36v 750w Motor with a 36v 500w Possible?

Roblee

New Member
#1
I am glad I found this site as my 90 year old neighbor has recently discovered Ebikes and has tasked me with getting him up and running. He has a non electric trike and purchased a 36v 750w front wheel kit. However he also purchased a 36v 500w lithium battery. I tried to talk him into a lower wattage but he got hasty and purchased these items. I am hoping the 500w battery will power the 750w motor ok. I am assuming it will just have less torque and top speed but still work, however I am not sure it it will work and not hurt the battery or motor.

Any help is appreciated. Thanks!
 

harryS

Well-Known Member
#2
No problem with the battery. It won't run as hard with less torque, but that's better in my opinion. I trust your neighbor will keep it slow, because I hear those Schwinn Meridians tip over if you turn at speed.

Justin LE of ebikes.ca says these motors will generate tremendous force, enough to loosen nuts and tear forks apart. Buy a pair. Also mount a front speedometer on it too.
https://www.ebikes.ca/product-info/torque-arms.html

This guy built one for his friend. You can see the torque arms. And he also upgraded the brakes. While I'm dubious of oldsters going fast on bikes and not getting hurt, this gal is happy.

I would also suggest that you read up on battery safety.

 
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Roblee

New Member
#3
Thanks so much for the information. I wanted him to get a 250w bike... but he is an old school iron worker, one of those guys who worked on high rises before safety equipment. I am going to upgrade his disc brakes in the rear as well. The more I read and research Ebikes the more I want one for myself and my wife. Thanks again!
 
#4
You’ll want to figure out if the battery is 500 watt hours as a rating of capacity or if the manufacturer has rated the pack for up to 500w of continuous power. It much more likely that the battery pack is 500 watt hours. Both are different ratings as watt hours is like the fuel capacity vs motor watts being a way to tell how much electricity you’re consuming.

Most kit motors and controllers aren’t pulling the rated wattage continuously. Also 750w could be a rating of nominal or peak power. Once you get into DIY land there’s almost no universal standard for the vendor and/or manufacturer to follow a power rating.

To answer your question, your friends kit setup is most likely completely fine for daily use unless the controller is programmed for some really high amp draw that the battery can’t handle.
 

Roblee

New Member
#5
Thanks Hurricane56. I am hoping it is a easy install, it looks like it will be... mainly with the input from you guys.
 
#6
Thanks Hurricane56. I am hoping it is a easy install, it looks like it will be... mainly with the input from you guys.
Usually if the kit was purchased from one vendor it should be plug and play. It gets tricky when you have to make your own wiring and do your own connectors.

A 750w motor should cover the wide swath of most uses. My daily bike can do 1700w peak power, but it only takes like 700w of continuous power to maintain a good cruise speed above 20mph. This is for a heavy fat bike commuter with spares, tools, and work stuff in two panniers.