Search found 458 matches

by garolittle
May 17 2022 10:07am
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

DogDipstick wrote:
May 17 2022 9:54am
Hahaha way to go Gary.
:-). Going for 110 mph this week. This is the only crazy thing I do but it’s really crazy 😜
by garolittle
May 17 2022 8:25am
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

Nice kart! I see a lot of ET to be dropped in shorter gearing my friend. I think you’re right. Will try again this Thursday and hopefully will lower the ET. In theory, I could get a slightly higher TopSpeed since I was no where close to the maximum RPMs with the other sprocket. Definitely will keep...
by garolittle
May 17 2022 12:32am
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

Hillhater wrote:
May 16 2022 9:41pm
You could reduce that time, and increase top speed if you just tilted the seat back to a “laydown” position.
Good point. Might try that. Thanks.
by garolittle
May 15 2022 8:16pm
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

Can you share the 60ft, 330ft, and 1/8th? Yes sir. Here you go. These times were not so good. Going to try a larger sprocket on the rear axle to improve the lower end acceleration. I am still accelerating at the 1/4 mark so I believe I can keep the same top speed and improve the lower end accelerat...
by garolittle
May 15 2022 4:45pm
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

Cells are connected with .25mm thick pure copper sheets.
AE9705B9-4292-4BBD-BC39-64F0011E9D0E.jpeg
AE9705B9-4292-4BBD-BC39-64F0011E9D0E.jpeg (3.16 MiB) Viewed 133 times
by garolittle
May 15 2022 3:49pm
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

Re: 107mph go kart on 28S/18P pack of Molicel P26A

Possible to show a vid that is visible to non-facebookers? Yes sir. It’s actually good to know that not everyone is on Facebook. I need to do the same :-). Here’s the last few seconds of 105 mph run. https://youtu.be/P5kUjMHM3Qs 736035D3-77BE-461F-A410-9FE624755717.jpeg 9905CA10-8B84-4619-A0B8-ABD7...
by garolittle
May 14 2022 5:47am
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

107 mph electric go kart

32CBDD6C-6315-46CF-BED2-BD31290CBE1D.jpeg
32CBDD6C-6315-46CF-BED2-BD31290CBE1D.jpeg (236.33 KiB) Viewed 137 times
by garolittle
May 13 2022 11:23pm
Forum: Battery Technology
Topic: 107mph go kart on 28S/18P pack of Molicel P26A
Replies: 12
Views: 280

107mph go kart on 28S/18P pack of Molicel P26A

107 mph electric gokart at the dragstrip…. https://www.facebook.com/247184812650883/posts/985572405478783/?d=n Components: AC-9 motor from HPEVS 1238E controller (650A max) 28S/18P lithium ion battery pack consisting of Molicel P26A cells connected with .25mm pure copper bus bars (pack assembled by ...
by garolittle
Apr 03 2022 5:31pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 550
Views: 103603

Re: Spot Welding Copper Strips to 18650 Battery Cells

Actually the PA250i can spot weld .40mm thick cooper.

https://youtu.be/mqJaKNb8L5M
by garolittle
Apr 02 2022 11:53pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 550
Views: 103603

Re: Spot Welding Copper Strips to 18650 Battery Cells

Copper (tabs) direct to cans!!! https://sunstonewelders.com/products/battery-welder-systems/omega-pa250i-copper-battery-tab-welder Sunstone is awesome. I purchased their PA250i and I can spot weld .25mm thick pure copper directly to cylindrical lithium cells. See video link below… https://youtu.be/...
by garolittle
Nov 10 2021 12:20am
Forum: Battery Technology
Topic: LiFePO4 voltage drop question
Replies: 4
Views: 249

Re: LiFePO4 voltage drop question

BVH wrote:
Nov 09 2021 8:53pm
All of the LFP cells I have used fall to about 3.45 VPC plus or minus, soon after charging. Whether charged to 3.5, 3.55 or 3.6VPC, the results are the same.
Excellent info. Thanks for the response
by garolittle
Nov 10 2021 12:11am
Forum: Battery Technology
Topic: LiFePO4 voltage drop question
Replies: 4
Views: 249

Re: LiFePO4 voltage drop question

e-beach wrote:
Nov 09 2021 9:42pm


How long do you leave them on the charger?

:D :bolt:
Basically I just waited until the packet 54 V. At that point the cells were properly top balanced so I turned off the charger. Really appreciate your response. :thumb:
by garolittle
Nov 09 2021 3:00pm
Forum: Battery Technology
Topic: LiFePO4 voltage drop question
Replies: 4
Views: 249

LiFePO4 voltage drop question

Question for the experts. I have a 15S/30P configuration of lithium iron phosphate (LiFePo4) cells. These are cylindrical K2 cells which I have connected with a spot welder. I carefully checked the voltage of each cell before spot welding and all cells were within an acceptable voltage range of each...
by garolittle
Oct 17 2021 7:01pm
Forum: Items for Sale - New
Topic: 48V - 80V Ashwoods Dana TM4 Internal Permanent Magnet IPM
Replies: 2
Views: 528

48V - 80V Ashwoods Dana TM4 Internal Permanent Magnet IPM

Ashwoods Dana TM4 Internal Permanent Magnet IPM Model: IPM-200-50 Brand new/Never used $1,300 (Buyer pays shipping) Originally paid $1,750 and these motors are on six-month back order Incredibly efficient motor (94%) Voltage: 48V - 80V Peak Torque @ 350Arms 74Mn IP65 24mm Keyed Max RPMS: 8,500 Weigh...
by garolittle
Oct 12 2021 4:57pm
Forum: Battery Technology
Topic: Quick question about pack design idea
Replies: 12
Views: 485

Re: Quick question about pack design idea

john61ct wrote:
Oct 12 2021 4:20pm
garolittle wrote:Sunstone Pulse Arc Welder PA 250i …. https://sunstonewelders.com/products/ba ... tab-welder
Wow! pricing ballpark?
$25k
by garolittle
Oct 12 2021 2:38pm
Forum: Battery Technology
Topic: Quick question about pack design idea
Replies: 12
Views: 485

Re: Quick question about pack design idea

Please link to sources for factory-new cells, not secondhand/dismantled. How close are the LFP 32700? Also link to the "pulse arch welder"? Hard to believe it can weld the copper directly, no nickel in between? Is there much vertical gap between cell end surface and copper sheet, height o...
by garolittle
Oct 12 2021 2:25pm
Forum: Battery Technology
Topic: Quick question about pack design idea
Replies: 12
Views: 485

Re: Quick question about pack design idea

Also link to the "pulse arch welder"? Hard to believe it can weld the copper directly, no nickel …. Answer: Sunstone Pulse Arc Welder PA 250i ….where is the link https://sunstonewelders.com/products/battery-welder-systems/omega-pa250i-copper-battery-tab-welder I will have to get you the r...
by garolittle
Oct 12 2021 12:36pm
Forum: Battery Technology
Topic: Quick question about pack design idea
Replies: 12
Views: 485

Quick question about pack design idea

Question for the experts: Assume the use of 32650 Lithium Iron Phosphate (LiFePO) Cells. The cells do not have the original plastic a ring gasket but will be re-wrapped with have a paper “stick-on O-ring gasket” (see green arrow below) as well as a 3-D printed gasket (red arrow below) that will sit ...
by garolittle
Oct 11 2021 11:37pm
Forum: Battery Technology
Topic: Paper or Plastic ... O-ring gasket for cylindrical lithium ion cells
Replies: 2
Views: 262

Re: Paper or Plastic ... O-ring gasket for cylindrical lithium ion cells

liveforphysics wrote:
Oct 11 2021 3:38pm
Paper/fiber washers generally have the best mechanical cut-through resistance and vibration chaffing performance…..
Thanks sir. I really appreciate your response.
by garolittle
Oct 11 2021 2:07pm
Forum: Battery Technology
Topic: Paper or Plastic ... O-ring gasket for cylindrical lithium ion cells
Replies: 2
Views: 262

Paper or Plastic ... O-ring gasket for cylindrical lithium ion cells

Question for the experts … If a cylindrical lithium ion cell does not have any wrapping or the white plastic O-ring gasket that goes in it, could you put a paper O-ring gasket in it rewrap it and expect it to be just as safe as the original set up? A .25mm thick copper sheet will be spot welded to t...
by garolittle
Jul 14 2021 6:37pm
Forum: Battery Technology
Topic: Acceptable voltage difference in 22S/22P lithium ion pack?
Replies: 8
Views: 337

Re: Acceptable voltage difference in 22S/22P lithium ion pack?

I believe I found what may be the issue. The last cell in row 22 had a “questionable weld“ so I removed it. That particular lithium ion on cell was at about 3.7 V. That is likely culprit since it was probably dragging down the voltage for the entire row of cells. I removed the 22nd cell in each row ...
by garolittle
Jul 11 2021 5:51pm
Forum: Battery Technology
Topic: Acceptable voltage difference in 22S/22P lithium ion pack?
Replies: 8
Views: 337

Re: Acceptable voltage difference in 22S/22P lithium ion pack?

22p is a huge pack. I doubt the BMS current draw would be enough to bring the end cell down that much. I would double check with a voltmeter directly to the cells if possible…. If you do the math on how much % state of charge that voltage difference represents, I suspect it won't be more than a few...
by garolittle
Jul 11 2021 10:53am
Forum: Battery Technology
Topic: Acceptable voltage difference in 22S/22P lithium ion pack?
Replies: 8
Views: 337

Re: Acceptable voltage difference in 22S/22P lithium ion pack?

goatman wrote:
Jul 10 2021 9:40pm
is that the group that powers the bms?
Good question. I’m checking with the manufacturer to see if the BMS is powered by the last row of cells