Opinions on Litton motor

[iangreenhalgh]

Hi folks

After the original motor I picked didn't work out, I found this Litton model dirt cheap new old stock:



View attachment 7



The exact model number is: BN34-35AP-04LH

I found the specs sheet:






However, my motor has an 04 for it's winding code and the sheet only list 01, 02 and 03. My motor is marked 24V and an 01 winding is also 24V so let's take the 01 figures as probably being accurate.



According to the specs, it has 2.56Nm torque, is this a high figure? I have no frame of reference to interpret it.

At 24V, the motor is rated for 7100rpm, which is fine for me as my drive train has a 21:1 reduction.

The rated power at 24V is 475W. although the other two windings are rated a lot higher.

The only controller I have is a 36V 800w unit, which would mean overvolting this motor. Should I give it a try or buy a 24V controller? I haven't assembled my battery pack yet so I could make it either 24V or 36V.

This is the controller I have. one of the common Yiyun units cheap from ebay:

 

[Miles]

According to the specs, it has 2.56Nm torque, is this a high figure? I have no frame of reference to interpret it.

Hi Ian,

Unfortunately, that is the figure for peak torque. The rated torque is 0.55 Nm.

To give some reference point, 2.56 Nm is slightly less than the rated torque of the Astro 3210 motors

 

[iangreenhalgh]

Cheers Miles. Considering I'm gearing it down so much (21:1) it should be fine as we've seen a lot of successful Astroflight builds.

 

[Miles]

Well, from the specs, you'll get around 1/4 to 1/5 of the continuous torque output of the Astro 3210, from a motor of almost double the weight......

 

[liveforphysics]

If you're seeking opinions, its a bit of a turd motor that requires stages of added failure modes and loss (gearing) to become useful towards moving a bicycle.

 

[iangreenhalgh]

I don't understand 'requires stages of added failure modes', would you please elaborate.

The way I've designed my drive system I can easily replace the motor at a later date if I find I need something with more poke.

 

[DanGT86]

The "stages of added failure modes" is talking about the gear reduction stages required to get the RPM down to a usable rpm. Most people would require multiple stages to get reductions over 20:1 like you mentioned. Each gear reduction stage is another possible failure point and another loss of efficiency.

Generally if you are going to be dealing with efficiency losses with a large gear reduction it becomes even more important to use the most efficient motor possible at the beginning.

This motor looks like its a bit heavy for its output compared to other options on the market. Those other options are indeed more expensive so the ultimate results/dollar is up to you. The pitfall you have to beware of is the price and reliability costs of all the reductions. No point in blowing all the savings from the cheaper motor on chains, sprockets, belts, and pulleys that wear out quickly in high reduction situations.

 

[iangreenhalgh]

Thanks for the explanation. The motor only cost me 19.99ukp so it is as cheap as you're gonna get. If it doesn't work too well I can always replace it with something better.

 

[SlowCo]

If it's that cheap you should use two or more of them. Something like this:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=74176

 

[iangreenhalgh]

Aah, Recumpence's amazing bimotor build.

I happen to have two of these litton motors so I could indeed use both. They have dual shafts - 8mm on both ends, so it would be simple to couple them together. However, wouldn't it require two controllers and some rewiring of throttles etc?

 

[SlowCo]

In the data of the motor it states that standard a HP HEDS-5500 encoder is used. I am a n00b but does that mean there are no "normal" Hall sensors inside? If so you're probably going to need them to run with a sensorless controller. So two of these might work:
http://www.aliexpress.com/store/pro...ed-and-sensorless-motor/313864_427353623.html

And use your throttle output signal splitted to both controllers. There is info on this forum how to do that (can't find it yet). i think it requires to take the 5V input for your throttle from one controller and only use the 1-4V signal for both controllers (but I might/probably be wrong...)

 

[SlowCo]

Aha, found it:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=18108

 

[iangreenhalgh]

Thanks for that. There are wires for the hall sensors, I think the encoder is an option whereas I have a plain motor sans encoder.

I'll put a single motor on the bike and run with that for a while. I can always add the second one later if desired.