Can I run a 48v 20ah lifepo4 with a 36v 500 watt hub motor?

[wheresthepassion]

I have been researching alot of issues concerning electric bike conversion. I have ran into a concern and my technical knowledge is lacking. I would like to know if I can run a high power 48v 20ah lifepo4 with a 36v 500 watt motor. I would like to go fast more then anything. But do not want to get to crazy and get a 48v 1000 watt motor. I have heard that not all lifepo4 batteries give the true power that is usually listed. So I wanted to make sure I had enough power to have good torque and speed. I will not be going long distances. Just basicaly a few miles here and there around town. I also have looked into the phoenix racer 3640, but also would like to know if it is cool to hook a 48v battery to it, with a 48v controller. I am new to this new way of riding and very excited. However I would like to make a good purchase and get what I want. Which is power and speed, with reliability. So if anyone could help me out with answering any of these questions, it would be so greatly appreciated.

 

[dogman dan]

Most 36v hubmotors can handle 48v, but the controller is another story. Some 36v controllers can take 48v, which can be close to 60v hot off the charger with lifepo4 batteries. On one of my 36v bikes, when I looked inside the controller I see capacitors labled 50v. That one for sure, can't go to 60v.

Another of my bikes has a 36v controller that has 63v caps inside. That one, a wilderness engergy type from high tech bikes can handle 48v, and since it's sensorless, it is very easy to figure out the wiring for if you want to change controllers. No hall wires to bother with.

The other thing to look for in a new controller, is matching the amps ouput of the controller to the battery. Less expensive round cell lifepo4 batteries or v1 Ping are best kept near 20 amps or less for the average discharge rate. So unless you are buying high discharge rate lifepo4 like headways, or a123's you may want to avoid buying a 48v 40 amp controller that would allow the motor to pull a lot of amps. 48v 20 amp hour battery and a 20-25 amp controller should get you about 4-5 mph more speed out of your motor. And a little bit more torque and acceleration.

Since you intend to run 48 volts from the start, you should get a kit, or at least a controller that handles 48v. but if a deal good enough comes along on a 36v kit some, such as the WE- Aotema kits come with a 48v capable controller.

If you want real speed, then you need the bigger 5303 motor, a higher amp controller, and a really big wallet, since the battery will need to be able to handle high discharge rates. The 5303- phoenix racer motor can pull 60 amps at times, and a lesser battery will just die early. So you need headways for those. Some good prices for those batteries are at ev solutions.

The less expensive options will still get you between 25-30 mph, such as the aotema kit, that will go about 27mph at 48v. Other options like the 9 continents from ebikekit may be a mph or two faster, and the whole kit under $1000. For shorter rides, these kits, that come with a 10 ah battery would work fine for you.

 

[Drunkskunk]

The simple answer is Yes, you can power a 36V 500watt motor with a 48 volt, 20Ah battery. you can power one on Much more voltage than that. I'm running mine at 74 volts, and thats not even pushing them all that hard.
The only questionable part of the equasion is if the controller will handle it. Most will, but its best to have a controller ment for the battery size, if there is any question about weather it will work.


On the subject of the phoenix racer, that motor is actualy a 750 watt Crystalyte 5302. Its 25 pounds, and ment only to go fast. a 48volt 20AH battery would be dramaticly under using the motors capability, and therefor it would be wasted weight and expense. It also would be a dog on any kind of hill.

If you're looking for high speed on low voltage, there are several 500 watt motors in the 10 to 15 pound range that will match that speed cheaper and without turning your bike into a heavy brick.
9 Continent, Aetoma(W.E), and the 40X series from Crystalyte (sometimes called the roadrunners, but there are more and faster motors in this range.)

If you're looking for a good, general purpose motor, its hard to beat either the Crystalyte 408, or the 9 Continent 9X7. both 500 watt motors.

 

[wheresthepassion]

Thanks alot for the answers and suggestions guys. I will definitely check out the 500 watt motors that you mentioned. This is worse then purchasing a new home, but without the jacuzzi!

 

[dnmun]

i got several of the 36V 500W (9x7) 9 continents kits from jason at e-bikekit.com and have converted several controllers to run up at 72V and i also converted one to run at 48V on my nicads by adjusting the LVC to 37V to protect them from overdischarge.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=10222

 

[RNJohn]

I just purchased a ebikekit, 9C 500 watt motor. Running it on a 48v 20A Ping LifePo. I assembled it all on a Giant Mount Bike. The bike goes fast. For the most part faster then I can peddle, so I dont open the throttle all the way. Climbs hills like a mountain goat. Very happy with this set up. I had WE and it was lets say "unstatisfactory" and a waste for me.
RNJOHN