yet another solderless DIY battery pack via NIB's

Batteries, Chargers, and Battery Management Systems.
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TheBeastie
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Re: yet another solderless DIY battery pack via NIB's

Post by TheBeastie » Nov 01, 2016 2:22 am

Hummina Shadeeba wrote:Are u doing just one strip of .05" for all the connections or is it folded over and how many times? How many amps do u do?

My batteries, magnets, and copper are still sitting here and waiting for the answer to that question..but much more so really waiting to finish the skateboard
With the cavity im still set on potting the battery in...w 50duro silicone.
I was thinking of ways of how to answer this question. I think most importantly if your not an adult then make sure you seek adult supervision when making a pack like this as potentially serious fire/smoke damage can be done.

My main goal is still just on average 500watts of power.. I have a Bafang 500W CST hub motor.. and a S12S 500watt controller.. It can go up to 1000watts on take off though.
The reason I have made a somewhat large battery pack of 7P is because I only like to have to recharge maximum of once per week, mainly because I have no access to power outlets to where I keep my bike.

I currently rebuilt my pack with two layers of the adhesive copper foil. The biggest pain in the arse with using the copper adhesive foil is I had to remove at least some of the adhesive glue on the inside so that it wasn't pointlessly insulting the two layers..
To remove some of the adhesive glue I dipped the copper foil in acetone and then scrapped it off with a coin.. Once submerged in acetone the adhesive glue expands and discolors.. The amount of adhesive they put on the one side of this copper tape has to be seen to be believed once its dipped in acetone. I scraped off all of the middle adheasive and left the sides in tacted so I can still fold the second layer over and have some stick.
IMG_0157b.JPG
For just one 2S7P link I decided to use the ebay "Copper Sheet 0.05 x 100 x 1000 mm" that I ordered, cut to size, the massive upside to this is there is no adhesive but its still thicker..
http://www.ebay.com/itm/181443383724?_t ... EBIDX%3AIT
It feels way more 'springy/less contouring' against the postitive terminals as at least for Samsung 29E cells the positive side sits a bit inward from the round top edges of the 18650 cell.

I was thinking that for most folks who build their packs they draw enough current that the links get very hot to the point of BBQing.. So I was thinking that if your going to be drawing a large amount of power that creates a lot of heat then theres no real point of building a nib pack as your going to be putting your cells through the same or more amount of heat over time then just using them in the first place.
In other words if your going to draw heavy amounts of power out of them you may as well just use a soldering iron and solder your cells together as theres not going to be any difference in the heat they endure in the first place.

https://endless-sphere.com/forums/viewt ... 5#p1234810
https://endless-sphere.com/forums/viewt ... 5#p1236850
getting hota.jpg
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So in that case you might consider building a pack soldered together like this guy did.
https://endless-sphere.com/forums/viewt ... 19#p988212
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Vanarian
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Re: yet another solderless DIY battery pack via NIB's

Post by Vanarian » Nov 02, 2016 5:57 am

I think I've posted about it before but why not use copper strips or wires glued on isolated nibs (ex: nibs enrobed with slim silicon sleeves or a rigid high temp polymer)?

Main source of heat and current limit with no solder joints is how much of current goes through the magnets or how close the warm tabs / wires are from the magnets right? Too much heat = no more magnet strength, too much nickel = limited current. And useless distance = higher resistance and lower magnet strength.

My main issue with pure copper is corrosion... Your conductive grease though could do a great job to protect it no?
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TheBeastie
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Re: yet another solderless DIY battery pack via NIB's

Post by TheBeastie » Nov 03, 2016 3:10 am

Vanarian wrote:I think I've posted about it before but why not use copper strips or wires glued on isolated nibs (ex: nibs enrobed with slim silicon sleeves or a rigid high temp polymer)?

My main issue with pure copper is corrosion... Your conductive grease though could do a great job to protect it no?
Thats a good idea, I think a nib thats 'enrobed' with copper foil but barely any bigger then its existing physical width would be great for the positive side of the cells. The negative side is very easy to deal with as its surface area is roughly 4-5 times as much and its perfectly flat and even, a 12mm x3mm magnet has incredible clamping force on a few layers of copper foil, its the positive side of cells that is difficult.

I think copper foil enrobed for about 2-3cm then soldered onto a wire would make it very easy visually to see if your positive cells are well centered on the positive side, currently for me with the whole 2SP7 copper foil tabs I can only verify they are centered on the postive side of the cells by feel or by lifting the tab up and visually inspecting.

I don't know if this is exactly how you envisioned it but I just created a quick real concept of enrobed copper nib with two layers of copper foil wrapped over a 8mm neo magnet which is a good size for positive terminals.
I think if you can solder the wire onto the copper from at least 2cm away from the nib the heat wont transfer over to the nib and destroy its magnetic properties. Alternatively using a crimp tool and crimping the copper to the wire could be used as a solderless method.
IMG_0170.JPG
8mm nib magnet enrobed in two layers of copper foil on positive side of 18650 cell concept

So far from test riding at only a low assist level my pack does feel like its delivering more power than it did before.. I have the controller/LCD set to not draw much above 400watts, I want to allow the CW7100 conductive grease that I placed on each cell to cure a bit longer as it seems to greatly increase its conductive properties the longer out of its tube and applied thinly.

All up I think I am done with my pack, I don't think I will be changing it again, I should be able to use this for many years now, I already been using it this whole year, but now its been upgraded I think I can safely get more out of it...
I think the amount of stuff I bought to build it and the time it took probably outweighed its benefits of just buying a spot welder or even soldering.. I got 3 different thickness sets of copper sheeting I ordered that I barely used.. $50 on the CW7100 conductive grease which I still have plenty left over so that can be used for something else.

I think if your the type that uses recycled cells then this magnet connector approach is probably quite practical, otherwise your mileage may vary.
Last edited by TheBeastie on Aug 10, 2017 4:27 am, edited 1 time in total.

Hummina Shadeeba
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Re: yet another solderless DIY battery pack via NIB's

Post by Hummina Shadeeba » Nov 03, 2016 8:22 am

i soldered the copper foil to the wire and then wrapped the magnet in the copper

Thebeastie why do you say your milage may vary or that this method is better suited for recycled cells?

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Re: yet another solderless DIY battery pack via NIB's

Post by Hummina Shadeeba » Jan 15, 2017 2:29 am

I'd like to test magnet and copper connectors by getting the cells connected to them to discharge 5 amps continuously "on the bench". Is there a way...integrating a resistor of the right size i guess, that I can get my 5 cells in parallel to discharge 5 amps each continuously? I'd like to see how hot they get.
How badly does a battery's internal resistance affect voltage sag?

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Re: yet another solderless DIY battery pack via NIB's

Post by spinningmagnets » Jan 19, 2017 5:41 pm

I had a couple of reservations about using magnets to hold the busses onto the cell ends, in the beginning. I recently came back to this thread to see if there had been any more developments, and I am impressed. I finally looked at the button-magnet 12mm X 3mm prices, and I am somewhat shocked at how cheap they are. (also 10mm X 2mm, 100 pc for $7)

This is now something I actually want to try. Copper for the busses

Who's a good supplier of magnets for USA? Earlier I read that ebay seller "l-che27" was highly regarded. If I have one magnet per cell-tip, a 12S X 6P pack would be 72 cells, so... 144 magnets (probably need to order 150 to allow for a few damaged)...

edit: I now believe (June 2017) that these mmagnets holding a copper ribbon onto the negative end is the best DIY way to go. However, for the positive nipple, I like the soldered fuse-wire.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

edit: soooo...these exist...0.20mm thick copper busplates that fit the common plastic cell-holders.
SpotWeldCopper1.png
If the series portion of the strip is 10mm wide, then it is 10mm X 2mm = 20mm in area (cross-section), which is 4.5mm sq, which equals 10.5-ga. The three shapes below would all carry the same current, although the flat plate has the most surface area, and "might" shed heat a little better?...
SpotWeldCopper2.png
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markz
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Re: yet another solderless DIY battery pack via NIB's

Post by markz » Jan 19, 2017 8:27 pm

I cant find l-che27 when I try to find the seller in Advanced Search in ebay.
I think its best to put a little bit of epoxy to secure the magnet in place so it doesnt move around along with a plastic clamp. Either that or straight up solder to the cell.

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Re: yet another solderless DIY battery pack via NIB's

Post by parabellum » Jan 21, 2017 10:01 pm

(to spinningmagnets). Do you think it is real, not copper coated steel? (formed) Pure copper strip is perfect for no weld, with nickel bath as enhancement. Links? :)

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Re: yet another solderless DIY battery pack via NIB's

Post by spinningmagnets » Jan 21, 2017 10:55 pm

I don't know if that pic is from a legit supplier, so I apologize for teasing. However...as stated earlier in this thread, the parallel connections can be a very thin wire, which is cheap and easy to do. The series connections carry the current, and that is the part that needs to be thick copper. I am certain that strips like that can be made from a roll of 10mm wide copper ribbon. I will investigate this further, in order to find out exactly how much crap I am full of.

One parallel wire is shown at the far left, in the pic below. Click on it to enlarge...
BatteryMagnets.png

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Re: yet another solderless DIY battery pack via NIB's

Post by spinningmagnets » Jan 22, 2017 8:17 pm

Here is an E-motorcycle, (small 50cc size) with a 14S 19P pack (52V). The pic shown is one P-group of 19 cells. I see copper busplates? (waiting for a response from the builder for details).

Cell is the LG HG2, factory rated as 20A peaks and 3000-mAh, so 19 in P is 57-Ah and 380A peak...this guy looks well-researched and he chose copper, so...

https://endless-sphere.com/forums/viewt ... 10&t=85758

Image

Image
BatteryPackLooseCell1.png

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Re: yet another solderless DIY battery pack via NIB's

Post by Hummina Shadeeba » Jan 22, 2017 8:42 pm

looking at that thread and the pics he posted I'm confused by how he had that copper positive terminal bar made (it isn't flat and has a lot of curve to it) and I'm also wondering if there's more parts he hasn't shown because otherwise it seems that same curved positive terminal part has "tabs" coming off the side of the busbar without any support and their not being steel I can't imagine there'll be much spring and pressure. looks like a good nibs candidate.

all this nice design work might go out the window when it's shown duct tape, hand cut 2mil copper, and nibs work well

whats the math to know how much current is flowing through the p connections?



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Re: yet another solderless DIY battery pack via NIB's

Post by spinningmagnets » Jul 10, 2017 11:35 pm

There are several similar threads, but this one seems to have the most info and interest about using magnets to clamp the bus-strip to the cell end. I contend that the positive end of an 18650 cell can easily handle having a fuse-wire soldered onto it safely and consistently, with the proper technique. However...the broad and flat end of the cell is the most vulnerable, as shown on several youtubes of soldered cells that were dissected.

I believe that button magnets holding a thin copper strip against the negative is a useful configuration to use. I just got some 12mm X 3mm button magnets, neodymium, N48 strength, very cheap, and they hold the strip onto the cell very well. I will add compression too, but when it comes to heat expansion, cold contraction, and bumps/vibration, I believe the magnet pressing down will work very well. The copper is not magnetic, but the 18650 shell is nickel-plated steel, and the magnet wants to pull towards the steel.

The strip I used is 0.20mm copper. Flexible enough at the neck to move slightly if needed to maintain flat contact. The round pad is 12mm, and since the bottle-neck is the 8mm slots on the common black plastic cell-holders, if the 0.20mm strip is 7mm wide at its narrowest, that is 7mm X 0.20mm = 1.4 square mm of area in the copper cross-section. Copper will create less waste-heat when carrying current, and any warmth that happens will be easily shed. It's 1.4mm squared cross-sectional area is equal to 16-ga wire.

The highest-amp cell right now is the LG HB6, factory-rated at 30A each. If we are only hitting 30A per cell on occasion, then 16-ga wire/ribbon per cell should be fine for this as a minimum thickness.

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Re: yet another solderless DIY battery pack via NIB's

Post by TheBeastie » Jul 13, 2017 2:53 am

spinningmagnets wrote:There are several similar threads, but this one seems to have the most info and interest about using magnets to clamp the bus-strip to the cell end.

I just got some 12mm X 3mm button magnets, neodymium, N48 strength, very cheap, and they hold the strip onto the cell very well. I will add compression too, but when it comes to heat expansion, cold contraction, and bumps/vibration, I believe the magnet pressing down will work very well. The copper is not magnetic, but the 18650 shell is nickel-plated steel, and the magnet wants to pull towards the steel.
Yeah this thread has a lot of good info in it and folks that want to build a "neodymium pack" should really read the whole lot as its just riddled with good tips.
Yeah 12mmx3mm are great for the negative side of 18650 cells, I found myself grinning in amazement when I first placed one of those sized magnets on the negative cell terminal, and yes if you use the common black 18650 cell holders you can't actually fit 12mmx3mm magnets on them as the little plastic tabs get in the way.
What I did was merely snap them all off with long nosed pliers, they break/snap off easily in a quite convenient fashion.
You can see from this pic posted below from a few pages back in this thread that after snapping those tabs off I was able to push through the whole black plastic cell holders down and out of the way of the cell terminals. While this adds more convenient access for good contact to the cell terminals it also comes at the price of having to ensure good manual alignment of magnet/copper contacts.

I think looking back if I was going to make a new pack in this style I would still snap off the tabs but try and leave the cell holders sitting on top. The reason I didn't do this originally was because I was experimenting with different thickness level copper sheets/foils before deciding that the skinniest copper foil possible with 2 layers was the best overall approach for me, as it allows more contour while still providing thickness/gauge and flexibility just like why stranded copper wire exists.
Image

As discussed in this same thread back here ( https://endless-sphere.com/forums/viewt ... 00#p949962 ) when the neodymium magnet is heated it practically loses all its magnet strength, the change is so extreme I recommend you sacrifice one of your magnets to see the dramatic change by just putting under a flame for 5 seconds or so.
This is where I hope this style of pack design works out to be like a fuse. As if one cell goes bad hopefully the heat will only be big enough for the nib to lose its magnetic strength and disconnect/blacken the copper connection from the terminal.
This is only logically most likely going to happen if the pack is on its side in a frame bag, which is the position of how my pack is kept on my ebike.
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Re: yet another solderless DIY battery pack via NIB's

Post by tomjasz » Jul 14, 2017 12:41 am

2 seconds is enough. I soldered magnets to balance wires to make charging harnesses for my iCharger. It's rapid. That said, 36v and 48v Battery Blocs running up to 30a controllers have never heated up a properly sized battery, enough series cells, sufficient to fail.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: yet another solderless DIY battery pack via NIB's

Post by spinningmagnets » Aug 07, 2017 8:07 pm

This thread is the one that has the most info on using magnets to attach buses. Pic from "TheBeastie"

https://endless-sphere.com/forums/viewt ... 75#p981259

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Re: yet another solderless DIY battery pack via NIB's

Post by markz » Aug 07, 2017 8:12 pm

Epoxy the magnets on, using epoxy on the top and sides of the magnet and not the bottom where the contact is.

Just a thought.

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Re: yet another solderless DIY battery pack via NIB's

Post by TheBeastie » Aug 10, 2017 7:02 am

Was thinking about build a 18S 4P Vruzend kit of below.
https://endless-sphere.com/forums/viewt ... &start=350

But then I thought about the fact I have to order 2 kits for a 72cell build, then there is shipping and then there is talk it can't handle a big amps.
So I wondered if I should turn to my magnetic pack build again..
Some of the inital input costs.
60mm wide x10meter long copper tape $10
http://www.ebay.com/itm/Various-Size-Gu ... w1V7ykdaPw

4 x cell holder bracket sets $5.60
http://www.ebay.com/itm/2PCS-4x5-Cell-1 ... SwicJZXj0c
50 x 10mmx3mm neos $7.69 (negative side)
http://www.ebay.com/itm/5-100Pcs-Super- ... Z710h-8E4g

50 x 7mmx3mm neos $5.88 (positive side)
http://www.ebay.com/itm/Diameter-7-mm-s ... nnctAP63Sg

$29.17 total cost, and the value of having a battery pack that makes you look like a half nut mad scientist? priceless. The price of having a considerably dodgy looking more awkward battery pack? Hard to measure.

Might update the urls prices etc as I go over it all.. One of the most annoying things about this pack build from memory was the positive side on Samsung cells, because the positive terminal sits almost inwards around the rim I am thinking 7mm is better than 8mm. I have noticed Sanyo cells positive terminals sit about a good 2mm above the rim almost like a button top cell but they are considerably more expensive cells.

I guess the bigger question for me is does this type of build allow more or less current than the Vruzend kit which do look pretty cool.
Or just solder, I got a pretty good soldering iron but I am just ok with soldering skill wise, I wonder if anyone soldered an 18650 cell and have it blow up in their face or notice with conviction any damage to their cells?
Also I verge on just buying a spot welder but I only ever build a new pack every few years, what to do.
Speed Kills Range, 10mph = 46 miles range, 20mph = 20 miles, 30mph = 8 miles range http://goo.gl/1JNL53
Over Charging Kills ur battery bit.ly/1hzWKl4
Beware of dodgy 18650 cells! youtu.be/eOshOXcSkDA
Consider PAS as your only throttle http://goo.gl/m17J9j
CO2 is core to Photosynthesis https://youtu.be/t5mvDONB6FI
Check out the Bill Gates nuclear reactor https://goo.gl/Rtky9q
10 Square Miles of solar panels = 0.12GW average power! https://goo.gl/Ub1S39

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Re: yet another solderless DIY battery pack via NIB's

Post by andy1956 » Aug 10, 2017 4:20 pm

what about flat tinned copper braid direct to battery with magnet on top??

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Re: yet another solderless DIY battery pack via NIB's

Post by markz » Aug 10, 2017 8:00 pm

andy1956 wrote:what about flat tinned copper braid direct to battery with magnet on top??
Might be too thick and not have enough "staying" force or shall we say contact force.
How thick is it?
:lol:

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Re: yet another solderless DIY battery pack via NIB's

Post by GalFisk » Aug 11, 2017 7:37 am

The problem with tinning a braid is that it loses all flexibility.
How about stuffing NIBs inside a braid? Stretch the braid on both sides to keep the magnet in place. Only half the thickness of the braid will be between the magnet and the pole.

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Re: yet another solderless DIY battery pack via NIB's

Post by @lby64 » Nov 10, 2017 2:01 pm

Hi everyone!
Since several years I assemble DIY ebike.
I came to this interesting 3D since I'm going
to try assembling DIY lithium battery by using
Sony VTC5 cells and neodynium magnets without BMS.
Many people are assembling custom batteries by
the mentioned cells without BMS with no problems.
I'm not expert in this matters but if I undestood properly
it seems charging the battery the Sony VTC5 cells
do not overvoltage despite they are not singularly
controlled by the BMS.
Using this feature my idea is to create rubber tubes 10s
by cells connected by magnets connecting than 3 or 4
tubes in parallel.
I contacted one year ago a USA company which patented
a magnets based lion battery assembling but due to high
delivery cost to Italy (65$ delivery over 50$ staff) I gave up.
Have you similar info on Sony VTC5 cells?
Sorry for errors, my English is a bit rusty...
:lol:
I'll keep you posted, at this moment I'm waiting
for receiving the magnets.
Ciao!

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Re: yet another solderless DIY battery pack via NIB's

Post by @lby64 » Nov 10, 2017 2:09 pm

http://www.batteryblocs.com/

This is the link of the company I mentioned;
Assembing videos are on Youtube.

And one of my DIY ebikes.

:)
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