The bistander thread

[altrez]

Hi Altrez and all,
I've been working on a 4 cell LiFePO4 battery. Just got it to a point where I can start testing. I want to go through several cycles and purposely overvolt, overcurrent and unbalance cells to verify the BMS is working properly as well as check out my wiring.
Cells are A123 brand LiFePO4, 26650 (26mm dia × 65mm long). Cells are a few years old but never used however appear to be disassembled from packs, probably DeWalt tool batteries. They are 3.3 volts nominal.

Screenshot_20200808-220639.png
[ATTACH]n499997[/ATTACH]

And a couple photos:

IMG_20200808_175554350.jpg

IMG_20200808_175527203.jpg

Just a short 'see if it works' test. Discharge at ~1A.

IMG_20200808_175747093.jpg

Next, a cell logger. It will keep track of the 4 individual cell voltages during the tests.

IMG_20200808_175636586.jpg

If tests go ok I'll heat shrink the 4 cells and BMS together in a nice little 2.3Ah 12V battery.

Link to BMS if you're interested:
https://www.electriccarpartscompany....agement-System

Regards,
bi

Looks cool bi. I look forward to your testing! Do you know of a battery analyzer for the cells? It would be interesting to see that as well.

-Altrez

[bistander]

Hi Altrez,

fourcellMod.png
This is a download graph from the cellLogger. Blue trace is battery V and 4 other traces are individual cells. Cell #3 was under charged to start with. BMS did open circuit (turn off the battery output) when lowest cell (#3) hit 2.5V just like it supposed to. And as I monkeyed around with charge current from a power supply, it indeed did open circuit (prevents overcharge of any cell) on cue. However when left disconnected overnight, the BMS did little if anything to balance the 4 cells. So I've been manually equalizing cells today. Unless cells are equal in voltage and state of charge I won't get full capacity from battery.

I have a few different cell/battery analyzers from the hobby industry for smaller capacities. I'll list or take photo of those once I get this thing balanced and on test. A lot of past experience was with medium capacity stuff like 10 to 100 Ah. Occasionally barrowed big high voltage/high ampere rig from nearby university, but most was done on homebuilt analyzers, meaning discharge and charge apparatus and data collection instruments.
bi

[bistander]

Altrez,
Here's my collection of cell/battery analyzers.

IMG_20200809_225543103_copy_1057x999.jpg It's been a while since I've used a couple of them. I think I'll need to try one of these on this new battery. Might just be that cell #3 is bad from the start. Ignored or forgot my own rule.... Test components prior to assembly.
bi

[altrez]

Hi Altrez,

fourcellMod.png
This is a download graph from the cellLogger. Blue trace is battery V and 4 other traces are individual cells. Cell #3 was under charged to start with. BMS did open circuit (turn off the battery output) when lowest cell (#3) hit 2.5V just like it supposed to. And as I monkeyed around with charge current from a power supply, it indeed did open circuit (prevents overcharge of any cell) on cue. However when left disconnected overnight, the BMS did little if anything to balance the 4 cells. So I've been manually equalizing cells today. Unless cells are equal in voltage and state of charge I won't get full capacity from battery.

I have a few different cell/battery analyzers from the hobby industry for smaller capacities. I'll list or take photo of those once I get this thing balanced and on test. A lot of past experience was with medium capacity stuff like 10 to 100 Ah. Occasionally barrowed big high voltage/high ampere rig from nearby university, but most was done on homebuilt analyzers, meaning discharge and charge apparatus and data collection instruments.
bi

What product did you use to get that graph? I have been looking for something to do exactly that in the sub 1k range. I need standalone 8 channel 0-50 volts DC.

Thanks!

-Altrez

[altrez]

Getting ready for my next round of tests!




Any input on what tests I should be doing? I was just going to redo the Tests recommended by Turion but this time I am going to track watts on both the output of the battery and the charge to the battery.

-Altrez

[bistander]

What product did you use to get that graph? I have been looking for something to do exactly that in the sub 1k range. I need standalone 8 channel 0-50 volts DC.

Thanks!

-Altrez

https://www.progressiverc.com/celllog-8s.html

Discontinued. Too bad. Same thing, same functionality is unavailable. Per channel volt limit is too low for you. If I see something to fit your bill, I'll let you know.
bi

[Turion]

close
https://www.icharger.co.nz/celllog-8s

[bistander]

Hey Altrez,
Turion found a possible source. The place is out of stock for the CellLog-8S and 8M (same as the 8S except w/o logging feature. They also list PowerLog-6S. 'out of stock' is not indicated. I used the PowerLog-6S years ago. Only 6 cells but also current and temp with logging. Might be worth a shot. Price is higher than it used to be and you're dealing with NZ. Check out the specs. All other sources I saw indicated out of stock. I believe it is also discontinued.
I've also used this:
https://www.dataq.com/
You'd need to condition inputs over 10V. Simple voltage divider works. I'm sure I still have mine. Just misplaced it. It'll show up.
bi

{edit} If you're really serious, check this out:
https://www.dataq.com/products/graphtec/gl240/
I used it on a project. My colleague (computer science grad) set it up and I ran the tests with it and created the charts with Excel. A lot nicer and more capable than the little devices, but more $.

close
https://www.icharger.co.nz/celllog-8s

[altrez]

Hey Altrez,
Turion found a possible source. The place is out of stock for the CellLog-8S and 8M (same as the 8S except w/o logging feature. They also list PowerLog-6S. 'out of stock' is not indicated. I used the PowerLog-6S years ago. Only 6 cells but also current and temp with logging. Might be worth a shot. Price is higher than it used to be and you're dealing with NZ. Check out the specs. All other sources I saw indicated out of stock. I believe it is also discontinued.
I've also used this:
https://www.dataq.com/
You'd need to condition inputs over 10V. Simple voltage divider works. I'm sure I still have mine. Just misplaced it. It'll show up.
bi

{edit} If you're really serious, check this out:
https://www.dataq.com/products/graphtec/gl240/
I used it on a project. My colleague (computer science grad) set it up and I ran the tests with it and created the charts with Excel. A lot nicer and more capable than the little devices, but more $.

I have the Dataq 10volt already. It's hiding somewhere in the house. it is a good logger I used it for my super cap tests in the old thread. The next one you posted is what I am looking for and only $995! I did say sub 1k lol thanks!

-Altrez

[altrez]

Hows everyone doing? No new posts in a long time!

-Altrez

[bistander]

IMG_20200913_150330466_copy_1332x999.jpg

Hows everyone doing? No new posts in a long time!

-Altrez

Hi Altrez,

Been busy. Still waiting for Turion to post evidence of his generator running as he claims. In the meantime I've built several batteries. This is a seven cell LiNMC 18650 2700mAh 28V unit on charge. Intend to test out Chinese BMS/PCM which has bluetooth.

Hope your battery testing is progressing.

Regards,
bi

[bistander]

bi,
...

His machine has places for 48 coils, but only has 12 because of the magnetic drag issue that you claim goes away at speed.
...

Turion,

I've never said that. I have claimed that cogging effects diminish as RPM increases.

bi

[BroMikey]

Turion,

I've never said that. I have claimed that cogging effects diminish as RPM increases.

bi

Yes you did. You said that at speed no cogging exists so not to bother with it, it is nothing. No effect. You also said that this applies to a 2 pound rotor or a 2 ton rotor. same, no cogging at speed and that we are wasting our time and efforts. That is what you said for weeks if not months then slowly you waffle, splitting up phrases to mean what you really meant. Cause you didn't mean or say that. This is what you did and do. silliness. Just admit it, you are unable to think clearly about what you said. Of course we are to spend another number weeks and month following your non sense. Sit back and enjoy the ride, let someone who can do the work show everyone that govt controlled schools not only brainwashed everyone in the past, still do. You paid good money for it. Little Bye

Big Turion will post the results soon, don't make a mess, sit still and have faith. be a good little lapdog and beg for morsels.

[bistander]

Cogging and "magnetic drag" are 2 distinctly different phenomena. Cogging is rarely even noticable at rated speed and power in a generator mainly due to rotor inertia smoothing out the negative and positive torque perturbations. Magnetic drag is noticable at speed regardless of load due to core loss. Besides torque required to overcome core losses there is also friction and aerodynamic losses which increase with speed. Load torque could be included as "magnetic drag". Magnetic drag is not common terminology associated electric machinery, but I never said it goes away at speed as Turion stated. I've addressed this numerous times. Turion's "magnetic neutralization" scheme counteracts cogging only. Since cogging isn't an issue with power delivery at speed, "magnetic neutralization" is of no benefit to generators operating delivering power at rated frequency.

bi

[BroMikey]

Cogging and "magnetic drag" are 2 distinctly different phenomena

Turion's "magnetic neutralization" scheme counteracts cogging only. Since cogging isn't an issue....... at speed, "magnetic neutralization" is of no benefit[/I]

bi

Wrong answer cogging is drag but I'll give you this, you are a consistent mess of conflicting disinfo

Take Two: Your rendering is inaccurate. Sit back and enjoy the show. While you are waiting show us what you are doing with batteries. That is where we all start. BTW you can make a very small paperclip version to test these phenomena.