Beginners Guide to Processing 18650 Cells | Cell Database


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Evolve Skateboards Range Extender + Battery upgrade
#1
Greetings

I have 2 Evolve electric skateboards. One is the Carbon 2nd Generation with the single motor and 10Ah battery and the other is the Bamboo 2nd Generation with single motor and 7Ah battery.

I use it to commute every now and then (whenever I wake up with a pair big enough since Ive been seeing a lot of police on the road I would ride on and you don't want to catch a german police officer on a bad day as he will take the board away)
and I cant make it to where I want to go and back going full speed. I get to my destination but on the way back, usually 1/3 the way the board doesn't let me go into the fast mode anymore, so im limited to 15Kmh (annoying when its usually 30-33Kmh. I run the all terrain tires as part of the way is a dirt track. All terrain tires lead to higher energy use. Its an 14.5km stretch, so after like 9-10 the voltage sag is too much it limits to low power mode.

Anyway, I want to build a new internal battery for the Carbon. I have plently of NCR18650PD's. In a 10s6p config this would give me 17.4Ah. Significantly more.
There is some guy on endlesssphere who has done exactly this but with NCR18650B's and got 20.4Ah. Ill be copying his build for this.

For the Bamboo though I had a different plan. More then two weeks ago I was looking into this all ready and a new internal battery doesnt really fit. A 10s4p could maybe just fit if I really push it  but I cant just place the battery case of the bamboo 3mm lower to allow for enough room and I would be squishing the BMS in there. Not going to risk it. I thought Id leave this one out and go for an external Range Extender pack.

Ordered a spot welder last week and over the weekend and a couple hours this week I built and refined my pack.

So my plan was that I can have a pack in my backpack and run a cable down to the board. First I thought I could use a switch of some sort so I can plug in the pack, flip the switch and use the external one. Clean and simple. 
Ordered some switches but came to the conclusion that it wont work with those so I abandoned that and just went with plugging out the internal and plugging in the external pack. Ill post later today about those switches, maybe I just wasnt thinking straight and of you guys can figure it out ;D


I extended the cables from the internal pack and the cable going to the controller. They are just T plugs so that was easy. The two cables are now going out the back of the board. To find out what current the motor uses I plugged a Watts Up meter (also with T plugs) in between and it ended up being a whopping 24A! and a constant load of about 12-15A to hold a speed of about 28Kmh. (it is a 350w motor after all)
Then I thought of safety and practicallity. Plugging in the external pack with a T connector is kind of dangerous if I fall of the board or jump of and it doesn't come loose so a magnetic plug would be the way to go, also makes plugging it in easier.
I have these magnetic Rosenberger plugs from ebikes which are perfect. 
Soldered up a male plug with a female T plug to place on the board permanently (into the little hole being the axle mount. This would be the bit I just plug into the controller/motor cable. 
Then I would place a female T plug on the battery and build a roughly 1.4m long cable with male T plug and female Rosenberger plug to connect down to the board.

Now to the pack
Its a 10s4p from the NCR18650PD cells. Ordered a BMS from ebay, 10s 35A. I double and trippled up the nickel strip where needed and soldered on the end wires onto all 4 of the last cells to spread out the current on the nickel. To attach the two 5s banks with one another I used 2 thick wires.
At first I wired it all up and the BMS got warm, didn't think much of it as I thought it was just balancing the cells. Next morning it was still warm so I took it apart and noticed 1 pack of cells went down to 3.84V. I checked all the wires again and it turned out I mixed up two wires. 
Used my iMax to charge up the low block and the block in front and behind it since they were at 4.05V for some reason.
Since then the BMS doesn't get warm and seems to be doing its job.
To charge the pack I have a male Rosenberger plug on the side as I have a charger with that end all ready.


Placed a s*** load of duct table and some foam in between the two 5s banks and did the same on the outside of the pack. I might order some huge heatshrink for the outside as well to make it look more professional :Big Grin the duct tape doesn't give the best image of safety sadly.

Ran a discharge test on it using a West Mountain Radio and a 36V 8A load. The Load slowly tapers down to about 6.5A while the voltage drops. It ended up discharging 11 Ah. So now I have abut 17.5Ah of usable capacity for my Bamboo at an extra 2.5kg that I have in my backpack.

Ill post more pics later but im pleased to say that IT WORKS PERFECTLY!!! 

Any feedback is appreciated of course :Smile especially regarding safety.


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#2
Good job!

My only concern for the moment would be that cheap BMS. I would never trust a cheap BMS. With this sort of application for lithium cells I wouldn't have bothered to use a BMS at all.
I would charge the pack with a proper balance charger and use a LiPo beeper set to a rather conservative treshold. So once that goes of you know you still have some way to go at slower speed until your pack is totally empty.
BlueSwordM likes this post
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#3
Cool project.

I'm seriously considering getting an electric board..thinking the meepo for starters
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#4
(09-06-2017, 09:57 PM)DarkRaven Wrote: Good job!

My only concern for the moment would be that cheap BMS. I would never trust a cheap BMS. With this sort of application for lithium cells I wouldn't have bothered to use a BMS at all.
I would charge the pack with a proper balance charger and use a LiPo beeper set to a rather conservative treshold. So once that goes of you know you still have some way to go at slower speed until your pack is totally empty.
cheers Smile

yeah thats a good point. I think a BMS is still better then no BMS unless of course it destroys the pack, but thats unlikely. Yeah I could have gone that route with the beeper but when other people use the board and pack (other family members) Im not going to risk them not hearing it or forgetting or whatever and then they discharge the pack to empty and kill it. Not worth it I think. A 10S balance charger is pretty expensive too, rather buy a high quality BMS then.
I have this BMS from the original ebike pack, thats where I got these cell holders from, and its a real good BMS but for some reason I couldnt get it to work. It worked before with a different pack (posted about it here, the BMS i mention in there but not the one in the pictures (http://www.diypowerwalls.com/t-BMS-Wiring-HELP?page=1)) so im not sure whats going on to be honest. I would much rather use that BMS as its definitly made to handle a real 30A and it also has temperature sensors and charge indicator. 
I might try it again at one point.

(09-07-2017, 10:36 AM)Wattsup Wrote: Cool project.

I'm seriously considering getting an electric board..thinking the meepo for starters
they are awesome things. 
Meepo seems decent and for that price you cant really go wrong either to just play around but 4.4Ah in my case really wouldn't do me any good at all. I live in the middle of nowhere :Big Grin
It uses a 10s2p battery out of Samsung 22p cells so at least you could just build yourself a 10s2p out of those new high current 3500mAh cells and get like 7Ah which is a lot more usable.
The Meepo seems a lot like the hoverboards in terms of quality and I will never have one of those in my house. Took apart so many of the hoverboard battery packs and its shocking how badly put together some of those packs are. Not surprised at all they many caught fire and that the cheap ones where banned in many countries. Ebay doesn't even allow private sale of hoverboards for a reason.

I would really like the Evolve GT but I cant really justify that price. The ride beautifully though and have so much power. I borrowed my friends Carbon GT and I didnt want to return it :Big Grin The older boards I have with the one motor are perfect for commuting but have no where near the acceleration or breaking power of the GT's. Also because only one wheel is powered it does pull to the left under acceleration and a right turn at slow speed when the ground is wet or bad surface tends to spin the wheel.
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#5
(09-08-2017, 08:35 AM)The-J-Man Wrote:
(09-06-2017, 09:57 PM)DarkRaven Wrote: Good job!

My only concern for the moment would be that cheap BMS. I would never trust a cheap BMS. With this sort of application for lithium cells I wouldn't have bothered to use a BMS at all.
I would charge the pack with a proper balance charger and use a LiPo beeper set to a rather conservative treshold. So once that goes of you know you still have some way to go at slower speed until your pack is totally empty.
cheers Smile

yeah thats a good point. I think a BMS is still better then no BMS unless of course it destroys the pack, but thats unlikely. Yeah I could have gone that route with the beeper but when other people use the board and pack (other family members) Im not going to risk them not hearing it or forgetting or whatever and then they discharge the pack to empty and kill it. Not worth it I think. A 10S balance charger is pretty expensive too, rather buy a high quality BMS then.
I have this BMS from the original ebike pack, thats where I got these cell holders from, and its a real good BMS but for some reason I couldnt get it to work. It worked before with a different pack (posted about it here, the BMS i mention in there but not the one in the pictures (http://www.diypowerwalls.com/t-BMS-Wiring-HELP?page=1)) so im not sure whats going on to be honest. I would much rather use that BMS as its definitly made to handle a real 30A and it also has temperature sensors and charge indicator. 
I might try it again at one point.

(09-07-2017, 10:36 AM)Wattsup Wrote: Cool project.

I'm seriously considering getting an electric board..thinking the meepo for starters
they are awesome things. 
Meepo seems decent and for that price you cant really go wrong either to just play around but 4.4Ah in my case really wouldn't do me any good at all. I live in the middle of nowhere :Big Grin
It uses a 10s2p battery out of Samsung 22p cells so at least you could just build yourself a 10s2p out of those new high current 3500mAh cells and get like 7Ah which is a lot more usable.
The Meepo seems a lot like the hoverboards in terms of quality and I will never have one of those in my house. Took apart so many of the hoverboard battery packs and its shocking how badly put together some of those packs are. Not surprised at all they many caught fire and that the cheap ones where banned in many countries. Ebay doesn't even allow private sale of hoverboards for a reason.

I would really like the Evolve GT but I cant really justify that price. The ride beautifully though and have so much power. I borrowed my friends Carbon GT and I didnt want to return it :Big Grin The older boards I have with the one motor are perfect for commuting but have no where near the acceleration or breaking power of the GT's. Also because only one wheel is powered it does pull to the left under acceleration and a right turn at slow speed when the ground is wet or bad surface tends to spin the wheel.
Yep like you say I can't really go wrong with the meepo for the price.
I really like what the owner Kieran is doing and his story, alsonthat he is totally transparent about his boards and the manufacture process.
But I will charge and store it in the shed. I have an abundant supply of high drain/capacity cells, like Samsung 30Q and 25R to make some packs for it so should be fun  Smile

The evolve boards look good but not gonna get that one past the missus after just spending $2000 on my ebike   Tongue
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#6
(09-09-2017, 09:14 AM)Wattsup Wrote: Yep like you say I can't really go wrong with the meepo for the price.
I really like what the owner Kieran is doing and his story, alsonthat he is totally transparent about his boards and the manufacture process.
But I will charge and store it in the shed. I have an abundant supply of high drain/capacity cells, like Samsung 30Q and 25R to make some packs for it so should be fun  Smile

The evolve boards look good but not gonna get that one past the missus after just spending $2000 on my ebike   Tongue

ohh ok thats interesting.
Abundant :O how did you manage that Tongue 
I had these PD cells lying around. Felt like a waste to put them in my powerwall. so 100 have now been used for my boards.
got 20 left, they were revived cells. great capacity but probably higher internal resistance. I had to use 5 of these revived cells in the external pack as I had no more good cells.... hope they dont go wrong at one point, but thats why they are in an external pack which can be chucked out the window if necessary. Big Grin

Spent most of yesterday building the new internal pack for the carbon.

I impressed myself with my results Big Grin

Placed some extra insulator rings on the positive side for more protection. This pack with be under lots of vibrations and so forth. I dont want to risk anything.
So I spot welded the cells into groups of 6 as it will be a 10s6p pack. Single sheet of nickel was enough here.

   

I then lined them up upright in the right configuration. The plan was to connect them here and then fold them open.
Dont have any pictures but I interconnected each cells with a nickel strip. 

   

To connect the cells in series I quadrupled up the nickel strip. Sadly at one stage I screwed up and place the blocks of cells together the wrong way and then finished all the series connections. Held my multimeter to the + and - and got 18V. Hmmmm, man I was confused hahaha.

   
   

Had to break open most of the connections again as I didnt have enough nickel to redo them all.
Took me over an hour to break them open.  Angry

Cool thing about then folding the pack open is that you get this natural channel between the cells which is perfect for the balance and + wires.
BMS used was the exact same model which is allready in the board. So I trust this one stands up the currents and wont do anything stupid.

   

Fed the balance cables through some heatshrink and always had the 2 wires come out before the rest goes into the next piece again. I think I will still add some duct tape into this channel to protect all the cables from abbrasion against the nickel strips as some corners are quite sharp.

   

So yeah soldered it all up and placed it into the channel. 
Lastly I places a double copper wire for the positive connection. I probably could have just used 1 strand (its about 2mm diameter) but I went the safe way and double that up too. Shrink wrapped it and done.
Now I just need to finish connecting the BMS (2 solder joints) thats it and im done.
               

Silly me and my perfection, I ordered shrinkwrap that 150mm wide. Calculating that its just the perfect size to fit around the cells. WELL IT DOESNT!!!!! waste of money Big Grin
orderring some wider stuff. It does shrink after all.  Rolleyes

           

Considering this is the second pack I ever built it looks pretty damn good Smile
BlueSwordM and Wattsup like this post
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#7
Heres a question for you all.
If the wrapper on the cells comes off will this short out the pack???
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#8
Whats the amp draw on the motor?
The cells you listed have a 550ma discharge
http://www.diypowerwalls.com/t-Panasonic...NCR18650PD
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#9
If the wrapper comes of yes then it can short out if it shorts out... Tongue
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#10
(09-18-2017, 07:32 AM)1958 greyhound Wrote: Whats the amp draw on the motor?
The cells you listed have a 550ma discharge
http://www.diypowerwalls.com/t-Panasonic...NCR18650PD

That is the 'Standard' 0.2C discharge current, the 'test' current for determining cell capacity only.

If you check the datasheet these cells are rated to 10A max.
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