My First Build : MILDA MK 1 /out of Commision Please Help!

General Discussion about electric bicycles.

Re: My First Build : MILDA MK 1 Please Help!

Postby glenn0010 » Wed Apr 05, 2017 1:42 pm

amberwolf wrote:
glenn0010 wrote: That's true a steel frame would be much easier to work with but then there is a weight issue.

Not in my experience. Most of the cheaper aluminum frames are really thick tubing and end up weighing the same as a good butted-steel-tubing frame, though there are very thin/light aluminum frames they usually are expensive. I have one of those used from someone else, but the toptube is dented to a point that it could potentially collapse under the wrong kind of stress. I think it was a Giant brand, cant' remember for sure.

I don't recall the actual weight but the frame on my DayGlo Avenger is at least as heavy as the one on my old steel Nishiki.


Also most steel bikes are quite old so they'd have no front suspension.

Oh, there's been lots of full-suspension or front-suspension steel bikes; some are good suspension components and some are junk.

Though I guess I could swap the suspension from my current bike if the fittings are the same (have no idea about bike standards)

You can swap lots of parts around. How do you figure I got front suspension on my CrazyBike2 and SB Cruiser? ;)

And if the headtube is the wrong size on the steel bike, you can just swap it out for one that is the right size (I did this on CB2, welding the new one on in front of the old one, so I could use either as needed for experiments).

As for standards, and other bike repair/maintenance info, http://sheldonbrown.com is my first recommendation.


Another idea I had was to chop the frame and make 2 steel clamps that clamp around the aluminium seat tube and then go to steel for the back of the bike. Though I would question the durability of such a design.

Then any stress on the back is passed not thru the tubing but across it's surface, and only under the clamps themselves. Eventually it'll probably either crush the tubing or cause stress fractures, but you'd have to test it to find out.

Designing the clamps so you don't get any side-to-side waggle is another problem to conquer....

This is essentially teh problem I had with DayGlo Avenger's added-on cargo rack/pod, and what eventually cracked the seatstay.


SUCCESS!

My bike made the 34 Km round trip to uni took me only about 35 min each way which is great.

I can confirm that my BMS is cutting out due to voltage sag. When the battery is fully charged I have to give quite a lot of throttle for the BMS to cut out but as the battery is drained the BMS cuts out much earlier. that's what you get I guess for Chinese cells.

Now I want to save up to upgrade! This is addicting.
I want to save some money to upgrade. But don't know which direction to go.

So I want a new battery for sure.

I can chop the frame or get a steel frame and mount the mid drive behind the seat tube and install a new battery.

Or get a 3kW hubmotor @ 72V and a new battery and charger and possibly mod my controllet, new fets and caps to handle 72V. But this will be really expensive.

Would be nice if I can go slightly faster. Else I can make a 48V battery which can supply more current and put a larger drive sprocket on the motor

Any tips?
glenn0010
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100 W
 
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Location: Mgarr, Malta

Re: My First Build : MILDA MK 1 Please Help!

Postby glenn0010 » Fri Apr 21, 2017 8:53 am

Hi All,

My bike is doing great but I plan on saving up to upgrade it in the summer.

I plan to upgrade it in two stage Milda Mk1.5 and Milda Mk2;

Milda Mk1.5

I plan of making my own 74V 15Ah battery pack Using the 30Q cells. (20S 5P)
I plan on buying a MXUS 3000W hub motor and Kelly controller to go with it.
This will allow me to ditch the current complicated drivetrain and make things more reliable better looking and faster.

Attached find an Excel sheet where I do some calculations on comparing different battery cells prices etc. Some calculations in there some of you may find useful.
Please fell free to edit the document and give any suggestions. Take a look at it and let me know what you think!

Thnks Glenn
Attachments
Calaculations.xlsx
(10.98 KiB) Downloaded 9 times
glenn0010
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Posts: 101
Joined: Wed Jul 01, 2015 3:56 pm
Location: Mgarr, Malta

Re: My First Build : MILDA MK 1 Please Help!

Postby glenn0010 » Mon Apr 24, 2017 8:15 am

Out of commission,

Here's the story. While I was away and charging my bike, the voltage at home dropped to roughly 110V and then went out. (keep in mind we have a 230V system here). Fast forward to this morning and the charger was off and I could smell the magic smoke coming out of it.

The battery is fine however since I took it out for another 35Km today.

Here is what the charger looks inside

Capture1.JPG
From the top
(113.39 KiB) Not downloaded yet


Capture.JPG
From the Bottom
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I will get a new one since I don't have the time to fix it. Does anyone know where I can get a cheap 13S (Roughly 56V) charger with an XLR output?

Regards Glenn
Last edited by glenn0010 on Mon Apr 24, 2017 8:35 am, edited 2 times in total. View post history.
glenn0010
100 W
100 W
 
Posts: 101
Joined: Wed Jul 01, 2015 3:56 pm
Location: Mgarr, Malta

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