Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
HUUUGE USB POWERBANK
#1
Greetings,

I set out to build a powerbank for camping / Festivals etc and finished it  last week. 

I used the best cells I had to date that were similar, all from ebike batteries. Altogether I used 160 cells in a 4s40p config. It was 80x LG MG1's, 40x Panasonic NCR18650PF and 40x Panasonic NCR18650BE. They all had close to new capacities, testing in at 3000-3100mAh on the OPUS, the BE cells had 3250-3350 on the OPUS. I split the cells equally per group.

The steel case was originally a battery case all ready. I got these from a customer and the Li-ion puch cells configured in a 13s had all died. Upon pulling them out of the case, the second rubber internal case they were in expanded to roughly double the size and broke open. These cells were really really really dead! and dangerous, but the voltage was super low so no problem there.
The case had some holes in it for the +- cables, charge port and switch but they were too small so I drilled out bigger hols for the 4cm wide USB chargers etc. 


I fused them singly because I wanted to keep the option of easily dissasembling the pack again when I want to use the cells for something else. 
A 10A fuse between blocks 3 and 4 acts as a mid pack fuse. 


I was able to fit 120 cells in the base of the case in a 10x12 and another 40 cells in 2x 2x10 on top of these. lying flat, essentially in the top part of the case.


From the 4s BMS I used another fuse to connect to the 3 way position switch I had. Output from the swtich has another 10A fuse that then splits up into the two 12-24V dual USB chargers. Another positive goes to the magnetic Rosenberger charge port. BMS shares the same +- for discharge and charge. *** I have not yet tried to charge the battery yet because I still havnt managed to empty it...... :Big Grin **


The current draw would be so low (max 8.4A at 5V so about 2 A at 16V (cell level) that I really did not have to worry about equal loads etc. 
The one USB charger has a voltmeter built in, that way I know the capacity and I didnt have to bother with another device. 


For some reason the pack were at 16.6V, but the BMS only ouputed 16.07V??? Anyone know why? cheap chinese BMS maybe?

I then added a lot of silicone around the switch to stop potential water ingress,  and the terminals to glue them in place. The USB chargers and Rosenberger are waterproof all ready. 



Padded the case with thick foam,  hard plastic sheet and foam gives a safe layer between the 40cells on top and the 120 underneath.
Lots of duct tape covers all the contacts Smile


Closed up the lid with a lot of silicone again, popped in the screws and let it dry. 

Ended up using this for 5 people for 4 days all ready, charging phones and speakers and running 2 USB fans constantly. 

remaining voltage, 15.6 from the 16.1 I started with.

Total weight, about 8kg. 
Total capacity, about 1640Wh.  Cool  (2850mAh average x 160, x 3.6V )

If I end up using it more I will add a proper 12V output socket as well so I can power some more stuff.
Korishan and Redpacket like this post
Reply
#2
Which bms did you get? Possibly voltage drop from diodes
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#3
(08-04-2018, 01:17 PM)Korishan Wrote: Which bms did you get? Possibly voltage drop from diodes

it should be this one:
https://www.ebay.de/itm/4S-30A-14-8V-Li-...%7Ciid%3A1
Reply
#4
Yeah, I don't see any diodes, other than what's built in the FETs.

Check all the solder joints and make sure all the pads are making good contact. If not, hit it with the iron after applying flux to the area (this minimizes the chances of bridging)

I suppose it's also possible that there's a FET that isn't closing all the way, but I doubt that.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#5
how are you measuring the voltage output? If you are using a multimeter then the voltage need to very close to each other. But if you are reading the voltage from the blue LED meters, those meters can be off in there readings. That might be your problem.
Reply
#6
Agreed that is HUGE! Any plans for solar charging? Not that you really need it. 1.64kw is a lot of phone charge time. You could even keep a small fridge going for a day.
Reply
#7
(08-04-2018, 10:19 PM)jonyjoe505 Wrote: how are you measuring the voltage output? If you are using a multimeter then the voltage need to very close to each other. But if you are reading the voltage from the blue LED meters, those meters can be off in there readings. That might be your problem.
When i first plugged in the usb charger with the voltmeter it said 16.1. so i was confused. I measured around with a voltmeter and at the output terminals of the bms it measured 16.07. so yeah...


(08-05-2018, 05:48 AM)Geek Wrote: Agreed that is HUGE! Any plans for solar charging? Not that you really need it. 1.64kw is a lot of phone charge time. You could even keep a small fridge going for a day.

I could certainly add it in, then i would have to get rid of the 40 cells on top tho to make room for thr cherge controller. 
When i was deciding on how to put the cells in i noticed that i can put 120 in the base with using the stabdard cell holders but with cell holders that can package them of center to each other i can put 160 just in the base. So i can actually move all the cells into the base. 
If i redo it id use the new cells i just recieved. NCR18650GA and LGMJ1. Then id have even more in it and have a solar charger etc. 
maybe Smile
A little fridge wouldve been great last weekend..... warm beer isnt the best Wink

(08-04-2018, 03:55 PM)Korishan Wrote: Yeah, I don't see any diodes, other than what's built in the FETs.  

Check all the solder joints and make sure all the pads are making good contact. If not, hit it with the iron after applying flux to the area (this minimizes the chances of bridging)

I suppose it's also possible that there's a FET that isn't closing all the way, but I doubt that.

Interesting ok. Ill check it out when i open it up again... resolder etc. 
in that case the FETs or the FET should get warm from the resistance right?
Reply
#8
If you're only drawing ~2A & the BMS is rated for 30A, the FETs should stay cold. If they're warming up, there's something going on.
Korishan likes this post
Running off solar, DIY & electronics fan :-)
Reply
#9
(08-05-2018, 12:24 PM)The-J-Man Wrote:
(08-05-2018, 05:48 AM)Geek Wrote: Agreed that is HUGE! Any plans for solar charging? Not that you really need it. 1.64kw is a lot of phone charge time. You could even keep a small fridge going for a day.

I could certainly add it in, then i would have to get rid of the 40 cells on top tho to make room for thr cherge controller. 

...

Stick the charge controller to the back of the panel(s).
Reply
#10
(08-05-2018, 12:48 PM)Redpacket Wrote: If you're only drawing ~2A & the BMS is rated for 30A, the FETs should stay cold.  If they're warming up, there's something going on.

Oh yeah for sure. I was just thinking if one of them isnt closing right and it causes that voltage drop there should be enough resistance to get it to go warm. 
I was going to test the whole thing ubder max load but ended up not having the time too..
(08-06-2018, 12:45 AM)Geek Wrote: Stick the charge controller to the back of the panel(s).

Good point :Smileeep it external and plug it straight into the charge port. I like it
Reply


Who read this thread?
100 User(s) read this thread:
hbpowerwall, Sean, mike, Joaquinsfy, NiVa, Majorphill, Korishan, A + A, PAF, Franky Beuselinck, jdeadman, wim, wimpie007, typ49, The-J-Man, rebelrider.mike, watts-on, Dan Lim, Hanssing, IronSky, Stefaan De Ridder, Chicken, tremors, idiomatically, Shade, Daveyboy, al4sound, Seedser, Mazlem, ivnz, Geek, Rad, SWEwall, Ivo Staelens, floydR, AlexCPU, Jonas Goiris, hookemdevils22, DarkRaven, Gerard Achternaam, Lucian Macota, ChrisD5710, cristof, how about that, okent, Pavel Razzorenov, Eplas, DropB3ar, Ben Hooker, Ste Collister, Charly144, djuro, SecondHandPower, rkelly, acidice333, Jason Morris, marcin, brwainer, drchips, Brent, lowrad, Roland Domke, mhoungbo, rtgunner, Drokz, costty, gpn, viralprankster, Chablis_m, Headrc, phikzel, mbrunton, rodagaster, Dala, Jaggerz, Crimp Daddy, Bakteria, jonyjoe505, Redpacket, completelycharged, Ibiza, Krokodino, Christian Schneider, Onizuka, Zvonko000, magic8192, davidtrn24, Oliman, solar_18650, micsa84, indigo, Michel, Bubba, Leo_C, JDish, Willowvale, Cherry67, Scrud, Sholphin02, Walde

Forum Jump:


Users browsing this thread: 1 Guest(s)