can I use a 78v battery on my 2000w motor?

[Paul T]

Hi all , as above, is that cool? Im running a 48v 10ah lipo now, but I can get a 78v10ah lipo on my hub motor, its 1500 or 2000w Im not quite sure. A place in the US sells these and claim a 35 mile range, thats 56km, I only get about 30kms with my battery and thats with me peddling a fair bit up hills etc. If I can use it would the 78volts give my hub motor a lot more grunt without damaging it? Thanks

[John in CR]

Probably. Exactly what motor is it? Is it brushless? We need pics. Keep in mind that the higher voltage will only give it moderately more "grunt". What adds "grunt" or more accurately more torque for better acceleration is higher current. Higher voltage will give you more speed. The ideal combination if you are close to enough speed already, would be going to the higher voltage, using a smaller diameter tire, and increasing the current modestly. That combo will give you eye opening grunt.

John

[Paul T]

Its a 9 continent brushless hub on the rear, Im pretty sure its gearless. How do you up the current? and are these very reliable motors? Ive only had it a couple of weeks, so far so good.

[dogman]

My personal estimate is that 1500w continuous will not likely harm a 9c motor under "normal" riding conditions. I think the return from more watts added does taper off by 2000w. The motor just starts to make heat out of the increased watts past a certain point.

I run a 72v 20 amp controller on my dirt bike all summer, and the riding is far from normal. 1500w is seen on a CA. In winter, when the motor will cool much quicker, I run a 3000w 72v 40 amp controller, but real world, the CA rarely shows more than 2500w for very long.

72v 30 amps controller would be a good compromise, assuming your summer climate is not as brutal as mine.

On the battery side, 72v 10 ah is about 750 watthours. So that means getting wh/mi down to 21. You won't likely see wh/mi that low at 20 mph or above on an MTB. I have gotten 35 miles from a battery that size, but it took riding 15 mph or less.

Typical wh/mi on my dirt bike riding hard is 45-65 wh/mi. 8 miles is my typical ride distance, leaving the batts less than 100% discharged.

So as usual, just cut the range claims in half. SOP to assume any range claim was done at 12 mph.

[shock]

Really what will get you more range is a pack(s) with more AH, so really a 48v10ah and a 78v10ah are going to have pretty close range, just the 78v will be faster. If range is what you want buy another 48v10ah pack, parallel them to have 48v20ah, and you have doubled your range. (in a perfect world)

[dnmun]

78V may be too much for the controller.

[pdf]

Many people run 9C motors on at least 72v, but make sure your controller is rated for 72v. To get high currents, you need a battery and controller that can feed them. A small Ahr-rated battery with a low C rate is not going to provide much current. I am using 18s LiPO, rated at 20C (LiFePO4 will be rated a lower C rate). It is only a 5 Ahr pack, but the C rating allows it deliver high current. I have a controller that will handle 40 amps but I have never had to feed it over 30 A (one advantage of a higher V pack is that the current required to deliver a given power is lower). It kicks butt. You can parallel small A-hr, small C rating packs to increase the effective Ahr rating and so the max. current delivery rate.

[wesnewell]

My question is where did you buy the new 2000W motor. I can't find a dealer that carries it yet and inquires to Sunny Chen at 9C have gone unanswered for over a month.

[dogman]

I assumed it was the same familiar 9c 28xx motor, which somebody sold as a "2000 w". Many of us do that, so somebody will start calling it a 2000w soon.

I also assumed the guy knows he'll need a new controller to go to 72v. If he didn't he does now.

FWIW 48v 10 ah is about 500wh while 72v 10 ah is about 750. So if you didn't haul ass, you would see a big range improvement. n

[wesnewell]

AFAIK the it's not the same motor. This is the one I'm asking about.
http://www.alibaba.com/product-gs/51633 ... cycle.html

[GrayKard]

Looking a lot like the new Xlytes.

426378248_390.jpg (27.73 KiB) Viewed 148 times

Wire comes out inside the dropouts too.

426378249_410.jpg (24.39 KiB) Viewed 148 times

Need to see the insides now!

Gary