Scrap-E my first (sort of) build

[67spyder]

After much deliberation, between an e-bike and an e-scooter I decided on an e-bike. Where I live, e-scooters are motorcycles and must be licensed as such also are then not alowed on bike paths AND you must wear a helmet. I have no opinion on wearing helmets other than I love riding without one.

I was going to start with a junk suspension MTB and beef it up with better forks, disc brakes etc then I found this Kona Scrap that I bought for $275 today. Hence the VERY clever name "Scrap-E"

The only firm plans I have so far is the rear tire will be swapped for a Big Apple or maybe a Hookworm depending on what the local bike shop carries.

I have collected 110 Konion US18650VT so far and am thinking of going with a 10P15S pack. I am open to suggestions for motor/controller etc. I don't know if I will be able to get more than 150 cells by summer and the nominal V of 55.5 and peak of 61.5 seems to be easy to deal with while still giving decent performance

 

[wheelbender6]

Good choice. I don't think I have ever heard of a frame failure on a Kona in my 20+ years of mountain biking.

 

[etard]

Nice find, that should get you grinning in no time! You are going hub motor? Which controller?

 

[67spyder]

I just PM'ed cell_man about his hub motor kit. I have been collecting konion cells and have about 100 so far. I am planning a 10P15S pack but tried mocking up the battery box in the frame triangle and found that I can only fit 10 of the 10P sets of batteries in there. I think this is the small 13" frame, I may have to put a pack on a rear rack which I really did not want to do.

 

[etard]

I would agree that it is a 13" frame, if it doesn't fit, maybe buy another frame that does and just transfer all the good components over?

 

[67spyder]

After talking to a buddy that rides an e-bike alot, he pointed out that the lower CG of the smaller frame will provide much better handling. It is to small to comfortably pedal any distance but that is not the point here

 

[67spyder]

My initial plan was to build 15 packs of 10 parallel cells

But with such a small frame triangle I would only be able to fit 7 or 8 of these.

So I did a cardboard mockup of a battery box to fit the frame triangle
View attachment 2


And here is the battery box full of cells. These are garbage cells so there is no chance of shorting anything out. The actual cells are Konion US18650VT

This will be my first battery pack build so if I am heading down a bad path please let me know. I know that by building the pack in a layout like this it will be more difficult to do any cell maintenance but hopefully with the Konions that won't have to happen very often (maybe Doctor Bass has thoughts on this).
By arranging the cells this way I will be able to have 9p15s which is close to my desired 10p15s pack and still fit in the triangle.

 

[Doctorbass]

You should insulate the skin of each cell that are in contact with another parallel group cell. to avoid short caused by vibrations. I M P O R T A N T S !!!! Each cell ia a parallel group can touch themseld with the negative thrue the cell shinn.. no prob... but from one group to another that is connected in serie.. YOU MUST INSULATE BETWEEN BOTH

Dont use different cell model unless each parallel group have the same number of each cells.

ex:

parallel pack 1:
2 makita cell
8 rigid cell

parallel pack 2:
2 makita cell
8 rigid cell

but you can not make ex the parallel pack 3 with:
3 makita and 7 rigid cells

You must have the same total internal resistance and capacity on each parallel pack as well as the same number of cell with different brand name

10 more hour to carefully build the pack with the right way is cheaper than a house fire can cost!! :wink:

Good luck

Doc

 

[67spyder]

Doc,
I am planning on using all Konion cells, Most are us18650vt's but I do have a number of us18650gr's (laptop konion's) they are higher power but lower current than the vt cells. Would it be ok to use one of these in each parallel set?

 

[Doctorbass]

they are higher power but lower current than the vt cells.

I'm not sure to understand what you mean..

for the same voltage of 3.7V nominal, a lithium cell that have higher max current IS higher POWER.

Laptop cells are NOT the same chemistry than powertool. I would NEVER recommand using them with the Konion.

Laptop cells are not Konion. the fact that they are 18650 format ( 18mm dia and 65.0mm long) does not mean they are Konion.. Konion IS a cell model that have LiMn chemistry and they JUST exist in the 18650VT and 18650V and 26650VT model.

DONT mix LiCo cells ( laptop Lithium Cobalt cells) with LiMn cells ( lithium Manganese power tool cells).

LiCo have more energy density but have lower power output.LiCo are not safe cells compare with Konion ( the green skin cells)

Doc

 

[karma]

i have a box full of the Laptop cells i wont touch theme. any cells that has thermal runaway scares me.

ouch i just saw the battery pic that's what i call a mix of different cells. theirs even e-moli's in there is there any bms?

 

[67spyder]

As I mentioned the cells that I stacked in the mockup are garbage cells that have zero charge and were just used for mockup because there is no danger from shorting them out.

The cells I have for the actual pack are Konion US18650VT that have been charged to a storage charge of 60% which is enough power that they must be handled with care.

The US18650GR cells I was refering to are found in Sony Vaio laptops and have the same green skin and are from the same manufacturer as the cells in makita and hilti packs. Most definitly not the same cells as they are rated at 1900Mah, but most likely also different chemistry.

 

[67spyder]

Ordered the direct drive kit from Cell_man a couple of days ago, with the 12 fet infineon controller. Patiently waiting now while getting ready to build the battery box.