New battery rack, plus modifications

[Altema]

When I did my dual batteries, I loved the range, loved that it looked like there was no second battery, and liked how the package looked overall: just a simple e-bike with a rack bag.

However, I did not like not having any storage, which meant wearing a backpack or leaving the battery at home when I needed space.

I said in the dual battery article that, if I had to do it again, I'd use a rack battery. Then I upgraded the RadMini to 52 volts, and my stealth battery needed an upgrade as well. Unfortunately, the 52 volt versions of my battery were too wide for my current bag, meaning I'd have get a larger bag, and STILL have no storage. So I went ahead and ordered a rack and battery combo. I got the systems installed, and did not like it. Oh, the battery was fine: 52 volts, 20aH capacity, 40 amp BMS. The problem is that the rack itself was too tall, the design put the weight of the battery hanging off the back of the bike. Another problem was the entire weight of the battery, rack, and any cargo, rested on two mounting points.

So, I got out the angle grinder, and hacked it apart. Literally. I cut off the bottom mounting brackets, separated the legs that were welded to it, bent them into the position I wanted, pressed the tubing ends in my 12 ton press, drilled all new mounting holes, and redesigned the front stays so they could support weight instead of just preventing the thing from flipping backwards. The end result of this is the rack is now 3 inches lower, 3 inches further forward, the mass of the battery is more centered, and there are now 6 different mounting points supporting the weight. I can pick the entire bike up by the rack and it does not budge.

Now, it's not as pretty as the former rack, and the taillight/taillight/rearview camera combo looks far less elegant now, but it is functional, and I now have  range AND storage. Or if I want to go crazy, I can run a third battery in a rack bag, and have no storage again!

The battery itself is a solid unit in an aluminum case. Almost looks like an ammo case when you stand it up. It has a large Anderson connector for the power output, which I may change to double or triple XT 90 connections for expansion (3rd battery, 12 v converter, etc). I ran the power output to the connector inside the front 52 v battery mount, which I designed to be removable, so that bit was fairly easy. There are two charging ports top make it easy; one in front and one in back. The back of the battery has an integrated handle, charge indicator, and integrated taillight. The taillight is weak, and I don't think I'll be using it. There is no USB port on the battery, which is too bad. The key lock is by the front of the battery, and is used similar to the Rad battery key lock: OFF and battery unlocked, OFF and battery locked, and ON with battery locked. Unfortunately, you cannot remove the key in the ON position, which is something I dislike very much. I originally picked the black battery color because it would be more subtle, but changed it to silver because it would be cooler for the battery in the summer. That, and my gaming buddy said she liked the silver one better

I did ride the bike with the rack installed but no battery, as the electrical work was not done and snow was on the way. A formal test drive with the new dual 52 volt batteries will have to wait, and we got snow, then snow, and more snow is coming.

Some indoor photos are below, and as usual, feel free to ask questions!

PS: Changed the post title to be more descriptive.

[Loulou718]

You are the man. You did stuff to the radmini that I dreamed off doing to mine. 32mph and extra battery plus folds. This is the dream mobile.

[vudude]

Starting to like your Radmini rack

[Altema]

Starting to like your Radmini rack

I'm much happier with it after the mods, but I don't care for the cluster hanging off the back. I may move the rear view camera to the top part of the rack, and place the aftermarket taillight where the camera is now. The aftermarket taillight is redundant, but is also the brightest and has laser lane guides and turn signals. Another possibility is to leave the camera and Rad taillight where they are, and put the aftermarket taillight in front of the battery taillight, which is dim anyways. A flip up mount would move it out of the way for battery removal.

[Altema]

I made a couple changes. I found that the taillight was having reliability issues because the battery was between it and the wireless controls on the handlebars.
So, I moved the aftermarket taillight to the back of the top rack. It would have looked neater tucked in more, but the battery and the pannier braces were getting in the way of the laser lane guides. This position fixes the radio and laser interference issues, so I'll just have to let form follow function. The other change was making the front stays straight, as the curve in them served no purpose and looked odd. Below is an picture of the whole package (rack bag is optional now), and the second picture show why I didn't go out riding it yet!

[Veggyhed]

Awesome work. Nice and tidy.

What brand rack is that?

Sent from my Pixel 3a using Tapatalk

[Altema]

Awesome work. Nice and tidy.

What brand rack is that?

Sent from my Pixel 3a using Tapatalk

The rack came with the battery and has no branding, so I believe it is made by the battery company (Joyisi), or made for them. The rack has holes specifically for the battery mounting plate, and the battery comes packaged inside the rack.

[Altema]

I ran into a problem with torque and weight distribution. With the new batteries delivering higher amperage to the controller, and the additional weight in back, twisting the throttle from a standstill pops an unintentional wheelie. To help, I put new mounting holes in the battery mounting plate to move the battery about an inch and a half forward in the rack. It may not sound like much, but it made a difference. The front wheel still comes off the ground, but not as much, it's less likely to scare someone who is not expecting it.

I also bought some black semi-gloss paint and touched up a few spots, and bought some panniers. The Panniers are not very big and look nice, and the front portion is angles to avoid catching your heel while pedaling. I don't plan on keeping these on the bike all the time, but it's nice to have handy if I do need the cargo room. A side benefit (no pun intended), it that it hides the rear battery, so I can go stealth again if I want to 😉

[Altema]

I made one more little change. The forward position of the battery improved everything, but I found it lined up better with the panniers if it was moved rearward just one inch. So instead of moving everything around again, I simply drilled a second hole for the battery lock mechanism. Now I can place the battery in two different positions with a twist of the key.

[reggy]

How is the bike balance affected with having a batter above the back tire?

How heavy is the battery?