Making 12s7p battery pack for trampa

ESK8 Electronics
1

Hi Esk8:ers.

I have started to make a 12s7p battery pack for a top mounted pelican box on my trampa.

So far hot glued 3s7p.

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I have positive isolation ring and I cut strips to cover bottom and top on sides. This to protect the cells if they rub against each other during riding and letting me to glue cell to cell.

I will use 25x0.15 nickel strips to cover parallel and series connections. Connection to the pack will be 12.5 mm nickel strip and 6 cables going to one 10 awg cable.

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I will use BMS for charge and discharge (Bestech D596), though it might be good to have that protection for my first build.

Now waiting for arduinos spotwelder, kapton tape, and 8959 scotch tape to arrive.

Please comment by build if you like, I appreciate both positive and constructive feedback. :slight_smile:

/Best regards S

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2

Silicon is better for connecting the batteries than hot glue. Other than that it looks good. Can’t wait to see the final product

3

test weld timing when welding nickel to nickel, they have different properties than nickel to steel.

just take two pieces of nickel and test it out until you get nice welds.

because using the same timing for nickel to nickel welds as nickel to steel will get you really weak welds.

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4

Thank you for reply. Have not seen many who has done it with silicone. How do you apply it in an easy way?

It do feels a bit bad to put heat on the cells with the hot glue and I read that it becomes brittle at -22 degrees Celsius.

I will continue with the glue for this build but might change for next :slight_smile:

5

Thanks for the reply.

I put the nickel strip on top of each other on the picture to simulate what it will look like. I won’t do double strips since I do not like the idea of a gap between the strips between the welds. :slight_smile:

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6

Im pretty sure that you will not ride your board on -22 lol and even if you will your cells wont ever be that cold unless you leave your board outside, temperatures below zero can damage cells

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7

You are right, the battery will never be that cold :). Tried the glue in the freezer. It became a bit brittle but still strong.

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8

I tried to find an temperature sensor to put in the middle of the pack. A sticker sensor would be great.

The closest one I could find was on banggood: Screenshot_20181227-231815_Banggood It would be so nice to se the hottest temperature continuous of the pack during riding.

9

Can you link that sensor please? :slight_smile:

I can only find ones like this image

10

It was the two items in the links below. Did not manage to link direct so copied from Google.

Have not tested them, want an easier solution.

https://www.google.com/aclk?sa=l&ai=DChcSEwiW562l08PfAhUQHRgKHcDnD98YABAGGgJsZQ&ae=1&sig=AOD64_0AWOL4fLcgI5LiB35Wd93fnAnMkQ&ctype=5&q=&ved=2ahUKEwiH7Kel08PfAhVIhSwKHWysCV4Qwg96BAgOEAc&adurl=https://m.banggood.com/sv/NTC-Temperature-Probe-Temperature-Sensor-Probe-Acrylic-Panel-and-CNC-Aluminum-Alloy-Case-For-WEB-U2-p-1369154.html%3FgmcCountry%3DSE%26currency%3DSEK%26cur_warehouse%3DCN%26createTmp%3D1%26ID%3D557514%26utm_source%3Dgoogleshopping%26utm_medium%3Dcpc_union%26utm_content%3D2zou%26utm_campaign%3Dssc-se-sv-all%26gclid%3DEAIaIQobChMIluetpdPD3wIVEB0YCh3A5w_fEAQYASABEgKoz_D_BwE

https://www.google.com/aclk?sa=l&ai=DChcSEwiLpLrM08PfAhWGtRgKHf5uCn4YABAIGgJsZQ&ae=1&sig=AOD64_0MLh1CxYueh-kyF4yhA2nyZyKZJw&ctype=5&q=&ved=2ahUKEwi2p7TM08PfAhVDWiwKHWXaB30Qwg96BAgOEA8&adurl=https://m.banggood.com/sv/WEB-U2-Current-And-Voltage-Meter-USB-Tester-QC4-PD3_0-2_0-PPS-Fast-Charging-Protocol-Capacity-Test-p-1347851.html%3FgmcCountry%3DSE%26currency%3DSEK%26cur_warehouse%3DCN%26createTmp%3D1%26ID%3D517535%26utm_source%3Dgoogleshopping%26utm_medium%3Dcpc_union%26utm_content%3D2zou%26utm_campaign%3Dpla-all2-rm-se-mb-purall%26gclid%3DEAIaIQobChMIi6S6zNPD3wIVhrUYCh3-bgp-EAQYAiABEgKVH_D_BwE

11

12s7p glued, sadly no more will be done on this until January when I get the welder.

1546039050962809479413513285445

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12

The D596 should come with a temp sensor maybe you can use this one to read out somehow http://www.bestechpower.com/64v20spcmbmspcbforlifepo4batterypack/PCM-D596.html

Or get something like this

13

Ordered one temperature monitor and a small “stamp” like sensor from Conrad.se

Will show it if it works:)

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14

Today I got my battery welder. Took some time to assemble but worked great right away.

Did some testing and 15ms on 2x nickelstrips worked great.

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15465431286777461454155243242488 Tried to bend it that’s why it got a twist. Was really stuck.

Please give me hints on how to not screw my batteries when I weld.

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15

Tested on one cell also.

jpg_1546542434519

Here is the welder close up.

jpg_1546541540397

16

Seems good, maybe go a little lighter on the welding? You don’t want to go through the nickle, and please be careful accidentally missing the strips

I wouldn’t use this cell that you tested on, in the build 20190103_144316

17

Thx for info.

This was testing cell. Was trying to make it as near real scenario.

Thinking of 4 or 6 welds.

Tested to increase and decrease time and below 5 m&s won’t give a weld and over that it’s random from perfect to going through.

How clean does the tips has to be?

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18

Timing for nickel to steel and nickel to nickel will be different, and everyone’s setup will yield unique timings. So just practice for both then go for it.

But the test welds on the cell, that looks over cooked, back it off a bit.

The nickel to nickel test though looks ok, maybe back off a bit so it doesnt create a hole.

Just my opinion

19

I have no experience welding, but I would say that a pentagram shape (one on each star point) would be a good one for welding, enough welds, good placement to prevent stress ripping so it’s not weak horizontally or vertically

I dunno if that plays a big part in it, I’m just theorizing :slight_smile:

20

Tried a lot on that cell I burned the top on and found the best welds at 11ms.

Tried it on a new cell and the results

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I noticed that takes a bit of practise, important to keep electrodes very vertical and a bit of pressure.

Thanks alot for steering me in the right direction!

I think I will do 6 spots :slight_smile:

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