Motor on a reasonable budget

[highflier]

Well I just looked at the medusa site. The motor is about the same size as the Mega 22/45 series. The cost is much better, 20% cheaper.

Running 6s A123 is about 16volts under a moderate load. ( 20 volts No load)
Running 9s A123 is about 22 volts under a moderate load. ( 30 volts No load)

2000KV= 32000 RPM or 44000
1600KV= 25000 RPM or 35000

That said, I don't have a controller that will let me run 9s A123's I am secretly hoping that MMM will be tested to that level by some daring individual. For 6S I think the 2000KV would be better and for 9S I like the 1600KV.

#$%^&* I am so confused....

Whats more effient, The Mega or the Medusa?

Highflier

[tc3_racer_001]

Originally Posted by highflier

Well I just looked at the medusa site. The motor is about the same size as the Mega 22/45 series. The cost is much better, 20% cheaper.

Running 6s A123 is about 16volts under a moderate load. ( 20 volts No load)
Running 9s A123 is about 22 volts under a moderate load. ( 30 volts No load)

2000KV= 32000 RPM or 44000
1600KV= 25000 RPM or 35000

That said, I don't have a controller that will let me run 9s A123's I am secretly hoping that MMM will be tested to that level by some daring individual. For 6S I think the 2000KV would be better and for 9S I like the 1600KV.

#$%^&* I am so confused....

Whats more effient, The Mega or the Medusa?

Highflier

im also a bit stuck. ill be running 6 or 7s a123 (hopefully in 1p setup, is this enough for these huge motors? no one has been able to tell me this yet. having just over 500g of batteries is fine... having over 1kg is not.
im looking for something to run for 6+ minutes racing. which is why i thought going a higher voltage and gearing down = more efficiency.

on a scale of 1-100 in efficiency, what are the motors In YOUR opinion.

eg: neu 90
medusa 80
feigao 60
etc. just make up some numbers!

thanks guys for your help,
ryan

[highflier]

Ryan, I can help you a little bit.

I run a 9xl with 6s1p setup. Geared for about 45 MPH. The batteries are holding up just fine. I agree with you that 2p on the batteries is a lot of weight, not to mention a lot of space to make inside the truck. 6 min run times should be no problem. I just bash but I am getting 15 min easily. I selected 6S because I can charge that config in 8 min. or less. With 7s you will need either a really badass charger or be willing to wait a little longer for a charge. This is the reason that you see me looking to make the jump to 9S. More run time, Cooler running, More power, and still 8 min charge times.

To your question on the ranking of motors I would love to see some real facts, on that also. I am wondering if I will even be able to tell a difference between any of my current choices. The above posts make it sound like Medusa is the #2 motor as far as best goes.. and priced much better then several of the other lesser motors.

Highflier

[tc3_racer_001]

thanks for that. im suprised your getting 15 minutes! i thought id struggle with even 5. do you use a lvc? i will buy 2 chargers, probably from the hyperion range, ive got a decent 30A supply, which will allow me to charge 2 packs @ 8-10A = 15 minute recharge, will my supply be powerful enough? (charge 4s and 3s)


im wondering if the 2 port charger would be the best option... its only 180W each side, but could probably hold the 10A on each side...

im using a modded antec power supply, with 2 12v outputs, rated at 19A each rail... if i only have one charger, i could only use one rail and possibly overload that one and cause it to blow. its running well, and i tested it for a short time and it took 22A of charger current (well i charged batteries @ a total of 22 amp and the chargers aint 100% efficient) so id guess close to 27A, before it dropped below 12v. the weird thing was, it brought the other rail down to about .5v above the loaded side, begging the question, are there really 2 seperate lines? and what would happen if i paralled the 2 outputs together... anyone tried this, as not even on computer forums mentions this!

sorry for hijacking,
ryan!

[highflier]

Have you looked into Zip Charging. Your 300.00+ of chargers is = to my $20.00 setup when it comes to charging A123's. That said if you are going to use the chargers then I would go 7S.

Now back to topic. Tell us about the motors guys. Will I really be able to get away without the fan, Will I be able to tell the performance difference. What are the real world effiencies.

Highflier

[tc3_racer_001]

Originally Posted by highflier

Have you looked into Zip Charging. Your 300.00+ of chargers is = to my $20.00 setup when it comes to charging A123's. That said if you are going to use the chargers then I would go 7S.

Now back to topic. Tell us about the motors guys. Will I really be able to get away without the fan, Will I be able to tell the performance difference. What are the real world effiencies.

Highflier

zip charging hey? hows that work, ive seen it on youtube but not on 6s. please explain in here or pm.

im from the esavage gang. the people (kosta, possibly even bithed) have used this motor and were happy with it. i dont think its as good (from what ive heard) as a neu, but far far better than feigaos etc. 4 pole design will confuse some controllers, but MM will be fine. ill problably go with a neu created by castle... hopefully better than a feigao but cheap enough. id like to see them up against the REAL neus. if they are only slightly less efficient ill go with them :)
ryan

[BrianG]

zip charging is simply charging through a long wire directly from the power source to the battery. It relies on the fact that there is resistance in the wire to limit the current somewhat. To me, it's just too unreliable as the charge current would depend on the voltage of the power source, the voltage of the battery, and the gauge/length of the wire. In any case, the supply voltage has to be higher than the battery voltage. So, for 6s A123s, you'd need at least 22-23v. But if it's too high, the charge current will skyrocket as well. Best to just use a charger IMO.

Oh, and I would not do this on ANY lithium battery except A123s as they are much more tolerant.

[highflier]

Ok to be honest I built a couple of DIY 3s cutoff's Then I built all my packs into 3s1p setups. I then charge 2 or 3 of the packs at a time. When I run my rc truck I just use a Y connector and make 2 of the 3s packs in a single 6s pack. I use a deep cycle battery as the power source. Charging starts off at about 18 Amps each. I.E. 36 amps. It quickly tappers down to 12 amps and then slowly drops from there. Batteries barely get warm.

To answer a earlier question. I do not use a LVC. When the truck slows down I know it is almost time to charge them. Unlike Lipo's you can run these suckers way down. I have run it to a dead stop. But for the most part I stop when it is no longer fast enough to be fun.

I have about $10.00 into each charger. Talk about good deal!

I also lengthen the wire so that charging starts at about 8 amp and then charge using a PC power supply as a source. Of course this is what I do at home when I have plenty of time.

So unhijack. Will the Medusa 36-60 1600 KV be able to offer better power and speed then the wanderer 9xl on 6S1p



Highflier

PS. NEVER EVER use this method on LIPO. But I disagree with BrianG it is a awesome method. Brian have you seen the DIY thread on the cutoff in RCgroups. Thats what really made this method work so well. No more monitoring of the charging. Just start it and walk away. When LED goes out Battery is charged. I used my astro watt meter in line to monitor first few charges. If not in use for anything else I still use it but just to see how many AH the charge took.

[tc3_racer_001]

hmm. id love a link to that guide!
so i can use my pc power supply, and use metres of cable to limit like that? id want a 10A charge rate max, but with only 12v, but would it be possible to charge 3s via that, or would it charge it too much, over 4v... id need a cutoff. a link would be great, as i could test it out before buying the chargers!

ryan

[highflier]

Originally Posted by tc3_racer_001

hmm. id love a link to that guide!
so i can use my pc power supply, and use metres of cable to limit like that? id want a 10A charge rate max, but with only 12v, but would it be possible to charge 3s via that, or would it charge it too much, over 4v... id need a cutoff. a link would be great, as i could test it out before buying the chargers!

ryan

I have used computer P/S to charge 3s packs. I use a longer cable to try and hold the starting charge to 8 amps. My supplies are rated to 10 AMPS. I use this cutoff device, With both deepcuycle and P/S as input source. The only difference is I use about 5' less wire when I charge from the Deep cycle.

http://www.rcgroups.com/forums/showt...highlight=A123

Highflier