UMF Freddy build, custom high power battery, mxus 3k

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wolf   100 µW

100 µW
Posts: 7
Joined: Jun 27 2016 11:45am
Location: Austria

UMF Freddy build, custom high power battery, mxus 3k

Post by wolf » Jan 13 2021 8:06am

I've built this bike about a year ago and I'm really happy how it turned out!
I'm posting this mainly as an inpiration for other people, maybe it is useful to someone :wink:
There are a lot of pictures, i hope that's ok.

the bike weighs around 36kg with battery

battery:
21s4p, Sony VTC5A (2600mAh, 35A)
60A standard china bms

I really like this kind of battery setup, it is lightweight and has enough energy to ride around the hills around my town for 2 hours or go 40km at reasonable speed on flat terrain.
Plus it's easily removeable and on a long trip you can just take more packs with you. Plus you can easily charge the battery inside the house.
I also already have 3500mAh cells lying around for a low power, high energy version of this pack.

controller:
Kelly KLS7218S, set to 120A battery current (never had a problem with bms cutting off, or getting hot)
ca. 9 kW peak
I'm quite happy with the controller, runs smooth and super quiet, more than enough power for this setup, never gets hot
but i didn't get regen to work like i would expect it..
and my old infineon controller had a lot more punch at startup. really a LOT, two of my friends crashed while making an unwanted power wheelie. so the lack of startup torque is probably a good thing^^ and I'm also not so afraid anymore while driving :lol:

motor:
MXUS 3k 4t


bike
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UMF freddy two
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motorcycle helmet buckles (can be bought in china) and 20mm belt
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lasercut 3mm aluminium plate
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held by 3d printed parts, which fit tightly on the frame and are secured with hose clamps
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torque arms
IMG_20201130_134714.jpg
lasercut 5mm stainless steel. I can provide the dxf files if needed. I also have files for an UMF Freddy one, which uses different torque arms
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2 parts on each side which are prestressed to prevent motion
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display
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self made display, using an arduino nano and 16bit adc, pretty similar to CA, but smaller and potentially more features.
I also have a new version using an ESP32, but this is something for an own thread.
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battery
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cnc cut plywood, 21s4p
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nickel strips with soldered copper wire, 1mm copper sheet at edge
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the wood parts have pre cut paths for the wires. I didn't leave enough space though
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wraped in 0.75mm polycarbonate, this is great for protection, I really like this material!
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0.15mm nickel sheet and 1.5mm² copper wire. I wound the wire many times around two rods, sliped it off and cut everything with metal scissors
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the wood board has the same cut out as the battery, so the strips fit perfectly later.
the parts are held down by the tube and soldered with hot air. this worked pretty good.
I used this technique, because spot welding several nickel sheets on top of another didn't work with my home made welder.
IMG_20210112_183539.jpg (1.5 MiB) Viewed 165 times

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pwd   1 kW

1 kW
Posts: 441
Joined: Oct 11 2011 12:01pm
Location: Ontario, Canada

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by pwd » Jan 13 2021 9:29am

Nice build and setup. Looks well thought out. I like the battery tray setup with the buckles. I was using hook and loop straps on a previous setup; the ratcheting buckles would have been much better.
Commuter/Street Build viewtopic.php?f=6&t=98286:
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Magic Pie 4 front + Leafmotor 1500 rear w/ WCEC 18fet
Samsung 40T 14S7P

Offroad Build viewtopic.php?f=6&t=102195:
2019 Rocky Mountain Blizzard 20
Cyclone "3kw" 13T motor to 36T chain ring then 32T chain ring to 11T-46T Cassette
em3ev 14S5P 30Q or 14S6P 25R pack

markz   100 GW

100 GW
Posts: 11964
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by markz » Jan 13 2021 5:31pm

Thanks for the pics

Whats the deal with the ta and tensioner mount?
Aluminum I take it, whats the thickness?

raggertje   10 mW

10 mW
Posts: 20
Joined: May 17 2020 4:45pm
Location: Utrecht, The Netherlands

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by raggertje » Jan 13 2021 6:05pm

wolf wrote:
Jan 13 2021 8:06am
battery:
21s4p, Sony VTC5A (2600mAh, 35A)
60A standard china bms

I really like this kind of battery setup, it is lightweight and has enough energy to ride around the hills around my town for 2 hours or go 40km at reasonable speed on flat terrain.
Great build Wolf! Thanks for sharing.
I'm setting up the same controller and hoping to get a bigger range compared to the KT 22-42A controller I'm running know. With a 1500w hubmotor and a 14S5P 12.3AH Battery (Samsung 25R) I'm getting max. 25km. Yours 2 ours around the hills or the 40km involves some strong legpower I suppose?

Do you use a switch between your battery and controller?

And I really like your display! Is that hard to setup?

99t4   100 W

100 W
Posts: 113
Joined: May 10 2020 10:31pm
Location: PNW

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by 99t4 » Jan 13 2021 10:39pm

Lots of innovative aspects in your build wolf. :thumb:

Can you show details of the rack mounting? My next build will be a FS and my usage requires a strong carrier rack.

wolf   100 µW

100 µW
Posts: 7
Joined: Jun 27 2016 11:45am
Location: Austria

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by wolf » Jan 14 2021 4:45am

markz wrote:
Jan 13 2021 5:31pm
Thanks for the pics
Whats the deal with the ta and tensioner mount?
Aluminum I take it, whats the thickness?
I'm not exactly sure what you mean.
All the parts I've added are 5mm stainless steel, the frame is aluminum. On the left side the inner plate is screwed to the brake mount. On the right side two plates are clamped together with the frame in between.
torque arms.PNG
torque arms.PNG (155.32 KiB) Viewed 99 times
raggertje wrote:
Jan 13 2021 6:05pm
Great build Wolf! Thanks for sharing.
I'm setting up the same controller and hoping to get a bigger range compared to the KT 22-42A controller I'm running know. With a 1500w hubmotor and a 14S5P 12.3AH Battery (Samsung 25R) I'm getting max. 25km. Yours 2 ours around the hills or the 40km involves some strong legpower I suppose?
Do you use a switch between your battery and controller?
And I really like your display! Is that hard to setup?
I should have explained in detail how the 2 hours are meant. The tour I'm referring to is 14km one way and 600m in height, half gravel, half road. I don't pedal at all. 2 hours are the whole round trip with some stops for enjoying the view. I'm going at a comfortable speed, not pushing it to the limits. And I never came close to running out of battery.

I don't have a switch on the main power lines, just the controller turn on switch and an anti spark connector.

Well once it's built it's easy to setup the display, the connections are just like the CA. For configuration, you have to upload the program via usb though. The new version I'm building has wifi and bluetooth and can be configured easily with your phone. But I have a lot of other projects going on and don't know when I will continue.
All of my ebikes have this display, or an older version of it. Mainly because of the "legal mode" :wink:
99t4 wrote:
Jan 13 2021 10:39pm
Lots of innovative aspects in your build wolf. :thumb:
Can you show details of the rack mounting? My next build will be a FS and my usage requires a strong carrier rack.
In this build I made a 3d printed piece and clamped it to the frame. And the lower parts are screwed to the torque arms. But the rack I'm using isn't very strong unfortunately.
The other picture is showing the mount on my non ebike. This one is not very sturdy, but it could easily be built stronger.
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markz   100 GW

100 GW
Posts: 11964
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: UMF Freddy build, custom high power battery, mxus 3k

Post by markz » Jan 14 2021 6:18am

Oh those are steel, to me it looks like aluminum. I guess I am just used to working with darker steel.

I just take 3/8 flat plate and cut axle notches out and slap on some hose clamps.
I should try to do something like your design, mine would be cruder but I see why I havent done it that way. I buy 3/8 flat stock thats 1.5"x5", but I could have that angle area a bolt. Yeah I'll try that tomorrow because various bikes have differet rear axle slot that rotate the axle flats to different angles.
Clipboard02.jpg
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