I am trying to use the bike battery off-line to power a trolling motor for my kayak. It is from my RadCity bike 48V 14 Ah. I can connect to the power output and get a 53V output when the key is on. When I connect the battery to the convertor input this voltage drops to zero at the convertor. This of course doesn't happen when the battery is on the bike. Are the 3 smaller connections on the battery used to control the batteries power on and off?

Check out Rad's video for the tools and procedure for replacing the internal Radcity controller.  Probably going to be the same steps and tools for the external controller.  The issue I had was the replacement internal controller wires were too long and I couldn't get the replacement controller seated properly inside the hole to insert the mounting screws from the bottom of the bike frame (it was wedged in there and I plugged up the screw holes to water proof). 

I won't have the long cable issue and probably faster replacement with the external controller.

https://support.radpowerbikes.com/Maintenance_and_troubleshooting/Controllers/RadCity_5_Plus_Controller_Replacement_Guide

Thank you so much for the quick reply!  Im trying to figure out if its something I can do myself or try to find a shop to do it-the video for the internal one doesn't look appealing to me and my limited mechanical skills!

Yup!  My spouse 2023 Radcity step thru had a controller failure a week after purchase in July 2023 (zero codes on LCD, no PAS/throttle power to rear hub).  The replacement controller was similar as the original; but, some of the cables were 2X longer.  Fast forward to Aug/2024 and I had an error 21.  The replacement controller was the external type that mounts to the back of the seat post down tube.  I haven't installed it yet.  We still have her 2018 Radcity Step Thru as a back up. We were going to sell the 18 Radcity and kept it instead because of the issues with the 23 Radcity.

Hi all - anyone purchased the new controller for the Rad City Plus 5? My 2-year-old one is being replaced with the new design/upgraded controller. It should be shipping out this week, but I got the following message from Rad support after my order "our controller is a new undated design and will install to the rear seat post with the mounting plate included". This sounds like an external one, or am I wrong? A link to the video was included but the video is for the old design, where the controller is seated inside the downtube. If anyone has installed the new one and can share their install experience (or post a picture) that would be great. I'll report back once I figure out what I am up against as the video looks pretty intimidating! Thank you

Thanks for the feedback but so far I don't see a smoking gun here. It sounds more like the luck of the draw. I was getting ready to order the upgrade from Area13 but they are currently out of stock so I got a factory replacement from Rad.
I'd like to add that we live at 6200 feet in Colorado, literally on the side of a mountain. I was reluctant for years to get an ebike but it has been a joy to not have to fight the hills.

Quote from: 6plusradrover on September 02, 2024, 12:18:27 PM... There is a little red light near the pedals that flashes when the pedal is moving forward. When pedaling, the watts will show up to 003 watts but again no assist or throttle.

3 Watts isn't very much. Even Walk Mode should burn up something on the order of 30 watts.

That red light is odd. It makes no mention of it at all in the Owner's Manual.
The fact that it flashes when the pedals turn sounds like it has to do with the cadence sensor. Is it something like 12 or so flashes per revolution?

QuoteBegan my ride home and about 5 minutes in, the throttle and pas kicked in and haven't had an issue since.

Wait, did you actually mean "haven't had an issue until now", or does it still work since that first time a few months ago?

How about Walk Mode? (Press and hold the Down arrow on the remote.) Does that work? I'm guessing that does not depend on anything related to the cadence sensor or twisting the throttle.
The brake handle cut-out switches would probably work the same as usual.

---

[later]
Somebody on https://forums.electricbikereview.com/threads/red-light-by-bottom-bracket-on-a-2018-rad-power-city-st-no-power.35362/ has this theory:
"It indicates the bike has power. I think it's intended to warn someone doing maintenance work that they forgot to remove the battery."

No it doesn't...

Rad sent me a different controller that mounts on the outside of seat post down tube instead of internally in the space in-between the pedals.  Just haven't been motivated enough yet to start the repair. The wife still has her old 1st gen 2018 Radcity step thru to ride. The 2023 Radcity step thru was her new and improved upgraded model and we were going to sell the older Radcity.  I'm thinking I made the right choice going for a Himiway Cobra Pro instead replacing my 2016 Radrover with the latest Rover model.

Quote from: mrgold35 on September 15, 2024, 09:39:43 AMI'm on my 3rd controller for the wife's 2023 Radcity step thru

This does not give warm and fuzzies.

Great, please keep us updated.