Assembled Hi-Power LiPo battery packs - any interest?

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Rube   100 W

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by Rube » May 26 2017 5:15am

Hi Chris, hope you are well.
Quick question, have you considered solvent welding sections of the polycarbonate enclosures? My current ride doesn't fit one of your batteries but hopefully the next design will.
I've been messing around with polycarbonate and m3 into 4.5mm is tight.
Cheers

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » May 26 2017 5:58am

Hey Rube,
I solvent weld the 3 mm sides and base along the length of the pack, but they are all screwed into the 4.5 mm polycarb ends. I've never had an issue with getting 4.5 mm to take a thread, and even when countersunk the heads never protrude. The might need a little file here and there.
I'm looking into using aluminium for some special applications. It will be expensive, but look horn :)

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 05 2017 6:30am

Finally got around to testing these 7000 mAh cells.

The cell is a 9050135 format pouch, meaning it measures 9 mm thick, 50 mm wide and 135 mm long, excluding the tabs. So effectively, the same size as all of my previous batteries. It's claimed to be a 5 C cell, but I suspect that's peak.

So I put together my usual 2s2p pack for testing and did a quick ~1 C discharge and got the following results:
Discharge test 9050135 7000 mAh 1C.jpg
Discharge test 9050135 7000 mAh 1C.jpg (38.12 KiB) Viewed 2735 times
So it's saggy, but probably par for the course when you are up around 208 Wh/kg.

Next test is a 2C discharge, and then a 4 C discharge.

After this I will be cycle testing and seeing how the capacity changes over 250 cycles.

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jonescg   1 GW

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 05 2017 9:00pm

Hey Everyone, looks like there's an appetite for some more high-power LiPo cells.

I'd like to get an order in pretty soon, as a few projects are coming up calling for a few hundred cells. If you want in, please get in touch! The cells are AUD$16 each. Australian orders only sorry.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 07 2017 9:12am

Discharge test 9050135 7000 mAh 2C.jpg
Discharge test 9050135 7000 mAh 2C.jpg (26.56 KiB) Viewed 1715 times
2C data added for comparison. Mmmmm saggy.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 25 2017 7:38am

Just a quick post to show a pack I'm building at the moment. It will end up in a go-kart - 24s3p (90 volts, 15 Ah) of the high powered cells. It's the first 3-row battery I've built for someone and it's also the first battery where I've needed to build a bridging buslink:
Under construction sml.jpg
Under construction sml.jpg (124.15 KiB) Viewed 2601 times
This is because the battery consists of three rows of an even number of cells - the negative ends up on the same side as the positive. If it was a 21s pack you could have avoided it, but 24 in series is what's needed. Anyway, there will be a sheet of G10FR4 in there I can assure you! Once all three are in the polycarb enclosure I'll have to run another long busbar over the top of the G10FR4 and out the end of the pack.

If anybody wants more of these 30C/60C burst cells (5000 mAh, 158 Wh/kg) let me know - I want to order another 550 of them pretty soon and only have half the MOQ.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by agniusm » Jun 26 2017 3:11am

This is so good. Its nice to watch, brings nostalgic A123 times :) The addition of soldered nut is a win win situation and it should be better than soldered tabs. Copper is way more conductive than tin and it also acts like a heat sink to radiate heat coming from the tabs in demanding applications.
The hole punch is a ticket, well done. Check pricing for brass nuts, they might be cheaper than plating with nickel. Also i would suggest to look at my take on soldering nuts although refining it to be workable. Basically i made a board with aligning pins according to cell pcb plate:
Image
then use solder paste, put the nuts on, and stuff it in an oven. Done :)
Great work all around, sexy packs, looks quality

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 26 2017 3:26am

Thanks Agnius! Copper busbars for the win!

Yeah the nut soldering is a slow step in the process, but not show-stopping.

I bought some M3 set screws with dog points with the intention of using them as the locator for the nut while I soldered. It works, but the tolerances are sloppy. And I've not needed to make more than 6 boards at a time, so I can put up with the screwing and unscrewing for now.

I found the brass nuts are ideal as they are 5.5 mm across. Between this, the soldered edge and the 1 mm slot either side, it's just narrow enough to fit the cells. The nickel plated steel nuts, although cheaper, are 6 mm across and means the cells will foul on the side of the nut.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by agniusm » Jun 26 2017 4:44am

Research press nuts :https://m.alibaba.com/product/604722088 ... .23.4CkdTf
You could mill your plates to the size of the lip, so there is your locator

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by agniusm » Jun 26 2017 10:20am

Chris, what wire gauge do you use for balancing? Is that something like 20awg? Is it silicone or something else? Looking for some too

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 26 2017 8:53pm

I normally use medium gauge hook-up wire from Altronics: http://www.altronics.com.au/p/w2266-14- ... -up-cable/
21 AWG. However on the race bike because space is tight and I have so many cells in series, I've used the light duty wire http://www.altronics.com.au/p/w2253-7-0 ... ancy-inner which is 26 AWG.

Rarely to I put more than 5 amps through it during balance charging, and only from a high state of charge anyway.

It's just regular PVC - the insulation is a bit tougher than silicone.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 28 2017 3:59am

agniusm wrote:Research press nuts :https://m.alibaba.com/product/604722088 ... .23.4CkdTf
You could mill your plates to the size of the lip, so there is your locator
Ideal nutsert.jpg
Ideal nutsert.jpg (55.45 KiB) Viewed 1706 times
Wonder if such a nut exists? No real need for knurled edges or biting faces, just a press-fit which can be soldered?

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by Ratking » Jun 30 2017 5:53am

Hello Jones,

What cell is in your opinion the best value, when you consider weight/cost/power density? Why did you go away from the 40c 5Ah Turnigy cell?
I am trying to get up to speed on the best solution for light weight cells/battery. Maybe some hidden gems have been discovered since I read this tread the last time,

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 30 2017 5:59am

Well I have to say these FEP cells are pretty darn good. 30C continuous, 60 C burst, 158 Wh/kg and 335 Wh/l.
Better than Turnigy individual cells, and the quality is certainly higher.

I also tried their high energy density cells which are a ~2C continuous, 5 C burst; perfect where power and speed aren't critical. They make cells in the middle too, but they are a 1000 cell MOQ. Approximately the same price per Wh too.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by Ratking » Jun 30 2017 6:06am

jonescg wrote:Well I have to say these FEP cells are pretty darn good. 30C continuous, 60 C burst, 158 Wh/kg and 335 Wh/l.
Better than Turnigy individual cells, and the quality is certainly higher.

I also tried their high energy density cells which are a ~2C continuous, 5 C burst; perfect where power and speed aren't critical. They make cells in the middle too, but they are a 1000 cell MOQ. Approximately the same price per Wh too.

Ouch 1000 pcs, that is quite a commitment. Not a problem if you have a large order and a large customer base, but not easy for someone trying to test different solutions.
I am looking for a pack with a maximum weight of 25kg, and more than 4.5kWh for a paramotor project. I would like to use pouches and not 18650, but will use whatever cell that performs the best.

Do you have a name for these cells?

Seems like https://www.xaltenergy.com/index.php/so ... cells.html also is a solution, but not cheap either

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jun 30 2017 7:33am

Ratking wrote:Ouch 1000 pcs, that is quite a commitment. Not a problem if you have a large order and a large customer base, but not easy for someone trying to test different solutions.
I am looking for a pack with a maximum weight of 25kg, and more than 4.5kWh for a paramotor project. I would like to use pouches and not 18650, but will use whatever cell that performs the best.

Do you have a name for these cells?

Seems like https://www.xaltenergy.com/index.php/so ... cells.html also is a solution, but not cheap either
I just refer to them as FEP8250135 - 5000 mAh - 30C/60C cells. They have about 8000 in stock I think.
If you use these cells a 25 kg pack, including buslinks and fuses, should give you about 3.65 kWh. Plenty of power at least.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jul 02 2017 7:53am

Nearly done. The three rows of even numbers of cells is a bit of a pest to terminate, but it's working out.
20170702_173347.jpg
20170702_173347.jpg (100.19 KiB) Viewed 2434 times
The positive terminal will have to be a long bus bar all the way out to the front. Room for a couple of ZEVA BMS modules. Just.
20170702_173401.jpg
20170702_173401.jpg (111.9 KiB) Viewed 2434 times

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by agniusm » Jul 03 2017 2:21am

jonescg wrote:
agniusm wrote:Research press nuts :https://m.alibaba.com/product/604722088 ... .23.4CkdTf
You could mill your plates to the size of the lip, so there is your locator
Ideal nutsert.jpg
Wonder if such a nut exists? No real need for knurled edges or biting faces, just a press-fit which can be soldered?
I think you might just ask them. They might even make it to your spec.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by Arlo1 » Jul 03 2017 2:29am

agniusm wrote:
jonescg wrote:
agniusm wrote:Research press nuts :https://m.alibaba.com/product/604722088 ... .23.4CkdTf
You could mill your plates to the size of the lip, so there is your locator
Ideal nutsert.jpg
Wonder if such a nut exists? No real need for knurled edges or biting faces, just a press-fit which can be soldered?
I think you might just ask them. They might even make it to your spec.
So an copper rivnut?
My Leaf motor controller build. http://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jul 03 2017 2:33am

No, I don't want anything which might sit proud of the PCB - so the upper section can't be any longer than 1.6 mm.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jul 08 2017 4:38am

Finished this 24s,3p pack. I'll call it the Voltron PowerCube(tm) :D It differs from most packs in that I've built as it uses three rows of cells, not two. And because of the increased size I could use 4.5 mm polycarb for all 4 walls, making it particularly rigid.

It will be sporting a pair of Zeva BMS modules and powering a mad go-kart. Well under 10 kg for so much power!
Bretts pack iso.jpg
Bretts pack iso.jpg (103.5 KiB) Viewed 2382 times
Bretts pack side.jpg
Bretts pack side.jpg (111.84 KiB) Viewed 2382 times
Bretts pack top.jpg
Bretts pack top.jpg (194.33 KiB) Viewed 2382 times
By the way, I'm pretty close to the MOQ for another order of cells, so let me know if you want in. I found some press-nut suppliers too, so that step should be a little quicker at least...

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Jul 27 2017 10:06pm

Woohoo!

Looks like I can shave about 1 hour off each battery I build by using these press nuts!
20170727_222121.jpg
20170727_222121.jpg (80.45 KiB) Viewed 2259 times
Sorry about the potato-cam.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Aug 22 2017 8:26pm

Another 550 of the 30C/60C pouch cells have been ordered. I'll have quite a few spare (which I'm keen to sell) so get in touch.
Chris

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by wire.rat » Aug 26 2017 4:37am

The screw and soldered nut on the PCB meteors is truly a innovative method of connecting pouch cell tabs together.
Do you think M3 screw and pure copper/brass nuts (standoffs similaer to that of a motherboard standoff in a computer)would work as well?

I'm thinking of using the same method to connect large pouch cells of at least 30Ah together using your method. These pouch cells are much thinner than the 5Ah ones, so using smaller screwd will be a must for these large capacity cells.

Im located in Singapore so I will be getting the cells from taobao and shipping to me is quite cheap from China at $4 per kg of sensitive goods.

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Re: Assembled Hi-Power LiPo battery packs - any interest?

Post by jonescg » Aug 27 2017 9:28am

The nut on the underside is a pretty strong and safe way of doing it. 1.6 mm thick PCB is pretty tough too.

If you go back a few pages you'll see where I built some packs using 25 Ah NMC cells, but these were about 8 mm thick I think. The 5.5 mm brass nut was the only option - even a nickel plated steel nut was 6 mm diameter, which didn't leave much room. These new round press nuts are 5.4 mm diameter, so I think they will work with cells as thin as 7.5 mm.
wire.rat wrote:The screw and soldered nut on the PCB meteors is truly a innovative method of connecting pouch cell tabs together.
Do you think M3 screw and pure copper/brass nuts (standoffs similaer to that of a motherboard standoff in a computer)would work as well?

I'm thinking of using the same method to connect large pouch cells of at least 30Ah together using your method. These pouch cells are much thinner than the 5Ah ones, so using smaller screwd will be a must for these large capacity cells.

Im located in Singapore so I will be getting the cells from taobao and shipping to me is quite cheap from China at $4 per kg of sensitive goods.

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