Search found 911 matches

by Matador
Oct 29 2016 5:28pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

I suspect a 0.5 mm copper layer on that 0.9 mm spring wire may just restrict the spring action more than a little ? Have you considered using some short pieces of heavy copper braid inside the spring ? Maybe soldered each end ? Your're right. 0.5 thickness plating would make the wire 1.9 mm diamete...
by Matador
Oct 29 2016 3:36pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Checked on the internet... Seems like electroplating of copper has been done to up to 1/4 inch thickness in the past (6350 microns) in the past http://www.finishing.com/240/62.shtml 6350 microns would make my springsteel wire go from 0.9 mm diameter thick to 12.7 mm thick LOL (equivalent of 0000 AWG...
by Matador
Oct 29 2016 1:47pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

I think I'm going to try to copper-plate the springs... Gotta make copper acetate first though. But even if I do 30 microns thickness plating, i'm not sure It'll make a such big difference in conductivity on thoses springs (the springsteel nickel 0.9 millimeter diameter and 19 cm long). According to...
by Matador
Oct 29 2016 10:55am
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

9-10V sag is way too much. My 13s20p is overkill for 1000w hub. It only sags 2-4volts while drawing 40-60 amp ~ 2800w full throttle on startups !! I doubt my battery generate any significant heat since the thermal probe is on the BMS heatsink, but the fan sure cool it down very quickly. Fan has its...
by Matador
Oct 29 2016 10:39am
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 318
Views: 55657

Re: Common pack design mistakes, how to avoid?

I tried experimenting a bit with copper to make more conductive springs.... Not easy ! Here's some pics Feel free to make suggestions if you know of any good high amp springs I coud use.... (I need at least 182 of them for my 14S13P) PS : for some reason, some pics don't appear... you have to click ...
by Matador
Oct 29 2016 10:15am
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 318
Views: 55657

Re: Common pack design mistakes, how to avoid?

Matador, Congrat for your built, it is well made for a spring type conection. the serie link are correct because the copper bus bar that you have to link all cells of the parallel groups are very conductive compare to the sum of all the spring per row that you have.. i mean you probably have alot o...
by Matador
Oct 28 2016 10:50pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Cool, as you likely know that is the main source of your heat and sag. I used a salvage laptop sourced pack for a time while my main pack was being assembled. With a 1kW pack @600W(12A?) I would expect a very minor heat increase even with used laptop cells. Keep us posted :D Thanks, that's good to ...
by Matador
Oct 28 2016 5:50pm
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 318
Views: 55657

Re: Common pack design mistakes, how to avoid?

So YES current share and thermal management ARE IMPORTANT :wink: and if well made the pack last longer. I went completly artisanal on this one. It's my first build and I'm more an amateur neophyte than an expert like you. Asides from the springs in my build (I plan to modify that), Are my series co...
by Matador
Oct 27 2016 9:45pm
Forum: Battery Technology
Topic: Ampacity?
Replies: 35
Views: 3666

Re: Ampacity?

As you can see by resistivity values on the wikipedia, aluminium is also a great conductor, but indeed a bit more fragile. Also aluminium can be a PITA to weld, necessitating special techniques (since aluminium oxidises as soon as it enters in contact with air, even more so when it is heated, alumin...
by Matador
Oct 27 2016 9:11pm
Forum: Battery Technology
Topic: Ampacity?
Replies: 35
Views: 3666

Re: Ampacity?

anyone have the formula on hand or in head for figuring the wattage lost to heat in a wire? copper preferably. based on wire resistance, length, and amps is all I think. P = dV x I (where P is power lost in heat as Watts, dV is the voltage drop in volts and I is the current going through the wire i...
by Matador
Oct 26 2016 3:54pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Yes, the springs are in the conductive path. Probably the "weakest link" in my battery build... I will need to address that issue in the future. I plan to use copper or brass piece to fit at the end of the springs (probably by soldering), and wire the piece to the bussbar bolt through a thick enough...
by Matador
Oct 26 2016 3:20pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

I'm also currently in the process of Nickel electroplating my copper bussbars so they don't oxidise anymore. In that way, I keep the amazing conductive properties of copper, but with the thin Nickel layer, I wont get copper oxide formation on the surface to create additionnal resistance over time. H...
by Matador
Oct 26 2016 2:58pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Hi. How is your pack constructed? Nickel tabs used for series? In my case, I'm using all copper bus bars made of flattened copper pipes. See my post for photos : https://endless-sphere.com/forums/viewtopic.php?f=14&t=57810&start=150#p1213147 As you can see I also use brass (65% copper alloy I think...
by Matador
Oct 25 2016 5:14pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

It's tempting to say that if a pack is making a lot of heat during normal discharge use then the cells are inappropriate for the application. Active cooling will help keep them cool but doesn't stop the waste of stored energy being converted to heat in the first place. When a high energy density ce...
by Matador
Oct 25 2016 5:07pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Heres some good info on battery capacity and discharge temp http://www.che.sc.edu/faculty/white/2002CapacityFade%20ofsonPart%201%20RamadassHaranWhitePopov.pdf I keep my latest pack open and not shrinked wrapped or duct tape, it stays atleast 10*C less and cool down much quicker. I also been experim...
by Matador
Oct 24 2016 10:01pm
Forum: Battery Technology
Topic: modular Battery box for 18650
Replies: 25
Views: 3720

Re: modular Battery box for 18650

I had a similar idea except with 13 cell in each module : https://endless-sphere.com/forums/viewtopic.php?f=14&t=57810&start=150 250 euros for 4 empty units (sold as starter kit)... So an empty 32 cell battery box for 250 euros.... Way to expensive :shock: The springsteel contacts they use also seem...
by Matador
Oct 23 2016 9:20pm
Forum: E-Bike General Discussion
Topic: How To, 50A BBSHD Controller Mod
Replies: 247
Views: 47174

Re: How To, 50A BBSHD Controller Mod

Same here. Subscribed ! The thing is, more amps means more torque which is good (assuming we refrain from using that extra torque in steep hills with tough gears, where the already pushed to the edge motor would possibly start overheating or burning) ... But top speed would still be the same since v...
by Matador
Oct 23 2016 4:59pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Search the forum, this has all been done before and the data posted. Generally a "good" 18650 cell like the Samsung 25R will have a DCIR of 25-30 mohm. But it will vary depending on many factors like SOC, Temp, etc etc Also there are independent sites that have lists of performance data for ALL 186...
by Matador
Oct 23 2016 2:51pm
Forum: Polls & Surveys
Topic: Your Whours for kms
Replies: 33
Views: 20743

Re: Your Whours for kms

BBSHD on a 14S9P Lithium cobalt made of old laptop 18650 that heat up like hell. Bike : 700C wheels, 46T chainring, 14T rear gear, tyres to 70 PSI, bike weight (with motor kit and battery) 67 lbs, me 155 lbs Did 17 km with 524 Whr averaging 28 km/h (lot of wind in my face because riding on the borde...
by Matador
Oct 23 2016 12:04pm
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

For sake of comparison Can anybody measure the internal DC resistance of a fresh, high-amperage rated 18650 cells and post their results here ?? (like the Samsung 18650 30Q 3000mAh - 15A , the LG 18650 HG2 3000mAh - 20A , the SANYO NCR18650GA 3300mAh - 10A , the Panasonic NCR18650PF 2900 mAh - 10A ,...
by Matador
Oct 23 2016 11:50am
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Just to be thourough, I forgot to say. After these 30 km rides. I stopped riding not because my battery was empty, but because it was getting hot ! After these 6 equivalent 30 km trips , my cells were generelly between 3.72 to 3.80 Volts...So around 52 to 53 volts for the 14S pack... So I figured th...
by Matador
Oct 23 2016 11:15am
Forum: Battery Technology
Topic: Acceptable internal resistance values on 18650 cells
Replies: 43
Views: 21956

Re: Acceptable internal resistance values on 18650 cells

Something like a 1-2 Ohm resistor across the cell while measuring voltage sag (with a real DMM, at least 4.5digits) after 5 seconds is a much more meaningful value with respect to selecting them and matching them for building a pack. I did some DC internal resistance tests myself with a 3.7 Ohm res...
by Matador
Oct 20 2016 8:10pm
Forum: E-Bike Non-hub Motor Drives
Topic: Ultimate BBSHD Grin Phase Runner FOC 3000W
Replies: 179
Views: 35105

Re: Ultimate BBSHD Now on 88V bring it on the powerrrr!

I'm sure that this Phase Runner could be fitted in the original BBSHD controller aluminium bolt-on encasing... If it could only be compatible with the Bafang PAS system and the Bafang speedometer, break inhibitors, gearshift sensor and throttle controller :roll: that would be the perfect solution......
by Matador
Oct 19 2016 4:52pm
Forum: E-Bike Non-hub Motor Drives
Topic: Ultimate BBSHD Grin Phase Runner FOC 3000W
Replies: 179
Views: 35105

Re: Ultimate BBSHD Now on 88V bring it on the powerrrr!

This is amazing. I was following your channel on YouTube, but Seb from Luna told me you were here on ES. I agree with the post I've seen before on this thread : I think that Karl blew up is BBSHD at 65A because he was using a square wave controller. I'm under the impression that a Sine wave controll...
by Matador
Aug 22 2016 10:36pm
Forum: Battery Technology
Topic: Thread for new battery breakthrough PR releases
Replies: 1650
Views: 238044

Re: Thread for new battery breakthrough PR releases

Salut DoctorBass, just un ptit hello de Québec pour dire que je suis tes post et tes videos youtube. C'est vraiment tres formateur. Hi DoctorBss, just a little post to say Hello from Québec City and to say that I follow your posts and your youtube videos. It's really educative ! Thanks bro, pout tou...