Wow that I didn’t know about them testing the battery down to 2.5V! I’m still trying to absorb the 25R’s 20A continuous and 35A peak specs. It can strain my old brain! What’s a good price per battery for the people that has already built their packs? I know I should not buy those cheap fake China ones.
If you live in the states you can find 25r’s for $5 each easily.
Can someone explain to me why the most used batteries seem to be samsung 25R’s? I’ve used them for my e-cigarettes way back, but switched to LG’s 18650HG2 because the performance was way better.
They offer 500mAh more per battery, and significantly higher discharge rate.
I think its mostly the price. They are nearly double the price.
This may not make a huge difference on the few cells you need for smoking, but does on 40-70 cells.
HG2: ~5.75€ per cell → 522mAh/€ 25R: ~3.65€ per cell → 685mAh/€
Where do you get your cells?
So it’s the price… okay 
I’ve found genuine HG2 for 6$, but couldn’t find 25R under 5$.
Where did you get these prices from?
Nice, they are cheap AF
Is there a special solder and flux to use for soldering to nickel strips? I want to attach my balancing leads.
I’ve seen people recommending using Aluminum solder and flux. Is that the stuff to get?
I would recommend skipping the whole soldering directly onto the cells if you can. Have you considered using 18650 sleds ? You can do your series/parallel soldering before even placing the batteries inside the sleds and if you ever need to replace a bad cell, it will be super easy to do without risking heating / desoldering individual cells. Below is what i am talking about and i think you can get them in any number combination you want on ebay for very low cost. Definitely worth considering.
I believe the reason sleds aren’t used is because of high current and heat that the sleds can’t withstand. I’m guessing the plastic will warp and deform and the constant vibrations may make for a poor connection to the cells since they’re not soldered or welded on.
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Don’t you think heat shrink or some kind of wrap treatment would solve that problem ? I think Enertion at some point was using sleds in their Space Cell. Not sure what they are doing now but it would be the sled along with some kind of wrapping to assure everything stays together and is protected.
I mean the housing for the nickel strip would melt. Enertion never used sleds, but they did use 18650 spacers which are a bit different as they dont’ have a nickel strip on them. They just welded the tabs on.
Does anyone actually know what to use to solder to nickel strips though?
I’m sure traditional 60/40 solder would work. That’s what I’m planning to use with my build.
Im using standard 60Sn/40Pb (actually 60% Sn, 38% Pb and 2% Cu) too with a soldering flux pen for easy application.
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What type of soldering iron do you use? Do you need one that get really hot?
standard solder with a good quality iron, probably set around 350degrees