Samsung 30Q hard voltage drop under load?

DasDouble

DasDouble

100 kW
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Jul 12, 2015
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GERMANIA :D
My Samsung 30Q pack is dropping hard from about 3.9 to ~3.35v at the lowest when pushing it to 10A while it could theoretically get to 15A (says the supplier). Is that a normal thing today? Because in such case my Adaptto Controller says the battery is empty and stops giving me more current :roll: ..

What is better in this case:
1.) Cooling the cell down to whatever temperature I want (I would suggest about ~8°C?) so the resistance of the pack gets lower

or

2.) Welding more nickel on the complete pack so the resistance also get lower. I have got 0,15mm x ~10mm Nickel at the weekest point but have a temperaturesensor on it so I know when it becomes too hot.

What do you think?
 
Cooling the cells will give you more voltage drop from slowed ionic motion rates inside the cell.

Maybe fake 30Qs, maybe stored at high SOC and high temp until impedance climbed, and that's pretty light busing likely causing at least a few tenths of a volt drop.
 
You can see what the voltage should be for the 30Q at different discharge currents over the discharge cycle in the chart on page 6 here:

https://eu.nkon.nl/sk/k/30q.pdf

See if it matches up with your observations
 
DasDouble said:
My Samsung 30Q pack is dropping hard from about 3.9 to ~3.35v at the lowest when pushing it to 10A ....
Click to expand...
How and where are you measuring this ?
..At the controller
...At the pack terminals ?
...At the cell end caps with a mMeter ?
What size pack and what max pack current draw. .
 
I measure this at the Adaptto Max-E Controller. I have a 20s 15p 300 cells Samsung 30Q pack. Maybe it is because of my poor nickel strips with its 0,15mm x 10mm x 3 for 15 cells in parallel?
 
If possible post a picture or a schematic of how you wired the back, but if only 3 nickel strips are used for the serial connections there is your problem, and if it is, I recommend you stop using the pack until fixed, the least that can happen is these 3 nickel strips melt, the worst they melt and short circuit something and make a big fira ball
 
DasDouble said:
I measure this at the Adaptto Max-E Controller. I have a 20s 15p 300 cells Samsung 30Q pack. Maybe it is because of my poor nickel strips with its 0,15mm x 10mm x 3 for 15 cells in parallel?
Click to expand...

What mohm resistance reading are you getting on the adaptto statistics screen?

Make sure your series connections are beefed up with either extra nickel strips or copper wire.
 
Pedrodemio said:
If possible post a picture or a schematic of how you wired the back, but if only 3 nickel strips are used for the serial connections there is your problem, and if it is, I recommend you stop using the pack until fixed, the least that can happen is these 3 nickel strips melt, the worst they melt and short circuit something and make a big fira ball
Click to expand...

yeah I hoped that this would not be the issue, but I guess you are right there. I have to level that stuff up.. (will be a ton of work yeeey.. :roll: :pancake:

Thanks
 
brumbrum said:
DasDouble said:
I measure this at the Adaptto Max-E Controller. I have a 20s 15p 300 cells Samsung 30Q pack. Maybe it is because of my poor nickel strips with its 0,15mm x 10mm x 3 for 15 cells in parallel?
Click to expand...

What mohm resistance reading are you getting on the adaptto statistics screen?

Make sure your series connections are beefed up with either extra nickel strips or copper wire.
Click to expand...

I have searched for it. Where can you read that?
Thanks in advice :)
 
It’s at the very bottom of a the screen that tells you the max speed you’ve pulled,, along with other statistics such as ah used and average voltage etc
 
It says 73,2 aVg on the left side and 117 mOhm at the right side. Damn, that used to be way more less.. Maybe because I have pushed that max. current a bit in the past? Im sure I have to add some more nickel / other material on my cells..
 
i just made a 10p 30q pack. looking for 150-200A. i used 10X 0.2mm strip for the serial connections and still think its borderline..
 
The voltage sag you are seeing on the pack is about 11volts in total(if using 20s configuration). With a 15p pack it should be less than half that number..... depending on how many amps being pulled by the motor.
I have just built a 30Q pack 20s 9p. I have only cycled the pack twice but this is what I have seen...
Adaptto recording resistance as 50mohms.
Battery from full charge sags up to 4v at 85amps
Battery near empty (60v resting) sags 6v
Each cell is having 9 to 10 amp discharge
 
Well I guess we would have to compare that at more equal circumstances. My pack is now maybe about 1.5 years old, I supercharged it like 5 times in total (but only 3 (180 cells) of them, two of them were not) and its -11°C outside right now here in Germany.. When I have more time I will take some hours and finally upgrade all of them to 16,2kW output. :)
 
ridethelightning said:
i just made a 10p 30q pack. looking for 150-200A. i used 10X 0.2mm strip for the serial connections and still think its borderline..
Click to expand...

Just have a look at that table. I made a formular for calculating that once but it ended up being too complicated to post it on the forum. :) https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

For 150-200 Amps you would need a bit more then 0,2mm x 10mm being one single strip from one to the other cell. I would recommend to go with this single strip to one big connector like a copper busbar or something like that.
 
DasDouble said:
Well I guess we would have to compare that at more equal circumstances. My pack is now maybe about 1.5 years old, I supercharged it like 5 times in total (but only 3 (180 cells) of them, two of them were not) and its -11°C outside right now here in Germany.. When I have more time I will take some hours and finally upgrade all of them to 16,2kW output. :)
Click to expand...

Maybe then you have answered your own question.
Some of the cells are different age. Pack is getting old. Very cold temperatures. All three would definitely add up to ooor performance.
 
DasDouble said:
ridethelightning said:
i just made a 10p 30q pack. looking for 150-200A. i used 10X 0.2mm strip for the serial connections and still think its borderline..
Click to expand...

Just have a look at that table. I made a formular for calculating that once but it ended up being too complicated to post it on the forum. :) https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

For 150-200 Amps you would need a bit more then 0,2mm x 10mm being one single strip from one to the other cell. I would recommend to go with this single strip to one big connector like a copper busbar or something like that.
Click to expand...

Here is a 4s 9p I made for my adaptto. I made 5 of these modules and put them in series. Nickel for parallels is .15mm, copper series connectors are 2mm diameter
95n5sl.jpg
 
brumbrum said:
DasDouble said:
ridethelightning said:
i just made a 10p 30q pack. looking for 150-200A. i used 10X 0.2mm strip for the serial connections and still think its borderline..
Click to expand...

Just have a look at that table. I made a formular for calculating that once but it ended up being too complicated to post it on the forum. :) https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

For 150-200 Amps you would need a bit more then 0,2mm x 10mm being one single strip from one to the other cell. I would recommend to go with this single strip to one big connector like a copper busbar or something like that.
Click to expand...

Here is a 4s 9p I made for my adaptto. I made 5 of these modules and put them in series. Nickel for parallels is .15mm, copper series connectors are 2mm diameter
95n5sl.jpg
Click to expand...
my bad. i meant to write 10 x 10mm X 0.2mm for the series connections. basically maxing out the nickle strip welds for the config.
 
brumbrum said:
DasDouble said:
ridethelightning said:
i just made a 10p 30q pack. looking for 150-200A. i used 10X 0.2mm strip for the serial connections and still think its borderline..
Click to expand...

Just have a look at that table. I made a formular for calculating that once but it ended up being too complicated to post it on the forum. :) https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

For 150-200 Amps you would need a bit more then 0,2mm x 10mm being one single strip from one to the other cell. I would recommend to go with this single strip to one big connector like a copper busbar or something like that.
Click to expand...

Here is a 4s 9p I made for my adaptto. I made 5 of these modules and put them in series. Nickel for parallels is .15mm, copper series connectors are 2mm diameter
95n5sl.jpg
Click to expand...

Wow, that looks like a hell of a pack.. And I thought my 300 Amper variation would arleady be crazy..
 
Have just disscharged the complete pack down to 3.2 volts. The one of five packs I have upgraded some time ago went back to 3.5v quite fast. Seems like Im gonna have to do the same with the other ones too. For sure this will help.
 
DasDouble said:
Have just disscharged the complete pack down to 3.2 volts. The one of five packs I have upgraded some time ago went back to 3.5v quite fast. Seems like Im gonna have to do the same with the other ones too. For sure this will help.
Click to expand...

Damn, I just calculated the lost range of 0,2v difference. Its 0,1666% (1/6%) of the range I do get right now (44km) means (44km * 1/6%) 7.3km of range! Wow and just all because of bad series connection. :eek: :shock:

Edit: 73 meters, not 7.3km :pancake:
 
Punx0r said:
You're off by a couple of decimal points:

0.167% of 44km is 0.073km = 73 metres!
Click to expand...

Oops.. thats a thing :pancake:
 
It can't be said enough that the max discharge claims of 18650 cells have to be taken with a grain of salt.
This video that tests a cell at 8a discharge shows it gets much hotter than it claims its supposed to be at 80c for the claimed possible discharge of 10amp, listen to what the guy says after the test.
https://youtu.be/an9-i23mGqc?t=4m29s
This is a consistent theme with 18650s, everyone wants to treat them like lico but I don't think they have as much cobalt in them to be treated in such fashion.
Another way to look at ideal 18650 usuage is Tesla battery modules, where the wire to each cell is tiny, almost so thin you can't see it easily in the pictures, in other words the draw from each cell is comparatively tiny.
tesla-cells-wire-bonding.jpg
 
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