Battery board design

[206monkey32]

I'm up for a group buy. Maybe even two.

 

[torqueboards]

We would first have to decide how much amps we are actually pulling. I suggest a 12S pack possibly 5ah and/or more.

Would be nice to have a complete enclosure for it too.

 

[Freshair]

I bought a vacuum bag from roararocket.com that'll fit a board if anyone wants to pay the shipping and borrow it. Not that you seem to have any plans for it maybe but it sits here unopened and its' 75 bucks charge to return things back to Canada so I'm keeping it.

Will be using a vacuum bag to do the carbon fiber, however I am in Canada otherwise would take you up on that offer!

I don't think a spring will be able to handle the amps these boards need. The spring will just turn into a heating element or just fail. Either way, you won't get enough power. I've been trying to figure out a solderless/weldless 18650 pack, but it may not be worth it. I keep running into concerns about the amount of pressure on the ends, and the chances of arcing if there is a little gap due to vibrations. I wish we could organize a group buy of a flat, single-layer Samsung 25R or LG HE2/HE4 pack. It would solve a lot of people's power needs in a compact way.

What about making springs out of materials with higher copper content, such as beryllium copper, phosphor bronze or spring brass? http://www.newcombspring.com/battery.php

A single layer battery pack with bms incorporated would be interesting, could definitely tuck that away into the deck pretty easily.

 

[Freshair]

Interest solve to using springs. Run a wire threw the middle to take the current, and use the spring to simply hold pressure.

 

[Eclectic]

There has been discussions about this in other threads but the idea of using the spring to press the contact instead the spring being the contact is probably a good idea. I know you are on your own journey of discovery but there are others who have walked this path before you.

A couple of links I found with the search function:
open source UNIVERSAL quick swap battery - http://endless-sphere.com/forums/viewtopic.php?f=7&t=65880&p=994187
Holy grail of solderless 18650 is close but not idiot proof. - http://endless-sphere.com/forums/viewtopic.php?f=14&t=65718
Solderless 3d L3GO design challenge - http://endless-sphere.com/forums/viewtopic.php?f=14&t=66678&p=1003686
18650 battery Kit development and discussion - http://endless-sphere.com/forums/viewtopic.php?f=14&t=63190
Swappable battery -vs- Fixed Battery - http://endless-sphere.com/forums/viewtopic.php?f=35&t=67478
yet another solderless DIY battery pack via NIB's - http://endless-sphere.com/forums/viewtopic.php?f=14&t=60517
Homemade Battery Packs - http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383

Reading some of these might make getting to your destination a little quicker.

 

[Freshair]

Thanks for the links eclectic, had searched and found the same links you provided.

Definitely seems like most feel the solderless battery pack is impossible or not worth it. Work at a machine shop, so wouldn't mind trying a few things, but then not into a headache and wasted money if it really is a lost cause.

If there were some sort of single layer batter pack using 18650's with bms incorporated, would likely just go that route since it would be easy to mould those into deck. At this point am not willing to sacrifice the low ride of my board by strapping bricks to the bottom of it. The reason why I am finally doing an electric longboard is because hubmotors are available, which makes it even more possible to keep this stance.

 

[Eclectic]

Yep... Maybe not impossible but the details seem to be a killer. The Holy Grail of a high Amp, high vibration, solderless 18650 battery pack seems to be just a little bit out of reach (I can see it but I can't quite touch it). For all the work others have put into it, I don't think anyone has shown a functional battery pack yet (I could easily be wrong about that).

Kinda' like cold fusion I guess.

 

[e-beach]

Interest solve to using springs. Run a wire threw the middle to take the current, and use the spring to simply hold pressure.....

:lol: Speaking of mind reading, this morning I was going to suggest using parts from a motor brush to use as a contact tab and wire while the spring did the holding but I had to get to work before I could post. I like your setup. It would work fine if the cells are also snug in a row in their slots.

 

[Freshair]

Interest solve to using springs. Run a wire threw the middle to take the current, and use the spring to simply hold pressure.....

:lol: Speaking of mind reading, this morning I was going to suggest using parts from a motor brush to use as a contact tab and wire while the spring did the holding but I had to get to work before I could post. I like your setup. It would work fine if the cells are also snug in a row in their slots.

So far it seems to be the only way this will work effectively, but wont really know until I try right!? Will do a new design this weekend to show concept a little better.

 

[Hummina Shadeeba]

a board made of aluminum that was a battery!!
just need to find the secret sauce that was discovered or maybe it's more battery hype:

http://www.reuters.com/article/2015/04/07/us-batteries-aliminium-idUSKBN0MY17H20150407

 

[bandaro]

Will be using a vacuum bag to do the carbon fiber, however I am in Canada otherwise would take you up on that offer!

What about making springs out of materials with higher copper content, such as beryllium copper, phosphor bronze or spring brass? http://www.newcombspring.com/battery.php

A single layer battery pack with bms incorporated would be interesting, could definitely tuck that away into the deck pretty easily.

So bagging the carbon, how about the core materials? Any ideas as to the layup?

As for the springs, why do we need them? A 30 cell pack will give 10s3p, so hook up 3 cells at a time in parallel with a rigid plate on each end and 3 insulated bolts clamping it all together. Then run a short length of wire between each set to allow for flex. Laid flat will give you 60mm long blocks, so have a foam padded compartment that is a about 22mm tall and you will bottom out before the batteries feel the bend.

 

[Freshair]

a board made of aluminum that was a battery!!
just need to find the secret sauce that was discovered or maybe it's more battery hype:

http://www.reuters.com/article/2015/04/07/us-batteries-aliminium-idUSKBN0MY17H20150407

The secret sauce is money, lots and lots of money! LOL

So bagging the carbon, how about the core materials? Any ideas as to the layup?

As for the springs, why do we need them? A 30 cell pack will give 10s3p, so hook up 3 cells at a time in parallel with a rigid plate on each end and 3 insulated bolts clamping it all together. Then run a short length of wire between each set to allow for flex. Laid flat will give you 60mm long blocks, so have a foam padded compartment that is a about 22mm tall and you will bottom out before the batteries feel the bend.

Foam core with an aluminum skeleton down the bottom middle of board the width of the g-bomb brackets. It is a very simple flat shape so should not be to complicated to integrate the skeleton, but is a must with the brackets as they put a load of leverage on the deck, which is why in the picture of my board I have metal plates top and bottom to secure them.

The problem with clamping the batteries like that is there is no room for expansion when the batteries get hot, though suppose you could put a rubber washer in said clamping bolts to allow for a bit of expansion. This problem is solved with springs though.
Will definitely be using foam or rubber wherever possible in this system to keep vibrations to a bare minimum or nil. There would be rubber between clamps to allow for expansion.
Will stew your idea over though, if somehow we can allow for expansion it would definitely be an easier route.

 

[Freshair]

Well after loads of figuring, have come to the conclusion that the only way to do solderless without any headaches and more work than am willing to do (not saying it is not possible) is to have screw terminals on the cells.

My board currently weights 13lbs, the 107 wheels are heavy monsters (love them!!), and am about to add a whole lot more weight in motors and batteries. My guesstamite is 25lbs all said and done. 10lbs will be from batteries.

Will stick to lifepo4 for reliability, cycle life, safety and a consistent flat discharge. Am going to increase the width of my plans by about 3/4 of an inch which in total will lift me off the ground about a half an inch more than my current setup...I can live with that.

The batteries I will use are the Headway Lifepo4 38140S 12Ah. Can live with the 12s setup that puts out like a Li-ion 10s. Am not looking for a rocket, am looking for a setup that I can commute up to 10-15km reliably.

Here is the revamped design


BMS will be incorporated into this system.

 

[Hummina Shadeeba]

Nice choice!

The distributer said they'd be solid enough for flying rocks. I called him asking when I was going to do the same.

How are u going to mount them still?! I was planning on making connectors that would screw into the board and also serve as the connectors between cells.

I think charging could be simplified with some alligator clips. But I don't know if u can charge while still connected to the esc?? Would be very convenient I think. The terminals would be somewhat exposed but the voltsge to break the skin I think is high enough mostly not to worry about it. Wouldn't ride in he rain though. Who wants to anyway.

Look forward to seeing it

 

[riba2233]

I'm sorry but choosing headways is epic fail. They are very heavy, three times larger, and weak, they are 2C cells and will sag like shit. They are also more expensive.

You should accept facts, sorry... Samsung 25R cells are as safe, and should last even longer.

 

[Hummina Shadeeba]

They're 10c continuous 25c pulse

They should definately last longer being lifepo4

Somewhere on this site there's a pic of an aluminum board someone made using them. It's the exposed board as apposed to having things hidden. I think it's one of the nicest boards

3 of the Samsung will get 7.5 amp hour and be 150grams total and one of the headway is 8ah and 330 grams
4.2 volts to 3.6 peak voltage. And 3.3 to 3.6 operating voltage.
18$ to 23$

 

[riba2233]

They're 10c continuous 25c pulse

They should definately last longer being li-iron. The cost is close too if I remember right

Far from that.. they are S version, which means 2C const. discsharge. I would love to se their 25C pulse lol :lol: They have better cycle life, but worse calendar life, so...

 

[Hummina Shadeeba]

They're 10c continuous 25c pulse

They should definately last longer being li-iron. The cost is close too if I remember right

Far from that.. they are S version, which means 2C const. discsharge. I would love to se their 25C pulse lol :lol: They have better cycle life, but worse calendar life, so...

Right. Yea he's got to get the hp version. That's the cell Ive been quoting numbers for above

If he gets those they should have better cycle life and calendar life I think. They don't degrade from storage as li-ion does a bit. The cycle life doesn't look good even after 200 cycles according to this
http://www.powerstream.com/p/INR18650-25R-datasheet.pdf

 

[riba2233]

You must understand that while that is true for most chemistries, it's not a case with NCA chemistry. They don't suffer that much from storage, and have best calendar life. Tesla gives 10 years guarantee for them (ok, with their conditioning but still).

HP headways are simply terrible when it comes to Wh/kg and Wh/l. No place for them on skateboard.. (or any EV if you ask me).

 

[Hummina Shadeeba]

From the graphs I posted above they seem to not have much cycle life but I just post what I read.

 

[riba2233]

That is in worst possible conditions, just for testing. In same conditions, headway would have similar results.

 

[Freshair]

Dammit, if they would just make NCA with screw terminals! REALLY do not want to deal with soldering battery packs...uhg

 

[Freshair]

Hey Riba,

Whats this about http://www.myvaporstore.com/Samsung-INR18650-25R-2500mAh-Battery-Flat-Top-p/jssinr25r.htm
"Cycle info: Capacity drops to 60% after 250 full charge/discharge Cycles"

 

[riba2233]

Dammit, if they would just make NCA with screw terminals! REALLY do not want to deal with soldering battery packs...uhg

Well you shouldn't solder anyway, you can spot weld or have someone spot weld it for you.

Hey Riba,

Whats this about http://www.myvaporstore.com/Samsung-INR18650-25R-2500mAh-Battery-Flat-Top-p/jssinr25r.htm
"Cycle info: Capacity drops to 60% after 250 full charge/discharge Cycles"

They can write whatever they want, info on most seller's pages are full of errors.

 

[Hummina Shadeeba]

I like the Samsung but ur in the market selling and you're contradicting what I see. Do u have any better comparisons that you feel are more true