Samsung 25R/LG 18650HE2/ Sony VTC5 high power 18650 battery

[Green Machine]

yes its 13s 6p.... Its an expensive pack huh? Next i am going to make a samsung 25r pack with high power bms it will be cheaper. I remember thinking when i ordered it that if I was going to pay the air shipping cost i better get the pack with the best cells no matter what the cost. I figured shipping to be around somewhere like 100 a pack. I was pleased with my decision until i realized that there might be a problem with amperage output.

So i havent tested the panasonic 3400mah until the last few days. Last night I put one in my 70 watt vape...most vapists recommend high amperage cells so i didnt expect it to work very well. To my astonishment it worked awesome...no need for more amperage. Whats amazing is i have been hitting this thing all day and even holding on the fire button and still havent managed to drain the battery. This thing seems to last twice as long as what i usually vape on which is a samsung 25r. I am not sure why this battery is not more popular among vapists...to me its a game changer.

So excited about this single cell, i turned my attention to the 48v 20ah pack made up of panasonic 3400 cells. Again after a recent phone conversation with Dogati where he warned me about voltage lag and low amps in this cell i did not expect much. I mean a vape is a vape but an ebike is a different gadget. So unfortunately my cycle analyst bike didnt fire up and needs a new controller....so i had to throw it in a bike with no cycle analyst...so my results are not yet scientific. But I know from this bike which i have rode hundreds of miles on is that the pack was putting out as much as the controller puts out which is 30amps continuous ....so around 1500 watts with no voltage lag. I am pleased with the results....but need to get a higher power bike with cycle analyst on to see what pack can truly do. But atleast i feel like its doing 30 amps continuous easily with no feeling of lag.

 

[anttipaa]

I received my Dn-10 spot welder and have been testing it. Im usin 0.3x8mm nickel sheets and I get good welds on 18650 cells. But when I try to weld nickel to nickel I cant get good welds. What im doing wrong? Im usin 1.5-2 power. How much pressure should I use? Maybe I got nickel plated steel strip instead of pure nickel..?

 

[dbaker]

What is your source for the DN-10? I do not know how to get one to the US.

 

[anttipaa]

What is your source for the DN-10? I do not know how to get one to the US.

From taobao seller yongdong168. I used local buying agent.

 

[ridethelightning]

I received my Dn-10 spot welder and have been testing it. Im usin 0.3x8mm nickel sheets and I get good welds on 18650 cells. But when I try to weld nickel to nickel I cant get good welds. What im doing wrong? Im usin 1.5-2 power. How much pressure should I use? Maybe I got nickel plated steel strip instead of pure nickel..?

in the russian vids of battery spotwelding, by andreym,ivanovlev etc, i saw they used vodka to clean the strip before welding.


im keen to see how you get on as i will be using one of these machines soon too.

do you think it could weld 0.5 or 1mm at full power as claimed?

 

[madin88]

IMO its not a good idea to weld 0,3mm or even 0,5mm to a battery which only has a wall thickness of about 0,1mm (Allex has cut a HE2 open and measured it). there is risk of cell leakage and also under vibrations the cell could tear open while with thinner tabs this would not be a problem -> if you pull off 0,3mm nickel the cell quite sure will have a hole.
here a pic how a welded cell looks from the inside: http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383&start=1100#p1006857

 

[anttipaa]

I need to try cleaning those nickel sheets before welding. I think it would weld 0.5 or maybe even 1.0. I try when I get some metal sheets.

If you use 0.1 nickel only how do you build packs for high amps? 0.1mm would generate lots of heat?

 

[Ohbse]

IMO its not a good idea to weld 0,3mm or even 0,5mm to a battery which only has a wall thickness of about 0,1mm (Allex has cut a HE2 open and measured it). there is risk of cell leakage and also under vibrations the cell could tear open while with thinner tabs this would not be a problem -> if you pull off 0,3mm nickel the cell quite sure will have a hole.
here a pic how a welded cell looks from the inside: http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383&start=1100#p1006857

Those are some seriously massive spot welds in that pic! There's no way that amount of current/duration is required for correct bonding. GOOD spot welds are relatively small but have absolute fusion between the layers. There should not be any burnt look. I've been experimenting with 0.3mm on 18650's and I think it's the best option at this stage.

 

[riba2233]

I don't think so. Even the 0.3 mm is too small for a decent current carrying capability. I prefer spot welding cells with thin nickel tape in parallel, and then connect parallel groups in series with copper cable. This gives much better performance, and your cells are safe. Here's an example:

 

[ridethelightning]

indeed, the 0.5-1.0mm stip i was considering welding is not for the cell paralelle connections, but to make the series connections between premade paralelle groups, like the one in above pic.

last time i used thick stips of copper sheet for this, but i would prefer to spotweld it for extra neatness and perhaps even less heat transferred to cells than with soldering...

 

[madin88]

Those are some seriously massive spot welds in that pic! There's no way that amount of current/duration is required for correct bonding. GOOD spot welds are relatively small but have absolute fusion between the layers. There should not be any burnt look. I've been experimenting with 0.3mm on 18650's and I think it's the best option at this stage.

probably the welds shown on the pic are not typically (they want to hype and sell theire product), but if you weld 0,3mm or thicker nickel it will not look much different because you need big current and heat for a proper weld.
As i said the problem mainly is risk of leakage and not heat, because the wall thickness of 18650 cells only is about 0,1mm
and if you calculate total resistance of a finished battery, how much does it add? the connections are so short that it has not much influence..

thats how tesla does it:

 

[Allex]

I would say marketing bullshit to those pictures about dark spots of the welding inside the battery. Technically you can succeed on doing it, but then you are welding with a pulse that is too long.

Here is a picture of inside on one of my DBHEII cells, they are welded with DN-10 and 0,3Nickel strip the only thing you can se is a slight bumb from one of four spotwelds.


And I have been looking at the thickness again. Could be so that the wall of my cell is 0,1 but the end Cap is def. thicker, actually looks like 0,3mm. See my comparison picture of a 0,3mm nickel strip and the cap. It is hard for me to measure with a caliper. One would need a micrometer for more accuracy

 

[madin88]

Allex, what about the pics you sent me where you could see black dots on the inside where you could see right through?
Maybe its mostly marketing bullshit, but it DEFINITELY has a bit truth

I have yet not cut open one of my samsung 25R cell, but i will do. however that be, i will use maximum 0,15mm nickel on my 18650 cells.
As example one 10mm (2 dots per cell) or 20mm (4 dots per cell) wide strap for serial AND also parallel connection is a nice solution and not much cutting work etc. Thats how i'm going to weld my 20s12p pack and i believe >30mm² cross section (which would be >6mm² copper equivalent) is enough.

 

[Allex]

That was another cell. Yes it was a hole from the spot welding. But this is because it was a problem with the foot switch. It did a double weld sometimes, so kind of a double pulse which we don't want to have.

Notice the black dot on the left, here is where the welder did the job to much. with a bit of cleaning I could see right thru the little hole.

 

[\/ampa]

For testing before welding i do lay 2x nickel strips on each other than weld them and look on the other side the result.

 

[scoot-e]

yes its 13s 6p.... Its an expensive pack huh? Next i am going to make a samsung 25r pack with high power bms it will be cheaper. I remember thinking when i ordered it that if I was going to pay the air shipping cost i better get the pack with the best cells no matter what the cost. I figured shipping to be around somewhere like 100 a pack. I was pleased with my decision until i realized that there might be a problem with amperage output.

Could you tell me where you are purchasing your bms units? I have a similar application with a 12s battery pack and am looking for a decent bms, thx!

 

[Punx0r]

Allex, that's a great idea dissecting and inspecting the inside of a cell after welding. We do not even seen any discoloration of the metal to indicate any heating. I wonder what the inside surface of a soldered cell looks like?

 

[Allex]

Not much different actually, you would not see any traces inside from a regular weld.

 

[BoomerChomsi]

I have a small question.
Is the outer case (cilinder shape) also negative pole?

Thank you!

 

[riba2233]

Yes, whole can is negative, and even at the top of the cell where it ends. That's why there is a white insulator installed.

 

[madin88]

..to prevent a short to the apposed p-group i stick small capton tape strips to the cells (can withstand 200°C):

glued together by filling hot glue into the gaps

btw: samsung 25R cells

 

[BoomerChomsi]

Yes, whole can is negative, and even at the top of the cell where it ends. That's why there is a white insulator installed.

Thanks mate! 8)

 

[BoomerChomsi]

Which soldering strip has a better conductivity?
Copper of brass?

 

[cwah]

..to prevent a short to the apposed p-group i stick small capton tape strips to the cells (can withstand 200°C):

glued together by filling hot glue into the gaps

btw: samsung 25R cells

Are kapton tapes good against chaffing? Because that will wear these down over time

 

[Punx0r]

Which soldering strip has a better conductivity?
Copper of brass?

I was surprised how poor brass was compared to copper:

https://www.bluesea.com/resources/108

Brass is typically only 28% of the conductivity of copper.