DIY assembly kit for 18650 without spot welding/Soldering

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Matador   10 kW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by Matador » Apr 04 2017 10:46am

The major strength of this pack is its ability to maintain spring action for each and every cell completely independently. I have not seen many packs designed like that. But I can see some major advantages (If, for one reason or another, one spring doesn’t make contact anymore, the other spring contacts are not affected and can still maintain their function). I think designing a pack with “individual suspensions springs” is a great challenge, even more so with highly conductive metals like copper, which is too soft to offer enough spring recoil. I love the concept of individual springs. This is one of the reasons that I’m very enthousiast about the Vruzend Pack. So I decided to encourage this product even considering my previous experience with my own design pack. Also, this solderless pack is fully costumisable, you can assemble it in the shape and size wou want (triangle, tube like, square, rectangle, 8-figure, name it LOL). Here’s my story:

Myself being a naive beginner at the time, I made a solderless pack last year. I wanted to have individual independent spring action for each cell. But I made a big mistake in my design. I want to tell you about it, so that everybody can learn about it and not do the same mistake I did.

First, here are some pics of my build (the Matador Pack version 1):
1.jpg
1.jpg (213.48 KiB) Viewed 2629 times
2.jpg
2.jpg (249 KiB) Viewed 2629 times
3.jpg
6.jpg
4.jpg
5.jpg
See build details here : https://endless-sphere.com/forums/viewt ... 0#p1213147

While the the bussbars (very thick copper) and the bolts and nuts (brass) offer very low resistance, the springs are made of very thin steel wire (called “springsteel” in the industry). More specifically, the resistances of the pieces in the Matador Pack V1 are as follow:
- Copper bussbars (23 cm) = 0.22 mΩ
- Brass nuts/bolts (1.5 cm) = 0.13 mΩ
- Nickel plated Steel springs (18 cm) = 46 mΩ
(Calculation details for my parts : https://endless-sphere.com/forums/viewt ... 4#p1213424 )

(General resistance calculations based on resistivity values and corresponding lost heat dissipation : https://endless-sphere.com/forums/viewt ... 0#p1238471
Exhaustive resistivity table of different metal alloys : http://eddy-current.com/conductivity-of ... sistivity/ )

I used my pack with a BBSHD Motor Setup with 52V 14S9P worth of laptop cells all fitted in the Matador Pack V1. I was flogging it full thumb throttle all the time. Yes, 30 amps all the time on my A/Ah/W/Wh-Meter. What a blast ! But in reality, on that 9P setup of suboptimal high resistance cells (around 120 mΩ DC internal resistance of the laptop cells), I was pushing 3.33 amps through each tiny springsteel springs. It’s no just because it is steel. It’s also because the spring wire is of too small wire gauge.

Guess what happened… After 200 km, I noticed lost of power… Opened the pack and I found some cooked springs. Once they heat up like red iron, the spring loose their recoil and will never make good contact anymore. I had to change 16 springs in the 126 that were used in the Matador Pack V1.
7.jpg
8.jpg
9.jpg
9.jpg (158.8 KiB) Viewed 2629 times
My mistakes on the springs (cooked) + V1 : https://endless-sphere.com/forums/viewt ... 7#p1236281

To solve the problem, I tried electroplating the springs with a thick copper layer to decrease spring resistance. The plating worked, but it was really brittle and would flake off right upon spring compression.
10.jpg
Copper plating tentative : https://endless-sphere.com/forums/viewt ... 5#p1236685

One other alternative was trying to use some copper as a conductive element, while still having some spring compression. This is hard to design… The springs cannot be copper as it is too soft and will loose it’s recoil right away. Maybe brass springs would exist. But I think the best would be a spring made of steel (best recoil properties) pushing a copper piece (or better yet, a nickel-plated copper) on the cell terminal, as the conductive element. The difficulty is how to link the copper piece to the bussbar and still have enough flexibility to let the spring, wedged in between, work well enough. I quickly experimented different approaches, but it was very very labor intensive try and design such pieces for a busy student like me. So I left the project (for a few years to come), but I plan on thinkering more on it in the future.
11.jpg
11.jpg (234.16 KiB) Viewed 2629 times
12.jpg
12.jpg (213.82 KiB) Viewed 2629 times
13.jpg
13.jpg (216.59 KiB) Viewed 2629 times
14.jpg
14.jpg (217.44 KiB) Viewed 2629 times
Copper braid as conductive carrier added to springs :
https://endless-sphere.com/forums/viewt ... 5#p1237600
15.jpg
16.jpg
17.jpg
18.jpg
18.jpg (247.94 KiB) Viewed 2629 times
I’m really happy to see that someone try to go the independent spring action route. While it is still made of steel, the contact do have waaayyy more cross sectional area than the tiny springs I used. Looking at some videos of the Vruzend product, I took measurement and estimated that each contact would be around 3 mΩ. In comparison, my springs in the Matador Pack V1 were estimated at 46 mΩ each ! Of course my springs heated up. Thus I have good hopes that the Vruzend Pack will work with my 1500W BBSHD.

At 19$, the price is right. And even if it might not be perfect, there is already some major advances and I want to encourage the person who designed it. That way, he can still have fund and continues to improve it in the future.

My dream would be to see this Vruzend kit with nickel-plated copper contact and steel springs to push them on the cells. A bit like I drawed on this scheme :
20.jpg
20.jpg (169.63 KiB) Viewed 2629 times
It's maybe also possible to subtitute the springs wedget between the teminal contact post and the bussbar with poron foam intead of springs.

Meanwhile, at 19$ per kit, I’m very glad to encourage the Vruzend product. I bought 4 kits.
I know, It's just, like, my opinion, man...

Matador
Last edited by Matador on Apr 04 2017 11:45am, edited 1 time in total.

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tomjasz   10 GW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 04 2017 11:24am

NOW were cooking!

Mine got shipped for trial. Very anxious!
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by Matador » Apr 04 2017 11:43am

tomjasz wrote:NOW were cooking! Mine got shipped for trial. Very anxious!
Nice that you're also trying it ! I have the feeling the kit will behave rather well. Judging by the number of people who did order the product, we will be a lot of people who will be able to give some real "in the field" testing feedback, coming from different type of users. If need be, we'll then have occasion to suggest possible improvement points for a product that is already available to the wide public for order...
19$, this is amazing, and Vruzend is really receptive to the comments of it's costumers. I like that!

Of course I could see myself pay double that price for the same kit if the contact could be copper, while being pushed on the cells terminal posts by underlying springs made of steel... But that's adding lots of R&D and additionnal complex parts... Copper bussbars is an easy upgrade though.

You know, I'm crazy enough that I'd want a solderless pack made out of supraconductors if it was possible to get one .... But at a certain point towards this extreme, the bottleneck is not even the contact resistance anymore but rather the intrinseque internal resistance of the cell itself...

Matador

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 04 2017 12:02pm

Matador wrote: You know, I'm crazy enough that I'd want a solderless pack made out of supraconductors if it was possible to get one .... But at a certain point towards this extreme, the bottleneck is not even the contact resistance anymore but rather the intrinseque internal resistance of the cell itself...

Matador
As I drift away to even smaller less powerful packs and become more enamored by more 36V setups and some 48V, I'm not as concerned. I do understand however that the market for higher power batteries is the growth for DIY. I hope it goes forward and those improvements can make high power packs possible. It all filters down.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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parabellum   10 MW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by parabellum » Apr 04 2017 12:46pm

Another exited buyer here, but you guys will have all the fun first. I took the slow boat option, will have some time to clean up my bench meantime. :)

Keep up the good work VRUZEND.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 05 2017 2:01pm

Matador wrote:The major strength of this pack is its ability to maintain spring action for each and every cell completely independently. I have not seen many packs designed like that. But I can see some major advantages (If, for one reason or another, one spring doesn’t make contact anymore, the other spring contacts are not affected and can still maintain their function). I think designing a pack with “individual suspensions springs” is a great challenge, even more so with highly conductive metals like copper, which is too soft to offer enough spring recoil. I love the concept of individual springs. This is one of the reasons that I’m very enthousiast about the Vruzend Pack. So I decided to encourage this product even considering my previous experience with my own design pack. Also, this solderless pack is fully costumisable, you can assemble it in the shape and size wou want (triangle, tube like, square, rectangle, 8-figure, name it LOL). Here’s my story:

Myself being a naive beginner at the time, I made a solderless pack last year. I wanted to have individual independent spring action for each cell. But I made a big mistake in my design. I want to tell you about it, so that everybody can learn about it and not do the same mistake I did.

First, here are some pics of my build (the Matador Pack version 1):
1.jpg
2.jpg
3.jpg
6.jpg
4.jpg
5.jpg
See build details here : https://endless-sphere.com/forums/viewt ... 0#p1213147

While the the bussbars (very thick copper) and the bolts and nuts (brass) offer very low resistance, the springs are made of very thin steel wire (called “springsteel” in the industry). More specifically, the resistances of the pieces in the Matador Pack V1 are as follow:
- Copper bussbars (23 cm) = 0.22 mΩ
- Brass nuts/bolts (1.5 cm) = 0.13 mΩ
- Nickel plated Steel springs (18 cm) = 46 mΩ
(Calculation details for my parts : https://endless-sphere.com/forums/viewt ... 4#p1213424 )

(General resistance calculations based on resistivity values and corresponding lost heat dissipation : https://endless-sphere.com/forums/viewt ... 0#p1238471
Exhaustive resistivity table of different metal alloys : http://eddy-current.com/conductivity-of ... sistivity/ )

I used my pack with a BBSHD Motor Setup with 52V 14S9P worth of laptop cells all fitted in the Matador Pack V1. I was flogging it full thumb throttle all the time. Yes, 30 amps all the time on my A/Ah/W/Wh-Meter. What a blast ! But in reality, on that 9P setup of suboptimal high resistance cells (around 120 mΩ DC internal resistance of the laptop cells), I was pushing 3.33 amps through each tiny springsteel springs. It’s no just because it is steel. It’s also because the spring wire is of too small wire gauge.

Guess what happened… After 200 km, I noticed lost of power… Opened the pack and I found some cooked springs. Once they heat up like red iron, the spring loose their recoil and will never make good contact anymore. I had to change 16 springs in the 126 that were used in the Matador Pack V1.
7.jpg
8.jpg
9.jpg
My mistakes on the springs (cooked) + V1 : https://endless-sphere.com/forums/viewt ... 7#p1236281

To solve the problem, I tried electroplating the springs with a thick copper layer to decrease spring resistance. The plating worked, but it was really brittle and would flake off right upon spring compression.
10.jpg
Copper plating tentative : https://endless-sphere.com/forums/viewt ... 5#p1236685

One other alternative was trying to use some copper as a conductive element, while still having some spring compression. This is hard to design… The springs cannot be copper as it is too soft and will loose it’s recoil right away. Maybe brass springs would exist. But I think the best would be a spring made of steel (best recoil properties) pushing a copper piece (or better yet, a nickel-plated copper) on the cell terminal, as the conductive element. The difficulty is how to link the copper piece to the bussbar and still have enough flexibility to let the spring, wedged in between, work well enough. I quickly experimented different approaches, but it was very very labor intensive try and design such pieces for a busy student like me. So I left the project (for a few years to come), but I plan on thinkering more on it in the future.
11.jpg
12.jpg
13.jpg
14.jpg
Copper braid as conductive carrier added to springs :
https://endless-sphere.com/forums/viewt ... 5#p1237600
15.jpg
16.jpg
17.jpg
18.jpg
I’m really happy to see that someone try to go the independent spring action route. While it is still made of steel, the contact do have waaayyy more cross sectional area than the tiny springs I used. Looking at some videos of the Vruzend product, I took measurement and estimated that each contact would be around 3 mΩ. In comparison, my springs in the Matador Pack V1 were estimated at 46 mΩ each ! Of course my springs heated up. Thus I have good hopes that the Vruzend Pack will work with my 1500W BBSHD.

At 19$, the price is right. And even if it might not be perfect, there is already some major advances and I want to encourage the person who designed it. That way, he can still have fund and continues to improve it in the future.

My dream would be to see this Vruzend kit with nickel-plated copper contact and steel springs to push them on the cells. A bit like I drawed on this scheme :
20.jpg
It's maybe also possible to subtitute the springs wedget between the teminal contact post and the bussbar with poron foam intead of springs.

Meanwhile, at 19$ per kit, I’m very glad to encourage the Vruzend product. I bought 4 kits.
I know, It's just, like, my opinion, man...

Matador
Hey Matador, Your packs real neat. Some real good engineering I must say. Dont give up on it

There are a few changes already underway and I will be posting the updates soon.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 05 2017 2:04pm

Matador wrote:
tomjasz wrote:NOW were cooking! Mine got shipped for trial. Very anxious!
Nice that you're also trying it ! I have the feeling the kit will behave rather well. Judging by the number of people who did order the product, we will be a lot of people who will be able to give some real "in the field" testing feedback, coming from different type of users. If need be, we'll then have occasion to suggest possible improvement points for a product that is already available to the wide public for order...
19$, this is amazing, and Vruzend is really receptive to the comments of it's costumers. I like that!

Of course I could see myself pay double that price for the same kit if the contact could be copper, while being pushed on the cells terminal posts by underlying springs made of steel... But that's adding lots of R&D and additionnal complex parts... Copper bussbars is an easy upgrade though.

You know, I'm crazy enough that I'd want a solderless pack made out of supraconductors if it was possible to get one .... But at a certain point towards this extreme, the bottleneck is not even the contact resistance anymore but rather the intrinseque internal resistance of the cell itself...

Matador
The price is $19 because I believe in giving the end user the most benefit. The plated copper variant kit is under works and will be out soon.

The kits will be available pretty soon locally as well. So this will definitely bring down the overall cost you guys have to pay as shipping is a bit high I agree.

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fechter   100 GW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by fechter » Apr 05 2017 2:15pm

I like the idea of having some kind of spring between the holder and the battery contact. I don't trust the plastic to stay springy for a long time (including zip ties). I like the modularity and ease of assembly. I'd like to see some independent tests by the members here to see how this might perform over a longer term.

My experience with weldless packs is the contacts always go bad after some period of time. Mostly oxidation issues. I'm sure there is something you can coat the surfaces with to prevent oxidation and this has been discussed in other topics. The graphene particle stuff might be good. Plain silicone grease has been used for years with good results on low power connectors. For higher current connections, I'm not sure what the best stuff would be.

Good material selection will also minimize corrosion problems. Avoid dissimilar metal contact. At least with a design like this, you could take everything apart and clean the contacts periodically if necessary. Better if it wasn't necessary though.
"One test is worth a thousand opinions"

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 05 2017 2:18pm

parabellum wrote:Another exited buyer here, but you guys will have all the fun first. I took the slow boat option, will have some time to clean up my bench meantime. :)

Keep up the good work VRUZEND.
May I please know the name with which you placed the order. It will help me relate better. If you dont mind that is.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by parabellum » Apr 05 2017 2:25pm

VRUZEND wrote:
May I please know the name with which you placed the order. It will help me relate better. If you dont mind that is.
PM sent.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 05 2017 2:28pm

fechter wrote:I like the idea of having some kind of spring between the holder and the battery contact. I don't trust the plastic to stay springy for a long time (including zip ties). I like the modularity and ease of assembly. I'd like to see some independent tests by the members here to see how this might perform over a longer term.

My experience with weldless packs is the contacts always go bad after some period of time. Mostly oxidation issues. I'm sure there is something you can coat the surfaces with to prevent oxidation and this has been discussed in other topics. The graphene particle stuff might be good. Plain silicone grease has been used for years with good results on low power connectors. For higher current connections, I'm not sure what the best stuff would be.

Good material selection will also minimize corrosion problems. Avoid dissimilar metal contact. At least with a design like this, you could take everything apart and clean the contacts periodically if necessary. Better if it wasn't necessary though.
Hello,

Its not the plastic thats springy but the internal contact inside it. Each time you remove the cell from the cap jut pull the contact upwards and you wont face any contact issues. Thats why the hammering is required too because the cells have to touch the internal contact and having independent spring action for each cell does get a bit trick especially for larger packs.

The material is SS so I dont thinks it will oxidise.

As Matador pointed out in one of his previous posts there is a review of the kit on Youtube done by Rocket Rose. You could view that or just hold on a bit cause I have sent out plenty of kits and more reviews will be out soon.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 05 2017 2:31pm

parabellum wrote:
VRUZEND wrote:
May I please know the name with which you placed the order. It will help me relate better. If you dont mind that is.
PM sent.
Thanks!.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 05 2017 3:12pm

fechter wrote:I like the idea of having some kind of spring between the holder and the battery contact. I don't trust the plastic to stay springy for a long time (including zip ties). I like the modularity and ease of assembly. I'd like to see some independent tests by the members here to see how this might perform over a longer term.

My experience with weldless packs is the contacts always go bad after some period of time. Mostly oxidation issues. I'm sure there is something you can coat the surfaces with to prevent oxidation and this has been discussed in other topics. The graphene particle stuff might be good. Plain silicone grease has been used for years with good results on low power connectors. For higher current connections, I'm not sure what the best stuff would be.

Good material selection will also minimize corrosion problems. Avoid dissimilar metal contact. At least with a design like this, you could take everything apart and clean the contacts periodically if necessary. Better if it wasn't necessary though.
I thought I'd use the same product I use on every connector, ACF50. Good for avionics. Should be useful here.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Matador   10 kW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by Matador » Apr 05 2017 4:12pm

VRUZEND wrote: The plated copper variant kit is under works and will be out soon.
^THIS...
I think THIS is the utmost challenge : having a copper plated variant of the Vruzend while still maintaining reliable independant cell springyness....
If you suceed in this, I will bow reverentially and touch your feet.
How many times did I wished I could acheive that level of engeneering !

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by fechter » Apr 05 2017 7:04pm

VRUZEND wrote:
Its not the plastic thats springy but the internal contact inside it. Each time you remove the cell from the cap jut pull the contact upwards and you wont face any contact issues. Thats why the hammering is required too because the cells have to touch the internal contact and having independent spring action for each cell does get a bit trick especially for larger packs.

The material is SS so I dont thinks it will oxidise.
OK, I guess I haven't seen any pictures of how it's built inside. If each contact is spring loaded with the right amount of force, then it should be OK. Stainless is good from a corrosion standpoint. I think most 18650 cells are nickel plated on the outside surface, so using nickel plating would be good. If both metals are the same, it minimizes long term corrosion. I've seen plenty of old battery holders with corrosion and the stainless steel ones seem to hold up the best. At least you can clean and reuse them if something happens.
"One test is worth a thousand opinions"

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 05 2017 7:22pm

For those who purchased the kits, how long did it take to receive?
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Matador   10 kW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by Matador » Apr 05 2017 8:02pm

tomjasz wrote:For those who purchased the kits, how long did it take to receive?
Took DHL, should have it by tomorrow.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 05 2017 9:13pm

Matador wrote:
tomjasz wrote:For those who purchased the kits, how long did it take to receive?
Took DHL, should have it by tomorrow.
argh, didn't consider thst. Sent on the 2nd and tracking hasnt updated. My bad...
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Matador   10 kW

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by Matador » Apr 05 2017 9:53pm

Well DHL is quite high on price. But I already knew that. DHL was 53$ (for 4 kits). But then I have to pay 26.65 CAD Taxes/Brokeage/Customs (21 USD).
I'm usually trying to avoid DHL, UPS and FedEx as much as I can as they really exagerate on the fees here in Canada, but they are quicker than the others.
When I order stuff from USA, I wont even consider these companies that charge almost the price of what the item is worth in shipping + hidden "surprise!" fees.
In USA, I always use USPS and Canada Post, as they only charge for taxes and sometimes a bit of custom fees. No big brokerage fees with them and shipping is more affordable from the get go.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 06 2017 3:22am

tomjasz wrote:For those who purchased the kits, how long did it take to receive?
Hello,
Your tracker will show updates soon. It will take about 20 days for the India post option.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by macribs » Apr 06 2017 3:56am

@fetcher to avoid oxidation/corrosion with the use of copper either for the v2 version of assembly kit or if you customize the v1 of this DIY assembly kit try to get copper with ie nickel coating or other coating that does not introduce galvanic corrosion or increase the resistance. If you can make O2 seal oxidation is not a problem anymore.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 06 2017 12:42pm

Matador wrote:Well DHL is quite high on price. But I already knew that. DHL was 53$ (for 4 kits). But then I have to pay 26.65 CAD Taxes/Brokeage/Customs (21 USD).
I'm usually trying to avoid DHL, UPS and FedEx as much as I can as they really exagerate on the fees here in Canada, but they are quicker than the others.
When I order stuff from USA, I wont even consider these companies that charge almost the price of what the item is worth in shipping + hidden "surprise!" fees.
In USA, I always use USPS and Canada Post, as they only charge for taxes and sometimes a bit of custom fees. No big brokerage fees with them and shipping is more affordable from the get go.
YIKES! That's why I probably didn't choose it. A tough price for a pensioner to pay! So I wait.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by tomjasz » Apr 06 2017 12:45pm

macribs wrote:@fetcher to avoid oxidation/corrosion with the use of copper either for the v2 version of assembly kit or if you customize the v1 of this DIY assembly kit try to get copper with ie nickel coating or other coating that does not introduce galvanic corrosion or increase the resistance. If you can make O2 seal oxidation is not a problem anymore.
Any of the ACF50 type products, Boeshield is another, will do an amazing job of protection. I've had it, or similar in my tool box for decades. There's even some good studies floating around comparing the class of products. Sorry don't mean to keep repeating, just a lot of successes have convinced me. So often products are made with less than ideal myalgic propertied and anti corrosives can save the day.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by VRUZEND » Apr 06 2017 2:19pm

macribs wrote:@fetcher to avoid oxidation/corrosion with the use of copper either for the v2 version of assembly kit or if you customize the v1 of this DIY assembly kit try to get copper with ie nickel coating or other coating that does not introduce galvanic corrosion or increase the resistance. If you can make O2 seal oxidation is not a problem anymore.
The copper supplied will be coated,so it will be resistant towards corrosion.

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emaayan   100 kW

100 kW
Posts: 1450
Joined: May 11 2012 12:47am
Location: israel

Re: DIY assembly kit for 18650 without spot welding/Solderin

Post by emaayan » Apr 07 2017 4:35am

i too just ordered 2 kits,


this the battery i'm planning to make , it's gonna be a14S9P pack, made for 1500w (52v x 30 amps) that eventually will replace em3ev's pack which i'm using for 3 years.
even though vruzend told me to avoid something larger then 14S5P for a beginner, i have no choice, because i don''t like to join packs without balancing, and the bms i've ordered from best-tech-power is 14s, i need one pack to rule them all. so i'l try to do some divide and conquer first.


my reasoning for choosing this kit , is that out of the 129 panasonic pf cells i have 102 are from nkon, but he "cut me off" because his postal service suddenly refused to send to israel, so i acquired from an ebay shop here:
http://www.ebay.com/itm/171676264541?_t ... EBIDX%3AIT

and 20 came from enerdan which i don't recall ordering from (seriously i was rather surprised when they came, i didn't even find any evidence in my mail i ordered them)

because i'm aware there might be issues with mixing cells from different manufactures, i want to ability to go back to a smaller pack in case i'll find issues. spot welding will be much harder to correct.

currently the things i'm most worried about is BMS connections, (you can't soldier the leads, only use the screws ) and heat, i'll have to test that.

i'm hoping to prove this pack is idiot/emaayan proof (how much of an idiot? i almost paid them 221$ cause i mistakenly switched between the number of caps in a kit and the price itself , so 98$ per kit :) )
as some of you might know i'm very good at destroying things due to a number or accidental reasons.

Image
Trek 7.7 fx, 22.5" frame, 38x700c,10 gears.
ecospeed mid drive 1300 watt engine, max speed 45 kph.
battery1: 48v 14 ah, frame mounted battery, range 40km.
battery2(spare) 52v 10ah frame mounted bag, range, 30km.

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