Assembled Hi-Power LiPo battery packs - any interest?

[Hyena]

Nice work. Whats the capacity and C rate of those big pouches ?
Not that they're powering submarines (yet ) but with the back of the 175A andersons and the edges of the perspex boxes filled with epoxy or silicon I imagine you can get them pretty well sealed for general purpose all weather use ?

[jonescg]

Nice work. Whats the capacity and C rate of those big pouches ?
Not that they're powering submarines (yet ) but with the back of the 175A andersons and the edges of the perspex boxes filled with epoxy or silicon I imagine you can get them pretty well sealed for general purpose all weather use ?

These are the same NMC cells you see being flogged on facebook. They come as 5p units which look like a prismatic cell. James needed 6p, so we came up with our own termination. I think they are a 5C continuous, 10C burst cell. 25 Ah pouches BTW.

I reckon you can easily fit this inside a polycarb enclosure and pump said enclosure with silicone grease or some other inert waterproofing agent. Perfect for a jetski battery

[jonescg]

Finished James' pack this weekend. These cells are only good for 3C I think, but for what he plans on doing with them, they'll be just fine (travelling 1700 km on a single charge). If you want to support Jame's record attempt, check out his GoFundMe page here:

https://www.gofundme.com/Coulombmotorsport1

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[bobc]

Probably "granny sucking eggs" time, but did you check out "clinch nuts" alternative to soldering nuts on the back of the PCBs? Even if you decide you still want to solder these may still be handy because they would stay located while soldering. You can get PCB friendly ones, we've used 'em in decent volume mass production.

[jonescg]

Probably "granny sucking eggs" time, but did you check out "clinch nuts" alternative to soldering nuts on the back of the PCBs? Even if you decide you still want to solder these may still be handy because they would stay located while soldering. You can get PCB friendly ones, we've used 'em in decent volume mass production.

Yeah, and the brass nuts are still a bit cheaper. I have devised a means of soldering the brass (or nickel plated steel) nuts to the boards quite quickly, but given the volume I'm working with I'm pretty content with the system for now.

[jonescg]

Alright guys, I'm adding 4p and 5p to the list of options. So just to recap -

2p, 3p, 4p, 5p, 6p and 10p.

Or 10, 15, 20, 25, 30 and 50 Ah packs. And when I eventually get the high energy density cells in, it will be multiples of about 6.5 Ah.

Now don't go asking for 7p or I might just scream

[ejonesss]

do you carry the bus bar kits?

i am looking into converting a 6s turnigy lipo to a 1s6p and would need to parallel the cells.

[jonescg]

Yep,
I can supply busbar kits. Although if you are unsoldering a 6s pack you might want to check that the tabs are long enough to hole-punch. From memory, some of those packs have the tabs spot-welded directly too.

[ejonesss]

yes i see they did weld the cells together however i can using a dremel cut them apart and even though the tabs are too short it looks like they can be soldered to the pcb stock where the bars bolt to.

[jonescg]

Cells are in!

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550 cells, with about 2/3rds spoken for. I still have about 120 or so left, so if you still want a pack let me know.

I will be doing some capacity testing, discharge testing and cycle life testing over the coming weeks.

[Arlo1]

Nice CRX you have there. It would be a shame if someone was to install a Leaf motor in it.

[jonescg]

Nice CRX you have there. It would be a shame if someone was to install a Leaf motor in it.

Yep, would be a terrible shame...

[jonescg]

Some people take vacations. I test batteries

Lighter than expected

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The shipment came in and the cells were in good condition. Amazingly, they are 8.2 mm thick instead of the requested 9 mm and weigh in at 120 g each. If they check out at 5000 mAh they would store an impressive 154 Wh/kg. Impressive given the high C-rating they come with. The missing 0.8 mm will have to be padded out with cardboard, or for the more thermal-management inclined, aluminium heatsinks

Screwkum skookum!

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My test rig is a 2s2p kit terminated using the screw terminals. They can take the current almost as good as a soldered pack and are easy to pull apart again.

I started off with a ~1 C discharge test for capacity. Basically a bunch of nichrome wires wound on a peg board. I normally use this load for cycle-testing, but it gives good numbers through the ammeter function on my DMM.

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This gives a full 10 Ah (2p) and equates to 158 Wh/kg. Winning

Next up, a 5.5 C discharge test.

The load has shifted to a coil of galvanised wire plunged in a bucket of water. The loads are around 50 amps, measured with a current clamp.

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So far so good.

10 C - this is about 100 amps through the test rig. My current clamp is the only tool for the job.

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So even at 10 C the cells are able to deliver all of the Ah claimed and the sag is at about 3.7 V.

Okay, 20 C - this is a 200 amp continuous load through a 2s2p battery. What kind of load would be appropriate?

Not quite a dead short, but close.

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Why did it stop at 7 Ah?

Yeah, silicone wire would have been better.

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I think we have hit the limit of continuous testing. For 10 second bursts, we can easily get 400 amps or so, but continuous high drain tests are pretty unusual in the real world.

Still, I'm satisfied these cells are as good as the current 40 C cells I use in Voltron, and they pack more energy per gram than before.

So who wants batteries?

[jonescg]

Couple of battery pr0n shots..

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I tell you what, ordering cells from China is getting better. 550 cells and not a single cell I could reasonably consider below par. I sorted them into piles of <3.90 V and >3.90 V. The less than pile was about 100 cells, and they were only just less than - like the lowest was 3.815 V or something. I'll use these for my own projects and R+D, but they should be perfectly fine for any application.

[jonescg]

I'm going to put a 12s10p pack together using the left over cells, unless I sell them first. The idea is to build a modular unit of about 2.2 to 2.8 kWh, depending on the energy density of the cell.

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I reckon these would generate some interest in the performance EV scene? Good for over 1000 amps continuous, and weigh about 15 kg.

Or 17 kWh if you used the hi-power cells.

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The terminations can be cooled with cross-flow of air during use and recharge. There would be a 3 mm polycarbonate lid which holds the module together, while the packs would connect in series with M8 bolts through the terminal holes.

Hope to put it together in the next month or so, depending on where I can find a cheap CNC router. BCJ have been good to me in the past, but they moved shops and must be paying more rent...

[Tomdb]

What kind of vehicle would you be trying to market these too?
50ah gives you roughly 20 kwh at 345V so quite low for a car conversion.

Would you mind sharing some sizes and rough weights?
Plus what kind of pricing would you be thinking about?

These cells do look promising in terms of a good balance between weight and discharge, 150 wh/kg and 20C is quite impressive. Did you measure temperature during the discharge?

[jonescg]

What kind of vehicle would you be trying to market these too?

Any converted electric car, but one with a performance tilt. Most folks opt for LiFePO4 cause its cheaper but comes with limitations. These would be ideal for people willing to build Tesla beaters I'd think.

50ah gives you roughly 20 kwh at 345V so quite low for a car conversion.

Would you mind sharing some sizes and rough weights?
Plus what kind of pricing would you be thinking about?

These cells do look promising in terms of a good balance between weight and discharge, 150 wh/kg and 20C is quite impressive. Did you measure temperature during the discharge?

Cost price is AUD $16 per cell, depending on the exchange rate. These packs would have 120 cells in them. The enclosures will add about another $100 or so I would hope. Whole package is 15 kg. The more energy dense cells will be a tiny bit heavier, and markedly more expensive. Probably about $26 per cell.

The cells did heat up at 20 C continuous drain (obviously) but they still delivered. We hit the same kind of cells in Voltron at 28 C and they only trip the thermistors at 55'C after 4 sessions on a power track at 35'C.

[liveforphysics]

50ah gives you roughly 20 kwh at 345V so quite low for a car conversion.

These would be the wrong choice for someone making a budget commuter, and perhaps the right choice for someone making a VERY powerful hot rod.

[dingoEsride]

Looks the goods, thanks to Chris and LFP and others who push for better battery performance on the way for future transport for the masses

[jonescg]

I'm pretty sure you'll see a mad video of a trike with these powering it shortly

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The pair of them weigh in at 10.6 kg; 1332 Wh.

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Shipping these off tomorrow. Got a few more to build before month's end, but it's all humming along. The polycarb enclosures are great, and essential if you are going to chuck these inside an ebike frame. Tough as nails!

[jonescg]

22s4p battery build in 4 minutes. All holes were pre-punched, all copper was pre-cut. Still took me a good 9 hours!

[litespeed]

That was a super cool build. Thanks for taking the time to make and post it. Excellent work.

Tom

[Rube]

That was a super cool build. Thanks for taking the time to make and post it. Excellent work.
Tom

Couldn't agree more, what is the glue/ sealant used? Do you counter sink the bolts in the polypropylene or use a normal M10 or M8 bolt?

[jonescg]

The glue was a polyurethane goo which sets quite quickly. It has the same properties as silicone sealant but sticks better. The polycarb enclosure is 4.5 mm and 3 mm thick, so I use countersunk M3 screws. Nothing as big as M10 on this pack.

[Rube]

Thanks, I read that countersinks increase stress fractures but I'm skeptical because in my build the enclose is under-stressed. I got the idea from you Chris, you know what they say about imitation.