.876, doing the math to figure out individuL cell voltage, is not as easy.
There is this nice little cheap device which will display voltage of uoto 7cells, and there is a blue 8 cell model too for a few bucks more
https://www.ebay.com/itm/141854296686
10bucks. sold!
The Lipo batteries are the most dangerous litbium chemistry with their volatile huge energy density and suoer low resistance.
And they have no BMS. they require the bobby charger to keep them in balance, or a human BMS with the tools and temerity to keep the cells close to each other.
The directions my ZEEE lipo battery came with, and the consensus on Lipos say to not store full charged, even for a week as it will destroy it, so unlearning lead acid habits is paramount.
Ill assume the lipos in phones and such are not ever brought upto 4.2v, but if they are, it explains why those who keep their phone plugged in all the time, can have very short battery lives.
I got to find out what the lipo balance charge connector is called, so i can more safely balance the 3 cells when they begin to drift, as purchasing a hobby charger just for it, is unlikely in the extreme, when I can use my CCCV xl4015 buckers which i employ on so many other tbings.
The comparatively inexpensive Zee lipo battery i have, with the 12 awg leads and xt60 connector, well the higher end lipos use 10awg. My xt60 connector was the hottest part of circuit when practice spot welding, and i susoect a poor solder joint under heatshrink.
My lipo has a plastic cover which will split apart once the pouch cells inevitable swell up. Id like to get 10awg to the buss instead of 12awg, and use an Xt90 antispark connector, but might just carefully splice 10awg and an xt90 into the existing 12 awg.
Kind of crazy this little LIPO battery can so easily staRt my 3!8 on its own.
I did staRt it with the 18amp hour mightymax agm battery, once.
pretty sure the lithium jump starter packs use these LIPO pouch cells.
I am wondering if they have a bms or a way to prevent charging them to 4.2v, but if lipos are as volatile as they apparsntly are, it seems these litbium jump starters would be splitting the pack open and or catching fire far more often than we hear about.
Anyway the purple BSW should arrive today.
Wish i had a fully discharged junk practice 18650 cell, but llenty of other stuff to do anyway, first.
The dual battery trick for the spot welder seems so simple, in theory, one strong battery for the actual spot weld, one just to open and close the current gates.
To accomplish this both battery - are tied to BSW negative but red welding pen goes to strong battery instead of bsw input/output which are circutly the same. The second battery for gate opening positive goes to BSW +.
Luca's recommended 'gate decoupling modification' are all about insuring the gate trigger voltage does not drop too low during the weld, and on the Purple bsw requirez a capacitor resistor and a diode and the ability to solder to a 0.75mm trace on the circuit board.
He sets up and oscilliscope to measure the microseconds for the gates to fully open and close, wbich revalss the purple is 4 times faster than the red on both rise and fall times, and the purples infineon MOSFETs are supposedly far better tha those used on ole red.
But apparently if the mosfets are not reasonably well matched, then you are kinda screwed as the lowest resistance one will take a majority of the load and eject the magic smoke.
The purple one has room for 5 more mosfets on the bottom of circuit board, to share the load, but no point in adding more unless they are matched to original 5, which means ordering 10 matched mosfets, which with shipping will likely cost 2x as much as the spot welder itself.
So maybe just ordering a second purple for backup purposes is the call.
The 3S 5.2ah 80C lipo battery i ordered, has two plugs, an xt 60 on 12 awg leads, and a 4 pin connector, not sure what it is called, that is designed for charging and cell balancing via a 'hobby' charger.
I was using my dmm leads to check individuLcell voltage, but the test leads are basicaLly 0.5mm from a dead short, which would likely weld the test leads tigether frhing it and shorting the cells and cause them to catch fire. One can put negative on the one end, and measure 4.01 on cell 1, 8.02 on cell2, 12.03 on cell three. easy peasy but when they are at ~3.876, doing the math to figure out individuL cell voltage, is not as easy.
There is this nice little cheap device which will display voltage of uoto 7cells, and there is a blue 8 cell model too for a few bucks more
https://www.ebay.com/itm/141854296686
10bucks. sold!
The Lipo batteries are the most dangerous litbium chemistry with their volatile huge energy density and suoer low resistance.
And they have no BMS. they require the bobby charger to keep them in balance, or a human BMS with the tools and temerity to keep the cells close to each other.
The directions my ZEEE lipo battery came with, and the consensus on Lipos say to not store full charged, even for a week as it will destroy it, so unlearning lead acid habits is paramount.
Ill assume the lipos in phones and such are not ever brought upto 4.2v, but if they are, it explains why those who keep their phone plugged in all the time, can have very short battery lives.
I got to find out what the lipo balance charge connector is called, so i can more safely balance the 3 cells when they begin to drift, as purchasing a hobby charger just for it, is unlikely in the extreme, when I can use my CCCV xl4015 buckers which i employ on so many other tbings.
The comparatively inexpensive Zee lipo battery i have, with the 12 awg leads and xt60 connector, well the higher end lipos use 10awg. My xt60 connector was the hottest part of circuit when practice spot welding, and i susoect a poor solder joint under heatshrink.
My lipo has a plastic cover which will split apart once the pouch cells inevitable swell up. Id like to get 10awg to the buss instead of 12awg, and use an Xt90 antispark connector, but might just carefully splice 10awg and an xt90 into the existing 12 awg.
Kind of crazy this little LIPO battery can so easily staRt my 3!8 on its own.
I did staRt it with the 18amp hour mightymax agm battery, once.
pretty sure the lithium jump starter packs use these LIPO pouch cells.
I am wondering if they have a bms or a way to prevent charging them to 4.2v, but if lipos are as volatile as they apparsntly are, it seems these litbium jump starters would be splitting the pack open and or catching fire far more often than we hear about.
Anyway the purple BSW should arrive today.
Wish i had a fully discharged junk practice 18650 cell, but llenty of other stuff to do anyway, first.
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