How to build a individual 18650 battery pack, Example 12S8P

[ecross]

How to build a individual 18650 battery pack, Example 12S8P Samsung 13Q



Hi,

this is ecross from Germany area Munich. I drive ebikes and etrikes from HP and Stein-Trikes. A fully trike with 2805 or 4080 with up to 100V-80A or more, input is so funny und fast.
Hopefully I can help and show you how to build individual 18650 core packs.

I have big battery experience because I`m a modeller, cars, boats, planes since many years.

My batteries are from 18650 cells because I have good contacts to power tools manufacture like Bosch, Makita, Metabo here in south Germany. To get the same good stuff is the key to have very good high current battery's with long life time like the profi power toll manufacture like Bosch, Makita and so on.
I use 4S, 6S, 10S and 12S with 6P to 20P setup.

I have taken some pics and will comment the building step by step.

 

[ecross]

-pic 519 to 523

-for this example pack i use the old but great Samsung 13Q cells with 1,3Ah. These cells are from a power tool manufacture, never used but core packs with some bad welding points, so I can show you the pack assembling with this cells. I remove all the welding tabs. For better isolation the cells become a additional shirk tube. The shrink tube is, flat dimensions is 31mm.

 

[agniusm]

This is good stuff and will help people building their own packs. Add more photos as you go along. Keep up the good work.

 

[madin88]

Hi,
im curious to see the finished pack. Do you think the additional shrink tube is really necessary? What solder did you use?
I built an 22s9p pack with Sony Konion 18650VTC4 a few month ago. I only sticked the cells togeter with CA and no problems for so far..
btw: im from austria in Passau area

 

[dezellis]

Subscribed, perhaps you could find the time to do a video of the whole process.
Regards
Dez Ellis

 

[ecross]

-the next pics from 524 to 528

 

[madin88]

Is this twisted wire for cell connection?

In my pack i used 2,5mm² copper wire for serial connectors. Tried a few differnt type of solder and the best from all i tested was "Fluitin" from Conrad electronic shop.
Fluitin needs one second less heating on the cells for same result as the other types.

 

[ecross]

pics 524 to 528


-pic 524 + 525

-I build into the past a simple plastic solder stand for Modeler cells like sub c and now for the great 18650 and 26650 cells
with this holder I can handle up to 14P or more cells

-it is very important to pre solder the cells with good tin-lead solder like Donau Sn60Pb38Cu2 or better Felder Sn60Pb40

-soldering wire are very different, like day and night, you need some time to find the really good stuff

-I use a Weller or ERSA solder Station with min. 80W better 150W please no cheap stuff because the temperature is very important for good results

-solder cells are only for pros with good tools and good tools are expensive

-please do not solder your DIY core packs without pro skills or better looking for a helping hand with pro solder skills

-you see the bad solder point because the welding points are not good for pro solder points

pic 526:

-this is my DIY silver copper wire from DEGUSSA
normal copper wire are not perfect for solder cells, because you need not to soft and not to stiff wire to connect the cells together. My stuff is made from 4 strands from 0,8mm, the same like DIY winding a motor but here self-made stranded,
for more current, no problem, 6 or 8 strands
Sorry I'm a little bit creasy.

pic 527 + 528

-some macro pics from the pre solder poles and silver wire from DEGUSSA here 4 times 0,8mm diameter

-silver wire and good solder wire for pro results

 

[ecross]

pics 529 to 533

 

[ecross]

-pic 529

-first soldering +pol

-pic 530 - 531

-all +pol are soldered

-pic 532

-all -pol are soldered

-pic 533

-the first 1S8P corepack are done
-the solder fun beginns...

 

[ecross]

pics 535 to 539

 

[madin88]

well made pack :wink:

are these cells new or harvested?
do they need balancing?

 

[cwah]

nice work

 

[1KW]

next, show everyone how to attach balance wires AND discharge leads

 

[ecross]

pics 540 to 544

 

[ecross]

-for corepack taping I use Scotch Brand Tape, like this, because very strong!
-the corepack is very small, here about only: 200 x 156 x 70mm

 

[ecross]

pics 546 to 549

 

[ecross]

pics 550 to 554

 

[ecross]

pics 555 to 557

 

[ecross]

-before more packing first some bench test with my charger Graupner Ultramat 18 and Hyperion 1420i

-Ri around 45mOhm
-charging voltage 4,200V per cell
-mAh out: 10434mAh (with 2,5V to 42V per cell)

-these are good results, because this are 1,3Ah cell and 8x1,3Ah is 10400mAh.

 

[ecross]

-and certainly some real testing into my 7kw Trike with H4080 into 20" rim and about 80A battery current

-it is sunny and warm about 15°C fun with my fully-Trike and some fast off-road riding

-after good results some last working at the new battery like Fuse and more...

 

[arkmundi]

Really like your whole approach & build process and the detailed in the pics. Thanks. But I'm not clear about your statement on sourcing the cells. Could you elaborate on that?

How to build a individual 18650 battery pack... My batteries are from 18650 cells because I have good contacts to power tools manufacture like Bosch, Makita, Metabo here in south Germany. To get the same good stuff is the key to have very good high current battery's with long life time like the profi power toll manufacture like Bosch, Makita and so on.

 

[ecross]

-thanks for the friendly words, I have some buddies at Sanyo, Sony and some bigger Industry-Dealer and Bosch because I`m a modeller since about 25 years. When there is some interesting I can organize maybe a group buy from some good cells for ebikes
-but the battery is not finished yet!

 

[Truusje79]

Very nice pack, very well made, only one thing about those charge / discharge plugs ( red ones 4mm ) I use them too but they do get warm at 50 amp draw, I personally would upgrade them to 5.5 mm plugs or something heavier.

 

[ecross]

-thanks for your thinking, don't worry, for my testing I use my good old MC-Contact 4mm Gold connectors. I now your cheap HK stuff is not good for over 30-50A. Please have a look to the best and not cheapest stuff.

-but for many, many stuff these 4mm Bullet are ok and when you use the ones with the plastic Grip you have a good inverse polarity protection

-do you now there are different types on the market, please test and use the good one

-I told this corepack is not finished, you will see much better connectors in the next pics, I have found some great stuff.