Well I’m using it for capacity testing. What do you recommend for accurate IR and capacity readings?
Ya I read that liito tester was decent. I too am testing new unused cells stripped from battery packs.
The LiitoKala Lii-500‘s capacity measurements are way off but, like all the chargers, if you don’t care what the actual capacity is and you just want to compare cells then you can use it as long as it’s consistent. Test the same cell a few times in the same slot and make sure the number doesn’t change more than a few mAh.
Accurate DC IR testing can get expensive. 
I recommend this ESR meter: https://www.progressiverc.com/collections/battery-testers/products/lipo-esr-meter-mark-ii
For AC IR testing I recommend the YR-1030 on AliExpress. Only a few percent off what a $1300 meter says.
But if you want to use a charger try the SkyRC MC-3000. About as accurate as a charger will get for IR and capacity testing: https://www.patreon.com/posts/28883945
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also got a turnigy heavy duty 3s 5000mah 60c to go with it.
lowkey wanna buy more of those model 3 batteries for the ones I still have but not enough of lol
I would definitely like to know the real capacity but my main purpose is to compare cells against each other.
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I dreamed of the moment I’ll finish my own batteries like you guys, and there is still a lot to learn, but hey, it’s also a lot of fun to build your own battery
firstly, I had quite a successful endeavor with my setup which had to be a little upgraded. the story as follows:
I’ve been riding some 3s lipos in the past on my first AT before it got ass-cracked
so, few months after that I had to do assemble my kweld and some other pieces to do my first fob
well, apart from the hot-glue holding the batteries, I’d say not that bat!
but then I had to get rid of the lipos. I just had a bad feeling about having them swollen like that while staying in dorms, where a fire would not be pleasant at all. so the batteries slowly deceased in the sink for a few days. great present in the bathroom for other roommates. the afternoon after I put them in the water I just received a message on messenger “Andrew?” and the picture attached
incredible how long it takes for them to self-discharge in saltwater. seems that they either have quite more energy stored than my brain would naturally perceive, or the process of breaking molecules of water into oxygen and hydrogen is not particularly energy demanding and takes a long time. and also, the green blue copper salts
here some of the sad story:
so, new battery, I tried car battery with some really jacked up connection, just 10awg wire, and some wood clamps.
too bad idea, too much resistance, too long welding time, too fucked-up everything. welds would not stick and I had dented the cell tops and bottoms. these were for times of 60-90ms on the kweld, with about 800-1000Amps of current in. that was something about 70J. that was really stupid. now I’m just worried that the cells might be internally damaged.
but then I changed few things
8AWG stock wire to 35mm^2 wire (about 2AWG) and things were changing.
I had to find an electrician in Prague just by calling numbers, and the guy I called gave me a number to another guy, I called him and he said he knows a guy who has the tool and does this job
after this, I finally had a decent connection. however, the shitty amalgam from definitely not copper just evaporated after at an impulse of current.
so I had to change the output wires back to the stock k-weld 8Awg with the propper copper electrodes
but after that and some electrode isolation with zip-tided tissue after some finger burns, I finally had some welds I’m happy with
it is a triple stack, I designed for roughly 100A of discharge. I’m sure I might be far away from that, but I have peace in mind with this margin of error or possible high safety factor. also, what do you think of the single-layer connecting ends? I see it as a balancing piece, as none to low current should be flowing through there, most of it would de flowing though the triple stack. next time I’d go for a different setup, where there is more space between the parallel groups than two cells - that would require fewer layers.
I might say something about the pack itself - 12S6P from P42A molicells. I was especially keen to have this orientation to get the benefit of having the positive and negative on the same side of the “box”.
well, this was the result
then some fishpaper
and balance strips and some cable management love
some more kapton tape and in the box she goes
I’ll be really glad to hear some feedback, on which parts you think are well designed and also what could be improved. I’ll also write a build thread about what this will be powering!
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The nickel looks a little under rated, you should have more or use thicker material, and it would be nice to see the corners rounded off some
Welds don’t look like they have much penetration, like they are high pulse time but low current, but if they pass the pull test they are fine
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Watch the nickle corners if thay get pushed in this could make a short the general accepted way around this is to round your nickle corners
Don’t weld in the center of the neg of the cell it’s were the main connections are welded on the other side it’s bad for them
3 strips of nickle is not enouth for 100A on your series links.
Is this a burn mark?
You have all that potenchal restricted by this little cable that will get very warm.
Be carful KWeld cables and batters ain’t plug and play the length and thickness are critical to the resistance and calibration. Same with the battery if you pull over 2000A you will cause damage to the KWeld will shut down.
800A bare minimum
1200A recommended minimum (this is what the KCaps deliver)
1400-1600 is a good place (this is what dule KCaps deliver)
Holed the peddle down and it will tell you the result of the weld. That will give you a good idea of how the Old leads are
If your going to play around with the cables and battery’s I recommend you do a quick bit of maths
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NEVER do this EVER.
Do not discharge lipos even when disposing of them
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As @Battery_Mooch stated a few times. This is terrible idea for self discharge. Please don’t do that again, it’s dangerous, it’s bad for environment.
Other than that, good progress with battery building.
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Is it just me or do those welds look toasty? I’ve had similar and was told they’re too crispy
nice input, thank you for that. I think I’ll never repeat this, I hope not to be in this situation ever again 
being scared of cells does not feel good
Too crispy and not good penetration. Too low current, for too long.
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wow @Darkie02 , so much information!
Watch the nickel corners if they get pushed in this could make a short the generally accepted way around this is to round your nickel corner
yeah, the first picture you reacted to is really the baaaad example that taught me to think twice and buy/do once. I’m not proud of this, but I’m happy that I saw that and edited the setup, stripped all this nasty nickel, and did it again.
rounding nickel would be cool, but so time-consuming, I was trying to put the corners more to the sides so that they are definitely over the fish paper ring.
Don’t weld in the center of the neg of the cell it’s were the main connections are welded on the other side it’s bad for them
yes, I was cautious about the negative centers, and I’m aware it is possible that sometimes I’m too close to them. I’m just trying to find a balance in the count of weld points.
3 strips of nickel is not enough for 100A on your series links.
It’s 0.2x10mm, I see it now I could give it more. all the other connections have 4 strips of nickel, here are 3. from what I’ve read this should be the borderline
Is this a burn mark?
yep, the only one, one electrode slipped right when the timer was up for the impulse. there was probably less pressure on it and some arc blew a small hole in the strip. the fish paper is not penetrated, nor the undelying plastic shrink or the cell damaged
You have all that potenchal restricted by this little cable that will get very warm.
fortunately, that is a picture from the past. the input cables were upgraded to 2AWG wires with proper battery clamps and pressed copper eye terminals.
800A bare minimum
1200A recommended minimum (this is what the KCaps deliver)
1400-1600 is a good place (this is what dule KCaps deliver)
I’m getting 1500A from the 65Ah 800A rated lead acid car battery. it seems the bottleneck now are the output leads to the electrodes
If your going to play around with the cables and battery’s I recommend you do a quick bit of maths
nice, I did not know about that image
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Would good penetration look like this?
From what I can tell these are more ‘dimpled’; and because of more pressure applied onto the electrodes/nickel with a shorter pulse width at a higher current, right?
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Update, this works great
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I push down hard when I’m welding, I don’t call the calibration on my lipos but it was something above 1400A. I typically run about 38-42J on a single layer of .2mm nickel. and thicker nickel seems to dimple more than the thinner stuff. The push also tells me if I’ve missed the mark on the positive terminal since it will flex a lot due to nothing under it. I keep the tips files to a neat ball point.
*that pack was before mooch taught me to avoid welding in the center of the negative terminal
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Does this apply to A123 cells as well, or is it the positive anode on those cells?
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Penetration isn’t really something you can look for. You gotta do some tests and see if you can rip the nickel off the cell. If it leaves the weld behind and tears the nickel, it’s great. If not, then that isn’t great.
You want the minimum energy/heat input while still achieving that strength.
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I have been thinking about making a dual tip grinder to touch up easily while welding, hopefully without putting them down.
Bad idea? doing them one at a time with sandpaper good enough?