I can see this is going to get addictive

[jackie_black]

Hi,

I'm a complete noob here and i've just completed my first electric bike project. I converted a specialized expedition sport with an 8Fun front hub motor and bottle battery. I will get some pictures up soon but the weather over here in britain has just taken a shocking turn for the worse and it has started snowing even though it was 23 degrees c last week!

From a quick ride on my new steed I have decided that I now need to create something cutom and full suspension for (off road) work commutes and general weekend fun, so I will be picking peoples brains quite soon. I teach electronics so know the basics and can solder and create my own bits and pieces.

I suppose my first question is can I get more than 15 mph from my 250 8fun hub motor without spending a fortune? the battery is 36v 10ah but only needs to carry me 4 miles each way at the moment. I suspect the limiting factor will be the controller. Anyhoo, i'm off to read a lot now, as I want to know how to make my own batteries!!

 

[ecowheelz]

You're right... the only thing limiting your top speed right now is your controller. I bet if you provided the controller details (and maybe a picture), the experts here could guide you on making it faster

 

[jackie_black]

Hi,

Its this kit here http://www.ebay.co.uk/itm/8Fun-26-E...0832964709?pt=UK_Bikes_GL&hash=item4ab3228865

There is a picture of the controller on there. It a basic starter kit I think.

 

[jackie_black]

Actually my controller is in a black metal box so is a little different. I'd have to venture to the shed to get its name and number!

 

[The Mighty Volt]

Addictive? You don't know the half of it!!!

When I started off, I had NO knowledge of bikes, batteries, amps, volts, horsepower, torque, anything. I knew nothing.

I spent a lot of money on some Duct-Tape batteries and hub motor. I liked it but was totally underwhelmed.

Since then I have pushed on a lot, getting involved on all fronts and learning about every aspect of the bikes- from mechanical issues of suspension to electric and electronic applications and diagnostics.

Ebike is a buzz, your life will not be the same again. It has come to dominate my spare time and alter my line of thinking on a wide variety of issues.

 

[Lebowski]

It has come to dominate my spare time and alter my line of thinking on a wide variety of issues.

a bit like pot you mean ?

 

[jackie_black]

Well i'm a complete techie and knew what would happen. But I bought the underwhelming starter kit to make a reliable commuting tool. The idea is to get to work suited and booted but without sweating having had some fresh air in the summer months. However i've had dirts bikes (2 strokes) in the past and currently have a nice honda in the shed but want to make something that uses electricity. I love 2 wheels so it makes sense to begin a project

I've read a lot of info on here already and pretty much decided to build a 48v lipo battery and find some kind of controller for my 250w hub motor, sure it'll be fine, although the front forks may not!

 

[Drunkskunk]

Welcome to the addiction.

My guess is that you have a Euro version of the controller, which is speed restricted. The usual way for that to be done is with a white wire that exits the controller, plugs into another white wire, then goes back in. Unplug it, you should get more speed.

More voltage will give you more speed if the restriction is removed.

More amps will give you more power. That should be a 6 MOSFET controller, limited to 10-15 amps internally, but you may be able to push it up to 30 amps if you're brave. Though 30 amps would likely fry your battery and could overheat the little motor. If it were me, I'd try to modify it first for 20 amps peak, and then add more power in stages. The mod consists of adding solder to the shunt resistor. you only need a tiny amount of solder to change it's resistance and fool the controller into allowing more amps to pass

 

[jackie_black]

Yeah it is definitely the euro version. I'll run it for a while on the bike while I mastermind something special.

 

[d8veh]

It's not the controller that'll limit your speed. It's the battery. The 8Fun bottle battery is pretty weak and your controller current is set correspondingly low - I think the last report was 12amps max. You can get a lot more current from the controller, which will improve hill-climbing and acceleration, but the battery will then keep cutting out due to overload. If you had a stronger battery, you could add some solder to the shunt in the controller, which would increase the current and allow the motor to hit its top speed of about 18mph. To go faster, you need more volts. 44v will get you to 21mph if you solder the shunt up to 20amps (try 18amps first) - about as much as that motor/controller will reliably give as long as you don't let it slow down up steep hills with full throttle. 48v will take it up to about 24mph, but I don't think it will have enough power to maintain that speed, so you need to be much more careful not to let the motor get hot. Several people run theirs with 48v, but you're much closer to melt-down

The bigger Bafang BPM, MAC and Cute 128 motors will all give a much more reliable higher speed and power without so much risk of damage.

As you said you don't want to spend too much money to improve the speed, you could try a pair of these lipos instead of your bottle battery plus solder about 1/3 of the shunt.
http://www.ebay.co.uk/itm/22-2v-5200mAh-25C-6S-Li-Po-RC-Battery-R-C-Trex-500-600-/280661823252?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4158bf8f14
and one of these to charge them
http://www.ebay.co.uk/itm/IMax-B6-Digital-LCD-RC-Lipo-NiMh-Li-ion-LiFe-Nicd-Battery-Balance-Charger-2S-6S-/260902051853?pt=UK_ToysGames_RadioControlled_JN&hash=item3cbef9600d
If you don't know how to use lipos, you should read up on them before you do anything with them,

 

[jackie_black]

This forum is already awesome and wallet lightening.

I've read a lot about the LiPo stuff and to be honest its complexity immediately draws me to it. I could make a pack with 4 of those packs in a sort of paralel/series combo if i've read things correctly to give me good run time and voltage. would that give me 44v and 11ah?

I'll run the bottle for a bit and see how I get on with it but already know i wont be able to leave well enough alone. WIll my 8fun motor be geared then?

 

[knoxie]

Welcome

And yes you will find a whole lot of info on here! it a shame that you didnt come here before you bought your kit, that said getting the kit will spark your interest though, there are a few options for you, you can get a sensorless controller and hit that motor with a few more volts and amps and yes its pretty easy to parallel 4 packs of lipo and run 50V 10AH, I have been doing just this for over 2 years with no problems.

You have a lot of reading to do, in the meantime enjoy your ebike safe in the knowledge that you can speed it up, trust me its better that way as its so exiting when you go from 15mph to 25-30mph! ha ha I remember being so exited about that although now its faded a little I still get the e bike grin at times. and it is sooo addictive the forum will become your new addiction. Welcome to this great hobby

 

[jackie_black]

I already have a sort of plan forming now. I will run the reliable and cheap 8fun kit on the commuter, all the while building up a stock of parts for another conversion then swap everything over in the future. or alternatively upgrade the battery and controller and get another 5mph from the little 8fun motor. I don't know how fast i'd want to go on it though as at 15 mph everywhere its a little skttish, the bike a cruiser type thing (old man bike). Think i'm going to enjoy these electric things.

 

[d8veh]

If you get a pair of the lipos, you can get an immediate performance boost as they will connect directly to your controller. You don't have to do any other mods other than connectors and a place to put them. You can buy another pair later if you decide to go for more range or more power. That's an advantage of lipos: they're very flexible.
A good way to mount them: You need a rear rack. Buy a football boot bag with a zip around the top. You can get them at car-boot sales for £1 or less. Cut a piece of 3mm plywood the same size as the inside base; put the plywood in the bag and bolt through the plywood and bag to your rack using washers to stop the bolts pulling through the plywood; place a piece of foam or similar in the base so that the bolt heads can't damage your batteries. Here's an example of a Bafang BPM motor conversion I did so that you can see how it looks. There's 25aH in that bag plus pump and toolkit!

 

[jackie_black]

With the lipos though would they not come in at just over 5Ah? My current battery is 9Ah will I not lose a lot of range?

 

[dogman dan]

You paralell two 5 ah lipos to make 10 ah pairs. Then make your series connections to get to the voltage you want to run.

Only limit is your wallet size. Your paralelled sets can be any AH you can afford.

Man, you want to see ES cost you money, wait till you find out a race is being organized close enough to your house! Suddenly you are building a racer when you never raced before in your life.

 

[d8veh]

With the lipos though would they not come in at just over 5Ah? My current battery is 9Ah will I not lose a lot of range?

Correct. You'll get about 10 to 15 miles. The reasons I suggest them is because they don't cost too much; it'll give you a chance to learn about lipos; they don't weigh very much, so you can make quick change-over connections and use them in addition to your bottle battery. You can get 4 packs with two pairs in parallel if you want

 

[jackie_black]

With the lipos though would they not come in at just over 5Ah? My current battery is 9Ah will I not lose a lot of range?

Correct. You'll get about 10 to 15 miles. The reasons I suggest them is because they don't cost too much; it'll give you a chance to learn about lipos; they don't weigh very much, so you can make quick change-over connections and use them in addition to your bottle battery. You can get 4 packs with two pairs in parallel if you want

I get what you're getting at now! My connector on the bottle battery is a 4 pin circular plug with a screw on lock ring so i'd just need one of those i suppose. If i run 48 volts with the standard controller the extra voltage will just give me a little more top speed won't it? I can just leave it standard. I need to monitor LiPo discharge as well don't I? Because if the voltages drop too low the packs don't like it.

 

[Ykick]

With the lipos though would they not come in at just over 5Ah? My current battery is 9Ah will I not lose a lot of range?

They make 5.8Ah RC Lipo bricks but I tend to stick with the more common 5Ah. Obviously, the latter in 2P will be cutting it close compared to your 9Ah bottle battery (which is probably somewhat optimistic, btw) but remember as any battery ages it will never deliver more capacity.

The main thing to remember is that more than one bike is a very, very good thing. You will not regret having another platform to experiment, compare and test. And, on those days when something breaks, flat tire, etc. you can turn to the spare.

It's fairly standard around here with RC Lipo folks to configure our packs in many different ways so that they can work on all bikes in the stable and/or even split them up when friends wanna go along for a ride.

EDIT - btw, I went back and looked at your OP - 36V 10Ah = 360Wh. Bump that up with RC Lipo to 44V 10Ah - 440Wh. More energy can deliver more distance as long as you observe the same throttle performance. But that's practically impossible to do without a CA.

 

[jackie_black]

Ok here goes, i've had a few minutes to take some pictures.

Here is the bike with the kit fitted.

here's the motor

The all important controller info

The view from the driving seat

and the bottle battery

As you can see i'm a big fan of jubilee clips and rubber mountings to protect my frame. I think it looks quite stealth and the weight is mostly in the middle of the triangle low down for weight distribution.

What do you guys think?

 

[jackie_black]

You paralell two 5 ah lipos to make 10 ah pairs. Then make your series connections to get to the voltage you want to run.

Only limit is your wallet size. Your paralelled sets can be any AH you can afford.

So to make a 44v 10ah lipo I would need 4 packs right? 2 paralell into blocks then series the blocks together? I can't seem to find the physical sizes of the packs to work out how to house them (don't want a rack).

 

[Tench]

Check out the Hobbyking site, they have loads of packs listed with all the specs and sizes.

http://www.hobbyking.com/hobbyking/store/index.rc


This page is just the 6 cell packs, 22.2v

http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=86&LiPoConfig=6

Simon.

 

[Ykick]

You paralell two 5 ah lipos to make 10 ah pairs. Then make your series connections to get to the voltage you want to run.

Only limit is your wallet size. Your paralelled sets can be any AH you can afford.

So to make a 44v 10ah lipo I would need 4 packs right? 2 paralell into blocks then series the blocks together? I can't seem to find the physical sizes of the packs to work out how to house them (don't want a rack).

I call 'em "bricks" from Hobby King and "pack" is the final configuration used on the bike. Yes, we're talking 4qty 6S (22v) 5/5.8Ah bricks/packs. Normally called 12S2P when connected to form your bike pack. They have dimensions for various brands on the sale page and many of use make dummy cardboard versions to try different physical arrangements and enclosures.

Have you seen those triangle battery bags? That might allow room to keep the bottle battery as a reserve, if you wish?

Btw, 44v is the low side in practice. Hot off charger they're about 50V and settle into 46-48v for majority of discharge. When 12S series RC Lipo reaches 44V resting, it's practically empty. Get a power meter or CA ASAP, it's helpful to see values of electricity going in and going out on the bike and the charger.

OMT - nice, clean build. Mild but a good start.

 

[jackie_black]

So 4 of these.

http://www.hobbyking.com/hobbyking/store/__18210__Turnigy_nano_tech_8000mAh_6S_25_50C_Lipo_Pack.html

Run in 12S2P configuration would give me 44-50v @ 16ah? That's a pretty cool battery.

I've been thinking about the next project. I have a reynolds rigid steel framed mountain bike spare. Thinking I could kit it out with the above battery pack, some decent rockshox and a rear hub motor. That would make a lovely next project!! Would probably be good for about 20mph too.

 

[d8veh]

So 4 of these.

http://www.hobbyking.com/hobbyking/store/__18210__Turnigy_nano_tech_8000mAh_6S_25_50C_Lipo_Pack.html

Run in 12S2P configuration would give me 44-50v @ 16ah? That's a pretty cool battery.

I've been thinking about the next project. I have a reynolds rigid steel framed mountain bike spare. Thinking I could kit it out with the above battery pack, some decent rockshox and a rear hub motor. That would make a lovely next project!! Would probably be good for about 20mph too.

Don't forget to add shipping costs and import duty. I had to pay about £40 for two of those, so expect to pay about £70.