DIY Conversion - Voodoo Marasa

jerrysimon

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Aug 27, 2009
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Yes I think it went up to 500W but it fluctuates quickly. Guess a better test will be when I go up a hill/incline.

So the controller won't ever allow more than 17A through it ?

Don't want to burn motor out.

Once it is all tidied up I will test it more.
 
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If he has a 17a controller and selects 18a in the LCD's advanced settings, that'll fry the controller won't it?
No. there's plenty of headroom. I've gone as high as 24 amps on a normal 15A controller. A point to remember is that you only get the maximum current at low speed relative to the motor's maximum speed. So, a lot of the time, you're riding outside the zone of maximum current if you use an appropriate (winding speed) motor.
 

anotherkiwi

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I have the huge version from BMSB:



You could probably fit one of your tiny batteries in there! Keeps all of the extra wire tucked away and out of sight. Has started to rattle lately so you have to tie the controller down in mine.
 
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jerrysimon

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Ok almost there a bit of tidying up to do plus decide what battery I need.

For tests I am using this battery. Fits in a pencil case. Made up of two series 5s2p packs connected in series with balance taps and fuse giving a total of 36v, 3Ah using 1.5Ah Sony Konion cells. Weighs 1kg.

IMG_0518.jpg

I also have a 36v, 6.0Ah pack made of the same cells as well. Max current draw should not exceed 20A for the smaller pack and 40A for the larger one. Note the date (6/13) this is now 4 years old and done thousands of miles, though that is with my Brompton pulling no more than 8-10A max (usually about 3-5A) its hardly been hammered. It doesn't have a BMS but has taps as I said for balancing. I doubt I have balanced it more than 3 times in its life time. I never charge beyond 41V i.e. 4.1V/cell.

You can now get these cells in 3.1Ah capacity and I am thinking about building a 10s3p pack later. These new cells can cope with 30A draw over the 10A draw of the above cells.

Going out on the flat I have done a few tests to see how much current I am drawing:

1. At setting 3 I draw no more than 6A and it easily accelerates me up to 15mph

2. At setting 5 I draw around 17A but it accelerates me quickly up to 19mph!

I am really rather pleased with this setup though need to go find and test it on some hills lol.

I have put the controller in a project box as shown below. I could probably put it in a smaller box but this one allows me to coil up the cables and not cut any of them. I may do that later.

IMG_0519.jpg

I have some ideas for a better arrangement to carry the battery (its carried in the pannier at the moment) so will post more later.

Its been such fun building this especially as it is different from my usual small wheeled, light bike front hub builds. Also my first rear motor conversion. I must admit I quite like the power up back and of course there is no weight on the front steering found with front hub conversions.
 
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jerrysimon

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Aug 27, 2009
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Possibly a better solution. You need a Topeak rack but this bag is selling discounted in Halfords for £30 at the moment.

IMG_0520.jpg

I never realised but this transforms into panniers both sides as well, which are hidden in side zipped pouches. Good if you get shopping.

IMG_0522.jpg

The main unit simply slides on and clips fast. You can remove if you don't want to leave battery and take with you.

IMG_0524.jpg

Battery in the bag. Needs some sorting out still.

IMG_0523.jpg

Having done a few more tests I think I will need a min of 6Ah battery for anything more than about 10 miles.

Found a few inclines and on setting 5 it pulls hard peaking at about 550W and easily getting up to 15-16mph. As I said on the flat you can easily get to 19mph. Mostly setting 3 is fine around Cambridge.

Interestingly the throtttle seems linked to the power setting and still only takes the bike to about 14mph even on setting 5 ?
 
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anotherkiwi

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Ooooo! I like that pannier! They do a strap version as well, I'm having one!
 
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jerrysimon

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This one comes with a carry strap as well. I think they also do a larger one.

Ah you mean straps to attach to a generic carrier. I Like the idea of being able to remove and put it on quickly. The racks are only about £28.
 
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jerrysimon

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Aug 27, 2009
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So done a few rides now and overall very pleased. For me the screen sticks out, I guess I could move it somewhere else. Would be nice if it was removable. I wondered if the other more discreet screens sold by PSWPOWER might do the job like this one:

http://www.pswpower.com/peng/iview.asp?KeyID=dtpic-2016-2V-0R46.8KBTG

I assume you would have to buy the KT-LCD1 and data copy lead to program the KT-LED890 or can you copy data from the LCD3 to the it ?
 
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You don't have to use the mount supplied. You can make one out of 16g aluminium. Dremmel out a hole the size of the stem cap, then drill two holes for the LCD screws. Cut out the rest of the shape around the holes. Screw on the LCD, then fix it to the bike with the stem cap and bend it up to the right angle. It'll then sit over the stem rather that above the bars.
 
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jerrysimon

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Dave I meant the size/prominence of the unit, not the mount lol

Now I know the amps/watts being drawn dont really need the large screen. My removable GPS trip meter (Garmin Edge) will suffice.
 
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Get rid of the Garmin and use your phone. You get much more that way and you can keep your phone in your pocket. Most people have it with them anyway, so it doesn't make sense to bring both.
 
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jerrysimon

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Aug 27, 2009
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Its only an older one from a few years ago. I will try it as I want to see how the mph compare to the LCD3.

What apps are recommended for the iphone ?
 
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What apps are recommended for the iphone ?
Best advice is to get rid of the iphone and get a proper one, then you can use the nice apps like Sports Tracker, Strava, Clonometer and many more.
 

jerrysimon

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Aug 27, 2009
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Lol o_O

What I love my iPhone!

Strava is available for it. I am all iOS with my Macbook and 27" iMac with its lovely retina screen!

Used Windows for years building it every 12 months as it got full of virus, spyware etc and slowed to a snails pace. Had a Android phone for a year or two and then switched to an iPhone. We (whole family) use them share photos, face time etc :p
 
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Lol o_O

What I love my iPhone!

Strava is available for it. I am all iOS with my Macbook and 27" iMac with its lovely retina screen!
Jeez, that's a very bad case! I think the doctor can give you pills for that if you ask him nicely. They're free if you're over 60.
 

jerrysimon

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Aug 27, 2009
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As a type 1 diabetic I already get free prescriptions :p