Jugernaut Ultra 1000 - Dutch commuter style w/ integrated lights

mbouck

New Member
Just finished re-configuring my new Jugernaut Ultra 1000 in "commuter mode" complete with integrated 48V front and rear lighting! Before I get to the integrated lights (because that's it's own story) here are the changes I made to the stock configuration:
Now for the integrated lighting...For background the Bafang m620 (a.k.a. "Ultra" or "Ultra Max") has both front and rear lighting outputs on the motor controller. The nice thing about these outputs are that they are controlled from the display so you get auto on/off from the ambient light sensor and obviously the headlight button on the thumb controller controls them as well. That's all cool but what's not cool is the outputs are rated 6V @ 500mA (barely adequate). This is an engineering flaw IMHO - those outputs should be rated more like 2A @ 6V. As sold, Bixtrix has the front light output hooked-up to a laughable 6V light which is pathetic in its light output. The 150 lux Busch + Müller headlight I purchased to replace it accepts input voltages from 6-60V so cool right? Not really because the Busch + Müller headlight requires 7.5 watts and at 6V pulls about 1.25A, exceeding the current rating of the Bafang controller - caveat emptor. So what to do? I decided I wasn't going to let this situation defeat me so after some thought came up with a simple solid state relay circuit to control a separate 48V feed straight off the main battery. I could use the controller's pathetic 500mA 6V headlight circuit to instead power the control signal to the SSR. So more shopping. Here's the BOM (bill of materials) I used to complete this circuit:
  • An optically-isolated solid state relay to handle 48V up to a few amps. There are a few options but I love Opto 22's stuff and it's rock solid. A DC60MP should do the trick. Whatever you do, please don't use old-school mechanical relays - SSRs are silent, more reliable, optically-isolated and avoid issues like feedback current in applications like this.
  • For circuit protection we'll need a polyfuse (a.k.a. resettable fuse). Littlefuse makes good ones - something like the 60R250X (2.5A hold current and 5A trip current) should work fine.
  • Miscellaneous wiring, heat shrink tubing, cable ties and connectors.
To wire the circuit you'll make the following connections (see pictures):
  • Connect the existing 6V headlight wire to the VDC Control inputs (pins 3 and 4) of the SSR (red or white-striped wire to + and black to -).
  • Tap the red positive feed of the main battery and connect that to the + side of the normally open relay on the SSR (pin 1).
  • Connect the other side of the relay (pin 2) to one end of the polyfuse.
  • Connect two red wires to the other end of the polyfuse and terminate with your connector of choice - these are your two new switched 48V lighting outputs.
  • Tap the black negative feed of the main battery and split that to two new outputs, connecting them to the negative side of the 48V connectors coming off the polyfuse above.
Assembling the circuit is trivial if you have decent soldering/wiring skills. The harder problem is where to tap the main battery. I first attempted to tap in at the motor controller (behind the black plastic cover which is secured by 3 screws above the left crank arm). The problem is there is literally no real estate at that location - no room for the SSR circuit. My next thought was to tap it on the down tube at the connector side of the battery mount. You'll need to remove the battery and then the unscrew the 3 screws/bolts holding the battery mount onto the down tube. Pulling the upper battery mount away from the down tube reveals easy access to the main battery wires/connectors as well as plenty of space inside the down tube to mount the SSR circuit (I used industrial strength Velcro for this). Make sure to tap the main battery by soldering new wires directly to the battery connector and not by splicing the wire. If you are unsure about your soldering skills buy your electronics friend some beer and get them to do it - this is the most critical connection and you don't want to have a crappy connection here. The only wrinkle I found with the down tube location was that you'll need to snake a new 48V wire to the rear of the bike if you want to run a tail light. Snaking the wire turned out to be a colossal PITA but here's the trick that worked for me - buy some lawn trimmer line from your local home center and snake that through the down tube first (you'll need to use the existing access ports on the front/bottom of the down tube). Lawn trimmer line is both stiff (so you can push it through the tube) and slightly malleable to traverse corners. Once you snake it through (be patient it takes time) attach your new feed wire to one end and pull it through.
 

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Deafcat

Active Member
Nicely done and excellent write-up, especially concerning the lighting circuit modifications. I'll be doing some soon, so it's much appreciated on component selection!
 

mbouck

New Member
The lighting circuit is simple - 2 parts. I think the market is probably limited for a "lighting kit" as capable hobbyists can just as easily build the circuit themselves. Makes more sense to integrate into the bike on the manufacturer side where it could be sold as a differentiating feature - especially in the mid-market Bafang space. You have to get up into Riese and Müller territory before you start seeing integrated, high-lux headlights/taillights. As a matter of fact, the Busch + Müller headlight I used on my bike is used by RM on their bikes. The added cost on the manufacturer side is fairly minimal I'd think. Maybe sell it as an option customers can select and then you could add it on the bike in Saskatoon during final assembly/checkout.
 
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roshan

Active Member
The lighting circuit is simple - 2 parts. I think the market is probably limited for a "lighting kit" as capable hobbyists can just as easily build the circuit themselves. Makes more sense to integrate into the bike on the manufacturer side where it could be sold as a differentiating feature - especially in the mid-market Bafang space. You have to get up into Riese and Müller territory before you start seeing integrated, high-lux headlights/taillights. As a matter of fact, the Busch + Müller headlight I used on my bike is used by RM on their bikes. The added cost on the manufacturer side is fairly minimal I'd think. Maybe sell it as an option customers can select and then you could add it on the bike in Saskatoon during final assembly/checkout.
We're already in the talks. The fact that we can simply replace the top cap with a pre-fab top cap that has the light attachment is genius. We'll definitely be offering these, just a matter of when.
 

mbouck

New Member
We're already in the talks. The fact that we can simply replace the top cap with a pre-fab top cap that has the light attachment is genius. We'll definitely be offering these, just a matter of when.
Excellent! I can't believe Bafang still hasn't rectified this problem on their end (by increasing the current rating of the outputs) but in the interim you can take advantage of the situation by marketing a differentiating feature. If you have your overseas manufacturer run an extra taillight feed wire thru the downtube it would make this option especially easy for you to add during final assembly/checkout. Also, for the SSR assembly, you can have the SSR 48V feed wires tap-off the main battery in a plug-compatible fashion (vs. direct connect) - easier installation (see diagram).
 

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