I actually found those strips when looking online but the shipping was quite steep to EU. And then extra fees on top of that for import handling etc
By 30mm x 0.2mm you mean get wide strip and then cut out my own tab to fit in the ~17mm slot of the PCB? 30mm seems doable as the length of the tabs I have is about 27-28mm.
The product description said 0.2mm and also recommended the same spot welder, but measuring its actually 0.3mm… Looking at the product images they actually say 0.3mm nickel (in chinsese)… I was hoping for a stressless care free assembly but there’s always something…
You would just have to cut the notches to the size of the holes in the pcb. You might not even have to cut notches at all. I would just be sure to round the corners but this can be done with common scissors.
Rouding the corners for the sake of my fingers not getting sliced in half or theres other reasons? Thanks for replying, I think the 30mm nickel is a better idea than any idea I managed to figure out during the day. Seems to be available at nkon.nl as well. If anyone has more suggestions I’m all ears!
That, it looks nicer, and you don’t want a bunch of nickel sticking out at the bottom of the cells once you weld. If you accidentally get anything in there, stuff will be less likely to make contact if the nickel does not stick out beyond the profile of the cell.
They are thicker, which definitely makes a big difference.
They’re also slit and dimpled, both of which are designed to make them easier to weld, but you need to know how to take advantage of those features.
You really need to be able to practice and tune your welding settings for the exact nickel you’re using, and it’s unfortunate that they didn’t send any spares to practice with.
With dimpled and slit nickel strips, you want your electrodes to be pointed enough to fit into the dimples and touch the bottom, and you want to straddle the slit. One electrode on each side, so the weld current is forced to go down, through the nickel, into the cell, across, and back up, rather than just across through the nickel without going down into the cell.
This current path helps get a good solid weld with less power on thicker nickel.
Continuing my last post, we we’re able to take the flexway er battery apart. I was really impressed by the mechanical engineering and thought put in to it😁 The groups however were not okey, first and last group were 0.2v down from the others and the fourth group was 0.6v lower, replace the cell/s? Also, cells were Lishen lr2170la, I know it’s not good to practise but can I use something similar to it’s values?
LTO (lithium-titanium-oxide) battery chemistry is very interesting. These batteries are said to have profound cycle-life, at 10,000 to 30,000 cycles to 80% DOD. The following company claims to have 21700 LTO cells with an 8C discharge rating, and 4500 mAH capacity, though I think they are full of shit, as some of the specs just don’t make any sense. Regardless, LTO is the safest lithium chemistry with far-and-away the longest cycle life.
Good to hear! I ultimately went with a Bonka Power 75C 150C burst 5200 mAh as it was available locally. Seems to work fine with a single battery so far!
How much current draw affects capacity loss as the cell is cycled? No.
It’s very cell dependent and would take thousands of total cycles to derive the data…for each cell.
IMO, there’s not much of a difference between reasonable current levels as long at the cell stays below about 60°C. For huge short-term pulses it depends on how much damage is done…how much lithium is plated out, how much electrolyte decomposition there is, etc.
I haven’t seen any specific data for that as the manufacturers always say to test for your particular application. And IMO no company is going to share that product development data they spent so much time and money on.
Hmm…I’m wondering if there’s a short version of this I could do to verrry roughly estimate where real capacity loss starts happening. I’m guess it’s where the cells start getting pretty hot and there are very few uses that allow the cells to continue to do that. Just a guess though.
This is more hypothetical than anything really, but it would be nice to know how much of a battery has been used and how much longer it could be expected to go for
In say for the sake of argument a P42A is 3500 mAh at 10A and decays to 70% capacity after 600 cycles at which point the cell is to damaged to be safe, so at 10A the cell has a 1.785 KAh life span, and there’s some sort of curve for every current draw
If I have a 4P battery I’d expect something on the order of 7 KAh for the pack and if I integrate the current draw based on the current to total KAh rating of the pack I’d have an accurate % lifespan remaining on the pack…probs only useful on something like a car but still would be interesting
Characterizing a cell like that could work but I’m thinking there could be an easier way.
By measuring DC IR increase along with the 0.2C capacity as the cell is cycled I think you can get the data needed. I say that because the research papers I’ve seen use the degree and rate of change of capacity and IR to estimate the end-of-life point for any cell without all that testing.
This automatically takes the current draw and usage profiles (continuous, pulsed, etc.) into account since how the cells were used doesn’t matter. You use the cell until the capacity has dropped and/or the IR has increased (indicating the increase in voltage sag, reducing run time) by a certain level that matches the minimum level of performance you’re willing to accept for that application.
By tracking the degree and rate of change for capacity and IR you can estimate remaining life.
Hey folks. I had to strip the waterproofing on my battery apart for my Tyneeboard mini 2 as water had gotten in. It’s now all dry and looks like it’s working perfectly. However I’m wondering two things:
can I wrap the battery in masking tape for the time being whilst I ride it in the summer unwaterproofed, or does it need to be in lithium paper, which I don’t have at hand?
does anybody have any good links for materials like lithium paper, some foam sheet, and heatshrink that will do the trick in the UK and arrives quickly?
You should have the appropriate fish paper and shrink wrap, it helps hold the pack together which prevents stress on the weld/solder joints and protects it from shorting out on anything inside the enclosure when it shakes around
I think Fogstar is the preferred cell and battery building supply company in the UK?
