This is completely false. 0.15mmx7mm nickel is rated for about 5A continuous. Above that the nickel will heat up, leading to premature failure of the strip, or melt insulators and definitely reduce pack efficiency due to heat. I’m not trying to be a dick but simply correct the number so that others don’t think that a single 0.15mm strip can handle 15A and lead to a pack fire like the OP. You definitely do want to layer 4-5 nickel strips depending on the current load you will need, so no argument here.
Yup regarding putting out the fire the only thing I’ve heard works with lithium fires really is removing the source of oxygen so it can’t burn (completely covering it with sand is the best technique I’ve seen to contain the smoldering fire). Still probably doesn’t hurt to have an extinguisher on hand to suppress it or stop it from spreading to anything near by. I’ve considered keeping a small sandbag in my backpack but lots of extra weight if it were to be enough to actually cover 2 5S 5Ah (let alone something bigger)
Regarding charging I imagine most people are just plugging in a BMS and assuming everything will be good I made my lipos removable so I don’t have to worry (as much) about it when charging can put them in a lipo safe bag at the very least or if you want to go gung ho and feel really safe do something like this:
or buy something like this https://hobbyking.com/en_us/bat-safe-lipo-battery-charging-safe-box.html
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This is the issue with nickel stripping. It’s not the best material due to the low amp ratings it can do. if it’s 5a con, then I need what, 20 layers, to do 100a con safely… This is what pushed me away from them in the first place and to copper. But copper is hard to spot weld without damaging the cell also.
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@Eboosted can you clarify what you mean by “isolate the charging port”? I’m not yet building my own packs, but trying to gain enough knowledge to someday consider it.
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Depending on the pack layout, you don’t need most of the nickel to handle 100A. For example, if I’m connecting 30Qs in series and I calculate 15A continuous then my series connection between then needs to only handle 15A continuous or 3 layers of nickel.
The issue as at termination, where all your parallel cells come together at a single (-) or (+) terminal and THAT does need to handle the full pack current. I ended up crimping a 10AWG bus bar to accomplish that.
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It depends on the nickel width. You can find very different statements on the current for nickel strips, some says 15A, some says 5A, some says 8A. Can you underline your statement with a temperature measurement? I would be interested.
We are agreed that one stripe isn´t enough. And i saw pictures here with just one stripe. So it is very dangerous, because the nickel will heat up and could be a trigger for battery fire.
Best regards, Solar
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It is not just the thickness, a nickel strip of 5mm wide vs 10mm is twice the current Just calculate the surface (like we do in EU with copper wires) 5x0,15 = 0,75mm2 and take the resistance /m for the strip, this way you could calculate the resistance over the length used, following to calculate the power lost over the wire and last calc the heat-up of that. Theoretically the wire is cooled by the cells mass. So,… it’s hard to tell the exact melting point of the nickel strip. I would care much more about the quality/quantity of the welds. A bad weld gives much more heat-up than overloading a piece of nickel strip
When I first saw all the single strip versions on these forum. I couldn’t believe the charts with these incredible low rating were correct.
So I took current injection tool and started inject 10-70A into different size of nickel. After these test I can confirm the table below from Endless Sphere is correct.
Many people have quite some luck. I think it’s a combination of lower loads during the ride and the max required power is only during short amount of time. Still it’s very risky to operate the nickel strips in this high current window.
12S3P - 2x 6355 motors, I used 4x 12x0.15mm (good for around 40-45A continous) 12S5P - 2x 6384 motors, I used 1x 12x1.0mm copper (overkill)
Difference in resistance between copper and nickel is incredible. That’s why spotwelding works very well for nickel 
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Man, great overview! to add, it will get even worse with bad welds.
now I’ll consider to take my pack apart soon (used .15mm strips and set the vesc to 40A), I do monitor the cell temperature but not the strips. 
Thanks for doing this. I built my pack a year ago based on this table using optimal values, ie 5A per 0.15x7mm strips. IMO, its foolish to build your pack at the bleeding edge of capability. You always want to leave a large safety margin. As I said earlier, some guy here built his 90A pack using single layer 0.15 and claimed it was fine because his pack hadn’t blown up. 
A possibility you left out, while remote is still possible; a counterfeit cell(s) that didn’t hold up to the energies your system placed on it. It can also take time for the counterfeit to fail. All it takes is one bad cell and the entire system is at risk.
Even quality resellers suffer from the occasional counterfeit battery/cell. Counterfeit parts happen to the military, aerospace, hospitals, etc all the time even with their quality checks. They can be very difficult to detect and cull from a supply.
Should you double up the strips in between the p groups, I’m building a 12s8p using 10mm wide .2 pure nickel.
If it’s mounted to the deck, you may not be able to get to it when you need it. The general advice is to not store an extinguisher right next to the possible direct source(s) of fire (like in a kitchen, you don’t store the extinguisher right next to the stove).
Am I the only who uses 2 8mm or 2 7mm for parallel because its simply easier to weld? Anyone else out there doing this am I doing something wrong lol.
I did 2 10mmx .15mm strips for the parallel connections. Next time I will probably just do one layer after talking with some people more.
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Yeah there shouldn’t be much current running between cells. But more nickel isn’t really a bad thing Imo lower internal resistance can’t be a bad thynj
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series connections take the full current and the parallel connections see very little
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Temperatures, Insufficient Cooling, Thermal Cycling: contributors to catastrophic failure
Something I’ve not seen much attention to on personal builds here, is heat-sinks and system ventilation. From what I see, most people seem to be more concerned about water-resistance than ensuring adequate cooling of electronics and the battery packs. I would think exposure to water should be the exception, and avoided wherever and whenever possible. Cooling should be a very high priority, especially on these high-power boards. Properly implemented heat-sinks can also significantly reduce system heat while maintaining water-resistance.
Also, do you have or have you considered any instrumentation that measures and reports the temperatures in your cell packs? Any warning alerts when temps get too high? One can also put thermal sensors at key locations of power bus elements. Real-time temperature sensing could give one minutes of warning before imminent catastrophic failures, even allowing one to avoid a failure. It can also provide data for improving future builds’ ability to dissipate heat.
Edit to add: Another important factor to consider is thermal expansion and contraction. Depending how the board is used/stored, some of the components might see VERY sudden temp changes of from say 32F to 200F (or higher with insufficient cooling). That could cause major structural dimensional changes in elements like the bus strips. In some cases it may thus be undesirable to have a completely rigid pack design that doesn’t allow for the physical changes in the nickel or copper strips, or the physical stress on solder joints. Expansion and contraction could potentially even cause welds to pop or partially pop, thus causing hot spots. Temperatures cycle repeatedly as the board is used thus the damage could be cumulative and failure appear only after days, weeks, or months of use.
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Has anyone performed any before-high-current (cold) and during-high-current (hot) dimensional measurements on bus strips in battery packs? Or measured separating gaps under the same conditions?
I suspect thermal expansion/contraction plays more of a part than some may have considered in some electrical failures. I’ve noticed what appear to be millimeter or less “insulating” gaps in some projects. There are not only possible changes in length and width, but also the potential for warping in the thinner strips of metal as they heat up.
I’ve seen this phenomenon in high power battery packs that amateur radio operators have built and then sold at amateur radio conventions or to provide backup power for repeater stations. But, I don’t have practical exposure to any of these very high power skateboard battery packs.
So what is the general concensus on what thickness/width of nickel to use on the parallel connections on say a 10s5p pack? For the series connections I know to use a 12awg wire but am I right in thinking a single strip of 7mm x0.15mm nickel for the parallel connection would be fine also?