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by spinningmagnets
Jun 03 2019 9:08pm
Forum: E-Bike Technical
Topic: Proposal for soldering onto the negative end of 18650s
Replies: 4
Views: 256

Proposal for soldering onto the negative end of 18650s

The positive nipple of an 18650 / 21700 is very robust and can be reliably spot-welded or even soldered. However, the negative end is sensitive to heat. I know that billions of cells have been spot-welded by industry, but of course they are done by very expensive machines that provide very precise a...
by spinningmagnets
Jun 03 2019 5:51pm
Forum: E-Bike General Discussion
Topic: Ok, I bent the new rim... Looking for a stronger rim.
Replies: 10
Views: 674

Re: Ok, I bent the new rim... Looking for a stronger rim.

20-inch bicycle rim is the same diameter as a 16-inch moped rim...maybe an option.
by spinningmagnets
Jun 02 2019 12:27pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 217
Views: 34521

Re: Spot Welding Copper Strips to 18650 Battery Cells

Here's a video about spot-welding aluminum, using this trick of making a steel sheetmetal sandwich with the aluminum in the center. Start at 1:11

https://youtu.be/gcgC3V3mkcw?t=71
by spinningmagnets
Jun 01 2019 6:52pm
Forum: Battery Technology
Topic: Mapping current through high-amp bus materials (spot welding)
Replies: 2
Views: 201

Re: Mapping current flow through high-current buse materials

Now, I have to wonder what the cost would be, of 8mm wide stainless steel ribbon @ 0.10mm-1.15mm thickness as the "cap" layer...

...since it would not hurt conductivity, and it would facilitate an easy spot-welding process for the DIY battery pack builder...
by spinningmagnets
Jun 01 2019 4:51pm
Forum: Battery Technology
Topic: Mapping current through high-amp bus materials (spot welding)
Replies: 2
Views: 201

Re: Mapping current flow through high-current buse materials

Here is a pic of "dimpled" nickel buses. I don't know if they have a copper core. If we use dimples on our DIY buses, then the coppers high conductivity doesn't matter, because the spot-welding current direction only has one contact point to flow through. SpotWeldingCopper7.png SpotWeldingCopper6.pn...
by spinningmagnets
Jun 01 2019 4:50pm
Forum: Battery Technology
Topic: Mapping current through high-amp bus materials (spot welding)
Replies: 2
Views: 201

Mapping current through high-amp bus materials (spot welding)

I am now convinced more than ever that the positive end of an 18650 / 21700 cell can take quite a bit of abuse. However, the negative end is sensitive to heat, with the most common culprit being a high-watt soldering iron. I accept that the BEST method is ultrasonic wire-bonding (Tesla, Alta, LunaWo...
by spinningmagnets
Jun 01 2019 1:09pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 217
Views: 34521

Re: Spot Welding Copper Strips to 18650 Battery Cells

I'm looking forward to retirement, because then I would have had the time to perform dozens of experiments that have been on the back burner for a couple years. Making a sandwich of copper/nickel is affordable and easily done with existing supply-line materials. DIY nickel-plated copper? what thickn...
by spinningmagnets
May 31 2019 11:33pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 217
Views: 34521

Re: Spot Welding Copper Strips to 18650 Battery Cells

Don't know if this is legit, but it appears intriguing. Earlier in this youtube, he shows that he has a FET bundle (75 FETs) as the on/off switch. Probably way too many, but if you have a pile laying around, why not? The 12V timer is powered by three 18650 cells in 3S / 1P (the red cells in the back...
by spinningmagnets
May 31 2019 10:21am
Forum: Battery Technology
Topic: Another No Solder/Weld 18650 Build (Updated 03/09/2014)
Replies: 344
Views: 61308

Re: Another No Solder/Weld 18650 Build (Updated 03/09/2014)

Luke / LFP discusses the specifics of how heat on an 18650 cell affects the insides (the common method of spot-welding nickel buses onto the cell-ends)

https://endless-sphere.com/forums/viewt ... 2#p1450141
by spinningmagnets
May 31 2019 8:55am
Forum: Battery Technology
Topic: Cheap spot welder or DIY CD welder?
Replies: 5
Views: 243

Re: Cheap spot welder or DIY CD welder?

The Malectrics and kWeld seem to be the most popular.
by spinningmagnets
May 29 2019 8:09am
Forum: E-Scooter and Motorcycle General Discussion
Topic: Does a cheap DC-DC converter have significant parasitic draw?
Replies: 11
Views: 363

Re: Does a DC-DC converter have significant parasitic draw?

This is a good question, and I will also be looking for the answer. however, have you considered adding a switch to the input, so you can have the DC/DC converter off when it is not in use?
by spinningmagnets
May 28 2019 8:08pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Electra e-cruiser build
Replies: 4
Views: 385

Re: Electra e-cruiser build

Looks like a plush ride...
by spinningmagnets
May 25 2019 6:42pm
Forum: Battery Technology
Topic: refidgerating cells?
Replies: 10
Views: 411

Re: refidgerating cells?

Performance is best when the cells are warm. In fact, 1/4-mile drag racers heat-up their battery packs before a run. That being said, they know ahead of time that they will be getting very few runs per pack. For long life, store the cells at somewhere around 3.3V per cell, and keep them cool. You ca...
by spinningmagnets
May 25 2019 11:06am
Forum: Alternative Energy
Topic: Inverter recommendations, 48V sine wave, no grid tie
Replies: 15
Views: 635

Re: Inverter recommendations, 48V sine wave, no grid tie

Occasionally my life conditions have forced me to purchase "affordable" products. That being said...during those times when I have been doing well, I have never regretted buying a high-quality name-brand product. The "Outback" brand recommendation is a new one to me, and I will remember it. Samlex a...
by spinningmagnets
May 25 2019 10:31am
Forum: Battery Technology
Topic: Panny or Sanyo?
Replies: 44
Views: 1258

Re: Panny or Sanyo?

I am also hearing good things about the LG MJ1, as an option...
by spinningmagnets
May 25 2019 10:27am
Forum: Battery Technology
Topic: what 18650 brand cells are best for this application 36v 500watt needs to be 10s6p
Replies: 1
Views: 154

Re: what 18650 brand cells are best for this application 36v 500watt needs to be 10s6p

36V from 500W is only 14A from the entire pack. Since you plan on a medium-sized 10S/6P pack, this is only 2.3A per cell. You have many options. Only charge to 4.1V per cell, 10S X 4.1 = 41.0V If you want max range, the current leaders are LG MJ1, Samsung 35E, and Panasonic GA (roughly 3400-mAh each...
by spinningmagnets
May 24 2019 8:54pm
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 751
Views: 87584

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

ride the lightning, I don't know if carbon tips would work, but I have some for experiments. PM me your address and I'll send you a couple.
by spinningmagnets
May 24 2019 6:38pm
Forum: Alternative Energy
Topic: Inverter recommendations, 48V sine wave, no grid tie
Replies: 15
Views: 635

Re: Inverter recommendations, 48V sine wave, no grid tie

Thanks for the info! I think a lot of people will find that data useful... If nobody has a strong warning against this, or a strong recommendation for something else, I am likely to order the Meanwell TS-1500-148A (TS=true sine wave, 1500W, 1=120VAC output, 48=48V input-63V max, A=USA sockets https:...
by spinningmagnets
May 24 2019 10:51am
Forum: Alternative Energy
Topic: Inverter recommendations, 48V sine wave, no grid tie
Replies: 15
Views: 635

Re: Inverter recommendations, 48V sine wave, no grid tie

Even though yours are all 12V, could you please tell everyone what your 12V advice is, since it sounds like you have a lot of experience...

I may even get at least one 12V inverter as a backup...
by spinningmagnets
May 23 2019 6:57pm
Forum: E-vents
Topic: Lost Sierra Races 2019, July 12-14
Replies: 49
Views: 2194

Re: Lost Sierra Races 2019, July 12-14

I'll bump this once a month until the event...
by spinningmagnets
May 23 2019 6:50pm
Forum: Alternative Energy
Topic: Inverter recommendations, 48V sine wave, no grid tie
Replies: 15
Views: 635

Inverter recommendations, 48V sine wave, no grid tie

So far I have brand names of... Aims Xantrex Samlex Meanwell There is a youtube video that persuaded me that I would need a 1500W-rated unit to run a full-sized home refrigerator, due to a high start-up surge. During a temporary power outage, I might only need 1000W more to run TV, a couple lights, ...
by spinningmagnets
May 23 2019 11:47am
Forum: Battery Technology
Topic: DIY spot-welder, FET-switched, processor-timed adj. pulse
Replies: 611
Views: 57955

Re: DIY spot-welder, FET-switched, processor-timed adj. pulse

Ridethelightning, when soldering components onto a thick copper bus, you might consider a DIY RSU made from a 1000W microwave oven transformer...
by spinningmagnets
May 22 2019 2:15pm
Forum: Battery Technology
Topic: end cells always fail first, why?
Replies: 15
Views: 774

Re: end cells always fail first, why?

There are so many factors to consider. I fully charge my packs on occasion so the balancing function engages, but most of the time I charge to 4.1V per cell, instead of 4.2V, so...have you noticed this phenomenon mostly on packs charged to 4.2V? Is is more often the positive end or the negative? (Or...
by spinningmagnets
May 20 2019 4:26pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Affording a powerful battery
Replies: 15
Views: 655

Re: Affording a powerful battery

You might consider Chevy Volt cells as an option, although there might be difficulties in finding them to buy, and then finding an acceptable way to assemble them.