40T, neodymium magnets, plasti dip cycle test

[goatman]

I think im going to cycle test these settings


and then post the results in its own thread, probably start monday with new battery

im just going to play with the magnets now in this thread

* how do I put ebc-a20 in thread title*

[goatman]

I was trying to find a magnet like this one so the wire comes out the side, theres ceramic high heat that could probably be used for cooling
https://www.mcmaster.com/5688k51

[goatman]

im running a test of the electrode magnet with a tiny film of Permatex

at 7.5 amp discharge the negative magnet was running 3f/2c higher than battery temp, other tests with no Permatex the battery and magnet were same temp.

heres the results



pulled magnet to wipe off Permatex





re did the test no Permatex, both magnets reached 90f and battery 88f. heres the results



re applied Permatex to retest magnet temperature



with Permatex positive magnet hit 90f, battery hit 90f and negative magnet 93f, lets compare first Permatex to no Permatex and then Permatex again.




I cycled the Permatex 6 times, the battery loses about 3mah/cycle

after the first discharge/charge the capacity was 3080 after the 6th cycle the capacity was 3063mah
17 mah difference divided by 6= 2.83mah

I cleaned the magnets and battery and started the same 6 cycle test

the zke pc software is very buggy, I might have to go get another laptop dedicated just to the tester, heres the frign 3amp glitch again



the glitch happened between 3-1 and 3-2


but after I had changed the magnets and did the com disconnect and tester off routine the first cycle stopped recording mah again so I got this reading after first cycle from tester
3073mah, no Permatex is 10mah higher than last reading of 3063mah w/permatex



once I got the reading, turned off tester, closed program, re opened program, turned on tester, try to connect through comport and nothing, I wiggled the usb, still nothing, unplug the usb from computer and plug back into computer, I got the bdoop sound from computer, then clicked connect/com port 3 and everything worked again

im not a computer guy but im wondering if its the USB to TTL serial cable?

ive been messing around trouble shooting, if you bump or move laptop the usb to ttl serial cable will cause the program to freeze.

the 3amp scratch on charge is there no matter which battery and no matter which magnets used, its the way the charge amps are stepping down in the program I guess. its not the batteries or magnets you can really see it from 3amps to 1.6amps



I haven't been able to recreate the glitch on the discharge, im working on that right now. battery temps peaked at that glitch and im wondering if the copper electrode expanded and pushed the magnet off the cell. ill be playing with that today

having troubles finding a new 40T for testing, found one in Ontario, itll cost me $40cad total to get it here. I can get 2-40t and 2-p42a from imr battery for about $80cad from the USA but im worried about shipping time and border BS. Called molicel in maple ridge bc, sales department was an answering machine and they haven't returned e-mails or phone calls.
anyone know where to get a 40t and p42a in Vancouver bc area?

im doing the 0.8a discharge to 2.5v capacity test to the 7amp/40T just to see how its doing

[goatman]

I found a new 40T, ill do the capacity test and start testing tomorrow with these settings, unless someone has a different suggestion, and put it in a different thread.

[goatman]

this is the 7amp battery im doing the capacity test on, check out the curve



its complete. ill do the new 40T and compare



the new 40T

[goatman]

when I looked at how the 40t degraded in the 3.5v to 3.0v, it had seen some high temps and I was also switching the amp discharge in that area. I tried a new test



it gives about a 36 minute ride time and temps peaked at 88f/31c. I also changed charge just to see how long it would take.
start temp was 72f/22c end of discharge was 82f/27c and the high speed fan on tester didn't kick in, it stayed on medium, maybe it will be a liitle more accurate with its readings.



10amp hit 80f/26c



7.5amp hit 88f/31c



5amp hit 86f/30c





the 3.75amp charge with a 4p pack would need a 15amp charger. about a 64 minute charge

the 3amp charge with a 4p pack would need a 12 amp charger. about 75 minute charge

there would be about a 20 minute difference in cycle time

[john61ct]

Wouldn't it be cleaner to dedicate a thread to one aspect at a time?

Leave this one to the topic in the title, independent of what model batteries are used?

Just a suggestion. . .

[goatman]

Wouldn't it be cleaner to dedicate a thread to one aspect at a time?

Leave this one to the topic in the title, independent of what model batteries are used?

Just a suggestion. . .

yes, I started the test, ill put it in a new thread tomorrow. all that thread will be is the first cycle, then ill cycle 49 times, then the 50th cycle. ill do 1 charge/discharge graph and that's it, ill post a chart for every 50 cycles, that's it, nothing else. im just going to keep this as a working thread for testing different magnets. if magnets work then ill post a simple barebones thread on how to build a cheap battery using magnets and plasti dip.

it is a working thread and I was going to go delete a bunch out of it but I wasn't too sure if that's frowned on.

[john61ct]

NP so long as the motivation is greater clarity, not re-writing history in a conflict situation.

[john61ct]

Personally, a thread focused on testing your experiments with the physical connections side would be great.

Resistance, both electrically and shock/vibration in particular

Building up to a recommended best practices HowTo, BoM, costs per cell etc

seeing if others can duplicate and test themselves.

[goatman]

funny you should mention vibration, theres been a packer running across the road for 2 weeks on a construction site vibrating the house and nothings showed up on the charts.

I was thinking of doing a pull test on the magnet/battery/plasti dip connection, I can probably hang 10lbs off the battery while holding the wire and not lose connection, that test is coming

[john61ct]

While actually measuring resistance, would be interested.

Weighted pull tests are how you establish milspec rating for gas-tight crimps, but there, the full conductivity remains right up to where the physical connection tears open.

[john61ct]

And of course the kind of vibration / shock something fixed to bike experiences is many orders of magnitude higher than tremors passed through the ground

[goatman]

I hear ya, I was just out with knobbies on the road, still feel the vibration in my hands.

[goatman]

Bought some more magnets, couldn't find exactly what I was looking for but I will be testing these next.
heres where I got them with the specs

https://www.indigoinstruments.com/magne ... 5x1mm.html

theyre 10mmx2.5mm hole x 1mm thick





you can hang the battery from the wire with 1 magnet but need 2 magnets to hang it like this



now I need to find some 16 gauge copper stranded wire similar to the picture but id like to find an 8 strand or 10 strand wire

to make the parallel connections I was thinking of using nickel plated steel guitar strings so you could solder a bms wire to it, lay it across the magnets and then plasti dip it or use heat shrink on it as an insulator?

even using this copper slug tape at first for parallel, its 10mm wide but you can also get 1 inch wide and wrap it around 2 magnets for serial, like MrBeastie, youd need to roll it up to figure its gauge to know amps but?

https://www.amazon.ca/Life987-Copper-Fo ... 68AG6YYJC7

heres a picture of what I mean, I cut a piece of paper about 30mm wide and folded over 2 magnets, I side is 1ply and the other side is 2ply. its only 1 magnet per side and holds no problem



with copper you might be able twist the two magnets to turn the strip inbetween into the shape of a wire, like you twist tie a garbage bag

[goatman]

I ordered the copper slug tape yesterday and got it today sometimes i like Amazon its 2 inch wide by 33 feet so i cut a square and rolled it across the 2 inch width











I rolled a piece to see what gauge it is roughly, 16 gauge? that's a 14 gauge copper electrode for reference





hooked for a 10 amp temperature test



after about 14 minutes battery hit 99f and so did the copper tape so I stopped



don't mind the title, its for the other 40T cycle test im doing, I just interrupted it to try this out



heres the slug tape I bought

https://www.amazon.ca/DanziX-Conductive ... 7084&psc=1

magnets are cheap if you look around but look for n42, they have a working temperature upto 80 Celsius

https://www.aliexpress.com/item/32807195858.html

[goatman]

I want to test at 15 amps and 20 amps so I made another magnet up. the copper is cut 1-3/8 wide and 3 inches long.











magnets still hold strong

[MorbidlyObeseKoala]

I am pretty interested in this concept. I know there is a majority here that say just get a spot welder but this offers more flexibility in swapping out a bad cell and doesn't need specialized tools to assemble. Additionally, if you were to change the shape of the battery for another application or added range, you can do that without tearing up the ends of the cells.

For someone that can never make up their mind on a configuration or which project should get the battery, this is desirable. Especially if investing a fair amount of money into brand new cells.

[goatman]

I am pretty interested in this concept. I know there is a majority here that say just get a spot welder but this offers more flexibility in swapping out a bad cell and doesn't need specialized tools to assemble. Additionally, if you were to change the shape of the battery for another application or added range, you can do that without tearing up the ends of the cells.

For someone that can never make up their mind on a configuration or which project should get the battery, this is desirable. Especially if investing a fair amount of money into brand new cells.

thanks, you can save money if your not running high amps, you can run 5 amps continuous with a 1inch x 1-3/8 copper tape on 18650 even smaller magnet and no temperature change is present. but add some copper and crank up the amps

[goatman]

heres the 15 amp and 20 amp test

15 amp





starting temp



end of 7 minute discharge



temp hit 108f but when the discharge ended temp dropped to 106f and after 1 minute



heres 20 amp



after 1 minute


2 minutes





3 minutes





4.5 minutes





battery temp 1 minute after discharge

[Dak77]

I like the work you're doing . Would have never given magnets a serious thought until now.

[goatman]

I like the work you're doing . Would have never given magnets a serious thought until now.

thanks, the 40T cycle test im doing in the other thread is using 3/8x1/8x1/8 ring magnets to see if they last. ive got a molicel p42a coming and im going to use these new magnets with the slug tape on that cycle test.

[goatman]

i was thinking of getting some of this braided nickel plated copper for testing. just slip the magnets inside

https://www.aircraftspruce.ca/catalog/p ... 20Products

[Dak77]

I like the work you're doing . Would have never given magnets a serious thought until now.

thanks, the 40T cycle test im doing in the other thread is using 3/8x1/8x1/8 ring magnets to see if they last. ive got a molicel p42a coming and im going to use these new magnets with the slug tape on that cycle test.

Nice. I've been wondering about those Molicels for a while. They have some impressive discharge curves .

[Dak77]

Since you're into the more obscure cell testing, another future consideration , maybe a Queen Battery qb26800 . If that thing has even decent cycle life , it would be very interesting.