Search found 916 matches

by Matador
May 28 2019 3:47pm
Forum: Battery Technology
Topic: mega copper battery spotwelder
Replies: 21
Views: 1808

Re: mega copper battery spotwelder

Wow ! I want to see this !!! You will need extremly high power compared to nickel.... Basically you need a pulsed TIG welder like the Orion Sun Ev welder ! I don't have experience personally. Your like Niel Amstromg, the first man to walk on the moon! Haven't seen anyone get as serious as you with t...
by Matador
May 28 2019 3:41pm
Forum: Battery Technology
Topic: Spacer/Holder for 21700 cells
Replies: 11
Views: 1523

Re: Spacer/Holder for 21700 cells

What are your power density requirements (in Watts per kg of battery and Watts per liter of battery) ? What are you energy density requirements (in Wh per kg of battery and Wh per liter of battery)? In general i would go for NMC. But if you ne crazy power from a relatively small battery, if you need...
by Matador
May 28 2019 3:22pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

The price on 21700 will continue to decline as it becomes more and more popular... But to compare cycle life of two different cells, you need to discharge with the same ratio (ratio=cycling C-discharge rate choosen / max rated C-discharge rate of a given cell). For example discharge both different c...
by Matador
May 28 2019 3:04pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

nice stats, but they do show the weakness of those bigger cells, they cant handle abuse unlike the 18650... What makes you think that they are weaker than 18650 ? because 18650's generally wear out less fast then that and are cheaper per Wh. I agree that Price per Wh is higher. However I think that...
by Matador
May 24 2019 9:04pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

flippy wrote:
May 24 2019 4:23pm
nice stats, but they do show the weakness of those bigger cells, they cant handle abuse unlike the 18650...
What makes you think that they are weaker than 18650 ?
by Matador
May 23 2019 6:59pm
Forum: Battery Technology
Topic: Powerful inside-frame battery
Replies: 15
Views: 970

Re: Powerful inside-frame battery

The inside of your battery would most likely look like mine. Carefully review my thread on this Ancheer eBike. I posted tons of pictures for reference. Here is the link : https://endless-sphere.com/forums/viewtopic.php?f=2&t=93576 But I must say... I think a 1.5 kWh motor-controller setup on this i...
by Matador
May 22 2019 11:35pm
Forum: Battery Technology
Topic: end cells always fail first, why?
Replies: 15
Views: 1434

Re: end cells always fail first, why?

I'd say all of the above I think play a roll. Unequal current sharing if using too resistive conductors. Heat more promient at the deep core of battery (can't dissipate as easily), kind of depends on battery geometry too. Cheap BMS with unequal parasitic quiescent current drain Use of unmatched cell...
by Matador
May 22 2019 11:29pm
Forum: Battery Technology
Topic: 14s2p Minicube w/ 21700 batteries
Replies: 5
Views: 661

Re: 14s2p Minicube w/ 21700 batteries

Thanks - that was what I was thinking. Hopefully there will be a high discharge 21700 cell in the future, I love the small size of the minicube but would also like a little more capacity. This battery is close, but not suitable for a hill climber. Check out the Samsung 40T 21700 cells. Seems promiz...
by Matador
May 22 2019 11:23pm
Forum: Battery Technology
Topic: Actual Test of Pure Nickel Heat?
Replies: 24
Views: 1280

Re: Actual Test of Pure Nickel Heat?

voltage drop is not the metric one should focus on, temperature is key. as long as the strip remains below 60ish degrees the standard aliexpress ABS cell holders and cell wrap wont lose strength or warp. you can bump this a bit if you use that green paper rings as extra insulation. personally i wou...
by Matador
May 22 2019 11:15pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

I agree with you as well Matador! :wink: The reason, why I bought a frog battery, based on the 21700 M50 from LG Chem, is because I use at 48V a motor (Tongsheng TSDZ2) with 250W. On 13S3P I have around 1,80A - 2,20A CDR on every cell...and I ride my bike in the city...and it is really flat (Hannov...
by Matador
May 22 2019 11:05pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

Just few remarks : 1) Zeroair finished measurement at 2,8 V. Discharging down to 2,5 V according specification is giving capacity nearly 5 000 mAh in the range 1 – 5 A. ( equipment : calibrated ZKETECH EBC A-10H, BF-2A fixture, 25 ±1 °C) Samsung 21700 - 50E f.jpg 2) Frankly, Zeroair measurement see...
by Matador
May 22 2019 11:43am
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

I think the INR21700-40T is very interesting in small dimensions of batteries like 10S2P, or 10S3P. I daubt it, if the 50E, or M50 will have more Wh at this configuration on 250W-350W motors?! I agree... Even if the 50E is supposed to be a 5000 mAh 21700 cell, that's probably only true at very low ...
by Matador
May 22 2019 12:39am
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

Still, the samsung 40T kicks ass. 60% residual capacity after 250 cycle when discharging it at 35A!!, without temperature cutoff.... Capture.JPG I mean, they sure as hell last reall long if you only pull 10A/cell on them from time to time... Wheras I really would'nt bet anything on the samsung 50E a...
by Matador
May 22 2019 12:23am
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

Agreed My VTC4 are rated for 30A, but I don't wan't to use them over 10A. So for the Samsung 40T, same thing, would'nt push past 10A. I don't think anybody ever got 300 cycle by pulling 30A continous out of VTC4 18650's in a large pack either. Plus the VTC4 were tested for cycle life with a 75 degre...
by Matador
May 22 2019 12:17am
Forum: Battery Technology
Topic: Actual Test of Pure Nickel Heat?
Replies: 24
Views: 1280

Re: Actual Test of Pure Nickel Heat?

So voltage drop, heat production all depend on resistance, gauge used, conductive metal type and lenght, for a given maximal tolerable voltage drop... is what I understand from all this.... How do we define what is an acceptable voltage drop for our EV application... Is their a sort of consensus ? I...
by Matador
May 22 2019 12:06am
Forum: Battery Technology
Topic: Actual Test of Pure Nickel Heat?
Replies: 24
Views: 1280

Re: Actual Test of Pure Nickel Heat?

Here are my original excel files
Metal Strips Ampacity & Resistances by Matador.xlsx
(87.62 KiB) Downloaded 25 times
by Matador
May 22 2019 12:01am
Forum: Battery Technology
Topic: Actual Test of Pure Nickel Heat?
Replies: 24
Views: 1280

Re: Actual Test of Pure Nickel Heat?

That is soo cool. I'll add my table to this:Ampacity (Powestream extrapolation).jpg In my table that same 0.8 mm wide x 0.15 mm thick pure nickel strip is rated 4.9A, which is about 5 degree celcius above room temp judging from your graph... what is your derating factor? temperature? if so what the...
by Matador
May 21 2019 11:55pm
Forum: Battery Technology
Topic: Actual Test of Pure Nickel Heat?
Replies: 24
Views: 1280

Re: Actual Test of Pure Nickel Heat?

Yes, I've done testing: https://i.imgur.com/mIOKzth.png That is soo cool. I'll add my table to this: Ampacity (Powestream extrapolation).jpg In my table that same 0.8 mm wide x 0.15 mm thick pure nickel strip is rated 4.9A, which is about 5 degree celcius above room temp judging from your graph... ...
by Matador
May 21 2019 11:47pm
Forum: Battery Technology
Topic: end cells always fail first, why?
Replies: 15
Views: 1434

Re: end cells always fail first, why?

Could also be that some cheap BMS have unequal quiescent current drain, sometimes on the first cell in the series of cells... Sometimes it's the first three cells. Same thing with the CellLog from progressive RC, display and electronic are powered by battery it monitors, but the device does not drai...
by Matador
May 21 2019 11:43pm
Forum: Battery Technology
Topic: Is PCM good enough to replace BMS?
Replies: 13
Views: 1726

Re: Is PCM good enough to replace BMS?

Here is an example from the "BesTech Power" website... Example of Model HCX-D131A... You can buy the whole BMS (PCM+Balancing board): 201211422736929.jpg Link: http://www.bestechpower.com/518v14spcmbmspcbforli-ionli-polymerbatterypack/PCM-D131.html Or you can buy just the "Balancing board" part of t...
by Matador
May 21 2019 11:24pm
Forum: Battery Technology
Topic: Is PCM good enough to replace BMS?
Replies: 13
Views: 1726

Re: Is PCM good enough to replace BMS?

PCM is wired to cells in series. PCM applies LVC (low voltage cutoff): when one cell is getting too low, PCM shuts down the whole battery. No more discharge... neither the battery asa whole, nor any cells that constitute the battery will be allowed further discharge. Even is they are imbalanced. PCM...
by Matador
May 21 2019 11:02pm
Forum: Battery Technology
Topic: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E
Replies: 65
Views: 4209

Re: Panasonic/Sanyo NCR20700B vs Samsung INR21700-50E

flippy wrote:
May 16 2019 10:08am
you are not going to get any decent cycle life on any of the 2xx cell form factors, not yet anway. if you want hard cycle life you need to dial it back to 18650 and stay under 3000mAh.
What about Samsung 30T 21700 : 3000 mAh rated 35A
and the Samsung 40T 21700: 4000 mAh rated 30A...
by Matador
May 21 2019 10:58pm
Forum: Battery Technology
Topic: 14s2p Minicube w/ 21700 batteries
Replies: 5
Views: 661

Re: 14s2p Minicube w/ 21700 batteries

The Samsung 50E are rated at a max discharge rate of 9.8A. The ad is misleading to the novice. Yes the BMS supports a discharge rate of 30A, but the battery only supports a discharge rate of 19.6A (2P) configuration, but I would not run it at more than 10A to expect any usefull lifespan out of it in...
by Matador
May 21 2019 10:46pm
Forum: Battery Technology
Topic: Powerful inside-frame battery
Replies: 15
Views: 970

Re: Powerful inside-frame battery

The inside of your battery would most likely look like mine. Carefully review my thread on this Ancheer eBike. I posted tons of pictures for reference. Here is the link : https://endless-sphere.com/forums/viewtopic.php?f=2&t=93576 But I must say... I think a 1.5 kWh motor-controller setup on this is...
by Matador
May 13 2019 7:48pm
Forum: Battery Technology
Topic: Solderless weldless 36V and 74V batteries could do over 200A
Replies: 54
Views: 4530

Re: Solderless weldless 36V battery could do 200A

Must say that Agniusm's work look really solid !
Best solderless product i've see on the market.
I will eventually buy some when I can finally afford it (time will come)...

Agniusm are you an engineer ? I can't help but think you are looking how solid you know the specs of your designs...

Matador