Project Electric (Push) Bike - Now With Video

[Aff]

For a while now I have wanted to build an electric push bike, however I have been held back by the extortionate cost of Lithium Batteries.

For a decent (not likely to be Chinese 1/4 capacity death bombs) LiIon, LiPo or LiFePo4 batteries you are looking at upwards of £600 for the battery and BMS.

This put the idea out of my head for a while until I happened to see a video on Youtube of a bloke taking apart Laptop batteries and harvesting the innards to use in his LiIon torch.

This peaked my interest again and I done a bit of research. Turns out that most popular laptop batteries (and most power tool batteries) use standard size 18650 LiIon cells, the 18650 describes the size, they are 18mm diameter and 65mm long, they look like beefy AA's.

So obviously I took the battery out of my laptop and tore it apart to see what was inside.

Inside I found 6 of these:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0378_zps8a310748.jpg

Looked promising, but I had no way to charge them to see what they would do. The markings on the batteries gave me no clue to their manufacturer or capacity (Chinese battery so I didn't trust the blurb on the case). You can't charge a LiIon like you would a lead acid, If you over volt a lead acid (like your charging system does in your bike) it will settle itself and return the battery's voltage back to its intended. If you do this with a LiIon it will explode. To get their best life LiIons need a special charge sequence, you normally charge at full current up to about 80% capacity then taper down to 10% of the initial charge current, making sure the voltage never goes over 4.2V per cell.

So I bought myself an RC charger, good bit of kit for £20.

I hooked up one of the batteries and discharged it down to 3.5V (considered empty on a LiIon, any lower and you risk damaging the cell)

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0376_zps859e0476.jpg

I then charged them to their max capacity to see what they would hold:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0381_zps3b85d03a.jpg

I was pretty impressed thats 2.2Ah per cell, defiantly adequate to make a electric bike battery.

So I ordered a couple more laptop batteries:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0382_zpsc632926d.jpg

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0383_zpsfcc828c4.jpg

20 HP HSTNN-C29C's to be more precise. I managed to get these for only £50, I wasn't expecting to get nearly new looking batteries for that price, but I still needed to check the voltage, hoping that they would be above 3V.

I took one apart (couldn't check the voltage on the exterior connector, I assumed it would either be because the protection circuit wouldn't allow it without a load or there was one or more dead cells)

I was greeted with this:


https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0384_zpsa9d18693.jpg

Was very happy to see some 18650's, and on closer inspection:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0385_zps4db940de.jpg

So not only 18650's but a very good brand and with an available datasheet. Turns out they are 2.2Ah with a maximum charge/discharge of 2C. The cells charge and discharge rate is expressed in multiples of capacity (C) so at 2.2Ah you can charge and discharge each cell at 4.4Ah, nothing compared to the RC LiPo's which have 30C and even 80C but I am expecting to build a 48V 25-30Ah pack so that will give me about 60A to play with, which should be plenty.

I stripped down the rest of the batteries, very slow going at the beginning, they obviously don't want you inside these things, so they are glued together pretty well. Towards the end though I had it down to an art, turns out brute force with your hands is the best way of getting them apart without damaging the cells. Damaging them is very easy, I found out by accident that the entire case of the cell is negative and the top nub, separated by about a gnats cock, is the positive. when removing one I accidentally touched a screwdriver to the positive and negative, producing a lot of hissing smoke and a melted screwdriver:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0380_zps506f8edf.jpg

With a few out I started testing the voltages, was a bit disappointed to find that about 1/3 were very dead, showing only 0.1V, the rest showing about 2.5-3V.
I was a bit worried this meant that I had to buy more batteries, but with a bit of research online I found that some people said it is possible to recover LiIons back to near their full capacity. I left a few of the cells on a very low charge rate for about 2 days, then cycled them from 3.5-4.2V I managed to get all the cells up to within 5% of their stated capacity, so I am quite confident that they will be OK, apparently the discharge rate can be affected by recovering them, but I am not overly worried as I have a lot of capacity and will only need about 30A.

So here they are with them all removed and I have begun soldering them (ran out of solder half way through):

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0387_zps4b7870d7.jpg

I have decided to connect them in this configuration:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0389_zpse37432e0.jpg

It seems to provide the most structural rigidity and configuration options when on the bike. I will have 12 of these packs wired in series and split into to packs of 6. this will give me 2 24V 26.4Ah packs that I can combine to make a 48v 24.6Ah pack.

I am splitting them into to for 2 ease of charging. Like I said earlier you cannot just pump voltage into these things and hope they will regulate themselves, you have to control the input and ensure the battery voltage does not go above 4.2v. Not too much of a problem with a single 4V cell (or group of cells in parllel) but when you start running them in series, funny things will happen if you don't control the individual cell voltages.

For example if I have 6 cells in series, for a total of a 24V battery pack, I would want to charge this up to 25.2V. If I just put 25.2V into this pack, because of LiIons inability to regulate its self, some of the cells may become overcharged, I could have say 3 cells at 4.8V and 3 cells at 3.6V, this would still give the correct output and the charger would think it had done its job, but the 3 cells at 4.8V are at risk of exploding.

You get around this problem by adding balance leads, these leads allow the charger to read the voltage of all the cells in the pack and discharge them individually. This means that if the charger sees that one of the cells is getting to a higher voltage than the others, it can discharge this cell while continuing to charge the rest, meaning that they all reach 4.2V at the same time.

So, back to the reason I'm splitting them. Most chargers will only have the ability to balance 6 cells, so I will be having 2 6 cells packs that I will charge in parallel using one of these:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0388_zps5778b899.jpg

I am now waiting on bits in the post, so will update as they come.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[c_dug]

Cool project
____________________
I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[c_dug]

Wait, pushbike? I feel robbed!
____________________
I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[Aff]

[MarJay]

Forgive me for asking a vague sounding leading question in the style of Sickpup but...

Do you have a flameproof bag to charge those Lipos?
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[tbourner]

Why did you go to the hassle of buying loads of laptop batteries and taking them apart rather than just buying rechargable 18650s? Was it just a cost thing?
____________________
Trev, now a biker?
Looking for first big bike.

[Aff]

[Teflon-Mike]

Sorry, but I'm still wondering how he's managed to post the thread up, having cannibalised his computer?
That, and pun ponders;
A Lap-Top Powered push bike?
I wonder if it would go faster if he over-clocked it, of would it crash?
Would it be more stable under Windows or Linux?
And the like.
On a slightly more serious note; my first 'lap-top'.. wasn't called a 'lap-top' back then but a 'Portable PC' DID actually run off ten 1.2v Ni-Cad D-Cells... from 'Tandy' You had to take them out of the battery compartment, and charge them up in a separate charger... that did four at a time!
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Clutchy]

What an educational thread
____________________
Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[Pete.]

I agree, a wonderfully innovative bit of thinking to kick off the new year. Hope it turns out well and your chestnuts don't get roasted
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[MarJay]

[WD Forte]

Will be following this with interest
I looked into this as one of my lads rides to work and back on a pushbike and mused over a self built electric bike.
Like you, I was put off by the cost of the battery packs.
____________________
bikers smell of wee

[Ste]

Laptop batteries?

You need these! https://www.wheelspinmodels.co.uk/i/108070/

[Pol Anorl]

I have them batteries in my torch.. Lol
____________________
GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

[Aff]

I decided to use hot glue to fix the cells together rather than tape, It worked well, very sturdy, but with enough flex to take into account any expansion from heat:

https://i1135.photobucket.com/albums/m637/Biles/IMG_0390_zpsb9850adf.jpg

I also calculated how long it would take to charge the finished battery using my current charger... turned out to be 39 hours.

So I went to find a new charger. I found and ordered this beasty:

https://www.rcheliresource.com/wp-content/uploads/2011/11/A1-CellPro-PowerLab-6-499x276.jpg

Has a charge capability of 1000W, which should be able to charge the whole batter in a few hours at its max charge rate. But i will be doing it for 8-10 hours overnight to prolong battery life a bit.

Problem is, to get 1000W out of it I need a 24V 40A power supply. So I will probably be making a custom supply out of a few PC PSU's later on in the thread. But for now I will run it at 12V 32A from an ATX PSU.

Also managed to nearly finish one of the battery packs:

https://i1135.photobucket.com/albums/m637/Biles/IMG_0392_zpsf1603d50.jpg

Still needs the balance leads and power connector adding, but it is showing 24V which is good.

I put it on the scales and it only weighs 3.1kg, which I was very impressed with.

I will try and finish this pack tomorrow and get it on its first series charge.

This cool little thing showed up today also:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0393_zps8c1f1df9.jpg

Will be connected to the batteries and gives all sorts of useful information, like the current output in Watts and Amps, energy used, peak output Amps, minimum voltage level, etc.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[Pol Anorl]

https://www.dailytech.com/Chinese+Man+Killed+By+Exploding+Cell+Phone/article14142.htm

This is going to be awesome!
____________________
GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

[_Iain_]

Seriously cool. Will be watching this one
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[Aff]

Some more progress.

Added all the balance leads and power connector, at the moment all my connectors are Deans connectors, but where I have 2 way power (to and from the battery) there is no safe way to use these connectors, there will always be a live connector with exposed terminals, so i will eventually swap them all out to Anderson connectors.

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0395_zps386b7a9b.jpg

Then a bit of padding and I wrapped it. The duck tape isn't final, I will heat shrink it when I can find a reasonably priced one that will fit, but i made sure no duck tape was touching the batteries so should be an easy removal.

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0400_zpsf606f056.jpg

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0402_zps1abf2620.jpg

I then started a charge to make sure it all worked properly:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0396_zps62b39377.jpg?t=1388841206

As you can see all the balance leads work fine. However having half the pack charging shows how pathetic the charger is, it refuses to draw more than 2.2A. The Power Analyser shows that the charger must be restricted to 50W, this battery pack is about 650Wh so will take about 20-24 hours to charge.

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0397_zps807e517a.jpg?t=1388841393

Things will improve when the other charger arrives from America, but as I said earlier I am going to have to make my own DC power supply to reach it's full potential.

These are the ATX PSU's I will be using:

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0398_zps337dca14.jpg

https://i1135.photobucket.com/albums/m637/Biles/EBike/IMG_0399_zps63951bfd.jpg

I will use 2, with their 12V rails run in series, to give me a 24V 32A supply, which should be enough for me.

I don't know much about computer PSU's but would I be able to run all the 12V rails in parallel on the 2 power supplies to get the full 54A they can supply? that would mean I could use the full 1000W of the charger.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[Pol Anorl]

Have you got a bike and drive mechanism sorted yet
____________________
GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

[Aff]

[BillyJ]

[Aff]

[BillyJ]

No, I lied... let me get this right:

You will connect the two 12v rails in series to get 24v@32A - Fine
You will do that again with the other two rails - Fine
You will then connect the two new rails in parallel to get 24v@64A - Fine
You will use this new new rail - Not fine

On the PSU the stated max power(wattage) is 729W
If we ignore the fact that all these rails together cannot draw more than 54A and assume you will not draw more then that we already have another problem... the max power.

The most current you can draw at 24v whilst not exceeding the 729W max would be:

P=IV
729=24I
I=729/24

Max current draw@24v = 30.375A

So call it 28ish and be safe, also whilst pulling 30Amps from a PSU do keep an eye on the temperature, 30A is a lot, and the weeny fan in the PSU didn't ever expect anyone to draw 30A continuous current from it!
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[Aff]

[BillyJ]