DIY: Range extender for Levo (and Kenevo)
- Thread starter villho
- Start date
I'll try 21700 indeed if it fit I could go up to some 5000mAh. If it's too big I'll try 20700 but they are almost the same size. I finally if it doesn't fit, 18650 will fit for sure.
I'll print tonight 10 PLA tubes with some 21700 size and build a fake battery for testing.
The only thing scaring me is that NKON doesn't sells any 21700 with the "tagged" option and I am not sure to be able to solder them…
the best I can find with tag on NKON are some very good Sanyo 20700 4200mAh.
How did you do on your side ?
I'll print tonight 10 PLA tubes with some 21700 size and build a fake battery for testing.
The only thing scaring me is that NKON doesn't sells any 21700 with the "tagged" option and I am not sure to be able to solder them…
the best I can find with tag on NKON are some very good Sanyo 20700 4200mAh.
How did you do on your side ?
villho
Active member
- Thread starter
- #33
I used a powerful Weller solder iron and nickel strips. Yes, the cell heats up a bit when doing it this way, but I wouldn't worry too much. I also used plastic spacers, but in your case I would try to put the cells in a tight package to minimize the need for space. Solder and nickel strips will keep the package well in shape, especially if you put a shrink wrap on top of everything.
Remember to leave some space for remote wire and cables inside the frame.
Remember to leave some space for remote wire and cables inside the frame.
ok thank's. If needed I'll borrow a powerfull solder iron. Of course cells will tightened together, balancing wires will passes between them and finally the pack will goes in some heat shink. I often had to do that kind of things for some drones LI-PO batteries.
The first step is to try to see if some 21700Li-ion fits. I should try it tonight. I'll put a photo of my proto battery.
The first step is to try to see if some 21700Li-ion fits. I should try it tonight. I'll put a photo of my proto battery.
ok, so yesterday I printed 10 tube of 21,5*72mm. So a bit larger than some 21700 Li-ion cells.
So here are my 10 cells
I can insert a first batch of 4 cells at the deeper. so they are just behind the steering column (is that the right word ? sorry for my english btw…)
and then, two batch of 3 cells. I couldn't make a batch of 6 because the cells have to pass over the hole for fixing the main battery.
and finally this white thing is a block a bit larger than the BMS I am planning to use. If fit here well and there's still room everywhere for adding wires, and very important for adding rubber and foam for absorbing shocks and vibrations.
Concerning the Ideal diodes, they go near the motor.
Well, I am not yet sure of the final installation of the cells, but because they fit with a bit of margin, I'll order the stuff and go for these LG INR21700-M50T 5000mAh.
So here are my 10 cells
I can insert a first batch of 4 cells at the deeper. so they are just behind the steering column (is that the right word ? sorry for my english btw…)
and then, two batch of 3 cells. I couldn't make a batch of 6 because the cells have to pass over the hole for fixing the main battery.
and finally this white thing is a block a bit larger than the BMS I am planning to use. If fit here well and there's still room everywhere for adding wires, and very important for adding rubber and foam for absorbing shocks and vibrations.
Concerning the Ideal diodes, they go near the motor.
Well, I am not yet sure of the final installation of the cells, but because they fit with a bit of margin, I'll order the stuff and go for these LG INR21700-M50T 5000mAh.
Last edited:
Ok then i am almost ready to build my light range extender.
I received the ideal diodes which looks pretty fine despite the price, and the bms which is really nice and compact.
So all I need now are the li-ion cells which should be processed at the end of this week according to NKON.
I received the ideal diodes which looks pretty fine despite the price, and the bms which is really nice and compact.
So all I need now are the li-ion cells which should be processed at the end of this week according to NKON.
You might want to take a look at the Aulakiria pocket tab welder. Its a great piece of kit for making up packs. A lot more useful than the massive box things from ebay etc and $100 ish.
I've made up a number of 18650 & 20700 packs for RC with it.
Spot Welder Display & Info.
I've made up a number of 18650 & 20700 packs for RC with it.
Spot Welder Display & Info.
hi Eckythump,
Thank's for the link. This tools seems really interesting for those who have to make a lot and often some battery packs.
In my case, it's a bit expensive for just making one 10cells pack. And I will receive my cells with tags allready soldered so soldering cells together will be much easier.
with a small pack like that the cost per watt hour increase really quickly. Just the 2 ideal diodes are the same price of my cells. With a bigger pack their price impact is lower.
But anyway, I bookmark your link because it seems to be very interresting if ever I have several or bigger pack to build.
Thank's for the link. This tools seems really interesting for those who have to make a lot and often some battery packs.
In my case, it's a bit expensive for just making one 10cells pack. And I will receive my cells with tags allready soldered so soldering cells together will be much easier.
with a small pack like that the cost per watt hour increase really quickly. Just the 2 ideal diodes are the same price of my cells. With a bigger pack their price impact is lower.
But anyway, I bookmark your link because it seems to be very interresting if ever I have several or bigger pack to build.
No worries.
If your pack is a success I imagine you are going to have folk wanting to buy them, might be easier to justify then??
Good luck, hope it is a success.
If your pack is a success I imagine you are going to have folk wanting to buy them, might be easier to justify then??
Good luck, hope it is a success.
Is a diode really required on the extender side of the circuit? The BMS should prevent high current equalisation from the main pack to the extender you would then be able to use the main battery to charge the extender. Main battery would just need a little top up afterwards.
so as long as your extender is the same or higher voltage than the main battery when you power every thing you are good. And because there's a diod on the main battery, the only one you risk to "kill" is the extender one right ?
I guess you're right. it's just a bit scary, even if my main battery doesn't risk at all is the principal.
I guess you're right. it's just a bit scary, even if my main battery doesn't risk at all is the principal.
You will need to check details on the BMS being used but it should see if the voltage across the terminals is higher than within the extender & go into charge mode.
yes my BMS can go into charge mode or discharge throw the same connector, so it would work. but it seems that it doesn't limit at all charge current...
I see two major constraints about not having diode on extender side:
- If the extender is lower charged than the main battery, I don't think the BMS would limit the amps so it could be pretty hard for the cables/battery extender with high Amps.
- even if it's ok and there not too much charging Amps in the extender, I guess you loss efficiency by "charging" the extender
So I think that doing so mean to be sure anytime that your extender is always at least as charge as the main battery or you take risks.
I see two major constraints about not having diode on extender side:
- If the extender is lower charged than the main battery, I don't think the BMS would limit the amps so it could be pretty hard for the cables/battery extender with high Amps.
- even if it's ok and there not too much charging Amps in the extender, I guess you loss efficiency by "charging" the extender
So I think that doing so mean to be sure anytime that your extender is always at least as charge as the main battery or you take risks.
To me, being able to charge an extender located inside the frame with the main battery would be an advantage.
I looked back at the BMS you are using and the maximum charge current it can handle is 8amp so you are right to be concerned about a high potential difference.
A work around would be easy enough. The downside is rather than eliminating a diode it may require an extra one.
I looked back at the BMS you are using and the maximum charge current it can handle is 8amp so you are right to be concerned about a high potential difference.
A work around would be easy enough. The downside is rather than eliminating a diode it may require an extra one.
villho
Active member
- Thread starter
- #47
Does the BMS have separate connectors for charging and discharging? I noticed accidentally (after connecting the charger there) that my bluetooth-equipped BMS allows charging through the discharge connectors as well. So yeah, two ideal diodes needed.
If getting your pack out for charging takes too much effort, it shouldn't be a too big of a deal to run a separate charging wires out from the frame (same hole where e.g. rear brake cable goes in) and then charge through those.
***
What comes to my original extender... Because winter and darkness is coming, I bought a 42V DC to 12V DC regulator; I plan to install a car led high beam light on the handle bar and run it with the extender power.. Should have plenty enough light on the trails
If getting your pack out for charging takes too much effort, it shouldn't be a too big of a deal to run a separate charging wires out from the frame (same hole where e.g. rear brake cable goes in) and then charge through those.
***
What comes to my original extender... Because winter and darkness is coming, I bought a 42V DC to 12V DC regulator; I plan to install a car led high beam light on the handle bar and run it with the extender power.. Should have plenty enough light on the trails
on my "light" BMS I have the same connector for charging/discharging.
On my side, I plan to remove the extender from the frame for charging it for two reasons.
- it's easier for me as the bike stays in the garage and my chargers are inside the house.
- in the winter when my garage can be between 0°c and 10°c it's too cold for storing some lithium battery, so I remove them and store them inside where it's 20°c.
but my extender we'll be re-chargeable inside the frame if needed
On my side, I plan to remove the extender from the frame for charging it for two reasons.
- it's easier for me as the bike stays in the garage and my chargers are inside the house.
- in the winter when my garage can be between 0°c and 10°c it's too cold for storing some lithium battery, so I remove them and store them inside where it's 20°c.
but my extender we'll be re-chargeable inside the frame if needed
villho
Active member
- Thread starter
- #49
Lithium batteries actually like to be stored in cool/cold. You of course don't get a full power out from a cold li-battery, but storing is different. They do warm up, when you start using them (due to internal resistance), but to get the best output and capacity from them, they should be warmed up before using.
Are you sure about that ? Before my Levo I had a Cube with Bosch motor and Bosch recommand to store batteries at ambient temperature, so I guess around 15-20°c.
But now I wondering if it's for the best storage conditions or for having a battery ready to go at any time because not too cold ?
Hello there,
Some updates. I've received the last but most important elements for my project, the Cells.
Once received I did again some test in the frame for finding the best way to fit all that world in the frame.
So I'll stay in the configuration of 3 modules. One of 4 cells at the bottom, and then, 2 modules of 3 cells each.
The most complicated is to keep wiring clean, and as short as possible between each module, but by taking my time to think about it that should be ok.
So last night I built my 3 modules by soldering cells together. With the tabs pre-soldered on the cells, soldering cells together thanks to this tabs is a child play. With a 45w welding iron is really really easy.
Here are the cells pull out from the parcel. the 10cells weight 704gr, so I target a overall weight under 800gr. We'll see.
here the white tape is just there provisionally during operations.
Some updates. I've received the last but most important elements for my project, the Cells.
Once received I did again some test in the frame for finding the best way to fit all that world in the frame.
So I'll stay in the configuration of 3 modules. One of 4 cells at the bottom, and then, 2 modules of 3 cells each.
The most complicated is to keep wiring clean, and as short as possible between each module, but by taking my time to think about it that should be ok.
So last night I built my 3 modules by soldering cells together. With the tabs pre-soldered on the cells, soldering cells together thanks to this tabs is a child play. With a 45w welding iron is really really easy.
Here are the cells pull out from the parcel. the 10cells weight 704gr, so I target a overall weight under 800gr. We'll see.
here the white tape is just there provisionally during operations.
Work In Progress.
My battery pack is finished.
The three modules are fitting fine in the frame, I just need to add some rubber protection.
But with the BMS it's a bit tight.
So I am wondering why do I need to board him on the bike. If I am right, the BMS balance the Cells only during charge.
It's only usefulness would be to protect the battery from over discharging and too low voltage.
BUT, I thought have read that with a main battery discharged, the Extenders wouldn't work or let the motor run. If that's right, this means that the main battery will protect my Range extender battery from low voltage or deep discharge.
Indeed, if the range extender battery is at lower voltage than the main battery, the bike will find it's power in the main battery as long as the main battery has higher voltage.
Then, the bike will get power from both. And once the main battery is "empty" it will cut off the motor right ?
Any opinions about it ? @villho can ou confirm this behavior ?
My battery pack is finished.
The three modules are fitting fine in the frame, I just need to add some rubber protection.
But with the BMS it's a bit tight.
So I am wondering why do I need to board him on the bike. If I am right, the BMS balance the Cells only during charge.
It's only usefulness would be to protect the battery from over discharging and too low voltage.
BUT, I thought have read that with a main battery discharged, the Extenders wouldn't work or let the motor run. If that's right, this means that the main battery will protect my Range extender battery from low voltage or deep discharge.
Indeed, if the range extender battery is at lower voltage than the main battery, the bike will find it's power in the main battery as long as the main battery has higher voltage.
Then, the bike will get power from both. And once the main battery is "empty" it will cut off the motor right ?
Any opinions about it ? @villho can ou confirm this behavior ?
as you can see on my last picture (see the photo below), my battery pack has her 11pins connector wired. This white plug boes in the BMS. and then I just need to connect this one to the BMS and the main connector.
So plugging / unplugging the BMS only for charging is clearly not an issue. I allready do that for model aircraft batteries. The battery is only balanced when charging.
So my main questionning is about low voltage protection of the battery while biking.
So plugging / unplugging the BMS only for charging is clearly not an issue. I allready do that for model aircraft batteries. The battery is only balanced when charging.
So my main questionning is about low voltage protection of the battery while biking.
This used to be the advice about 10 years ago. I went through a phase of storing charged, but between uses, lithium 36v dewalt batteries, bagged, in the fridge. They would hold their charge longer that way.
I think the technology has moved on and the chemistry has changed slightly, so I'm not sure if this is still applicable or not.
Ok so Some updates.
My extender is finished and in place. With every thing it fits really tight and I don't think I'll install the bms until I really need it. I'll do run test by discharging completely the main battery and checking the extender battery voltage.
But anyway my extender finished with everything and all the cables weight 800gr which is not so bad. I've made a 0,5 miles test with a hard climb and according to mission control the Amps were never over 12A while I am usually pulling 20A. So the extender works fine.
Some more picts :
The battery with some foam and old wheel tube for absorbing vibrations
The two ideal diodes back to back. The are nicely fitting in the tube above the motor
And finally all the stuff going the the bike. Every one found his place.
My extender is finished and in place. With every thing it fits really tight and I don't think I'll install the bms until I really need it. I'll do run test by discharging completely the main battery and checking the extender battery voltage.
But anyway my extender finished with everything and all the cables weight 800gr which is not so bad. I've made a 0,5 miles test with a hard climb and according to mission control the Amps were never over 12A while I am usually pulling 20A. So the extender works fine.
Some more picts :
The battery with some foam and old wheel tube for absorbing vibrations
The two ideal diodes back to back. The are nicely fitting in the tube above the motor
And finally all the stuff going the the bike. Every one found his place.
freerider85
Member
Please send us also pictures from installation to frame. Thx for this very interesting
Any progress here 
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