Are you using a 1k ohm pre charge resistor? I would guess it takes some time to finish pre charge in that case. I dont remember exactly, but I think for me with 20 or 30 ohm resistor it takes almost a second. Or at least half a second.
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First Electric Motorcycle Conversion Advice (1974 Honda CB360)
- Thread starter RealPolarBear
- Start date
RealPolarBear
New-ish here
Yeah it definitely takes a couple seconds, but I'm willing to spare that. I think of it like priming the fuel pump on a car.
On a related note, I have a question regarding the pre-charge circuit. So I know that when opening the circuit, the process is along the lines of: flip the precharge switch, wait 5 seconds or so, flip the contactor coil switch (to trigger full battery power). This makes sense to me, but is there a similar or inverse process for closing the circuit? Should I kill the contactor coil switch and allow the voltage to ramp down and then kill the precharge circuit or can I kill both switches at the same time. Or should I kill the precharge circuit directly after I energize the contactor coil.
I would really appreciate if someone could chime in about a process that works for them. I'm just trying to avoid the same fate of my last contactor (R.I.P.).
You can turn off precharge as soon as the contactor coil is on.
RealPolarBear
New-ish here
Alright now that the precharge circuit is tried and true, I have another question for y'all! I'm beginning to design my battery box. I will be making it out of mild steel. It will eventually being painted or powder coated, but I am wondering what to use to insulate and support the battery. I'd assume some type of non-conductive high-density foam but I figured it'd be small to check in with you all for any recommendations
Dui ni shuo de dui
Power poster
Usually the most common thing used is rubber sheets. They are inexpensive and easy to work with.
If you can, try to use another material for the battery box as steel is quite heavy. The less weight, the less strain on your powertrain.
Aluminum is easier to work with, it's easy to cut, easy to bend and if you don't have the appropriate welding tools you can always use rivets. Also, it won't rust, unlike steel.
It is advisable to use heat-treated aluminum, it is hard and elastic like steel, but 3 times lighter. I have been using this material for several years, the thickness of the sheets is 3 mm, on one of the mepeds I have repeatedly fallen and had several accidents, but the cabinet and the battery remained unharmed. By the way, after assembly and tightening with knitting needles, the battery was covered with 1 mm thick fiberglass, this is a very durable material with excellent insulating properties.
RealPolarBear
New-ish here
Hi all! It's been awhile since I last posted. I thought I'd update everyone on my electric CB360 progress. Just before the end of December I got my first test run in! There is still a long way to go in terms of wiring and appearance but it was thrilling to feel it move under its own power. Here is a quick video and some pictures. Thank you all of your help and willingness to answer my questions, I couldn't have done it without each one of you! I'm also happy to answer any questions about the build so far and I will update you all when I am closer to finishing up this project.
Dui ni shuo de dui
Power poster
Very nice, it's looking great.
Also it seems like its pretty quick already
Anything planned for the brakes? They might need a bit of upgrade now
RealPolarBear
New-ish here
Sorry for the late late late response. I've been working on some finishing touches on the bike and I can't wait to get it out on the road when some warmer weather comes! As for the breaks, you're certainly right. Double drum brakes is definitely not impressing anyone by today's standardsVery nice, it's looking great.
Also it seems like its pretty quick already
Anything planned for the brakes? They might need a bit of upgrade now
. I'll be keeping an eye out for a '74 CB360 front end with disc breaks (unfortunately mine wasn't optioned with those). But for now, I'm just looking to get out and ride! I will update my build thread with some more pictures and videos once I get out there!RealPolarBear
New-ish here
Hey all! I wanted to send out an update on my build process for my 1974 Honda CB360! I was able to have all of my metal parts coated in a matte black powder making everything look pretty sharp. I've put about ~200 miles on everything since I "finished" up in May of 2025 and it's feeling really good. As it stands, I'm able to get up to around 60 mph fast! I haven't done a comprehensive range test, but from what I've gathered, I'm able to squeeze around 50-60 miles off a charge (with spirited riding). I'm planning on doing a teardown during the off-season to take a look at some of my major components to ensure they're holding up properly. In terms of future plans, I'm still on the lookout for a front disc brake setup from a donor bike and I'd like to upgrade the stock suspension to get a better ride. On that note, I might also get a second pair of handlebars to swap out the current racer style bars which are pretty painful for any extended period of time. Likewise, being a taller guy riding a smaller bike, hunching over every ride has proved less fun than I anticipated. To get a little more legroom, I might fabricate some sort of rear brake relocation and rely primarily on the rear pegs. With all that said, here's a couple videos and pictures of my build as it stands today (with some extras from the process featuring my '73 CB750). As always, thank you all for your support and I'm happy to answer any questions that you may have!
Video 1: Takeoff
Video 2: Drive by
Video 3: Street ride
Video 4: Walkaround
Video 5: Dashboard
Video 1: Takeoff
Video 2: Drive by
Video 3: Street ride
Video 4: Walkaround
Video 5: Dashboard
Looking really slick!
looks bloody great
battery box: cut with CNC? how thick are d sheets? would love to see inside, cell arrangement and wiring.
RealPolarBear
New-ish here
looks bloody great
battery box: cut with CNC? how thick are d sheets? would love to see inside, cell arrangement and wiring.
I cut each panel of the box on a water jet, welded them together, and had them finished in a matte powder coat. The sheets I used were 1/8" A36 carbon steel. Unfortunately, I don't have the battery arrangement and wiring as I outsourced the job to Amorge, but I can include some pictures of the CAD models I made for the battery box!
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