Assembled Hi-Power LiPo battery packs - any interest?

[jonescg]

This thread, like all my threads, is the documented history of the development of my LiPo termination system. It's evolved from soldered battery packs (which worked very well) to a screw terminated system.
To see the latest iteration of my battery packs, visit this link:
viewtopic.php?p=1230272#p1230272

Otherwise read ahead and learn how I learnt

Hi Guys,

I have finished a 10s3p Turnigy 40C LiPo pack as a prototype. The balance leads will be much neater than this since I've had the PCBs made up, but I am wondering whether or not there would be a market for these.





EDIT: This very pack ^^ is for sale - $300 free shipping within Australia PM for details.

Edit #2 sold

The balance leads can come with any kind of plug you want, but the minimum main pack wiring gauge would be 8 ga.

What are the advantages of this system over a plug and play arrangement from Hobbyking? For a start, the wiring is reduced significantly. No paralleling of balance leads because it's already a complete 40 V, 15 Ah pack. It can handle serious currents - I have tested a continuous 50 A current and nothing gets hot. I have done 3 minute 100 amp discharges and the nichrome load gets too hot and melts. The soldering method is rock-solid - bursts of 400 A do nothing to these terminations. Also, I manually check each cell before loading it into a 40 V pack, so QC is probably better than HKs... I'm thinking of buying an internal resistance tester since I'll be putting 550 cells into the race bike.

It is also very compact - 560 Wh in a 4 kg battery, measuring only 145 mm high 50 mm wide and 270 mm long. I can easily make a 20S pack two rows wide, and the wiring is even more compact. (Edit, I had 660 Wh here - sorry! Typo!)

I have 12 or 14 of these boards I can use to build packs. If anyone is interested in these packs let me know and I will order more cells. The race bike will need ~600 cells to accommodate the odd DOA cell, but I can order an extra hundred or so and make these packs up. These cells are brand new and cost about $11 each from HK, and a pack like the one photographed would cost $330 to build. So I might consider selling them for $450. Sounds reasonable? I am so shit at the salesman pitch

Let me know what you think. I can also make 6S5P packs but these are for racing only, I would think

[Ykick]

That looks very interesting and tidy! Do you source loose HK cells or culling them from bricks? EDIT - nevermind, my reading comprehension took a dump...

"These cells are brand new and cost about $11 each from HK"

[migueralliart]

I like the arrangement! Neat and clean. You are in Australia right? I wonder how you will arrange shipping.

[jonescg]

I don't know about shipping overseas, it would no doubt be horribly expensive. So I might just start within Australia first. For OS shipping I would probably recommend you buy the boards and tinned copper from me and buy the cells from HK yourself. That said, part of the joy of these cells is the fact that someone else has assembled them.

However I'm able to buy the cells in bulk from HK (like a $7000 order) and while there is no real price break, the shipping costs are reduced (and customs fees are added ).

[jonescg]

OK, I worked out that shipping these packs overseas is not a cost effective way to do it. I could sell the boards and tinned copper, but then that defeats the point

However, I worked out that I could ship 150 kg worth of packs to the US for about $2000. That's about 35 of them. So it would cost me $15,000 to make and send to someone who would then have to sell them for over $500 each to make a crust...

I might just stick to selling them in Oz.

[Rodney64]

I'm interested. I'm in Perth. I'm looking for a 20 amp 72 volt battery. Can you do these. Do you know Matt.

Regards

Rodney

[jonescg]

Hi Rod, yes I know Matt 1000W (and Matt Timmins).

In the short term, I can do either a 15 Ah pack, or a 25 Ah pack. It would depend on the size format you want, but I can easily do a 75 volt, 15 Ah pack by putting two of these packs together. I'd need to get a new PCB made up for 20 Ah. What would you use for balance charging? I reckon a pair of 11 pin plugs would work with a Hyperion or the like.

PM me for any details!

Cheers,
Chris

[shock]

Nice work mate, giving me ideas..

[jonescg]

Cheers!
You wanna be my North American distributor?

[ohzee]

Yea I would say sell a kit minus batteries so people could make their own.

Id think it would sell very well . It sure looks damn good.

[shock]

Cheers!
You wanna be my North American distributor?

Actually this is something I would be interested in. I've been debating about starting a battery company for awhile.

[jonescg]

Hmmmm, I'm wondering if I should take a plunge here... Sending these from Fremantle to Los Angeles, for example, is only worth it if you do big loads. Minimum cost of shipping alone is about $2000. Then whatever it costs to get it from the port to the US distributor (customs fees, import duties, taxes, Alibaba and the 40 thieves Christmas party fund etc.). In the meantime I might just get all the bits I need, and I can decide to sell kits or whole packs. Then after they've had some good real-world testing I can decide on more or not.

I might start to take orders for a few local sales. The minimum order of cells from the HK wholesaler is $2000, or enough to make a few large (>1 kWh) packs. Shipping will be expensive, maybe an extra 30% on top of the cost of the cells, but once here I can do what I like with them.

Stay tuned!

[peterperkins]

What are the specs for the cells you are using? LinK?

For you demo pack what is it's capacity Ah? And the maximum charge current?

[jonescg]

These are the cell I use:

http://www.hobbyking.com/hobbyking/stor ... duct=18562

40C Turnigy individual cells. They are the 5000 mAh ones, measuring 50 mm wide, 9 mm thick and 140 mm long. I use individual cells cause I know they haven't been botched during 4S construction at the HK factory

The demo pack I have built is 15 Ah, nominally 38 volts. 42 volts fully charge and 35 volts empty. It weighs about 4.1 kg and is about 270 mm long, 145 mm high and 50 mm wide.

The copper terminations have a cross-sectional area of 35 mm2. I have drained it to 35 volts from fully charged at ~150 amps from this pack and nothing gets even remotely warm. The Anderson connectors got warm though. A dead short resulting in over 300 amps doesn't concern these cells at all, but this was tested at 7.5 volts, not 40.

All up, they rock

[jonescg]

OK so I sat down and calculated how much these things cost for me to make. I have a fairly good idea about most parts, but the shipping of cells from Hobbyking to Perth, plus taxes and customs fees are the real unknown.

Cost Breakdown of a 10s, 3p pack like the one pictured:
10 pieces of tinned copper bars @ $3.50 each = $35 (I have the quote if you don't believe me)
30 cells from HobbyKing @ $15.70 each = $471*
11 balance wires, JST plugs roughly = $3
1 PCB board to suit @ $7 each = $7
Total = $516, or about $905 per kWh.

* this is assuming the Hobbyking shipping rate as per the calculator on their website to Perth AU. Naturally it's quite expensive, but if I was to order a shitload of these cells from Hong Kong it would be a bit cheaper per cell, but then you have to add customs fees and the GST etc. So for now I think this is quite a reasonable estimate.

To ship stuff a single 13 kg pack overseas costs about $16 per kilogram. It can get as low as $7 per kg if I start moving 650 kg worth of stock, which would require me to get a massive bank loan to even buy the parts . Within Australia it's probably about $8 per kilogram. And none of this assumes I plan on making a profit

Anyway, there you go

[jonescg]

Some proof these packs are solid:

https://www.youtube.com/watch?v=jbQx5dpGJVs

[jonescg]

Rodney64 came ofer to my place to have a look at the pack I'd built and we got talking about different configurations. Right now I can do 15 Ah and 25 Ah based on the boards I have, but I'm wondering if 20 Ah (4p) would be useful too?

Couple of pics of layout and size:
Shorter

Longer


15 amp hour varieties:

10s3p - 10 cells in series, 3 in parallel ~38 V, 15 Ah, 570 Wh stored, 270 L x 50 W x 150 H (mm)
15s3p - 15 cells in series, 3 in parallel ~57 V, 15 Ah, 855 Wh stored, 410 L x 50 W x 150 H (mm)
20s3p - 20 cells in series, 3 in parallel ~76 V, 15 Ah, 1140 Wh stored, 270 L x 100 W x 150 H (mm)
30s3p - 30 cells in series, 3 in parallel ~114 V, 15 Ah, 1710 Wh stored, 410 L x 100 W 150 H (mm)

20 amp hour varieties (new!):

7s4p - 7 cells in series, 4 in parallel ~26 V, 20 Ah, 520 Wh stored, 250 L x 50 W x 150 H (mm)
10s4p - 10 cells in series, 4 in parallel ~38 V, 20 Ah, 760 Wh stored, 333 L x 50 W x 150 H (mm)
14s4p - 14 cells in series, 4 in parallel ~52 V, 20 Ah, 1040 Wh stored, 250 L x 100 W x 150 H (mm)
20s4p - 20 cells in series, 4 in parallel ~76 V, 20 Ah, 1520 Wh stored, 333 L x 100 W x 150 H (mm)

25 amp hour varieties:

12s5p - 12 cells in series, 5 in parallel ~45.6 V, 25 Ah, 1140 Wh stored, 270 L, 100 W, 150 H (mm)
18s5p - 18 cells in series, 5 in parallel ~68.4 V, 25 Ah, 1710 WH stored, 410 L x 100 W x 150 H (mm)

Energy density is about 140 Wh/kg.

Cost to customers is going to be about $1.15 per Wh, which includes me paying myself something.

[BunburyJason]

I'd be interested in something in between the 20s3p and the 30s3p - Do you also include a BMS?

20s3p - 20 cells in series, 3 in parallel ~76 V, 15 Ah, 1140 Wh stored, 270 L x 100 W x 150 H (mm)
30s3p - 30 cells in series, 3 in parallel ~114 V, 15 Ah, 1710 Wh stored, 410 L x 100 W 150 H (mm)

Idealy i'm after the most voltage @ 15Ah that I can fit in my front triangle I'm talking to Hyena Industries about his Hadron Mark IV kit but will have to go 72v 10Ah if I want to fit the batteries in the trinagle.

Would be interested to see what other sizes it could be done in - can you also heat wrap the end product?

[jonescg]

Hi Jason,

These packs are really ideally designed for big rectangular boxes, so the triangle will need to be pretty big. It can be broken up into smaller blocks though. Next time you are up Perth way, let me know and you should drop in for a cuppa and have a look at them.

The 15 Ah pack can be made up to 114 V nominal, but the standard size and shape is still pretty big. 1.7 kWh is necessarily big though

[jonescg]

Kits for overseas buyers:

For the keen DIYer, I can send the boards and tinned copper to you. You can order the cells from HobbyKing yourself, and pay whatever shipping it comes to yourself. You will need to know what you're doing with a pair of big soldering irons, and be well prepared. I can guide in this area

For a 38 volt, 15 Ah pack like the one pictured, I reckon I could sell the kit minus cells for XXX plus shipping (which won't be much). Can't get over the high cost of cut copper...

Kits will sell for $60 each, with free shipping! Any size, any destination, $60 per board includes all the tinned copper and balance leads if you want them.

[Rodney64]

Chris I'm ready for you to build my board and harness. 72 volt 25 amps.

[jonescg]

Rod - that's awesome! Now what is the biggest block of cells you can have? Obviously the 1.7 kWh block was too long and too wide, but we might be able to split it into three sub-packs?

If you have the dimensions let me know and we can start planning.

[Rodney64]

Chris-the 72 volt 24 amp pack measures 410/150/100mm. To fit we would need 5 packs measuring 82/100/150 with the frame being 97mm wide this leaves 15mms for padding (corflute sheets) and wires.

Would 5 be possible.

[Rodney64]

Frame dimentsions

[jonescg]

split pack design.JPG (38.65 KiB) Viewed 8938 times

Hi Rod,

I reckon we can still fit them in, but the cells need to face sideways. You say the inside of the frame is 97 mm? Dammit! Why couldn't it be 107 mm! This is annoying, cause the terminations are not lined up for serial connections. It could be done, but this means a short jumper cable will need to join each sub pack. This would also mean the terminations protrude higher than the 150 mm planned. Maybe 160 max?

An alternative is to go for a 15 amp hour pack, and accept a lower capacity for the same voltage? At least this way the terminations line up in series for easy one-bolt/nut connections.