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Old 09-18-09, 10:31 AM   #1
Jaydevil
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48v 1000w hub motor running on 36v?

Hi. I have a quick question for people who may have tried this; Is it possible to power my 48V 1000W hub motor with a 36v battery? I would think so just less speed and probably less range but I want to make sure before I accidentally blow up my bike and its surroundings messing with things. Thanks for your time and info in advance.
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Old 09-18-09, 03:11 PM   #2
chvid
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If you have a 48 volt controller, your bike may not function if the battery voltage is below the low voltage cutoff (LVC) on the controller which is probably around 41 volts. Otherwise, give it a shot...
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Old 09-20-09, 11:06 AM   #3
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If I ignore a lot of details, then operating it at 3/4 of it's rated voltage means that the motor will perform like a motor that is 3/4 of its rated power.....you'll have a 750W bike.
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Old 09-21-09, 08:30 AM   #4
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I have a chrystolite 4840 controller I've run with a 36 volt pack.

Chvid is right, it'll run untill it hit's the controller's Low Voltage Cutoff point, which usually means as soon as you hit a hill and load the batteries down. It works fine, you just wont get the full capacity out of your 36V pack, depending on where your controllor's LVC point is.
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Old 09-21-09, 10:59 AM   #5
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If I ignore a lot of details, then operating it at 3/4 of it's rated voltage means that the motor will perform like a motor that is 3/4 of its rated power.....you'll have a 750W bike.
Actually, motor output isn't quite that simple. Dropping to 3/4 of your input voltage will give you less than 3/4 of your power.
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Old 09-21-09, 04:49 PM   #6
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Actually, motor output isn't quite that simple. Dropping to 3/4 of your input voltage will give you less than 3/4 of your power.
How so?
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Old 09-21-09, 05:32 PM   #7
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Thanks for the info guys. I tried powering the motor with just 36v but the throttle light comes on red and the motor doesnt spin. I believe that my chinese controller is a 48v one and I think it does have a low voltage cutoff.
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Old 09-22-09, 11:24 AM   #8
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Jaydevil, there may be an easy way to defeat the low voltage cutoff, and if you are brave and willing to open up the controller, learn what the different parts are, etc, there is almost certainly a way to defeat the low voltage cutoff (or even change its voltage).


Quote:
Quote:
Actually, motor output isn't quite that simple. Dropping to 3/4 of your input voltage will give you less than 3/4 of your power.
How so?
If electrical resistance is the limiting factor, then dropping voltage to 75% will also drop the current to 75%, meaning that over-all power would drop to 56%.

In reality, you should expect that lowering the voltage by 25% will make almost no difference to how steep of a hill you can climb, but it will probably reduce your top speed by 20% (that is, power at high speed is reduced and power at low speed is not reduced).
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Old 09-24-09, 09:01 PM   #9
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Yes. Ive already opened my chinese controller. Ill have to take a look at the insides again though. So how do i go about removing this "voltage cut off"? This would be awesome because then i can just use my 36v battery from my bl36 kit to power my new motor. I have everything I need to make my 48v 1000w work normally except a 48 v charger...which i dont have the funds for. so if i can remove this cutoff that would be aweeeeesome!
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Old 09-24-09, 09:24 PM   #10
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Go to the "e-bike technical" section of the endless sphere forum. If there's anywhere you can get help with your question, that's the place.

http://endless-sphere.com/forums
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Old 09-30-09, 12:43 AM   #11
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Jaydevil, there may be an easy way to defeat the low voltage cutoff, and if you are brave and willing to open up the controller, learn what the different parts are, etc, there is almost certainly a way to defeat the low voltage cutoff (or even change its voltage).




If electrical resistance is the limiting factor, then dropping voltage to 75% will also drop the current to 75%, meaning that over-all power would drop to 56%.

In reality, you should expect that lowering the voltage by 25% will make almost no difference to how steep of a hill you can climb, but it will probably reduce your top speed by 20% (that is, power at high speed is reduced and power at low speed is not reduced).
I'll second that.

My bad. I was trying to simplify things and I knew someone was going to catch me.
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Old 10-02-09, 05:19 AM   #12
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Just buy a 36v controler. Its only going to be like 40$ on ebay.....
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Old 10-02-09, 08:57 PM   #13
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Thanks for the info guys. I dont know about buying another controller because the new controller may not have the correct connectors my motor has. Ill just buy a 48v charger but there in lies another dilema...I need a RCA male connector to match my RCA female plug coming from the battery. I want XLR connectors but I wouldnt know how to connect the wires to the connector. I dont have a soldering gun. Ive had this kit for a month and a half now and I wanna ride really bad. =( If anyone knows of a RCA male 48v charger please direct me to it. Thanks.
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Old 10-03-09, 01:27 PM   #14
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You are going to add another 12 volt battery in series to bring it to 48 volts then?
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Old 10-03-09, 03:33 PM   #15
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I have 4 batteries I just need a proper 48v charger.
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