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by spinningmagnets
Apr 25 2019 5:40pm
Forum: Battery Technology
Topic: DIY copper/nickel buses for 18650's
Replies: 10
Views: 300

Re: DIY copper/nickel buses for 18650's

I just remembered that we're not supposed to spot-weld onto the center of the negative ends. Here's my latest version...the red dots are the proposed spot-welds.
BatterySpotweldTab1.png
A
BatterySpotweldTab1.png (6.06 KiB) Viewed 10 times
by spinningmagnets
Apr 25 2019 5:13pm
Forum: Battery Technology
Topic: Samsung 30Q ideal Max/Min Voltages
Replies: 3
Views: 39

Re: Samsung 30Q ideal Max/Min Voltages

I don't have any good references, but from my study of this, I would never go below 3.0V per cell. I have a large pack, so I rarely go below 3.3V per cell. 3.0V to 4.1V is much better than anything outside that operational envelope. 3.3V to 4.0V is better, but narrowing the operational voltages more...
by spinningmagnets
Apr 23 2019 1:22pm
Forum: Battery Technology
Topic: Lithium battery chemistry experts: charging questions.....
Replies: 5
Views: 127

Re: Lithium battery chemistry experts: charging questions.....

I highly recommend to charge to 4.1V as a max. If you Google Jeff Dahn, and making a lithium battery last, he will spell it out with all the details.
by spinningmagnets
Apr 23 2019 1:18pm
Forum: Electric Aircraft
Topic: Manned multirotor
Replies: 14
Views: 1121

Re: Manned multirotor

Looks interesting. I'm looking forward to the improvements you are likely already working on.

If the pilot weighs 180-lb, that also means it could be run pilotless with 100 lb of cargo? Lots of possibilities open up...
by spinningmagnets
Apr 23 2019 9:26am
Forum: E-Bike General Discussion
Topic: Custom salt water electric cargo trike
Replies: 20
Views: 576

Re: Custom salt water electric cargo trike

Do you want to throw money at the problem, or are you willing to put in time and effort to save money? A custom frame out of stainless is going to be pricey. Is a trailer pulled by an ebike an option? Do you especially want a delta trike with the box on the back, or do you want a bikefiets tadpole w...
by spinningmagnets
Apr 23 2019 9:10am
Forum: E-Bike General Discussion
Topic: Parallel packs
Replies: 4
Views: 123

Re: Parallel packs

If you couple two packs, they of course (as dogman said) must be the same voltage. And especially, they must be within 0.1V of the same state of charge / SOC as each other at the first moment you hook them up. after the initial hookup, they will discharge and charge as though they were one big batte...
by spinningmagnets
Apr 22 2019 7:43pm
Forum: E-Bike Technical
Topic: Has anyone used wire as a fuse with the Vruzend kit instead of the busbars for parallel connections?
Replies: 17
Views: 348

Re: Has anyone used wire as a fuse with the Vruzend kit instead of the busbars for parallel connections?

I am about to do some experiments with making fuses, but I don't have any data yet.

The two places I have seen the most data about using wire as fuses is "second life storage" forum, and also "AveRage Joe" channel on youtube.
by spinningmagnets
Apr 22 2019 2:08pm
Forum: Battery Technology
Topic: Copper bus, plating with nickel for spot-welding.
Replies: 7
Views: 235

Re: Copper bus, bonding nickel strip for spot-welding.

Do you have a paypal address?

I'd like 3mm-3.5mm wide strips of copper that have been nickel plated.

At least two inches long, then I can trim them to whatever length works. Do you already know the thickness of the unplated copper?
by spinningmagnets
Apr 20 2019 4:37pm
Forum: Battery Technology
Topic: XT90 connectors stuck
Replies: 9
Views: 319

Re: XT90 connectors stuck

Between the red and black wires, cut only one, and then put tape over the stub on the battery side. Then...cut the other wire. Wire cutters have steel blades, and if you cut both at the same time, it will immediately cause a huge short, and it may damage the battery and/or the BMS. https://www.elect...
by spinningmagnets
Apr 19 2019 11:16am
Forum: Battery Technology
Topic: DIY copper/nickel buses for 18650's
Replies: 10
Views: 300

Re: DIY copper/nickel buses for 18650's

There's a good chance that this won't be worth the time or effort, just an experiment... The initial set will be hand cut with scissors. Even if this works as well as I hope, I doubt there would be enough demand to make it worth ordering some to be laser-cut. But if there was a demand for these, las...
by spinningmagnets
Apr 18 2019 7:25pm
Forum: Battery Technology
Topic: DIY copper/nickel buses for 18650's
Replies: 10
Views: 300

DIY copper/nickel buses for 18650's

I have seen nickel-plated copper sheet on makita, Metabo, etc cordless tool batteries. This gives you the high conductivity of copper, with the easy to spot-weld nickel. It's possible to DIY plate nickel onto copper, but that experiment is for another thread. An idea popped into my head, and this is...
by spinningmagnets
Apr 18 2019 2:45pm
Forum: General Discussion
Topic: Aluminium vs steel contraction when frozen
Replies: 8
Views: 146

Re: Aluminium vs steel contraction when frozen

I've measured steel holes for an interference fit. when you heat up the part, the hole gets bigger.
by spinningmagnets
Apr 17 2019 3:15pm
Forum: E-Bike General Discussion
Topic: Battery Location. Your Opinion Matters!
Replies: 25
Views: 569

Re: Battery Location. Your Opinion Matters!

If you have a lot of power, I prefer the downtube. Both are low, but downtube is more forward.

Also, as stated above, when you hit a big pothole or land a jump, downtube mount seems like it would take force from that direction a little better
by spinningmagnets
Apr 16 2019 6:45pm
Forum: General Discussion
Topic: Bryan Lunduke ( linux nerd ) argues against commercial electric cars
Replies: 11
Views: 281

Re: Bryan Lunduke ( linux nerd ) argues against commercial electric cars

I believe that Teslas will be almost impossible to steal by driving them away, and their GPS tracking can find them even if they were dragged onto a flatbed, to be stripped for body parts like fenders, etc. If someone is running from the police, I suspect that Tesla will be able to slow it down to a...
by spinningmagnets
Apr 16 2019 3:30pm
Forum: Battery Technology
Topic: 18650 spot welding -how to- ULTIMATE REPOSITORY
Replies: 735
Views: 139513

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Makita and several others use nickel-plated copper, and they are spot-welded
by spinningmagnets
Apr 16 2019 9:56am
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 617
Views: 74826

Re: kWeld - "Next level" DIY battery spot welder

I am working on some experiments where copper is bonded to the nickel strips in a separate operation. If your pack design can be satisfied with a 25% increase in conductivity, you might consider trying strips made from yellow brass. And of course I would experiment on old cells that would no longer ...
by spinningmagnets
Apr 16 2019 7:00am
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 617
Views: 74826

Re: kWeld - "Next level" DIY battery spot welder

It is true that Tungsten has a very high melting temperature. As a result, it will not get soft at the tips and begin sticking to the work when using the higher power settings. Be aware it has a higher resistance than copper electrode tips, so Tungsten will get very hot. I would recommend also inves...
by spinningmagnets
Apr 15 2019 10:17am
Forum: E-vents
Topic: Lost Sierra Races 2019, July 12-14
Replies: 5
Views: 381

Re: Lost Sierra Races 2019, July 12-14

Just for general info, the Lost Sierra festival is kit-friendly. You can have a factory ebike, but they like kits too...

This one fact might turn the Lost Sierra into the most innovative event for ebikes...
by spinningmagnets
Apr 14 2019 1:08pm
Forum: Battery Technology
Topic: 7mm 0.15 pure nickel 8A continuous?
Replies: 5
Views: 163

Re: 7mm 0.15 pure nickel 8A continuous?

The common high capacity cells (35E, GA, MJ1) are rated at 10A continuous, however...I consider 10A to be their peak rating, if you want these cells to last a long time. When an ebike accelerates, that is when the pack experiences the peak demand. A 4P pack of 10A cells should be able to provide 40A...
by spinningmagnets
Apr 14 2019 9:31am
Forum: Motor Technology
Topic: Sticky thread index for "Motor Technology"
Replies: 3
Views: 7184

Re: Sticky thread index for "Motor Technology"

CONTROLLER LINKS "Lebowski's motor controller IC, schematic and setup manual" (Lebowski, 48 pages) [plus index in first post, to all Lebowski threads] https://endless-sphere.com/forums/viewtopic.php?f=30&t=36602 Sensorless motor control from a standstill (Lebowski) https://endless-sphere.com/forums...
by spinningmagnets
Apr 11 2019 10:28am
Forum: Items for Sale - New
Topic: 1500W (35mm) V2 DD Hub Motor Group Buy *CLOSED*
Replies: 21
Views: 977

Re: 1500W (35mm) V2 DD Hub Motor Group Buy by Teslanv $200 + Shipping

As a side note, with this amount of power, you don't need as many gears, so I recommend a 6-speed megarange, and simply adjust the stops on your 7-speed derailleur. If you give a modest motor a tough job, it will struggle to get up to top speed, and that means it will spend a lot of time at full amp...
by spinningmagnets
Apr 11 2019 7:24am
Forum: Battery Technology
Topic: How to dismantle a spotwelded battery?
Replies: 14
Views: 333

Re: How to dismantle a spotwelded battery?

There might not be enough series connections, and that is a frequent source of voltage drop under load.
by spinningmagnets
Apr 08 2019 9:53pm
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 617
Views: 74826

Re: kWeld - "Next level" DIY battery spot welder

I have some nickel-plated copper wire (16-ga) that I can use to provide free samples for spot-welding tests When comparing 16-ga round wire to flat ribbon, a slightly smaller size 17-ga is equal to 7mm wide X 0.15mm thick ribbon. However, copper is 4 times more conductive, compared to pure nickel. E...