APL's Pressure Contact Battery box

Batteries, Chargers, and Battery Management Systems.
Post Reply
User avatar
ZeroEm   10 MW

10 MW
Posts: 2333
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: APL's Pressure Contact Battery box

Post by ZeroEm » Nov 15 2021 7:43am

It's seems the deeper you dive into this the more complicated it gets. I see the attraction of gluing the batteries together and welding the ends. Would like to glue or lock tubes together to isolate the cells from touching anything and still remove cells without having to clean them or break welds. On a bike weight is a big factor so to much housing would get heavy and bulky.
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 15 2021 1:51pm

Yea, your right BalorNG, 8s wouldn't be so bad, and it would take a while to go unbalanced, I guess I usually think in terms
of hundreds of batteries.

Right ZeroEm, the trouble starts with the 18650 style cell as the choice for power. They give us configuration options, and
the popularity brings cost down and the tech focus up, but along with that comes the assembly problems of numbers.

Different cell shapes and sizes may fit together better and save space, or make assembly easier, but cost and availability
might be the issue. I haven't really looked at other types of cells to closely because I have a lot of 18650's,.. but I should.

What's a poor e-biker to do,.. keep trying I guess. :thumb:

User avatar
ZeroEm   10 MW

10 MW
Posts: 2333
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: APL's Pressure Contact Battery box

Post by ZeroEm » Nov 15 2021 2:06pm

Know your right. Enjoying this, it's a learning curve on materials, cost and techniques.
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

BalorNG   1 kW

1 kW
Posts: 343
Joined: Nov 10 2019 7:22pm

Re: APL's Pressure Contact Battery box

Post by BalorNG » Nov 15 2021 3:21pm

APL wrote:
Nov 15 2021 1:51pm
Yea, your right BalorNG, 8s wouldn't be so bad, and it would take a while to go unbalanced, I guess I usually think in terms
of hundreds of batteries.

Right ZeroEm, the trouble starts with the 18650 style cell as the choice for power. They give us configuration options, and
the popularity brings cost down and the tech focus up, but along with that comes the assembly problems of numbers.

Different cell shapes and sizes may fit together better and save space, or make assembly easier, but cost and availability
might be the issue. I haven't really looked at other types of cells to closely because I have a lot of 18650's,.. but I should.

What's a poor e-biker to do,.. keep trying I guess. :thumb:
Basically, one 33140 equals at least 5 (or more like 6) 18650. Since the system chance of failure is sum of chance of failure of all elements, a battery that needs to be just 8s1p will be MUCH more robust than 8s5p...

User avatar
fechter   100 GW

100 GW
Posts: 15752
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Re: APL's Pressure Contact Battery box

Post by fechter » Nov 15 2021 3:37pm

You have to balance between contact pressure, contact area and total contact force. If there isn't enough contact pressure, long term the contact tends to go bad from oxidation. If you get enough pressure, it will tend to keep out oxygen and prevent oxidation. Too much pressure and you either dent or puncture the cell. You can use little spikes to get a lot of pressure, but then your current will be limited by the small contact area and the spikes will be easily damaged. If you apply too much total force, the end of the cell dents in. Force can see very significant peaks if you ride over bumps and shock load the contacts.

I think I'll stick with my spot welder. There's a reason most 18650 packs are spot welded.
"One test is worth a thousand opinions"

john61ct   100 GW

100 GW
Posts: 8438
Joined: Dec 18 2018 2:06pm

Re: APL's Pressure Contact Battery box

Post by john61ct » Nov 15 2021 3:39pm

Yes the ideal is cell Ah cap = pack Ah

just a single string

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 16 2021 2:30pm

Would be nice to have factory 18650 offerings with bottom and top tabs for spade connections of a sort.

Well, a little more progress out here on the plains,.. I have the buss-side strips made and almost ready to go, need the
holes for the thru bolts, and the end buss's yet. This side of the pack will be rigid with no spring, so I can rivet the strips in
place, and mount the buss strips solidly.
Buss side plate.jpg
Buss side plate.jpg (137.63 KiB) Viewed 615 times
I'd like to get 2Kw out of this pack if the used cells will cooperate, not all that much, but the end buss's will need to be thick
enough to handle at least that much comfortably. Later on if I get better batteries I can upgrade the end bars maybe.

Anyway, I probably need a little thicker copper on the ends,.. single dimple strips,13mm'ish wide, and 230mm long. Can't get
too thick though, unless I machine the phenolic a little. So,.. .035"copper thick enough, or need more?

Another thought I had was to just solder the tops of the dimples, and paint the rest of the copper. Easy to do with a solder
gun, but not all that consistent, kind of want the tops to be flat too, (maybe with some practice).
Soldered dimps.jpg
Soldered dimps.jpg (57.73 KiB) Viewed 615 times
Also, I have some 50 percent silver brazing rod that I could maybe braze the tops with, for a thick hard cap, that stuff is
really tough and won't rub off. Maybe I'll try a test sample and see what kind of mess that turns into.

Yea, I don't know how much contact pressure will be needed, and the surface of the battery cap isn't that flat either, but
these cells are made for contact connections in the first place aren't they?

SlowCo   10 MW

10 MW
Posts: 2110
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: APL's Pressure Contact Battery box

Post by SlowCo » Nov 16 2021 3:56pm

After the layer of solder you could flatten the dimpled strips on a flat surface with sandpaper on it.

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 17 2021 2:19pm

Hmmm, now that you say that, I wonder if I can just put it back in the dimple former and pound it flat too, solder is soft.
I'll give it a try, and a little sandpaper too.

I tried the silver brazing, and it works, but needs more trial. Want's to go everywhere and needs to be brazed upside down.
Something to be fooled around with later on I guess. Would make a lot more work too, probably easier just to plate it if
going the silver route.

I'll try the whole strip-dip tinning thing too, and see how that goes,.. if I can get good consistency with that approach then
it will be the easiest and best. It's good to have some back up options though, like tip soldering.

I looked around for info on solder oxidation, but didn't get very far. Anybody know how long it takes for solder to oxidize?
(substantial) As a contact material, more than a year?

User avatar
ZeroEm   10 MW

10 MW
Posts: 2333
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: APL's Pressure Contact Battery box

Post by ZeroEm » Nov 18 2021 9:01am

May I ask the purpose of the Solder, it raises resistance does it not. Is it to stop oxidation?
by APL » Nov 17 2021 2:19pm

Hmmm, now that you say that, I wonder if I can just put it back in the dimple former and pound it flat too, solder is soft.
I'll give it a try, and a little sandpaper too.

I tried the silver brazing, and it works, but needs more trial. Want's to go everywhere and needs to be brazed upside down.
Something to be fooled around with later on I guess. Would make a lot more work too, probably easier just to plate it if
going the silver route.

I'll try the whole strip-dip tinning thing too, and see how that goes,.. if I can get good consistency with that approach then
it will be the easiest and best. It's good to have some back up options though, like tip soldering.

I looked around for info on solder oxidation, but didn't get very far. Anybody know how long it takes for solder to oxidize?
(substantial) As a contact material, more than a year?
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
spinningmagnets   100 GW

100 GW
Posts: 12704
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: APL's Pressure Contact Battery box

Post by spinningmagnets » Nov 18 2021 9:52am

Yes, for reducing oxidation.

Vintage solder is 60/40 Tin/Lead the modern "lead-free" solder is tin at 90%+

I'd recommend zinc being better than solder, but may require a hotter temp to melt it.

https://www.electricbike.com/introducti ... -design-2/

SlowCo   10 MW

10 MW
Posts: 2110
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: APL's Pressure Contact Battery box

Post by SlowCo » Nov 18 2021 12:40pm

Would DIY nickel plating be doable? First flatten the dimples on flat surface with sandpaper and then nickel plate them.

User avatar
agniusm   100 MW

100 MW
Posts: 2551
Joined: Apr 16 2011 3:06pm
Location: Lithuania, Zarasai
Contact:

Re: APL's Pressure Contact Battery box

Post by agniusm » Nov 18 2021 2:15pm

APL wrote:
Nov 17 2021 2:19pm
Hmmm, now that you say that, I wonder if I can just put it back in the dimple former and pound it flat too, solder is soft.
I'll give it a try, and a little sandpaper too.

I tried the silver brazing, and it works, but needs more trial. Want's to go everywhere and needs to be brazed upside down.
Something to be fooled around with later on I guess. Would make a lot more work too, probably easier just to plate it if
going the silver route.

I'll try the whole strip-dip tinning thing too, and see how that goes,.. if I can get good consistency with that approach then
it will be the easiest and best. It's good to have some back up options though, like tip soldering.

I looked around for info on solder oxidation, but didn't get very far. Anybody know how long it takes for solder to oxidize?
(substantial) As a contact material, more than a year?
Have you thought of tin electroplating? Its easy diy stuff and the result will be far better and even

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 18 2021 3:33pm

Wow, what a merry-go -round, solder tin, zinc tin, zinc plate, nickel plate, silver plate,.. I'm looking and thinking, better
pack a lunch, this could take a while. :wink:

Thanks for the link agniusm, I've been watching lots of videos and looking up info on tin, zinc, silver etc. processes and
oxidation rates. Looks like more sleepless nights.

I guess if it comes down to plating, it should be silver, since it's an upgrade instead of a downgrade like the other plates.
From what I've read so far, it's oxidation rate is fairly slow, and even if it tarnishes it's still conductive But, lots to read yet,
and the cost and effort involved for each prospect has to be considered too.

User avatar
spinningmagnets   100 GW

100 GW
Posts: 12704
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: APL's Pressure Contact Battery box

Post by spinningmagnets » Nov 18 2021 3:37pm

Since silver is expensive, cover everything but the contact point with some kind of brushed-on rubber.

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 18 2021 10:42pm

Good idea! :thumb: Yea I haven't looked at the expense yet, that could be the game changer.

Well I tried the re-stamp of the test pieces that I soldered and brazed with silver, and they came out pretty good. Might have
to put a little more thought into this idea.

Silvers on the right.
Pressed silver caps.jpg
Pressed silver caps.jpg (55.41 KiB) Viewed 515 times
The solder pounds like butter but the silver takes a little more. When I put my weight into them with a screwdriver tip, the
silver caps wouldn't bend or crush, and it makes the dimples a lot stronger. (it's not pure silver yet though.)

Finished the buss bars, turned out to be .040"/1mm copper, and about 5/8" wide. No problem dimpling and seam pretty hefty.
1mm strips.jpg
1mm strips.jpg (53.96 KiB) Viewed 515 times

User avatar
agniusm   100 MW

100 MW
Posts: 2551
Joined: Apr 16 2011 3:06pm
Location: Lithuania, Zarasai
Contact:

Re: APL's Pressure Contact Battery box

Post by agniusm » Nov 19 2021 5:50am

APL wrote:
Nov 18 2021 3:33pm
Wow, what a merry-go -round, solder tin, zinc tin, zinc plate, nickel plate, silver plate,.. I'm looking and thinking, better
pack a lunch, this could take a while. :wink:

Thanks for the link agniusm, I've been watching lots of videos and looking up info on tin, zinc, silver etc. processes and
oxidation rates. Looks like more sleepless nights.

I guess if it comes down to plating, it should be silver, since it's an upgrade instead of a downgrade like the other plates.
From what I've read so far, it's oxidation rate is fairly slow, and even if it tarnishes it's still conductive But, lots to read yet,
and the cost and effort involved for each prospect has to be considered too.
I think you are overthinking coating :) Its already done. All automotive is tin plating. I think its a reason enough to copy and paste :)

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 19 2021 2:31pm

Your right of course, and I change my mind many times a day. We just want to keep the copper from oxidizing right?
I shouldn't get too carried away or make any big effort until I see if the system works in the first place. I should probably
put the whole thing together as raw copper first and see.

But it is a pressure contact system, and the main component of that is the "contact" part, and so that should be the best
part of the whole shebang I would think. Deserves a good look anyways, and what some options are, overthinking or not.

Plating or tinning is the way to go, I'm sure. But if it's plating, then the process is virtually the same for all the metals used
to plate, it's just a matter of choice and cost. Most of the copper can be painted or coated like spinning magnets suggested,
and the cost goes down substantially. I'm not sure if I can plate painted parts, but it's worth a test try for starters.

The merry-go-round keeps spinning..

SlowCo   10 MW

10 MW
Posts: 2110
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: APL's Pressure Contact Battery box

Post by SlowCo » Nov 19 2021 3:00pm

Your very labor intensive way of building a battery pack is a good reminder that spot welding is the best DIY way to go... :mrgreen:

User avatar
ZeroEm   10 MW

10 MW
Posts: 2333
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: APL's Pressure Contact Battery box

Post by ZeroEm » Nov 19 2021 8:28pm

That's been done and is the way to go for 99% of the people. Deep inside everyone, there is that wish to change batteries like a flashlight.
by SlowCo » Nov 19 2021 3:00pm

Your very labor intensive way of building a battery pack is a good reminder that spot welding is the best DIY way to go... :mrgreen:
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
agniusm   100 MW

100 MW
Posts: 2551
Joined: Apr 16 2011 3:06pm
Location: Lithuania, Zarasai
Contact:

Re: APL's Pressure Contact Battery box

Post by agniusm » Nov 20 2021 1:08pm

SlowCo wrote:
Nov 19 2021 3:00pm
Your very labor intensive way of building a battery pack is a good reminder that spot welding is the best DIY way to go... :mrgreen:
I have some customers who were welding before and after using my pressure system they commented -"never again i am going back to welding". Cut and burned fingers, and stupid amounts of time to build without an easy option to replace cells etc...

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 20 2021 2:46pm

Different spokes for different folks. I've always had an artist's or inventors approach to things that I build, and as such I've found
that it's better to go slowly and do a lot of thinking and experimenting.

Labor intensive for sure, but it's all on my back and I call it fun. :) (until something new comes along that I'd rather be building) :lol:

Most people take the quick and dirty route, "just get 'er done," and I can't blame them. Tried and true is always a good way to go, but the deck I was born with has a few more wild cards I guess, and I always think that there's another way.

And we still have the need to change out our batteries,.. that's right! Thanks guys! :thumb:

Anyway, nuff of that, I think that it would be best to just bypass plating the copper for now, and move on. There may be bigger
problems coming up, and the strips might even need to be rebuilt altogether,.. and this plating stuff is going to take up a lot of time and effort that may be wasted.

Once the pack is together and everything is working good, it won't be hard to take it apart and I can follow up the thread with the plating process. I should see how copper works by itself first.


(Had the crazy idea last night that a person could bond a threaded sleeve on the front section of a cell, and screw it into a socket like a light bulb, using the top case edge and cap for the connections. Battery box would just be a slab of screw in sockets. :?: )

User avatar
ZeroEm   10 MW

10 MW
Posts: 2333
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: APL's Pressure Contact Battery box

Post by ZeroEm » Nov 20 2021 7:46pm

It's not just you. Was looking at copper brads or rivets, they use in belts. To replace the copper dimples. My mind wonders to thin wall PVC. Cell size all kinds of configurations. Not going that route yet. :lol:
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
APL   100 kW

100 kW
Posts: 1055
Joined: Aug 06 2018 8:44pm

Re: APL's Pressure Contact Battery box

Post by APL » Nov 21 2021 2:59pm

Yea, we can't help thinking about all the different ways of building a pack, my brain won't shut off either. :wink:

Speaking of which,.. here's yet another approach for pressure contact. Still labor intensive, but might have an idea in there
somewhere for someone. Don't really see a spring though. YouTube; https://www.youtube.com/watch?v=uVx_4nsA8BM
Screenshot 2021-11-21 123639.png
Screenshot 2021-11-21 123639.png (383.31 KiB) Viewed 433 times

User avatar
spinningmagnets   100 GW

100 GW
Posts: 12704
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: APL's Pressure Contact Battery box

Post by spinningmagnets » Nov 21 2021 3:15pm

I like the idea. Looks like 13S / 48V. It looks like nickel strips for the contact and also the "leaf spring" action.

Spring steel is best for the spring, and copper that has a thin nickel plate is best for contacts (actually, silver-plate is best, but...)

Post Reply