Ebike battery help

Iker138

Iker138

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Jan 16, 2019
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Hi everyone!! I am making a ebike battery for a 1000w motor. I am making with 18650 recycle of laptop batteries. At full throttle it consumes 26A. My question is, if it is 1,8A per cell a very high current for a 2000mAh recycle 18650. I know that when less current to the cell, more cycles can have, but i dont know if 1,8 is soo much. Apart of that 1,8A is only when i go full trhottle. Only sometimes. At medium throttle was like 0,9-1A per cell. It is a good option? Thank you for reading and sorry for my bad english XD.
 
Depends on the cells chemistry and manufactured design.

Some are rated at .5C, others at 2C. If the cell was originally a 2400mAh cell, then it's rating is 2.4A. That would make .5C 1.2A. But, you'd need to consult the cell database to find the ratings of the cells you are using. Then use the lowest ranked one.

Alternatively, you could go LiFePO4's as they can handle higher amps. Or, if you want to stick with recycled cells, use power tool cells as they are designed for high amps discharge as well
 
Standard is the rate that is used to specify the cell. This is usually a small figure because it's used to determine the capacity that is then stated in the specification. And the manufacturer wants this to be as high as possible obviously.
Maximum is the highest continuous rate that the cell has been designed for. It will have lower capacity and will get warm but it can do it in a way that is still worthwhile and won't damage the cell so it can be repeated. It will lead to increased wear though, so while it can be repeated it will shorten its lifespan.

But these figures are only true for new cells. If they have been used then these figures aren't valid anymore, that's why you have to test it. Using reclaimed laptop cells is already a bad start for an ebike battery because they are always low power high capacity cells. What you want is more like power tool cells with high power and low capacity. Or at lest something in between.

Also, 26A divided by 1.8A isn't an even cell number. It's close to 14.5, so either 14p or 15p. Assuming the cells can't do it then you might even have to double it, at 48V (I guess it's a 48V motor) this means 14s30p = 420 cells. That's almost 20kg of raw cells without any connections or case. It might become a bit large and heavy for an ebike battery, don't you think? With 2000mAh cells it will be over 3kWh.
 
Yes, i was thinking to make a 15-16p battery. I understan all that you said but i dont understand why you said to put doble battery pack 30p. I suposse that with 30p was more good for the cells but i dont know...

I repeat that only was 26A when 100% thottle, and in the most time i go with 16A (low speed mode). And that its like 1A per cell.

Thank you for answer my
 
30p was just an example. You could end up in this area though with used cells that sometimes are barely able to do 1A at decent capacity and energy.
 
1 year ago i make a battery only to test the motor kit. I make a 13s6p battery from recycle 18650 with an average of 1700mAh. (yes i know is a very bad battery kit with many fire risk and fails) but was ONLY to test the kit. In the 26A mode, the voltaje drops a lot of and the controller cutoff the motor power. But with the 16A mode was very nice. The voltage doesnt ddrop a lot of and it was pretty well (in plain, no slopes). This ebike was for only having fun, no for any transport. But i want to be SAFE
 
Well, this isn't about safe or unsafe. This is about a properly working bike or an unreliable bike. If you want to use reclaimed cells and calculated the battery sizing in such a way that you need 1.8A per cell then test the cells at 2A.
 
DarkRaven said:
Well, this isn't about safe or unsafe. This is about a properly working bike or an unreliable bike. If you want to use reclaimed cells and calculated the battery sizing in such a way that you need 1.8A per cell then test the cells at 2A.
Click to expand...

Okey. But even if it 1,8 was a safe battery. With 4A fuses per cell. Thank you
 
It sounds like you want to draw 26A from a 6P pack. That peak draw will be roughly 4.3A per cell. There are 2000-mAh cells that are made for high discharge, and there are also some 2000-mAh cells that are made for low cost. Laptop cells are the low cost version, and they will get hot at 4.3A

I understand your desire to save money by using cells that are available at very low prices, but I recommend that you focus on cordless tool cells, which are made for high current. If there is no room in your budget for cordless tool cells, you would need to use a much larger pack of laptop cells.

At 13S, a 6P pack is 78 cells, and that might be a large pack to try and fit it into your bicycle frame. This is why you should use cordless tool batteries, even if it costs more. You can get very high power form a 5P pack, and the cells will not get hot.
 
Iker138 said:
Hi everyone!! I am making a ebike battery for a 1000w motor. I am making with 18650 recycle of laptop batteries. At full throttle it consumes 26A.
[...]
Click to expand...


My electric skateboard is running a 10s12p battery from harvested laptop cells. It runs 750W of motor, which translates to ~ 20A peak. I have had this running for months now, and generally thrash the living daylights out of it, and taken some logs from it running. Here are some thoughts:

1/ if you can, use all cells with same make/model. this will spread the load evenly throughout discharge curve. IE panasonics give out more power up high (>3.9V) while LG's give out more down lower (3.7-3.9V) ... or is it the other way around ... anyways, hoping you get my point.

2/ ALWAYS pay EXTRA attention to battery construction when used in mobile situations. EG I stack mine 'parametrically' (each row offset half a cell width, so it looks more like a honeycomb than a spreadsheet). So this means I risk the 'rows' (banks) of cells rubbing against each other and shorting out the -ve shell if there is damage on adjoining sleeves/wraps. Heat [dissapation] also can become an issue when I go for extended runs with Wide Open Throttle. but this is because my harvested laptop cells suck badly -- they are NOT rated for high discharge.

3/ I have found that with careful throttle management I can avoid too much sag. even better with a 'rest' (all stop) between fast stretches, which allows the pack to 'bounce back' up, and get the most energy (range!) out of the battery.

I have only JUST got my hands on some cells rated for high discharge ... so I understand if laptop cells are all you got ... use 'em! ;)
 
I have sold Boston Power Swing batteries to several Ebike users ...and they are very happy with them. You might at least give these a look. I also have some prebuilt packs listed in the marketplace here. Yes this is a little bit of a sales pitch ...but really it is meant to be a suggestion that the experience I have had is that Ebike folks have been very happy with the Boston Power Swing solution. Buy them wherever you like ....but at least look at them as an alternative. If you go that way ...do not use the Boston Power Sonata ...it has a lower discharge rating.
 
spinningmagnets said:
It sounds like you want to draw 26A from a 6P pack. That peak draw will be roughly 4.3A per cell. There are 2000-mAh cells that are made for high discharge, and there are also some 2000-mAh cells that are made for low cost. Laptop cells are the low cost version, and they will get hot at 4.3A

I understand your desire to save money by using cells that are available at very low prices, but I recommend that you focus on cordless tool cells, which are made for high current. If there is no room in your budget for cordless tool cells, you would need to use a much larger pack of laptop cells.

At 13S, a 6P pack is 78 cells, and that might be a large pack to try and fit it into your bicycle frame. This is why you should use cordless tool batteries, even if it costs more. You can get very high power form a 5P pack, and the cells will not get hot.
Click to expand...

I only make this batteru for ONLY test the ebike conversion kit. Only 1 cycle. Now i write this post to know the opinion about mi new pack that i want to make. 2000mAh 13s15p. 1,73A per cell.
Thanks for your recomendations!!

DCkiwi said:
Iker138 said:
Hi everyone!! I am making a ebike battery for a 1000w motor. I am making with 18650 recycle of laptop batteries. At full throttle it consumes 26A.
[...]
Click to expand...


My electric skateboard is running a 10s12p battery from harvested laptop cells. It runs 750W of motor, which translates to ~ 20A peak. I have had this running for months now, and generally thrash the living daylights out of it, and taken some logs from it running. Here are some thoughts:

1/ if you can, use all cells with same make/model. this will spread the load evenly throughout discharge curve. IE panasonics give out more power up high (>3.9V) while LG's give out more down lower (3.7-3.9V) ... or is it the other way around ... anyways, hoping you get my point.

2/ ALWAYS pay EXTRA attention to battery construction when used in mobile situations. EG I stack mine 'parametrically' (each row offset half a cell width, so it looks more like a honeycomb than a spreadsheet). So this means I risk the 'rows' (banks) of cells rubbing against each other and shorting out the -ve shell if there is damage on adjoining sleeves/wraps. Heat [dissapation] also can become an issue when I go for extended runs with Wide Open Throttle. but this is because my harvested laptop cells suck badly -- they are NOT rated for high discharge.

3/ I have found that with careful throttle management I can avoid too much sag. even better with a 'rest' (all stop) between fast stretches, which allows the pack to 'bounce back' up, and get the most energy (range!) out of the battery.

I have only JUST got my hands on some cells rated for high discharge ... so I understand if laptop cells are all you got ... use 'em! ;)
Click to expand...
Okey!! Thank you a lot of for your recomendations. I agree with you that with a careful management of the trottle we avoid too much sag. Im making this bike for my and maybe to a presentation of a projects competicion. I dont wanna go at full throttle. Only sometimes. My biggest question is if it is safe. I know that the battery will not degrade fast because also i have a 250w mode in the controler so this was very beneficial to the battery. Apart of that, my rides times they are very shorts, so only discharge like %25 of the capacity. And to charge im thinking to adjust the parameter of the bms to cut-off at 4,1v. Have you any video about your skate?. Thank you and sorry for my english xD
 
DCkiwi said:
1/ if you can, use all cells with same make/model. this will spread the load evenly throughout discharge curve. IE panasonics give out more power up high (>3.9V) while LG's give out more down lower (3.7-3.9V) ... or is it the other way around ... anyways, hoping you get my point.
Click to expand...

To be explicit, my context is USED LAPTOP cells, rated for LOW DISCHARGE.

Additionally there is another reason I strive for 'homogeneous' cells in my esk8 battery.. With all the cells being stressed so near to their [dis]charge limits it is essential that they all work in harmony. This specifically includes individual cell capacity. Hence a completely different beast of a battery than for instance, an 80P powerwall which might have cells with capacities that vary by 100+ %. It doesn't matter that a 2000mAH cell is charging at twice the current as its 1000mAH capacity tested parallel neighbour, because its in an 80Pa 40A battery charge is only an average cell charge rate of 500mA anyways!

To summarize -- matching thecapacities (reducing deviation) and discharge curves (brand/version) of cells in a battery becomes more important as the currents (charge or discharge) comeclose to cells max spec. Tuning a battery like this can help reduce maintenance and improve lifespan/reliability.


Iker138 said:
Okey!! Thank you a lot of for your recomendations. I agree with you that with a careful management of the trottle we avoid too much sag. Im making this bike for my and maybe to a presentation of a projects competicion. I dont wanna go at full throttle. Only sometimes. My biggest question is if it is safe. I know that the battery will not degrade fast because also i have a 250w mode in the controler so this was very beneficial to the battery. Apart of that, my rides times they are very shorts, so only discharge like %25 of the capacity. And to charge im thinking to adjust the parameter of the bms to cut-off at 4,1v. Have you any video about your skate?. Thank you and sorry for my english xD
Click to expand...

Yes I highly recommend you enter that competition. I recently participated in a Maker Faire (Wellington 2018) and it REALLY boosted along a lot of my projects, experience, and confidence too. We'd love to see your pictures, keep us all posted. : )

Me, I am very heavy handed on the throttle, and am more in the mode of making my stuff perform like I wanna drive, rather than the other way round. If I discharge 25% of my battery on one ride, it WAS a long ride. lol. about the only time I would dare to charge my battery over 4.1V/cell would be to 'trick' the charger into giving full CC by raising the CV limit to 4.12V and then it would just truck through to 4.10V without slowing down at the end. But then I'd manually stop the charge and pack/ride it from there. No video on my esk8, am a bit camera shy, but I will start another thread here soon ok, not wanting to hijack this one. Your english is better than my [pick any language]. Thanks for sharing.
 
DCkiwi said:
DCkiwi said:
1/ if you can, use all cells with same make/model. this will spread the load evenly throughout discharge curve. IE panasonics give out more power up high (>3.9V) while LG's give out more down lower (3.7-3.9V) ... or is it the other way around ... anyways, hoping you get my point.
Click to expand...

To be explicit, my context is USED LAPTOP cells, rated for LOW DISCHARGE.

Additionally there is another reason I strive for 'homogeneous' cells in my esk8 battery.. With all the cells being stressed so near to their [dis]charge limits it is essential that they all work in harmony. This specifically includes individual cell capacity. Hence a completely different beast of a battery than for instance, an 80P powerwall which might have cells with capacities that vary by 100+ %. It doesn't matter that a 2000mAH cell is charging at twice the current as its 1000mAH capacity tested parallel neighbour, because its in an 80Pa 40A battery charge is only an average cell charge rate of 500mA anyways!

To summarize -- matching thecapacities (reducing deviation) and discharge curves (brand/version) of cells in a battery becomes more important as the currents (charge or discharge) comeclose to cells max spec. Tuning a battery like this can help reduce maintenance and improve lifespan/reliability.


Iker138 said:
Okey!! Thank you a lot of for your recomendations. I agree with you that with a careful management of the trottle we avoid too much sag. Im making this bike for my and maybe to a presentation of a projects competicion. I dont wanna go at full throttle. Only sometimes. My biggest question is if it is safe. I know that the battery will not degrade fast because also i have a 250w mode in the controler so this was very beneficial to the battery. Apart of that, my rides times they are very shorts, so only discharge like %25 of the capacity. And to charge im thinking to adjust the parameter of the bms to cut-off at 4,1v. Have you any video about your skate?. Thank you and sorry for my english xD
Click to expand...

Yes I highly recommend you enter that competition. I recently participated in a Maker Faire (Wellington 2018) and it REALLY boosted along a lot of my projects, experience, and confidence too. We'd love to see your pictures, keep us all posted. : )

Me, I am very heavy handed on the throttle, and am more in the mode of making my stuff perform like I wanna drive, rather than the other way round. If I discharge 25% of my battery on one ride, it WAS a long ride. lol. about the only time I would dare to charge my battery over 4.1V/cell would be to 'trick' the charger into giving full CC by raising the CV limit to 4.12V and then it would just truck through to 4.10V without slowing down at the end. But then I'd manually stop the charge and pack/ride it from there. No video on my esk8, am a bit camera shy, but I will start another thread here soon ok, not wanting to hijack this one. Your english is better than my [pick any language]. Thanks for sharing.
Click to expand...
Yes, i suposse that i post some images but this project gets a lot of time to buil it. I need more cells and received all components from alliexpress. Im new in this forum. Can i put you like "friends"? . I dont no if i can xd.
 
Iker138 said:
Herkese merhaba !! 1000w motor iin ebike pil retiyorum. 18650 laptop batarya geri dn?m ile yap?yorum. Tam gazda 26A tketir. Sorum ?u, e?er hcre ba??na 1.8A, 2000mAh geri dn?m 18650 geri dn?m iin ok yksek bir ak?m ise. Hcreye daha az ak?m geldi?inde, daha fazla devrin olabilece?ini, ancak 1,8'in ok fazla olup olmad???n? bilmiyorum. Bunun d???nda 1,8A sadece tam gaz kulland???mda. Sadece bazen. Orta gazda hcre ba??na 0,9-1 A gibiydi. Bu iyi bir seenek mi? Okudu?um iin te?ekkr ederim ve benim kt ?ngilizce XD'm iin zgnm.
Click to expand...

48 v 23.3 ah samsung 1865 0 24E
[Diy] dhgyuc [/ diy]
[Diy] dgpkoi [/ diy]
[Diy] utpcwu [/ diy]
 
energy_man said:
Iker138 said:
Herkese merhaba !! 1000w motor iin ebike pil retiyorum. 18650 laptop batarya geri dn?m ile yap?yorum. Tam gazda 26A tketir. Sorum ?u, e?er hcre ba??na 1.8A, 2000mAh geri dn?m 18650 geri dn?m iin ok yksek bir ak?m ise. Hcreye daha az ak?m geldi?inde, daha fazla devrin olabilece?ini, ancak 1,8'in ok fazla olup olmad???n? bilmiyorum. Bunun d???nda 1,8A sadece tam gaz kulland???mda. Sadece bazen. Orta gazda hcre ba??na 0,9-1 A gibiydi. Bu iyi bir seenek mi? Okudu?um iin te?ekkr ederim ve benim kt ?ngilizce XD'm iin zgnm.
Click to expand...

48 v 23.3 ah samsung 1865 0 24E
[Diy] dhgyuc [/ diy]
[Diy] dgpkoi [/ diy]
[Diy] utpcwu [/ diy]
Click to expand...

what?

you are not quoting anyone. please dont post fake quotes. Iker138 wrote in english. your 'quote' is FAKE.
 
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