Author Topic: Underpowered solutions?  (Read 1277 times)

Ishy

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Underpowered solutions?
« on: May 12, 2023, 10:41:26 PM »
I live in a Pretty flat city.... Except for the river valley on the edge of downtown.

I picked the expand 5 because reviewers had shown the 750watt motor and I knew it could handle the crazy steep hills I would need it for.....

Well. I found out after Dying trying to get up one of these hills(should have got off and walked)

Aftwards I found out Americans get a 750watt motor which is what I see in the Climb reviews I watched where Canadians get a 500watt motor😢.

Anyone know if the wheel can be swapped for a American one to upgrade it to a 750 watt one?

handlebar

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Re: Underpowered solutions?
« Reply #1 on: May 13, 2023, 02:15:00 PM »
I was similarly disappointed in the Radrunner I bought in 2020. Ebike Reviews made a video featuring the founder of Radpower. At one point, the editor, with throttle only, passed two Radpower staffers pedaling their Radrunners up a hill.

Mine was nothing like that. I analyzed the video. I could calculate the speed of the riders he passed by their cadence and the grade by the horizontal roof line of a house along the street. The editor had given his weight and that of the Radrunner. To climb at that speed, that motor had to be putting more than 2,000 watts of mechanical power on the wheel.

A test on a 6.1% grade showed that my Radrunner had only 500 watts of mechanical power. I think when a manufacturer says he makes a 750-watt motor, he means it can produce that much mechanical energy indefinitely without overheating. Instead, Radpower means the controller will supply 750 watts of electrical power (about 15 amps from the battery). (They seem to have used a 60-amp controller for the video.)

For $219, I bought a 35-amp controller and display from Bolton. Now the same motor puts twice as much power on the wheel, about 1,000 watts. Overheating will damage insulation, magnets, and transistors in an ebike motor, but motor temperature rises pretty slowly. With an IR thermometer, I've seen only a degree or so above ambient. That's not enough to detect by touching.

I think your Canadian Radexpand may have the standard 750-watt motor but with a 10-amp controller, for 500 watts of electrical input. My Radmission was advertised at 500 watts but put only 350 on the wheel. For $179 I bought a 25-amp controller and display from electrobike world. Now the 500-watt motor puts out 700 watts. Riding up a hill at full throttle and without pedaling hasn't warmed the motor enough to tell by touching.
« Last Edit: May 14, 2023, 07:28:23 PM by handlebar »

Ishy

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Re: Underpowered solutions?
« Reply #2 on: July 24, 2023, 01:30:29 PM »
Thank You!  I will look into finding a higher power controller.   Bolton doesn't ship to Canada💔.   I went with rad mostly because so many parts are upgradeable! 

If anyone has experience with one I can get here I would love to know.  Otherwise  I will be searching forbonebon my next day off😅.

handlebar

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Re: Underpowered solutions?
« Reply #3 on: July 24, 2023, 03:35:11 PM »
https://electrobikeworld.com/t/upgrades

My Radmission was supposed to be 500 watts, but I found that it was putting 350 mechanical watts on the wheel. I could have upgraded to a 750 watt controller, but it looked as if it wouldn't fit between the seat post and the fender. I ordered a 500 watt controller, with the same display that the 750 uses, from electro bike world. It's much peppier than the Radpower controller, and I guess they can ship it to Canada.

(.... if it will work with your model... )

RadBob

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Re: Underpowered solutions?
« Reply #4 on: September 14, 2023, 08:36:35 AM »
Hi
Just out of curiosity on the Rad Expand 5
Is there information on the controller to know exactly what the specs are?
I?m looking to squeeze the most performance and range out of these bikes while protecting the battery at the same time.

Thanks
Bob

handlebar

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Re: Underpowered solutions?
« Reply #5 on: September 15, 2023, 09:01:50 PM »
Hi
Just out of curiosity on the Rad Expand 5
Is there information on the controller to know exactly what the specs are?
I?m looking to squeeze the most performance and range out of these bikes while protecting the battery at the same time.

Thanks
Bob

If complete specs were available, a rider would know whether a brighter headlight would be okay. Radpower doesn't even seem to state output amps to the motor.

Thirty months ago, I put a 35-amp controller on my Radrunner. That seems to be twice the OEM current for a 750 watt motor from Radpower. I didn't see a reduction in range, and my battery is doing fine.

The amount of pedaling the rider supplies will of course affect range. I have gotten 140 miles on a charge.

15 mph is where air drag begans to rise steeply. Riding faster will shorten range and probably service life.

I' ve read that demanding much power when a lithium-ion battery is in a low state of charge, will shorten its service life. I normally get about 70 miles on a charge because I recharge when the battery is down halfway.

I believe that letting the cells get out of balance will shorten a battery's service life besides its range. I believe Radpower says you balance a battery by leaving it to charge for 12 hours. At the same time, Radpower says not to leave a battery on the charger. I use a timer. My battery will gain about 2 volts per hour on the charger. My fully charged voltage is 54. When a battery needs charging, I use a multimeter to see how far the battery is below 54. I divide the difference by 2, then add an hour for balancing.

JimInPT

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Re: Underpowered solutions?
« Reply #6 on: September 16, 2023, 10:43:27 AM »
Is there information on the controller to know exactly what the specs are?
I?m looking to squeeze the most performance and range out of these bikes while protecting the battery at the same time.

From the looks of it (no hands-on experience with the Expand 5), it looks like there are no changes to the battery/controller from the Rad Minis it replaces.  I have a 2021 MiniST2 and love it, but I would highly recommend you consider a 35A controller upgrade - turns these little workhorses into stealthy little rockets and can now climb hills like they aren't there.  The controller upgrade won't add more top-end speed, but the torque increase is immense and other features like cruise control are nifty to have as well.

By the way, do you know about the theft danger for that type of battery Rad's been using for a number of years?  A Honda motorcycle blank key will unlock essentially all of them, making them easy to harvest by knowledgeable thieves.  I carry only a blank key, so I can prove this to other owners who can't accept something so ridiculous on my word alone.

Here's part of my solution, in addition to a hidden alarm.....

Have fun!
« Last Edit: September 16, 2023, 10:47:23 AM by JimInPT »
Shucks Ma'am, I'm no "Hero Member", I just like to wear this cape.

RadBob

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Re: Underpowered solutions?
« Reply #7 on: September 17, 2023, 10:18:19 AM »
Thanks for the information on the controller.
It?ll most likely be a winter project.

Again thank you 👍🏻👍🏻

Rad Power Bikes Owners Forum

Re: Underpowered solutions?
« Reply #7 on: September 17, 2023, 10:18:19 AM »