Qulbix Q76R 18650 battery build

Batteries, Chargers, and Battery Management Systems.
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Quokka   1 kW

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Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:04am

I have been asked by fellow members to show the battery build for my new Qulbix.
Before i kick off a few disclaimers. This was my first battery build and i am definately not a battery guru. There are many different ways of making batteries and this is by no means the "best way" but it was the way that made sense to me at the time of the build given the materials and batteries and welder i had access to.

Important!!! These batteries are dangerous. A mistake could result in a serious fire and as such they need to be treated with caution and respect.


Now.... On to the build.

My aim for the battery was to build something that maximized the capacity of the frame and to get some pretty decent amperage. I decided on a 20s 12p battery.

The cells i chose were the 3500ma Sanyo GA cells. If building the pack again i would probably go for Samsung 30Q cells as they can deliver 30 amps vs the sanyo's 10 amps for not much less capacity. I had massive issues with freighting these due to a change in lithium ion battery transport regulations. Hopefully the couriers sort this out soon as it was nearly a show stopper for me.
Attachments
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Package of 18650's
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More cells
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Last edited by Quokka on Jun 19 2016 8:32am, edited 1 time in total.
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Quokka   1 kW

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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:09am

The layout of the cells was based on an irregular pack design. I printed out the frame opening availible on the Quilbix website, checked it against the frame opening ( was a little smaller than the real opening i had) and strated packing in the cells to try out different scenarios
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Getting the cells in a preferred layout
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Last edited by Quokka on Jun 19 2016 8:19pm, edited 1 time in total.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:11am

This was the final layout (packs glued up)
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Cell layout
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:16am

To make the parralell groups, i hot glued them together, and then added a layer a fibrelass reinforced tape. The tape is there to add a little bit of a gap to help protect from chaffing and to add a mitigation to a possible short between groups. Individual cell holders are great for this, but the cost of cell holders comes at the expense of how many cells you can fit in your bike.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:22am

I then glued together all the parralell groups. This is hard... You need to work fast, the glue hardens quickly. For this reason you need a good hot glue gun.
I also added paper gaskets to the positive ends of the cells for short protection
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Last edited by Quokka on Jun 19 2016 8:33am, edited 3 times in total.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:45am

The method of making the parralell and series connections was to use .2mm pure nickel sheet. I used around 1.2 meters of sheet that was around 20cm wide. This stuff is expensive... The reason i chose .2mm was it was the minimum thickness i could get away with to achieve 80-100 amps. The thread "18650 the ultimate guide" has a great guide on material vs current characteristic. Remember, thick nickel is hard to weld and copper has a poor mechanical strength which i felt could cause an issue if/ when i stacked the bike.
Attachments
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.1mm pure copper test weld
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Last edited by Quokka on Jun 19 2016 8:35am, edited 1 time in total.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:48am

Now that the battery was glued together it was time to make templates for the nickel
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Making templates from tracing paper
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:51am

After you have the templates you need to trace outlines onto the nickel sheet and cut them out a pair of scissors
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:53am

Then i layed out all the nickel and templates to make sure i had them all.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 6:58am

I also marked the locations of the welds on the tracing paper to make sure i wouldnt inadvertantly make a weld in both the positive and negative on a cell. I used a dremel to make a small mark on the nickel
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Marking connection locations
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Dremelling a mark
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Making it idiot proof
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Last edited by Quokka on Jun 19 2016 8:35am, edited 1 time in total.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 7:07am

Now its time to fire up your welder and get serious. Make sure you have glasses and gloves on. After i attatched a sheet of nickel i taped some cardboard over it for a saftey barrier in case of a short. Also, take any metal off you. Watches, belts zipps etc.
Attachments
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Spot welder
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First plate
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Working my way through the groups
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More nickel
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Side 1 of the battery done
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Last edited by Quokka on Jun 19 2016 8:36am, edited 1 time in total.
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 7:08am

I then did the same process on the other side of the battery. But now the series connection alternate the first side
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 7:14am

For a bms, i am utilizing an adaptto. I made 5 4s jst balance leads using silicon wire. I wrapped the balance wires in an expandable sheath to keep the spider web of wire under control
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 7:18am

Now, i ran the leads to their respective group for soldering
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Re: Qulbix Q76R 18650 battery build

Post by Mammalian04 » Jun 16 2016 8:19am

Excellent Quokka!

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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 16 2016 9:20am

Bms test before wrapping in heatshrink :D
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Re: Qulbix Q76R 18650 battery build

Post by Wheazel » Jun 16 2016 9:26am

Good build!

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Re: Qulbix Q76R 18650 battery build

Post by Scottydog » Jun 16 2016 9:30am

Awesome presentation! I love the welder! :)

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Re: Qulbix Q76R 18650 battery build

Post by Rodney64 » Jun 16 2016 9:58pm

Excellent thread Quokka. A lot of thought gone into designing, making templates especially to determine the correct position of the spot welding.

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Re: Qulbix Q76R 18650 battery build

Post by Lash » Jun 16 2016 10:02pm

Great battery build. Interesting use of the nickel sheet as opposed to the strips.

I must investigate more on this battery welder for future projects :)

Look forward to seeing how the bike goes.

Cheers,
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Re: Qulbix Q76R 18650 battery build

Post by Hillhater » Jun 16 2016 10:12pm

Awful lot of work , skill, time and care required there...Well done.
did you test/check or balance the cells before assembly ? ..
I know they are quality cells, but its a lot of work to find & replace any bad cells after the build is complete.
This forum owes its existence to Justin of ebikes.ca

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Quokka   1 kW

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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 17 2016 12:03am

Yep. Good point. I ran the mulimuter over them all as i unpacked them. They were all pretty much spot on consistant voltage
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Re: Qulbix Q76R 18650 battery build

Post by Quokka » Jun 18 2016 12:27am

Ok.. Lets finish this thing off.
I cut out a piece of 3mm acrylic to protect the base of the pack and bent it to shape using a heat gun slowly working across where i needed to bend it to shape. I then hot glued it to the base of the pack for protection. I then cut out some 3mm self adhesive foam for the protection of the side of the cells.
Once this was done i wrapped the whole thing in giant heatshrink.
It just fits by a whisker- had to dremmel a tiny bit on the frame to get it in
Attachments
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Side foam and acrylic base plate installed
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Heatshink tube
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In the bike
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Last edited by Quokka on Jun 20 2016 5:37am, edited 1 time in total.
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Re: Qulbix Q76R 18650 battery build

Post by Tats » Jun 18 2016 7:28pm

Inspiring stuff quokka, very nice work

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Re: Qulbix Q76R 18650 battery build

Post by Mammalian04 » Jun 18 2016 8:53pm

Love it. Nice way to.

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