40T, neodymium magnets, plasti dip cycle test

Batteries, Chargers, and Battery Management Systems.
john61ct   100 GW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by john61ct » Apr 26 2021 12:45pm

Also for a mobile application the possibly extreme, and certainly constant shock and vibration needs to be taken into account

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 03 2021 7:12pm

need to finish a battery
have scrap nickel strip
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wrong dimension
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time to mickey mouse it
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1/8 x 3/8 magnets are strong
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10mmx1mm not so much
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10mm x 1mm will hold the cell at this angle
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trace onto foil
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shouldve made all like this
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10 gauge
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twist crimped with 20 gauge
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dont really like that, want more contact for amps, decided to wrap with copper strand
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using 7.5mm magnets and a 10mm to help keep everything in place while i caulk it in place
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Pajda   1 kW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by Pajda » May 04 2021 8:54am

I must say that I like to follow your inventive approach :)

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 04 2021 10:45am

ya :D amazon lost my 0.1mm copper in shipping and im moving June.01 so i didnt want to order anything til end of the month
im low on everything, magnets, cell holders, big battery wrap, 18 pin connectors....


in the meantime. the nickel is 0.15mm and 3 layers of foil is about 0.1mm for total of 0.25mm

5mm square magnet has 0.6lbs pull at 0.1mm
https://www.indigoinstruments.com/magne ... 222-1.html

to equal the pull of 1-10mm magnet 1.2 lb pull
i used 1-7.5mm ring and 1-5mm square, 1.4lb pull
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time for plast dip

Ianhill   10 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by Ianhill » May 04 2021 6:32pm

Thats perseverance for you got there in the end.
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Only one bit i spot is that little overhang would be ideally rounded on the corners so it stays within the tabs boundarys to guarantee no foul play later on but otherwise that a real nice bit of progress you got by there and looking forward to seeing how it performs thermally under load i think it should do quite well.

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 04 2021 8:49pm

yes i scrunched up the copper foil before spraying
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this is plasti dip when first sprayed
itll sit there and bubble like this til it settles down and give another coat in 30 minutes


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Hummina Shadeeba   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by Hummina Shadeeba » May 04 2021 11:16pm

How does potting effect the safety release valves on cells? I don’t know how but the A123 26650 cells will somehow disconnect when shorted for long enough and then magically come back. (Current will drop drastically but same voltage somehow, then later string current). It’s a pretty safe cell to begin with but what if u jam up the pid or whatever it’s called on some other cells? Maybe be a fun experiment

If going for maximum pull with small magnets maybe worth adding a back iron. Cheaper than a bigger magnet.

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 05 2021 1:01am

dont need back iron, theres enough in the can
bigger/heavier the magnet, the more lbs of pull required to keep the weight of the magnet in place

been trying to go as small and light as possible

7.5mm magnets with 0.1mm copper ill do a test when i get it to see how many amps it can do before the connection goes bad

7.5 mm magnets and foil will do 15amps, i run those on the trike at 7amps max with no issues
my 14 gauge battery leads were warmer than the batteries so im switching everything to 10awg

im putting this 5mm magnet battery build in the trike because they can handle 7 amps and putting the 7.5mm magnet battery build in the other bike because they can do 15 amps

i just dont know how the smoothness of 0.1mm copper will effect the connection but thats what i want to use for the terminal connections

theres no shorting out happening, plasti dip is an electrical insulator, i used the pour on plasti dip that comes in a can and covered the whole side of a 17s battery, i was kind of nervous thinking it might short out and blow up but nothing happened

as far as blowing up, im using 30Qs and 25Rs i havent seen them blow up from shorting them out
30Q
https://www.youtube.com/watch?v=Ys5wwUJOz58

25r
https://www.youtube.com/watch?v=oBlac5gWLfI

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nicobie   1 GW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by nicobie » May 05 2021 1:23am

That's unconventional and probably why I like it. Strapped on well, I would think it should work fine. :thumb:
Take it easy... but take it. (Woody Guthrie)

my eTownie build thread: http://endless-sphere.com/forums/viewto ... =6&t=23701
Magazine article https://www.electricbike.com/nicks-etownie/

Ianhill   10 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by Ianhill » May 05 2021 1:24am

Back iron on the rear of the magnet would guide the field lines on the reverse to give a higher surface tesla on the magnet 🧲 so it should increase pull strength.

I wonder if theres small enough magnets available to create a hallbach array no back iton needed it could double the pull to the cell and have less than half the field strength away from the pack where its not needed.

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 05 2021 9:22am

Ianhill wrote:
May 05 2021 1:24am
Back iron on the rear of the magnet would guide the field lines on the reverse to give a higher surface tesla on the magnet 🧲 so it should increase pull strength.

I wonder if theres small enough magnets available to create a hallbach array no back iton needed it could double the pull to the cell and have less than half the field strength away from the pack where its not needed.
you guys lost me, had to go google back iron and hallback array.

try to figure it out later :D

MorbidlyObeseKoala   1 W

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by MorbidlyObeseKoala » May 05 2021 9:22am

Wouldn't a back iron also provide a short path for current for the whole battery? Or was the idea to place that back iron over the layered plastidip?

A pull strength test might be interesting to compare crappy spot welds to the magnets but if goatman is getting repeatable amperage results, then this seems to be a novel approach with no specialized tools to me. My limited experience with plastidip on my car, I would say monitor it after a year or so for any flakes or tears. Tends to dry out and be painful to remove in one piece when it's fresh.

Just have to make sure your scissors or crap from the messy workbench don't get pulled into the magnets and short the whole thing out before you get it dipped.

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 05 2021 9:36am

been using plasti dip on my 25r packs for over a year

if you put it on thick it peels off clean
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after handling them every day i gave them another coat about a month ago

going to order shrink for the packs and just shrink wrap them once all wired up

Ianhill   10 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by Ianhill » May 05 2021 11:12am

Back iron in this case could be as simple as a metal button sat on top of each magnet so it wouldn't be part of the electrical circuit only magnetic.

Ive had a look for some small magnets that might be suitable to make an array but theres no chance from what i can find anything small enough.

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nicobie   1 GW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by nicobie » May 05 2021 3:10pm

I've been using these on cabinet doors for years.

https://www.leevalley.com/en-us/shop/ha ... asher-sets

Canadian company too.
Take it easy... but take it. (Woody Guthrie)

my eTownie build thread: http://endless-sphere.com/forums/viewto ... =6&t=23701
Magazine article https://www.electricbike.com/nicks-etownie/

goatman   100 MW

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Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 05 2021 7:22pm

took that 5mm pack to the hill i test the batteries on and pulled 47amps (almost 12 amps/cell) no problems then paralleled to the 7.5mm battery went for a 8km ride. the trike is set to 3000 watts, 8p means less volt sag so the max amps were 44 (5.5amps) packs were the same temp and no issues

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