72V 1500w rear hub recommendations

[stompatompa]

Hi!

I got two 36 10Ah Li-ion battery packs with a pretty crappy c-rate, I don't know the exact number but it's Defenetly not more than 2.
Each with a built in bms and alloy-Shell. These are pretty much the only type they sell here in Sweden.

In order to make the most out of what I got left from the old bike I'm going to use these for my first real build. I'm very excited since I've gotten hold of a cheep old santacruz bullit dh frame!
I want to put them in series since I want speed and don't care about range that much. This will make a combination of pretty high voltage and very low current. Unfortunately I have trouble finding 1500w hubs that are recommended for 72V.

So I could really use some advise on what motor and controller I should get in order to make the most out of the batteries I have. I would prefer a rear hub or possibly a mid drive.

Thank you in advance!
/Tomas

 

[Tench]

I imagine all of the direct drive rear hub motors would be fine on 72v, this maybe too much for some geared motors though. One of the many 9c clones would be great with that set up.

Some good info on those motors here;

http://www.electricbike.com/9c/

 

[stompatompa]

Thanx tench!
Nice link, loads of good info in there
Is seems like 9c is the perfect one for my setup, just like you said.

After reading some more articles I get a little concerned about draining my low c-rate-batteries pretty quickly. To prevent this, maby I should get a controller that I can set as low as maby 15 or 20A max, but still handles 72V?

And when the batteries finally wear out, I want to be able to set it to something like 50A and get me a "real battery" What controller would you recommend for this?

/Tomas

 

[bionx 1954]

If you have a Cycle Analyst you can limit the current to the controller, Get a controller that has your desired amperage eg. 40-50A. So you can use the CA to limit amps on the current batteries, then when you up grade your batteries, you can then re set your CA to a higher amperage. As far as I know controllers them self only have max. amp and are not adjustable.

 

[Tench]

If you want easy get the 7240 controller from Grin and also a CA from them, they will plug and play, do everything you desire and have the amps limit adjustable via the CA. Not the cheapest setup but simple and good quality. I have used this setup a couple of times and it works very well.

 

[stompatompa]

Thanx gous for your input!!

A CA definetley seems like a good investment!

I`m having secon thoughts aboout the 9c now for 2 reasons:
1: I read that they are not easy to fit with disc-breaks and I feal that the rear disc is really important at the speeds I`m going for.
2: From what I read, they are very noisy. I would like a motor that`s silent and then maby go for a sine wave controller with that. Any suggestions?

Sorry if I`m jumping back and forth, but there`s so mouch to choose from, and I still have so mouch to learn

 

[spinningmagnets]

1500W at 72V is only 20-Amps, so a 9C is certainly capable of doing that without overheating. The Crystalyte H35 has been frequently used with temporary peaks of 40A (3,000W @ 72V), but it is of course more expensive. The 9C (and their clones) have a 28mm wide stator, and the H35 has a 35mm wide stator.

The wider the stator, the more copper mass it has. That affects the amount of amps (and amp-heat) the motor can survive.

If you can truly be happy with only 20A, you have the option of using a very safe and unusually long-lasting Ping LiFePO4 battery. If you think you might enjoy 30A (from a 9C) or 40A (on the H35)...then you might consider a pack from em3ev.com. I never recommend LiPo to new builders, there's a steep learning curve that takes time to be safe.

As a general rule, a sinewave controller has been reported to quiet down hub motors. I haven't used one on a Direct Drive hub, but...Dogman recently did a hands-on review of the ebikekit hub (a well-made 9C clone?). https://www.endless-sphere.com/forums/viewtopic.php?f=4&t=53528. I think he has tried a wider variety of kits than anyone else here, and his published opinions have earned respect over time.

 

[kdog]

I've two 9c hub motors (2808 &2809) on 48v. Apart from some resonance in the hub and spokes at certain speeds they are very quite and this is on a non- sine wave controller. The 2808 is almost silent at all speeds except <10kph. At all other times road noise far exceeds motor noise so I wouldn't worry.

 

[stompatompa]

Thanx again!

As you say, I probably won`t be truly happy with 20A for long
And I`m definitely to inexperienced for Li-po`s but there seems to be a lot of nice development in battery-tec at the moment. If I go with my two 36V Li-ion`s for a while, hopefully some nice options will come up just in time before they are burnt out.

That`s a great rewiev by Dogman and good to hear they are now disc break compatible and not so loud. The 9c is back into consideration again along with a Crystalyte 4065. Anyone who can compare the sound of the two? As for disc break mounting, are there any differences between them?

 

[kdog]

Dunno about the clyte but my 9c's have been a bit tricky to run discs on. Spacing the disc out away from the motor and finding a narrow disc calliper does the trick, but it takes a bit of fiddling.

 

[spinningmagnets]

The Crystalyte H4060 is useful if you think you might like to run 40A+ in the future, otherwise it is heavier and more expensive.

The "pain in the @$$" of a heavy hub is broken spokes when you hit a pothole, the joy of a big hub is the brutal acceleration of very high amps on the street. An H35 on a full suspension frame will be lighter and have some "give" with the suspension. An H40 on a hardtail will occasionally have broken spokes if you have potholes. I'm not saying don't get the H40. Quite a few builders have ventilated an H35 to use more amps (rather than go to the wider/heavier H40), because the H35 was already pretty hefty. Just a thought...

 

[stompatompa]

Spinningmagnets thats another thing I never even thought of - the weight of the hub. Good thing I`m posting here as it seems like I´m moore of a newb than I wanted to admit

kdog - was that the new or the old version of the 9c?

I post some pics of my new, old beauty below. Sorry about the size, but I had to make them smaller and reduce the quality in order to post here.

Wich motor would fit good?
The distance between the dropouts are 135mm. I would really like to be able keep the calliper and disc as they are really nice! The gears however, are not that important. It`s a 9speed so I guess I`ll have to change it to seven? Is it possible to just remove 2 them, for example nr 3 and 6 and keep thesame derailleur?

 

[cwah]

What speed are you targeting?

 

[stompatompa]

Well, for now I'll just settle with what i can get with my batteries. But when i get a better battery it would be nice with something around 65km/h.

 

[cwah]

1500W constant allows you to reach to maximum of 50km/h. See simulator there:
http://www.ebikes.ca/tools/simulator.html?SID=c1c05a4f253eaf2299130bbb73821418

And you'd need a 25A controller.

Get a motor at 55km/h max speed at 72v to get better efficiency.

 

[stompatompa]

Nice simulator, Thanx! According to that, it seems like there is a limit somewhere around 50km/h for any 72V battery.
Ill probably have to settle for 50

It's also very clear that, when it comes to both speed and torque, the 9c is just about as good as any crystalyte running at 72V 20A.

How can i find out for sure that the new 9c compatible with my rear disc and calliper, pics above?

Does anyone know where I can get a 9c or similar clone in Europe or secondary in China?

 

[bionx 1954]

I am running a 9 C rear 2807 also a 2810 with a sensorless Lyen 12 fet 72V @ 40 A The REAL speed is 45KPH (2807) and 40KPH (2810)

 

[stompatompa]

Yep! Reality check - done.
I know now that I widely overestimated 72V and it's going to take a big investment in battery to get to 65km/h.
I'm settling for around 50 instead
Are there other good options than 9c and crystalyte?

 

[spinningmagnets]

Here is the most recent 9C clone to pop up, but...it actually looks pretty good. Usually clones are cheaper and poorer quality, to piggy back on the good motors reputation by simply looking similar.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=62137

 

[stompatompa]

Thanx for the link. Nice review!