Search found 132 matches

by hallkbrdz
Aug 08 2020 11:10pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 458
Views: 77666

Re: Spot Welding Copper Strips to 18650 Battery Cells

From facebook. 20S / 6P, copper/nickel sandwich method. Molicel 21700 P42A cells, 0.10mm copper sheet, plus 0.15 nickel squares only to facilitate welding. Edit: kWeld used, setting is 50-Joule Interesting. Looking at low resistance spot weldable solutions that can carry around a continuous 17A cur...
by hallkbrdz
Jul 09 2020 12:34pm
Forum: Battery Technology
Topic: Parallel series battery architecture
Replies: 15
Views: 546

Re: Parallel series battery architecture

zacksc wrote:
Jul 09 2020 12:00pm
Thanks. So then a 10 battery BMS could be used for either a 4p10s or a 1p10s.
Yes. Parallel cells are effectively treated as one larger capacity cell.
by hallkbrdz
Jul 09 2020 9:14am
Forum: Large EV General Discussion
Topic: Excellent information about diy Tesla Drive use
Replies: 14
Views: 2705

Re: Excellent information about diy Tesla Drive use

I would say that unlike ICE vehicles, EVs drive tend to fail suddenly, or at least in a way that makes them unusable until repaired. Normally (but not always) ICE vehicles will degrade slowly giving you warning to get them repaired. There's quite an opportunity there to monitor things starting to go...
by hallkbrdz
Jul 08 2020 10:07am
Forum: Battery Technology
Topic: Parallel series battery architecture
Replies: 15
Views: 546

Re: Parallel series battery architecture

So in a language I can understand, the only difference between these two is the amount of nickel (or any conductor) on the series connections, resulting in different sums of resistance? That, and the number of BMS leads and units you need. That is why normally they are wired parallel series, not se...
by hallkbrdz
Jul 08 2020 9:20am
Forum: Battery Technology
Topic: Parallel series battery architecture
Replies: 15
Views: 546

Re: Parallel series battery architecture

I guess I don't understand what you are trying to show here. Why would it make any difference which way you arrange them (other than for monitoring with a BMS)? Series resistance sums, parallel resistance divides.
ResistanceBattery.png
ResistanceBattery.png (21.09 KiB) Viewed 391 times
by hallkbrdz
Jul 05 2020 5:42pm
Forum: Large EV General Discussion
Topic: Electric Kart build
Replies: 26
Views: 7793

Re: Electric Kart build

frodus wrote:
Jul 19 2018 9:11am
I got a new ME1507 mount from Kartmasters that fits perfectly. Very happy with the resolution.
Curious - what is your rail spacing? I'll need a 32-90 mount.
by hallkbrdz
Jul 03 2020 3:50pm
Forum: Vendor Relations Corner
Topic: Reputable suppliers of LFP LiFePO4 pouch cells
Replies: 20
Views: 994

Re: Reputable suppliers of LFP LiFePO4 pouch cells

Thanks, I didn't realize that. :bigthumb:

I've emailed Farasis to see if they have any distributors. Seems odd if they didn't.
by hallkbrdz
Jul 03 2020 11:52am
Forum: Large EV General Discussion
Topic: EV helper spreadsheet
Replies: 5
Views: 1051

Re: EV helper spreadsheet

Version 1.8

Added / Changed:
Separated cells by packaging type
Added percent remaining of battery charge for time and load specified
Added more motors

https://drive.google.com/file/d/16D-9xh ... sp=sharing
by hallkbrdz
Jul 03 2020 10:19am
Forum: Vendor Relations Corner
Topic: Reputable suppliers of LFP LiFePO4 pouch cells
Replies: 20
Views: 994

Re: Reputable suppliers of LFP LiFePO4 pouch cells

I wish I knew who was reliable for pouch cells. A123 / LW should be, since that 26Ah cell is exactly like Zero used the first time after they switched from cylindrical cells in 2012. What I want to buy is essentially what Farasis currently makes for Zero. But I don't know anyone selling it, and Fara...
by hallkbrdz
Jun 30 2020 11:07am
Forum: Motor Technology
Topic: Induction motor sevcon gen4 issue
Replies: 10
Views: 1427

Re: Induction motor sevcon gen4 issue

It would be interesting to see how the Sevcon Gen4.5 (not sure what the .5 is) S4 controller used by Zero Motorcycles with their IPM ZF75-7R motors is programmed.
by hallkbrdz
Jun 27 2020 4:45pm
Forum: Large EV General Discussion
Topic: EV helper spreadsheet
Replies: 5
Views: 1051

Re: EV helper spreadsheet

Version 1.5

Added / Changed:
LiPo load ratings to better match kart measured values under load
Parallel calculations to fix low C rate battery amounts (high kWh low C rate)

https://drive.google.com/file/d/1qBYzZQ ... sp=sharing
by hallkbrdz
Jun 25 2020 4:22am
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 35
Views: 2955

Re: 30Ah 28s LiPo from 7s bricks

For non hobby cells the capacity rating discharge usually seems to be 0.5C, and that's slightly conservative. Plus the large manufactures publish their own discharge charts showing various loads, something that LiPo pack companies don't seem to do. So I based what before I had on 3rd party tests. A ...
by hallkbrdz
Jun 24 2020 3:10pm
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 35
Views: 2955

Re: 30Ah 28s LiPo from 7s bricks

Ouch. I had estimated (based on other tests of similar Lipo packs of that brand I found online) that the real capacity of those "5000mAh" bricks would be roughly 4500mAh under load. But 3600mAh, that really hurts at only 72% of advertised rating. At least now I've been able to update the s...
by hallkbrdz
Jun 24 2020 12:09pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 187
Views: 45116

Re: Electric kart

Looks good!
by hallkbrdz
Jun 23 2020 1:59pm
Forum: Large EV General Discussion
Topic: EV helper spreadsheet
Replies: 5
Views: 1051

Re: EV helper spreadsheet

Version 1.4

Added / Changed:
Split-up Setup from battery choices
More battery choices
More motor choices
More controller choices

Fixed:
Ah ratings

https://drive.google.com/file/d/1WJ3svD ... sp=sharing
by hallkbrdz
Jun 19 2020 10:56pm
Forum: Battery Technology
Topic: ISO 30C to 45C rated pouch cells
Replies: 49
Views: 1916

Re: ISO 30C to 45C rated pouch cells

Any update over the last month? Interesting project...

I'm looking at similar cells for racing with weight being very important as well, just over 8 minutes not 90 seconds. I've worked up quite a spreadsheet for my calculation, could be helpful if you are interested.
by hallkbrdz
Jun 17 2020 8:48pm
Forum: Large EV General Discussion
Topic: EV helper spreadsheet
Replies: 5
Views: 1051

EV helper spreadsheet

Here is what I think is a reasonably correct and complete motor / controller / battery spreadsheet for people interested in building an electric racing kart (or something similar in size) using PMSM motors to help understand how various choices of components effect the overall package. You will need...
by hallkbrdz
Jun 17 2020 7:10am
Forum: Motor Technology
Topic: Minimum battery voltage for sinewave controllers?
Replies: 2
Views: 206

Re: Minimum battery voltage for sinewave controllers?

Hmmm. I thought the nominal motor voltage specified refers to what is required to drive it to at max efficiency (and also the nominal rpm) and has nothing to do with supply voltage. If that's true, then with less voltage you cannot reach that rpm under load (assuming you also can push the motor rate...
by hallkbrdz
Jun 16 2020 9:11pm
Forum: Motor Technology
Topic: Minimum battery voltage for sinewave controllers?
Replies: 2
Views: 206

Minimum battery voltage for sinewave controllers?

OK, after reading and trying to understand what exactly is going on internally different controllers, I am now confused about is what minimum voltage needed for a controller to efficiently drive a 3-phase PMSM traction motor from a DC source (battery). If you go by what Cascadia Motion documentation...
by hallkbrdz
Jun 08 2020 5:48pm
Forum: EBike Technical
Topic: Sevcon, subsidiary of Borg Warner
Replies: 15
Views: 650

Re: Sevcon, subsidiary of Borg Warner

Wrecked zero's, not as many as you would think. Only one I can find with a very minor issue it looks like. Plus I'm not sure about the motor cooling for near 90 degree (32.2 C) days (I won't go above this as it's just too much for this "old" guy). I'll watch it and see where it goes. Altho...
by hallkbrdz
Jun 08 2020 1:42pm
Forum: EBike Technical
Topic: Sevcon, subsidiary of Borg Warner
Replies: 15
Views: 650

Re: Sevcon, subsidiary of Borg Warner

All this does make choosing a controller "painful" for small scale motors, caught in-between Ebikes and full size EVs. I wish that there was a PD-Axiom Jr, but there isn't. So that leaves us crazy e-karting people with the choices of the Kelly KLS-80801/IPS controller, the Sevcon (BW) Gen4...
by hallkbrdz
Jun 06 2020 8:09pm
Forum: Motor Technology
Topic: Scott Drive SD300 (300+KW)
Replies: 7
Views: 1454

Re: Scott Drive SD300 (300+KW)

How do you like the setup and configuration of this controller? I'm considering the little brother SD100 for my EKart project after reading about all the issues with the Sevcon controller support.
by hallkbrdz
May 31 2020 9:03am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 187
Views: 45116

Re: Electric kart

Thanks, those photos really help a lot.

I was also considering running aluminum tube supports under the seat for the smallish lipo pack I am building. I think that arrangement should work well and keep the frame reasonably flexible.
by hallkbrdz
May 30 2020 6:20pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 187
Views: 45116

Re: Electric kart

With your experience, what's the best way to attach the battery support to the frame? From what I can tell from photos, you have a solid tube front and back where the stubs for the sidepods used to attach. Did you just use a larger diameter tube to go over the original one, cut and replace the origi...
by hallkbrdz
May 30 2020 10:44am
Forum: Motor Technology
Topic: Development of a Sensorless PMSM ACIM FOC controller based on InstaSPIN
Replies: 1
Views: 616

Re: Development of a Sensorless PMSM ACIM FOC controller based on InstaSPIN

Looks like a neat project - how is it going?

I have a PMSM motor (Hawk60) that I need to buy/make a controller for, and this sounds interesting.