Eastwood’s first battery build

[amberwolf]

I don't know enough about spotwelders today to say what is better, but the little I have kept up on the Kweld types seem better for high-current interconnects (that need to be thicker or multiple types of materials, etc).

AFAICR the power supply people use on Kweld type welders is an RC LiPo battery, typically, but the big thread for them has better info than I can give.

If the cell holders/spacers fit the cells properly so the cells can't move at all within them, and the pack as a whole is enclosed and mounted so it can't twist relative to the way the pack was welded together, there shouldn't be any significant vibration or displacement between parts.

If the welds are good enough to carry the current required, they're probably good enough to withstand whatever vibration does get thru all that.

 

[Eastwood]

340 cells is a monster battery whereby most ebike batteries are about 1/5 th that size. Can you share what config of battery and bike you will be powering with such a large battery? Have you determined a cell brand and model for your build and/or a source?

This is for a motorcycle, not an electric bicycle
For a full size dirtbike to be more exact, i’ll post a link below of my build thread. As of now, the battery configuration will consist of two walls/sections of 170 cells folded which will equal 340 cells- So 20s 17p. I’m keeping the pack, more skinny and tall for two reasons. First it’s simpler to build, the second reason is, I will be able to pull the battery pack out from the top of the Dirtbike Frame. My battery configuration could change, but I’ve been working on this build for around a year now. Been playing around with the battery configuration for a couple months here and there as I’m still restoring and building the bike itself. I have the cell holders laid out that fit nicely between the frame and should be able to nicely fit 340 cells.
The cells will be Molice 21700 P42A 4200mah. They are the golden standard for 21700 cells for motorcycles or high powered electric bicycles. I was considering pouch cells but they’re much harder to source.

Suzuki RMZ 250 EV Restomod

Picked up this 2007 Suzuki Rmz 250 frame and swingarm. Also came with the triple clamp and rear shock. First priority is to get this into a rolling chassis. Will restore this frame before mounting the motor and figuring out which battery to build or buy. I’ve ordered the front fork tubes...

endless-sphere.com

 

[99t4]

Why not build a Barncat battery?

 

[Wattman]

Respect Eastwood. Hope you share the battery build with us and the result on the bike.
Cool project.

 

[Eastwood]

Why not build a Barncat battery?

What is Barncat battery?

Respect Eastwood. Hope you share the battery build with us and the result on the bike.
Cool project.

Thanks!

 

[Eastwood]

Does anyone have opinions on a spot welder like this?

GLITTER 801D Battery Spot Welder 12 KW Capacitor Energy Storage Spot Welding Machine, https://a.co/d/7E9FSDL

They also offer the 801H version thats 19.8 kw version but its a bit of of my budget at $440

The link I post the price is $289 which fit my budget better.

 

[Wattman]

Eastwood,
I love motorcycles in general as in gas powered and haven't made the foray into a high power electric motorcycle like you are doing.
What a great project.
Question please...
Have you ordered the Molice 21700 P42A 4200mah cells yet from 18650 batterystore.com?
Did you have a good buying experience? Is that source in the US?
If you have received the cells, have you done any capacity testing of the cells to discern if the cells are equivalent?
Thanks

 

[99t4]

What is Barncat battery?

The Barncat Battery- No weld/no solder

I designed and built these packs a year ago. After a couple thousand miles of testing and considerable internal debate, as a service to the DIY community and as a social experiment, I'm releasing the design publicly. You use my design and any information contained in this discussion thread...

endless-sphere.com

 

[Eastwood]

The Barncat Battery- No weld/no solder

I designed and built these packs a year ago. After a couple thousand miles of testing and considerable internal debate, as a service to the DIY community and as a social experiment, I'm releasing the design publicly. You use my design and any information contained in this discussion thread...

endless-sphere.com

Naw, not for me!
Realize that I’m building a battery pack that will be able to discharge around 50 kW, so this is nothing to play around with trying new ideas. I certainly won’t be pulling 50 kW with using the QS 138 but this battery pack with the Molicel cells would be capable of discharging 50kW. I’ll stick to the tried and true method of spot welding

Eastwood,
I love motorcycles in general as in gas powered and haven't made the foray into a high power electric motorcycle like you are doing.
What a great project.
Question please...
Have you ordered the Molice 21700 P42A 4200mah cells yet from 18650 batterystore.com?
Did you have a good buying experience? Is that source in the US?
If you have received the cells, have you done any capacity testing of the cells to discern if the cells are equivalent?
Thanks

I’ve only ordered 4 cells for sizing purposes with building the pack. No I haven’t done any testing, but I probably will test all the cells once I purchase.
Yes, there a US company, I believe the shipping came from somewhere in Georgia if I’m not mistaken.

 

[Eastwood]

Does anyone have opinions on a spot welder like this?

GLITTER 801D Battery Spot Welder 12 KW Capacitor Energy Storage Spot Welding Machine, https://a.co/d/7E9FSDL

They also offer the 801H version thats 19.8 kw version but its a bit of of my budget at $440

The link I post the price is $289 which fit my budget better.

Does anyone have opinions on a spot welder like this? This would be much more simpler for me to buy something ready to go, than trying to DIY the dang spot welder
The DIY Kweld seems like a great option but would much rather have something that’s ready to go that can be powered by AC power. It looks like this spot welder has capacitors built in, but I’m just so new to all of this battery building and would love to hear some advice on this.

 

[Barncat]

I see I was mentioned above. 14kW of p42a in use on the street daily- not that I would suggest my design is practical for housing 340 cells...

Don't make the mistake of assuming cell holders protect you from the beating you're going to dish out. I'd be REAL nervous about heading into the wilderness with that much incendiary potential, but wish you the best in constructing your mega pack.

 

[Eastwood]

I see I was mentioned above. 14kW of p42a in use on the street daily- not that I would suggest my design is practical for housing 340 cells...

Don't make the mistake of assuming cell holders protect you from the beating you're going to dish out. I'd be REAL nervous about heading into the wilderness with that much incendiary potential, but wish you the best in constructing your mega pack.

Great job on your battery design! I can see the advantages of this in certain applications. Like you mentioned, with 340 cells probably not the most practical approach.

I think with the cell holders and the combination of nickel copper sandwich with strong spot welds the pack should have good structural strength. I plan to use something between the battery pack and the battery box to help with vibration or impacts. Something like rubber, or a stiff foam should help with vibrations. Still have more homework to do before I jump in full speed of building this battery. Also need to purchase the controller, get it mounted, finish a few other odds ends on the bike and then the pack building will start.
This dirtbike build is taking a while, mainly due to finances, as I would rather take longer and purchase quality parts and get this done right instead of throwing a conversion together quickly.

 

[Barncat]

Given the high quality of your builds I'm sure you'll prevail with your pack construction. But it's the sort of thing that would keep me up at night given where it'll be operated. I ride my Ducati and Yamaha road bikes in the Roan mt region all summer- extremely rugged forested terrain.

I should have said cell holders 'alone' above. They locate/separate the cells but even after spot welding there's micro movement. I'd probably hot glue the cell sidewalls as they're assembled into the holders, then double heat shrink the whole thing, then further rubberized vibration damping between case as you said. Add in the complexity of a BMS and that wiring and it's a pretty daunting task, at 60lbs or so...

 

[Eastwood]

I'd probably hot glue the cell sidewalls as they're assembled

Great idea! That would definitely help stabilize the pack

 

[999zip999]

2170 Cell Holders

Here are square 2170 cell holders in 1x2 and 1x3 configuration. Just 4 cents per cell hole. These fit 2170 cells perfect. All of these cell holders will snap into each other as well. For example the 1x2 and 1x3 will snap together. If you want to build a 5x5 holder you can use 5x 1x3 and 5x 1x2...

batteryhookup.com

Hey call up battery hookup they'll talk to you find out if these holders will help you and how much does 340 cells weigh. I mean one man pick up that battery ?
I say go 20s with higher P. Cheaper controllers cheaper chargers easier to use chargers in most places.

 

[Eastwood]

Hey call up battery hookup they'll talk to you find out if these holders will help you and how much does 340 cells weigh. I mean one man pick up that battery ?
I say go 20s with higher P. Cheaper controllers cheaper chargers easier to use chargers in most places.

Just weighed one of the cells,
66.4 Grams x 340-cells = 49.77 pounds
Plus the copper busbars, large AWG wires, BMS and not to forget the battery box.
I’m guesstimating around 65 pounds max. If it’s more than that, I may eliminate a parallel group.
And yes, I can handle a 65lb-ish battery

Plan to go with 20s 17p. Have an adjustable charger already for 20s that goes up to 12amps.

I found some cell holders that fit, 21.3mm diameter hole for the P42A cells

 

[999zip999]

You need to put a separation between each parallel set one p or 17p separation plate then 2p separation plate then 3p as 1p is just one big cell up to 4.2 volt each parallel of cells
with a lot of capacity. Yeah you can handle that wait. Thank you

 

[Eastwood]

You need to put a separation between each parallel set one p or 17p separation plate then 2p separation plate then 3p as 17p is just one big cell up to 4.2 volt with a lot of capacity. Yeah you can handle that wait. Thank you

When you say "separation plate” are you referring to gaps between each cell group, like this pic?
Thanks!

 

[999zip999]

As a 17p I would keep 1p insulated from P2 and so on. M meaning your biggest danger is having one huge high capacity cell of 4.2 volts interact with the next parallel 2p as all cases are native and should not touch the only point that is positive is the titty.
You have one big parallel group it's not 4,000 mAh it's 40,000 mAh just guessing so separate one p one from the next p 2

 

[999zip999]

Sorry I'm trying to cook it's talk to text but there's don't let one use parallel group have access to the nether parallel group with it. Plus a insulater on the pos. end.

Insulator Rings

Here are insulator rings! You get a full sheet for just $1.99! 18650 sheet = 100 rings 21700 sheet = 72 rings 26650 sheet = 45 rings 32650 sheet = 36 rings Barley paper with an adhesive backing. Use them to prevent short circuiting when building your battery pack!

batteryhookup.com

 

[999zip999]

Yeah there's a lot of dangerous batteries out there especially in the old days. But buying a battery made by whoever is still a gamble at times. Yes companies have button counterfeit cells. And one way or another they just moved them down the line to the end customer willing or not.
Surrons has a box battery.
Make a card board box the size of your battery. Take it with you.

 

[Eastwood]

Matched meaning the *same* internal resistance and capacity and all other properties.

So it sounds like I need two different tools. one to check the capacity of each cell, then to check the internal resistance?

Are there any good brands you recommend for this? As you know, I’ll be purchasing brand new cells, but I still wanna check to make sure all the cells are very similar in capacity and resistance.

 

[harrisonpatm]

For IR, go with the RC3563, or the YR1035

 

[amberwolf]

I don't know specific models, but Jonyjoe's posts show what they use for testing; also Pajda's testing threads.

 

[docw009]

You need to put a separation between each parallel set one p or 17p separation plate

I pulled this photo off a facebook forum, It shows why p-groups cannot be glued together. They need a separating insulator/ This pack is still insulated, but now that the PVC on the right cell is ripped, a tear on the left side will short circuit the right hand cell,

The top of the left hand cell is the positive end of the group. It's missing o-rings under the nickel. Helps prevent the nickel from contacting the end of the case.