Beginners Guide to Processing 18650 Cells | Cell Database


Thread Rating:
  • 3 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
HBPowerwall (Official)
heheh i see what you did there lol
http://www.hbpowerwall.com for a full video diary of my project.... 
https://www.amazon.com/shop/hbpowerwall to buy stuff I use Smile 
Reply


Another back to basics video released - here is the play list for anyone interested https://www.youtube.com/playlist?list=PL...By7sYm3Xwj
http://www.hbpowerwall.com for a full video diary of my project.... 
https://www.amazon.com/shop/hbpowerwall to buy stuff I use Smile 
Reply
Hi. This is my first time on this website, so I'm not sure where the best places to post my comments are, so I just picked this one.
I want to say something about the bus bars. I've watched a lot of videos on YouTube from various people in this forum, and I think most (if not all) are not using enough copper. (BTW, I'm an electronic engineer with >30 yrs experience, including 11 years working on the electrical power system for the International Space Station.)
I did a quick simulation with LTSpice (a free download from http://www.linear.com) that models a pack that seems typical of the ones I've seen on YouTube. The simulation assumptions are: 1) 40 cells connected in parallel in a 2x20 array, with the bus bar running along the long axis; 2) the bus bars are 3 pieces of solid 12AWG wire twisted together; 3) the internal resistance of each cell is 0.15 Ohms; and 4) no fuses, although they could be easily added.
The results are: the cells closest to the output terminals provide 18% more current than the cells at the other end. In other words, suppose you start out with all cells fully charged and perfectly balanced, and then discharge until the cells closest the terminals are fully discharged. At that point, the cells farthest from the terminals with still be at 18%, and the pack as a whole will be at 9%.
Note that if you move the output terminals to the middle of the pack, the worst case current ratio drops from 18% to 5%, and the unused capacity of the pack drops from 9% to 3%.
I'm happy to post the simulation files so that people can play with them. LTspice is really easy to learn. There are many tutorials on YouTube, and a large user community.
Korishan, SimonW, daromer like this post
Reply
that would be true in a High current drain application. Most of us pull less than 500mA per cell. I Did a test a while back where i totally discharged 8 cells in a parallel set where the cells were aligned in a row and 1 strand of 12AWG was connected to the cells (friction connection only) from one end

I let the pack discharge at 1A per cell (8A) and yes the wire for warm but not hot.

As soon as it was done I pulled all the cells from their holder and measured the Voltage.

the voltages were as follows

Closes to the discharger
3.20
3.20
3.20
3.21
3.20
3.20
3.21
3.20
Farthest Away from Discharger

these Cells had been cycled and tested for capacity and were within 100mAh of each other.

So I'm not worried about a much lower draw on bigger packs
Reply
And some of us not even 100mA Wink
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
(09-14-2017, 06:10 PM)SteveRobbins Wrote: The results are: the cells closest to the output terminals provide 18% more current than the cells at the other end.

Did you run your simulation with the positive and negative terminals are at the same end?
Most people here seem to connect the terminals at opposite ends of the pack, which I think mostly cancels out this effect?
Reply
(09-14-2017, 06:36 PM)daromer Wrote: And some of us not even 100mA Wink
When I get more cells my goal is 100mA. Right now under max load I'm at 500mA.
Reply
(09-04-2017, 05:00 AM)hbpowerwall Wrote: Been tinkering with the old 3D printer for the last few days dreaming up uses for it.
Any links to the Opus bottom with the bigger fan you showed on a video recently? You mentioned sharing the files on facebook, but i haven't been able to find anything. Possibly because i don't do facebook.
Reply
(09-15-2017, 11:15 PM)monsted Wrote:
(09-04-2017, 05:00 AM)hbpowerwall Wrote: Been tinkering with the old 3D printer for the last few days dreaming up uses for it.
Any links to the Opus bottom with the bigger fan you showed on a video recently? You mentioned sharing the files on facebook, but i haven't been able to find anything. Possibly because i don't do facebook.

They were shared FB Group - https://www.thingiverse.com/thing:2267571 Fans can be found on ebay  - https://rover.ebay.com/rover/1/705-53470...2749.l2649
http://www.hbpowerwall.com for a full video diary of my project.... 
https://www.amazon.com/shop/hbpowerwall to buy stuff I use Smile 
Reply
Peter,

do you have any kind of Automatic Transfer Switch, for the case when Batrium turns the shunt trip off, or does AC stuff that you power from the PIP is not critical to be on all the time? I'm thinking stuff like fridges and stuff that should not be off for long time.

I'm thinking of situation when one goes on vacation and hopes that even if shunt gets tripped, there is still power to the house for such sensitive appliances..
Reply


Who read this thread?
100 User(s) read this thread:
hbpowerwall (09-20-2017, 01:57 AM), Azza9990999 (09-09-2017, 01:24 AM), One up the sleeve (07-19-2017, 12:15 AM), Remixd (07-19-2017, 02:22 AM), AZ_Tekkie (09-17-2017, 07:45 AM), Chickey (09-05-2017, 02:01 PM), Brian Lawrence (07-19-2017, 07:35 AM), ShaneE (05-31-2017, 05:41 AM), Minx (05-31-2017, 04:08 AM), daromer (Today, 05:51 AM), FiremanDIYPowerwall (09-06-2017, 07:30 PM), Sean (02-17-2017, 07:46 PM), mike (09-19-2017, 03:12 AM), DIY TESLA POWER WALL (03-28-2017, 08:41 PM), ote (08-13-2017, 03:27 PM), Toochi84 (09-05-2017, 11:59 AM), goodnowm (06-27-2017, 02:48 PM), Swolrath (07-19-2017, 08:41 AM), AveRageJoe (09-11-2017, 04:00 PM), BigBen (08-13-2017, 11:05 AM), station240 (07-17-2017, 02:15 AM), Chris (03-11-2017, 09:31 PM), PaulKennett (Today, 11:34 AM), RobPethybridge (07-19-2017, 06:07 AM), Joaquinsfy (09-02-2017, 09:28 PM), NiVa (07-18-2017, 10:39 PM), Lux_Gamer (09-16-2017, 05:20 PM), auxz2jz (05-14-2017, 05:54 PM), Andreas Kvernes (04-28-2017, 10:00 PM), owitte (09-18-2017, 09:21 AM), opus40 (09-12-2017, 06:52 AM), RudyLiPower (09-08-2017, 12:53 AM), avas911 (05-05-2017, 04:33 PM), Loboosh (07-19-2017, 12:57 AM), SeattlePowerwall (03-29-2017, 03:31 AM), ken (07-27-2017, 08:04 AM), OfGrid Ausie Preper (03-03-2017, 11:25 PM), dakoal (09-12-2017, 10:34 AM), VdVoort4 (09-18-2017, 07:24 PM), Grazor (05-24-2017, 12:42 PM), Bassiexp (03-28-2017, 08:01 PM), Majorphill (09-19-2017, 06:37 AM), Elwood (03-21-2017, 06:55 AM), jubaeg (04-27-2017, 11:50 PM), frasernator (07-14-2017, 10:18 PM), dobbers (05-26-2017, 10:37 AM), riveracc1 (08-19-2017, 04:03 AM), mikesdiypowerwall (03-29-2017, 03:27 AM), coolfx (08-07-2017, 09:39 AM), Antairus (02-10-2017, 10:34 PM), gulik154 (05-12-2017, 08:19 AM), cgrauls (06-22-2017, 04:14 PM), Herebus (08-08-2017, 04:26 AM), Pm240sx (02-18-2017, 12:50 AM), Blueshroom (05-11-2017, 01:19 PM), timholmesjr (05-24-2017, 10:18 AM), Rerouter (04-20-2017, 10:11 AM), Terry Texas (08-25-2017, 05:30 AM), DanielD (05-01-2017, 06:06 PM), ruby2 (09-22-2017, 10:04 AM), hatti (03-28-2017, 02:02 PM), TrueGeek (03-28-2017, 11:42 AM), JustJim (04-03-2017, 10:29 PM), bobcoyne (06-19-2017, 03:38 PM), Korishan (Today, 10:39 AM), moosepower (02-18-2017, 10:12 PM), A + A (09-20-2017, 05:44 AM), P.Tasyo Powerwall (04-02-2017, 02:47 PM), PAF (09-24-2017, 07:21 PM), sunnyfunny (02-11-2017, 07:14 PM), FERCSA (09-07-2017, 06:30 AM), rumey (03-29-2017, 08:49 AM), Prahe86 (09-01-2017, 11:00 AM), nikitto (04-01-2017, 06:22 PM), Janis (04-20-2017, 06:59 PM), Nemo90 (03-27-2017, 03:46 PM), FireFrog (02-22-2017, 09:32 PM), Jayesh Lakhman (03-28-2017, 06:35 AM), BuddyNorth (05-07-2017, 02:58 AM), Jo Ray (03-16-2017, 04:01 AM), pfromero (02-18-2017, 10:14 PM), Aspendell (02-12-2017, 01:23 AM), Asylumweb (03-28-2017, 10:39 AM), aymanmj (03-09-2017, 11:20 PM), Dizelis (07-29-2017, 10:21 AM), Alexander Lorenz (02-04-2017, 05:38 PM), graverl (07-20-2017, 04:15 PM), Agus Cahyono (05-02-2017, 01:53 AM), Alleys66 (02-06-2017, 04:55 AM), Sandwer (02-07-2017, 02:02 PM), BitcoinTrader (08-24-2017, 02:14 PM), kombibob (02-11-2017, 12:03 PM), theDIYHobbyist (03-29-2017, 12:46 AM), Yves (02-18-2017, 11:21 PM), Bob Muster (02-26-2017, 04:36 AM), Wolverine (02-12-2017, 02:12 AM), Pappy Bear (07-06-2017, 10:09 AM), Jose Reyes (09-09-2017, 08:48 PM), Zensay (06-12-2017, 09:09 PM), muhammedabu18@yahoo.com (02-13-2017, 03:18 PM)

Forum Jump:


Users browsing this thread: 5 Guest(s)