Is is it possible to build a 48 or 52v battery pack using removable (non soldered) 18650 cells

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Hello, I have been looking for info about building a battery with removable 18650 cells. Every battery I have seen uses soldered connections. I understand that this is the preferred method however I need to travel and to ship, and that is not possible with large soldered battery packs.

I would like to build my own battery pack and make it so the cells can be removable. Perhaps a 14s2p or 14s3p configuration with 6-10ah and a max amp draw of 16a. Perhaps I could use plastic battery holders with the bms attached to the terminals on the battery holders. The batteries can be taped to the holders tightly with electrical tape, but when I need to travel I can remove the tape and remove the 18650 individual cells and then I can travel with them.

Has anyone built a battery such as this or is there anything theoretically wrong with this? I am new to the ebike scene so I do not know much about li-ion batteries. Thank you!
 
If you use suitable size cells to build your battery, you can make modules of less than 100Wh each, which are flyable when detached from each other, but can be joined in parallel for a larger pack after you arrive. A 13S 48V lithium ion battery would need to be made of cells no bigger than 2.079Ah (assuming 3.7V nominal cell voltage) to conform to regulatory limits.

Many high power 18650 cells are in the 2Ah range.

Grin Tech makes 36V modules that are sized and packaged for travel.
http://www.ebikes.ca/product-info/ligo-batteries.html
 
dilkes said:
Here's one approach to doing that.
https://vruzend.com/about/

Hey thanks! Those are neat, like legos for batteries :) Legos are right up my alley. It looks like you can build odd shaped batteries to fit in tricky places too.

They are claiming maybe only 3.5a continuous per battery though so I would need to run at least 4 or 5 sets to get up to the 18a continuous discharge rate of my motor. This was my concern with the non soldered connections, higher amps will cause issues with non-perfect connections. Perhaps they will revise that number upwards after more testing. I really would like to make a smaller battery with more powerful cells (maybe 3 sets of 3+ah with 6+a continuous discharge).


Chalo said:
If you use suitable size cells to build your battery, you can make modules of less than 100Wh each, which are flyable when detached from each other, but can be joined in parallel for a larger pack after you arrive. A 13S 48V lithium ion battery would need to be made of cells no bigger than 2.079Ah (assuming 3.7V nominal cell voltage) to conform to regulatory limits.

Many high power 18650 cells are in the 2Ah range.

Grin Tech makes 36V modules that are sized and packaged for travel.
http://www.ebikes.ca/product-info/ligo-batteries.html

I wish there were more options for larger cells. I would love something like 12v 8ah batteries, then run 4 of them joined up through a bms. Simply disconnect the 4 modules and they can fly or be shipped. I do not understand why everything must be based on glorified flashlight batteries.:( I originally was thinking along the lines of 12v li-ion motorcycle batteries but no one seems to be using them.
 
John and Cecil said:
I originally was thinking along the lines of 12v li-ion motorcycle batteries but no one seems to be using them.

That's not true at all.

https://m.ebay.com/itm/34363-LITHIUM-BATTERY-YTX9-BS-12V-8AH-KAWASAKI-1000-Z-1000-2003-2004-2005-2006/132061365122

12V 10Ah are available much cheaper, but they exceed 100Wh nominal capacity.
 
Eeeks those are pricey. I might give the legos a shot. If ebay puts out a coupon I can probably pick up some cheap laptop batteries and take them apart for the cells, then lego them together with a 13s bms. I wish I could fly with my ego 56 -2ah but it is marked at 116wh. it was a steal for $42 brand new including a used charger so I see it as disposable in a few months.
 
The thing I find with batteries is that the best battery is one which is built fit-for-purpose.

If an application calls for 30 kW continuous, and 30 kWh of stored energy, you will need a cell capable of 1C continuous.

If you felt like you could get away with 15 kWh instead, but you still need 30 kW, you now need a cell capable of 2C continuous. So you can't use the same cells - you need more powerful cells. Even if you accepted lower power, you can't then add to this battery without some compromise. It would be a mixture of cells at different stages of ageing, and would need either two separate battery management systems, or you would need to completely re-build the battery so the number of cells in parallel was doubled.

A battery which is able to be disassembled with ease, is possibly not a very robust battery; certainly not for a road-going vehicle. I'm sure something can be devised, but it wouldn't be easy.
 
Thanks people! I will read through the links today and I look forward to seeing the updated "lego" concept.

I gave it some thought and I think I would prefer something like this - if it is possible and also safe. I would like to build 18" (7 cell) tubes. The tubes can be aluminum or pvc or something. I like the tube concept because I think it can be good for cooling, easy to mount on upper and lower frame, and the top and bottom can be threaded and screwed on tightly to press the batteries together firmly (heavy duty springs or just 1 soldered connection on both ends) for a better connection. Each tube would be half of a 52v battery so each one would be 26v x lets say 3ah with quality 18650s. Now I would like to wire between 6 and 10 tubes together to form a 52v x 9ah - 15ah battery.

I am new to this but I assume this setup would require a BMS for safety. I would like the BMS to control and monitor the individual tubes (26v 3ah). Is something like this possible and would it be safe? The tubes would work well with my bike since I could easily strap 6 of them onto my lower bar and a few more inside and on the upper bar.

A setup like this allows the batteries to be removed and replaced as needed, and when they get old it is easy to upgrade as all you need to do is load it up with new batteries.

Thank you for putting up with my ignorance :)
 
Dumsterdave said:
If you need higher specs, then wait a week or two. Vruzend are supposedly releasing their new higher amp version any day now

I saw on their website the new kits will allow greater than 10a per cell. :) They would probably make a nice 13s2p battery with 20a discharge and 6-7ah capacity, and only 28 flashlight sized batteries to carry on a plane! Hopefully it comes out soon.
 
If you are in the U.S. and are willing to operate with 12S configurations, another possible route are to use tool battery packs. Specifically Lowe's line of Kobalt tool batteries are a great combination of packaging (6S1P 1.5Ah, 6S1P 2.0 Ah, 6S2P 2.0 Ah), price ($10,$20,$50 USD respectively), frankly quality, being comprised of Samsung INR18650 cells that can be run up to 15 A for the 1.5 Ah cells and 22 A for the 2.0 Ah ones, and accessibility, both with the slide in tab locks, and the fact they can be dissembled by taking out 4 simple screws.

Consider that if you take the $10 packs (nominal 22.2V@1.5Ah which is 33.3 Wh), and repackage them into 6S3P bricks you get the following properties:

1. At 99.9 Wh, right at the travel limit.
2. Current draw easily at 40 A.
3. Retaining the top BMS and packaging makes it possible to use the standard charger to recharge.
4. Again a secure click-in locking pack installation system using the original casing.
5. 4 bricks gives you a 12S6P nominal 44.4V@7.5Ah that you can drive up to 90A and 400 Wh worth of capacity.

And all of that for a $120 USD investment in batteries and a weekend of repackaging.

I'm in the process of putting together a 12S5P pack to drive the Ryobi 48V lawn mower that I picked up for a song. At $0.28 USD/Wh for already soldered quality batteries with a BMS and packaging, the Kobalts look like a winner to me.

There's a guy on youtube named vuaeco that has a series of videos on both the teardown and buildup of these packs. His monster pack is a 6S5P 22.2V@10Ah. It shows all the technique to disassemble and rebuild multiple batteries into higher powered packs.

Hope this helps,

ga2500ev
 
ga2500ev said:
If you are in the U.S. and are willing to operate with 12S configurations, another possible route are to use tool battery packs. Specifically Lowe's line of Kobalt tool batteries are a great combination of packaging (6S1P 1.5Ah, 6S1P 2.0 Ah, 6S2P 2.0 Ah), price ($10,$20,$50 USD respectively), frankly quality, being comprised of Samsung INR18650 cells that can be run up to 15 A for the 1.5 Ah cells and 22 A for the 2.0 Ah ones, and accessibility, both with the slide in tab locks, and the fact they can be dissembled by taking out 4 simple screws.

Consider that if you take the $10 packs (nominal 22.2V@1.5Ah which is 33.3 Wh), and repackage them into 6S3P bricks you get the following properties:

1. At 99.9 Wh, right at the travel limit.
2. Current draw easily at 40 A.
3. Retaining the top BMS and packaging makes it possible to use the standard charger to recharge.
4. Again a secure click-in locking pack installation system using the original casing.
5. 4 bricks gives you a 12S6P nominal 44.4V@7.5Ah that you can drive up to 90A and 400 Wh worth of capacity.

And all of that for a $120 USD investment in batteries and a weekend of repackaging.

I'm in the process of putting together a 12S5P pack to drive the Ryobi 48V lawn mower that I picked up for a song. At $0.28 USD/Wh for already soldered quality batteries with a BMS and packaging, the Kobalts look like a winner to me.

There's a guy on youtube named vuaeco that has a series of videos on both the teardown and buildup of these packs. His monster pack is a 6S5P 22.2V@10Ah. It shows all the technique to disassemble and rebuild multiple batteries into higher powered packs.

Hope this helps,

ga2500ev


You must be referring to the 24v max batteries, I did not even know they existed until now thank you. I wonder if my motor (tsdz2) will be able to use them fully, 13s is a normal 48v e bike battery. Two 24v 4ah batteries wired together to put out 48v 4ah and would be double the battery capacity that I have now and I guess I could carry 2x 24v 4ah batteries on a plane. I carry my batteries in a handlebar bag so the size is not a problem. Plus lowes has coupons for 20% off, plus you can get 10% off buying a gift card first and also cashback for online order. That is like 70+ tax for what I assume would actually be a 44v 4ah battery. This sounds like a simple and cheap solution for the time being :)
 
John and Cecil said:
ga2500ev said:
If you are in the U.S. and are willing to operate with 12S configurations, another possible route are to use tool battery packs. Specifically Lowe's line of Kobalt tool batteries are a great combination of packaging (6S1P 1.5Ah, 6S1P 2.0 Ah, 6S2P 2.0 Ah), price ($10,$20,$50 USD respectively), frankly quality, being comprised of Samsung INR18650 cells that can be run up to 15 A for the 1.5 Ah cells and 22 A for the 2.0 Ah ones, and accessibility, both with the slide in tab locks, and the fact they can be dissembled by taking out 4 simple screws.
...
ga2500ev
You must be referring to the 24v max batteries, I did not even know they existed until now thank you. I wonder if my motor (tsdz2) will be able to use them fully, 13s is a normal 48v e bike battery. Two 24v 4ah batteries wired together to put out 48v 4ah and would be double the battery capacity that I have now and I guess I could carry 2x 24v 4ah batteries on a plane. I carry my batteries in a handlebar bag so the size is not a problem. Plus lowes has coupons for 20% off, plus you can get 10% off buying a gift card first and also cashback for online order. That is like 70+ tax for what I assume would actually be a 44v 4ah battery. This sounds like a simple and cheap solution for the time being :)

Yes, the series is called 24V Max. Note that the 24V is generous as they are comprised of standard INR18650 cells that run at a nominal 3.7V. So as I stated in my above post, the 12S configuration will get you just about 44.5V on average. Which is why 13S is generally considered 48V.

The 2x 24v 4aH certainly would be a winner. As I stated above, if you're willing to put in a bit more work, you could go with 4x 24v 2aH for the same capacity but a $20 less starting price. The extra cost would be paralleling pairs of the packs. It's a moderate disassembly, reassembly, and soldering job.

ga2500ev
 
ga2500ev said:
Yes, the series is called 24V Max. Note that the 24V is generous as they are comprised of standard INR18650 cells that run at a nominal 3.7V. So as I stated in my above post, the 12S configuration will get you just about 44.5V on average. Which is why 13S is generally considered 48V.

The 2x 24v 4aH certainly would be a winner. As I stated above, if you're willing to put in a bit more work, you could go with 4x 24v 2aH for the same capacity but a $20 less starting price. The extra cost would be paralleling pairs of the packs. It's a moderate disassembly, reassembly, and soldering job.

ga2500ev

Yeah I understand. Thank you very much. :) The 24v2ah def is a very good deal, especially when you get 30% off with coupon and gc too. I am cautious about parallel batteries though, some have warned that if you screw up and connect one fully charged and the other almost empty that they will try to equalize the power between them instantly and it can be hazardous. But joining batteries in a series is supposed to be relatively safe. I guess maybe if you join them internally and then charge them together there is no risk.

I think I like the idea of flying with the unmodified power tool batteries. 2x 4ah batteries would give us 4ah capacity which would be good for 8-10 miles which is not bad. It will be enough for grocery runs and short trips, the hills there can be brutal. I am hoping I can just wire them together (positive on one to negative on the other, then connect the 2 other leads to the motor for 44v 4ah. After we get settled in inside Europe I will buy (or build) a bigger battery anyway, but at least for a few months we will have something to use. The motor I have cuts out at 39v though, but people are working on a firmware mod now so perhaps by the time we go I can use the battery down to 36v.
 
dilkes said:
Here's one approach to doing that.
https://vruzend.com/about/
John and Cecil said:
Hey thanks! Those are neat, like legos for batteries :) Legos are right up my alley. It looks like you can build odd shaped batteries to fit in tricky places too.



this stuff is utter crap. i got a customer that wrecked 60 out of 200 cells by this. it is competly unusable in a mobile application. the shit WILL viberate loose. you have to tighten them so fas you will cave in the top or bottom of the cell.

just buy a spot welder and some nickel strip and regular cell holders. you will have a vastly superior battery.
 
flippy said:
this stuff is utter crap. i got a customer that wrecked 60 out of 200 cells by this. it is competly unusable in a mobile application. the shit WILL viberate loose. you have to tighten them so fas you will cave in the top or bottom of the cell.

just buy a spot welder and some nickel strip and regular cell holders. you will have a vastly superior battery.

Thank you. I understand. The problem is spot welding is not an option, once you do that you cannot bring the batteries on a plane. The easiest and safest option appears to be to buy under 100wh batteries and then connect them in a series.
 
John and Cecil said:
ga2500ev said:
Yes, the series is called 24V Max. Note that the 24V is generous as they are comprised of standard INR18650 cells that run at a nominal 3.7V. So as I stated in my above post, the 12S configuration will get you just about 44.5V on average. Which is why 13S is generally considered 48V.

The 2x 24v 4aH certainly would be a winner. As I stated above, if you're willing to put in a bit more work, you could go with 4x 24v 2aH for the same capacity but a $20 less starting price. The extra cost would be paralleling pairs of the packs. It's a moderate disassembly, reassembly, and soldering job.

ga2500ev

Yeah I understand. Thank you very much. :) The 24v2ah def is a very good deal, especially when you get 30% off with coupon and gc too. I am cautious about parallel batteries though, some have warned that if you screw up and connect one fully charged and the other almost empty that they will try to equalize the power between them instantly and it can be hazardous. But joining batteries in a series is supposed to be relatively safe. I guess maybe if you join them internally and then charge them together there is no risk.

There's a couple of ways of mitigating this problem. First is of course to make sure that the two batteries are relatively close in voltage. Second is that they can be balanced more equally without harm by connecting the grounds together, and then the positive terminals via a power resistor (like 100 ohms, 10 W). The current flow will be limited by the power resistor.

Once this is done, it's pretty easy to go ahead and solder the pairs of cells together. Note this only needs to be done once. Once the cells are tied together, it's effectively exactly the same 24V@4Ah cell that you proposed in the beginning.

I think I like the idea of flying with the unmodified power tool batteries. 2x 4ah batteries would give us 4ah capacity which would be good for 8-10 miles which is not bad. It will be enough for grocery runs and short trips, the hills there can be brutal. I am hoping I can just wire them together (positive on one to negative on the other, then connect the 2 other leads to the motor for 44v 4ah. After we get settled in inside Europe I will buy (or build) a bigger battery anyway, but at least for a few months we will have something to use. The motor I have cuts out at 39v though, but people are working on a firmware mod now so perhaps by the time we go I can use the battery down to 36v.

Series operation will not be a problem. It's always the paralleling of cells that is the challenge.

ga2500ev
 
John and Cecil said:
flippy said:
this stuff is utter crap. i got a customer that wrecked 60 out of 200 cells by this. it is competly unusable in a mobile application. the shit WILL viberate loose. you have to tighten them so fas you will cave in the top or bottom of the cell.

just buy a spot welder and some nickel strip and regular cell holders. you will have a vastly superior battery.

Thank you. I understand. The problem is spot welding is not an option, once you do that you cannot bring the batteries on a plane. The easiest and safest option appears to be to buy under 100wh batteries and then connect them in a series.
Probably a stupid question, but why bring a bike with you on a plane?
 
flippy said:
Probably a stupid question, but why bring a bike with you on a plane?

How are you supposed to ride it after you get where you are going if it is not with you? Some people use a bike as their only transportation.
 
I dont know how expensive it is to bring a bike with you on a plane. But in europe virturally nobody does this as most outdoor people just drive with the bikes on top or on the back of the car/camper.

But more ontopic: if you need to remain under 100Wh it means you cant bring any ebike battery. Those solderless vruze holders are single use so there is zero incentive. Only thing you could do is make a welded battery with each set of parallel cells separate. That way you can keep under the 100Wh per pack, you just ship 16 of them... At location you just have to connect them up and start driving.
 
John and Cecil said:
I would like to build 18" (7 cell) tubes. The tubes can be aluminum or pvc or something.
A few threads that might have useful info
https://endless-sphere.com/forums/search.php?st=0&sk=t&sd=d&sr=topics&keywords=tube+batter*&sf=titleonly
theres others too but guess they dont have tube in the title so not as easy to find.
 
I know where flippy is coming from and i have views on that approach:
1. Contact pressure relies on "springiness" of the metals used
2. Current flowing through bolted connection (which is never done anywhere)
3. Pressure maintained by zip ties on somewhat flexible cap material where side cells are squeezed more than middle ones.
4. New V2 version has copper clips plated with nickel. When you plate copper with nickel, it becomes brittle and when you bend it and then bend it back, it snaps.
Maybe OK for stationary low power.
John and Cecil, have you looked at my approach?
http://18650.lt/index.php/resources/6p-n-e-s-e-module/
They are modules and you can build your battery so the modules are below 100wh. My 6P is under 80wh and 8P just over 103wh if you take most dense 3500mAh cell at 3.7V.
and if contact with cell in vibrating environment is at question have a look at the tests:
[youtube]93JBo87LJiU[/youtube]
 
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