I calculated 120mm based on the assumption that you are using 21700s. 6 x 21mm is 126mm. Rounded down to 120.
Don’t have enough info on your pack design to comment further.
It all depends on what the controller will be pulling from the battery. The currents we’re talking about are all continuous calculations. You can reasonably double the amperages for short spikes. If this for an esk8, I’d say you’ll be fine. If it’s for an e-moto or something like a surron you’ll be pulling higher currents consistently and I’d say figure out a way to increase your current capacity so that you’ve got at least 20% headroom.
i saw this awhile back in this thread and seems fantastic and think we should all be using it instead of fiddling with stacked nickel and amp calculations.
and they say they even can make it custom to fit
i havent used it yet so I cant say anything for sure but will definitely be ordering for next battery.
Does anyone know a good way to bench test diy battery packs? Or just rock and roll, baby…put it in a board and floor it?
How do you guys usually do it?
makes sense to use the bigger number, not sure why i’ve been going with the smallest dimension which is about 80mm. The width is actually 125mm long, so its 352A-470A? (acceptable/hot)
so it looks like the nickel is enough for even a 10p or 12p of p42a (@ 30A per cell)
Big question needs lots more little details to answer, take some pictures and give a good description of what you’re trying to do. There’s usually too much power in an eskate pack to just wing it without making a fire out of all your hard work
It’s basically an educated guess, but key factors are the cells (voltage, amps, capacity, series, parallel) and resistance (welds, nickel, wires, solder, and connectors), based on that you can estimate a ‘safe’ use case
I’ve posted some photos on this thread a while back
Basically the plan is to draw up to a 100A
In theory the battery should be able to handle it.
I Don’t really understand how your answer Corelates to my question.
Lots of solder joints
And I’m a bit scared to test out the xt90 since I crammed 4 15avg cables in both sides so If there could be a fault it’s most likely there.
It doesn’t, but you gave us nothing to work with, write down everything you used to make the battery and take pictures of the configuration and all the connections
But no there isn’t a good way to test a pack to get a definitive answer, the best test would be hook it up to a load and monitor the voltage across the cells and pack as a function of ampacity, and watch the whole pack with an infrared camera. If the pack gets hot then you’re running it to hard
Seriously though, bench testing isn’t done around here much for packs. Which is why so much effort goes into the prep work. That’s a llt smart bms? Did you get any of the thermal sensors into the pack? If you’re worried about it - monitoring it is the best way. Hit it with a multimeter and check all the voltages and make sure it’s all nominal then send it. Take a few short easy test runs and check on voltages and temp sensors them give it a look and see if you need another bit of fish paper or some silicone.
What are the specs? Couldn’t find them in the link but im kinda slow sometimes. Did you take any build pics? Unsolicited advice: write the specs on the battery and the cells you used and the date, you’ll thank yourself later if you need to track down that info and it also lets you look back and see how it performed - if capacity drops off harder than it should or something else happens you’ll have a reference for improvements.
Everyone on here is trying to help, and im no expert - I don’t see alot of engagement on the previous post you made either so I wanted to try and help you out. Communicating via text requires extra clarity and over explanation or it could send you in the wrong direction with bad advice. And show off your shit - 100a pack is cool a fuck - tell us how and why man throw me a bone
btw I can’t quite see how you made your wiring harness, do you have a pic that shows how it’s all connected? What did you weld it with?
Less test, more prep and send it
Edit: was digging in you post history, is this the 4p 30q pack you were working on? Seems ok by spec and execution. Send it and keep a close eye on the bms
This is what I was looking for.
Thanks man!
I made some pics, I don’t want to photo dump here so I’ll upload it and link the thread.
Actually a 12s4p P42A pack
Unfortunately I haven’t really photographed the progress but all welds and solders are about the same consistency, same looks.
It’s the tradeoff haha streets are really shitty and I use it every day to go to work, rather trade the serviceability against being sure nothing vibrates and rubs
New battery pack, not been charged. Has been on a loop key since assembly. I went to charge it last night for a maiden run today but the charger light didnt go red nor did the fan start up like it usually does. Charger still works and charges a different deck.
I thought id neglected to plug in the charge cable so i took it apart today to correct and found that it was connected > headed to the app and discovered this…
Hey guys!
Could someone point me in the right direction? How do you calculate current density for the S connections? Maybe some working examples?
Its straight forward with this one:
each cable carries the current of two cells, all parts of the nickel only carry current from one cell.
Dont mess up the soldering and its perfect.
On the other hand:
This way, to my knowledge, you have to take into account that the current density is going to be higher so if the diameter of the solder cant support it, it might create hotspots.
How do you calculate the optimal current flow with a big sheet of nickel, how do you spread out the series connections?
