Samsung 25R/LG 18650HE2/ Sony VTC5 high power 18650 battery
- Thread starter Ebikebert
- Start date
Green Machine
100 kW
Ok i am gonna test later today with a thermometer and then will post my results. The pack is 13s 6p panasonic b 3400mah...the highest quality 18650 cell i know of but only capable of 7amp discharge.
Is anyone running any of these high power packs they are building? I imagine the life expectancy of these packs is not that much when they are getting this hot. I am only burning 48v 30amps....1500 watts.
Does this mean the chemistry in these cells is not that great? I remember LFP reporting burning huge amps out of packs made up of hobby king nanotechs and saying the pack was just warm to the touch.
Is anyone testing these 18650 packs in rigourous use?
Is anyone running any of these high power packs they are building? I imagine the life expectancy of these packs is not that much when they are getting this hot. I am only burning 48v 30amps....1500 watts.
Does this mean the chemistry in these cells is not that great? I remember LFP reporting burning huge amps out of packs made up of hobby king nanotechs and saying the pack was just warm to the touch.
Is anyone testing these 18650 packs in rigourous use?
Ypedal
100 TW
Seems it's a matter of Internal Resistance vs Capacity.. you can get lots of one or the other.. but never both at the same time.. without military grade price tags .
Allex
100 MW
It depends on how you build them as well, show us your pack!
Green Machine
100 kW
Here is a picture the construction of the pack...it has a bms on the bottom of it as pictured...Its a pretty sweet pack so far. I am just wondering about the heat issue and if its normal.
My guess it gets to about 100 degrees farenheit on the outside...but i will temperature test it later today.
My guess it gets to about 100 degrees farenheit on the outside...but i will temperature test it later today.
Allex
100 MW
Judging by the wires, they are too thin to handling your power, and what do we know about the spot welding, how is it done? Perhaps the welds are not made for your high current application like those the DC wires. This can make the pack too hot
Green Machine said:
I have a pack made recently with similar specs LG cells. 2.9Ah 7A max. 13s15p. I'm feeding a 1000W motor at the same 48V 30amps (30A cont - 60A peak BMS to 35A cont - 45A peak Controller)
I can't feel any heat, not even warm, charging (6A) or discharging (30A max uphill). Only the BMS warm 6A charging / 30A discharging.
Of Course hot should be avoidable, the only thing You could do Is having a good heat transfer through the cells and battery case. Before building the pack making numbers You should maintain a max of 25% - 50% of the max C discharge rated if want to avoid internal heat as much as possible.
In my case I'm doing 2 Amps max to 2.85Ah 2C max rated cells. thats 0.60C / 30% of the max rate. And In this case, heat is simply nowhere everytime.
Those ncr18650B cells are simply the best of the best at Ah, and although they are low max discharge rating, are not known for losing health easily.
The problem I see in that pack are those 16/18 AWG lead wires that the battery will desintegrate at high Amps
Green Machine
100 kW
I gotta see it to believe it .... a high power pack that can run at maximum amps and only get luke warm. ....were you running it at maximum amperage by climbing hills, accelerating, etc for long periods of time?
Allex
100 MW
Green machine, you have to change your wires, they are good for a laptop but not for an e-bike. This is probably where your problem is.
Green Machine
100 kW
Allex said:
yeah for sure i am going to change those....
Ohbse
10 kW
Green Machine said:
They key is avoiding exactly what you stated, running at maximum amps... your pack should be sized appropriately for the peak loads you anticipate, e.g rated current/2. My pack of HE4's running 80amps peak only sees 8amps peak per cell and as such is not stressed and maintains a low temperature. Having gone from 'just enough' battery to achieve a one way journey to ~3x that, it's so very much better to have more than you need. I now charge to 4v per cell and still have enough capacity for a full return journey while adding a mere 3kg to the total mass.
Green Machine
100 kW
Ok i just did some more torture testing....climbing a big hill at full power 30 amp continuous.
This time I had an IR Thermmometer.
Pack is getting to 150 degrees Fahrenheit and is hot to the touch where it is uncomfortable to hold tight. Is that too hot?
This time I had an IR Thermmometer.
Pack is getting to 150 degrees Fahrenheit and is hot to the touch where it is uncomfortable to hold tight. Is that too hot?
Allex
100 MW
Yes thats way to hot, you will shorten your battery life.
Question for anyone else who has used the Samsung 25R cells:
I ordered 60 cells a few months ago from an alibaba/aliexpress provider Lucy/UTLBatteries and they were about $6 per cell (with tabs welded for an included $.15 total for both sides of cells per/cell) so I could solder or spot weld them shipped to California so approximately $360 total USD for 60 cells with tabs (for total of 12s 5p or 12.5ah capacity).
At this cost, I could buy similar 20c 4s 5ah lipos (total of 6 packs for total of 12s 10ah capacity) from hobbyking for about $160-$175 shipped.
Question is, how much longer will the Samsung 25r's last than the Turnigy lipos at similar usage? I know I'm comparing 12.5ah capacity to 10ah but I understand the Samsung's have much more sag at 30amps which is my max discharge for my ebike but I understand the Samsung 18650's also have possibly a longer cycle life?
For more than double the cost, I wonder if used prudently I could get at least as many cycles out of the Turnigy's even if I had to buy a whole new replacement of the 6 packs of 4s vs buying the Samsungs and trying to spot weld or solder the 60 cells together myself and all that entails (possibility of one of the 60 cells shaking loose and breaking the solder joint, difficulty in getting replacements etc vs Hobbyking which has a West Coast USA location)?
I'm not pro one or the other and I hear good things about the life cycle of the Samsung's and the high amperage discharge they are capable of but they don't seem to have much difference when I compare the two in typical rides...
Thx!
I ordered 60 cells a few months ago from an alibaba/aliexpress provider Lucy/UTLBatteries and they were about $6 per cell (with tabs welded for an included $.15 total for both sides of cells per/cell) so I could solder or spot weld them shipped to California so approximately $360 total USD for 60 cells with tabs (for total of 12s 5p or 12.5ah capacity).
At this cost, I could buy similar 20c 4s 5ah lipos (total of 6 packs for total of 12s 10ah capacity) from hobbyking for about $160-$175 shipped.
Question is, how much longer will the Samsung 25r's last than the Turnigy lipos at similar usage? I know I'm comparing 12.5ah capacity to 10ah but I understand the Samsung's have much more sag at 30amps which is my max discharge for my ebike but I understand the Samsung 18650's also have possibly a longer cycle life?
For more than double the cost, I wonder if used prudently I could get at least as many cycles out of the Turnigy's even if I had to buy a whole new replacement of the 6 packs of 4s vs buying the Samsungs and trying to spot weld or solder the 60 cells together myself and all that entails (possibility of one of the 60 cells shaking loose and breaking the solder joint, difficulty in getting replacements etc vs Hobbyking which has a West Coast USA location)?
I'm not pro one or the other and I hear good things about the life cycle of the Samsung's and the high amperage discharge they are capable of but they don't seem to have much difference when I compare the two in typical rides...
Thx!
Green Machine said:
Ohbse said:
As ohbse said, the key is the max amps per cell, that's all but..
The heat would not only came from the cells, if the nickel/copper/whatever connecting the cells is not wide enough at mm^2 depending of their electrical resistivity it would heat more than the cells, or it would heat nothing at all.
In the case I example to You. I'm pulling 30 Amps max continuous through a 15p 7A max cells. thats a max of 2 Amps max continuous for each cell. The nickel strips between the cells in that pack are 2x 7mm x 0.15mm thick from each cell. If you make numbers You will notice that it is 21 AWG diameter equivalent. 21 AWG could stand between 9 and 10 Amps made from cooper, because nickel have 4 times more electrical resistivity than cooper, those nickel strips could stand ~2.5 amps maximum with no appreciable heat.
I couldn't say my battery become luke warm, it is not warm at all, I can't feel anything. The worst test I did was ascending a mountain pass from 600 to 1300 meters altitude, and that maintained my controller pulling the 30 Amps the BMS let (controller stand more) during half an hour continuosly, and nothing about heat.
(You are running 5 amps max continuous through a 7 Amps cells capable, thats 70%, too much If no heat is wanted. Are also your nickel strips / copper wires prepared for that? make numbers and You have the answer if the heat is normal or not, thats all)
this is the battery I made
[youtube]5L9hOVG_0RQ[/youtube]
ohzee
100 kW
Sorry if this is the wrong thread. I searched on this earlier in the week and only had limited info.
Anyone have personal experience with the LG 18650MH1 3200mAh 10A cell ? Other then the initial voltage sag it seemed
pretty comparative to the 25r with a bit extra ah. Could not find a spec sheet on the cell as I was interested in cycle life.
Anyone have personal experience with the LG 18650MH1 3200mAh 10A cell ? Other then the initial voltage sag it seemed
pretty comparative to the 25r with a bit extra ah. Could not find a spec sheet on the cell as I was interested in cycle life.
Green Machine
100 kW
wow that was an amazing video...thanks for sharing....and that pack was pure art 
ridethelightning
1 MW
- Joined
- Jul 21, 2013
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ohzee said:
i highly doubt the comparison ozee.
higher capacity usually always means crap c rate and will heat up. the extra capacity percieved will be wasted as heat at high current.
and also its lg :lol:
i dont think they would be in same real-life ballpark as 25R
Wheazel
10 kW
I have a similar spotwelder and made an improvement by attaching 30cm long, 20mm2 area powercables to the terminals.
Then use the footswitch to weld. Greatly increased the speed and usability of the welder compared to using the stock terminals.
I have the copperpins soldered straight into the thick 20mm2 cable, with about 15mm sticking out.
(sharpened the back side of the pins before sticking them into the cable.)
That means the thick cable can be held lik a regular pen for good precision.
Then use the footswitch to weld. Greatly increased the speed and usability of the welder compared to using the stock terminals.
I have the copperpins soldered straight into the thick 20mm2 cable, with about 15mm sticking out.
(sharpened the back side of the pins before sticking them into the cable.)
That means the thick cable can be held lik a regular pen for good precision.
silentflight
100 W
Wheazel said:
Great ideas, would you please share photos of your improvements and the welds they have made? I am about to buy a welder and would like to do the same if it still welds 0.15mm nickel to 18650s with a strong bond.
How did you connect the cables to the electrode leads on the machine itself?
Where did you attach the foot pedal wires to the machine?
Green Machine
100 kW
So what do you guys think I am thinking of having a 25r pack with no output control on the bms...but all other fuctions of the bms such as charge control and low voltage bms still functional...woudl this work?
Is it same to run one of these packs with no amperage output controls?
Is it same to run one of these packs with no amperage output controls?
Wheazel
10 kW
silentflight said:
Can get some photos next time I pass by the garage. The welder is is equipped with the option to use a foot pedal through a simple 2pole connector port on the front.
You can actually buy extensioncables for it, but they are slightly longer and i dont know the area of the cable. They were also pretty expensive i recall.
The cables i use are soldered to 1,5mm copperplate squares roughly ~18mm x~35mm big. One of the 18mm ends are curved around the 20mm2 cable for a good and low resistance connection.
There is a hole in the copperplate for the screw that fastens the stock tipholder. So the plate is basically clamped between the arm and the tipholder.
I figured 30cm would be plenty to have good enough reach from the welder, but still short enough to not lose too much welding capacity.
Welds 0,1mm no problem. Got 0,15mm nickelstrip coming in the mail shortly to try.
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