Any LiFe packs available for TC?
I'm genuinely interested in giving LiFe a try for something I'm experimenting with, but can't find one available anywhere. It looks like Reedy had something (a 4000) many years ago but that's about it.
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Originally Posted by syndr0me
(Post 14231012)
I'm genuinely interested in giving LiFe a try for something I'm experimenting with, but can't find one available anywhere. It looks like Reedy had something (a 4000) many years ago but that's about it.
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This is the BRCA's approved LiFe list, last updated in February.
They had to be available commercially in the UK to be on the list, I *assume* they are still available. http://www.brca.org/sites/www.brca.o...v1%20pdf_0.pdf |
Found the Orion in the UK at a good price;
http://www.wheelspinmodels.co.uk/i/226344/ They seem to be almost all discontinued, so finding any might be difficult :( |
Originally Posted by howardcano
(Post 14231014)
Can you share with us what your experiment is?
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You'll recall that the Europeans went to 5 cell once brushless mod hit the scene to make things easier to drive, and stayed competitive with 6 cell. I'm interested in trying something similar.
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Originally Posted by syndr0me
(Post 14231036)
Sure, nothing exciting. I want to see how mod sedan feels with a LiFe. I like faster classes (love 13.5) but struggle with the rip of open mod. Trying to run flat LiPos and adjust ESC software hasn't yielded the feel I'm after. Considering trying a LiFe to see how that feels. I want something more dead in the infield while still fast on the straight and longer infield sections.
This was my 7.5, you can see it doesn't lack ponies on the straight but I was beig pretty cautious (first time on ETS style carpet)
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Originally Posted by syndr0me
(Post 14231036)
Sure, nothing exciting. I want to see how mod sedan feels with a LiFe. I like faster classes (love 13.5) but struggle with the rip of open mod. Trying to run flat LiPos and adjust ESC software hasn't yielded the feel I'm after. Considering trying a LiFe to see how that feels. I want something more dead in the infield while still fast on the straight and longer infield sections.
You can also just run some long, light-gauge wires to the motor to add resistance. It doesn't take much. P.S. Reducing battery voltage, using a higher-turn-count motor, adding resistance to wires, etc., may not change what you want: all of these still leave you with maximum torque at stall, tapering fairly linearly to zero torque at maximum RPM. To REALLY change the feel, you want to change the shape of the torque curve. |
Originally Posted by Skiddins
(Post 14231046)
Have you tried a boosted 'mid' wind modified like a 7.5?
This was my 7.5, you can see it doesn't lack ponies on the straight but I was beig pretty cautious (first time on ETS style carpet)
I definitely haven't tried all the possible combinations of mild mod motors with boost, but I did experiment quite a bit with boosted 6.5 and found it was possible to calm things down somewhat through the ESC. I'm not sure if it's laziness or what, but I don't love tinkering with ESC settings as much as I probably should. I really like stock racing in that regard. Just set your drag brake and go.
Originally Posted by howardcano
(Post 14231047)
Sounds like a fun thing for a software guy to tinker with: tiny microprocessor reads throttle pulse from receiver, measures motor RPM via Hall sensors, uses look-up table to output new throttle pulse to ESC. Actually, I wouldn't be surprised if an ESC manufacturer has this already (though I haven't seen it).
You can also just run some long, light-gauge wires to the motor to add resistance. It doesn't take much. Some ESCs do a decent job of smoothing out throttle input, like the Orca. But of all the things I tried, undercharging my batteries (to about 8.0v) was by far the most effective and natural feeling. It's what got me thinking about reducing the voltage even further, and then maybe motoring up as needed. I suppose 1S could be an option, but that comes with the added hassle of powering your electronics somehow, and I don't know if there are any full-size 1S packs out there. The thinner wires are an interesting idea. Does that added resistance cause the ESC to run hotter? |
Originally Posted by syndr0me
(Post 14231099)
The software part sounds interesting, but without an open hardware project that provides some sort of SDK, I'd be out of luck. There are some open ESC projects out there, but I don't think any of them are intended for sensored motors.
Originally Posted by syndr0me
(Post 14231099)
But of all the things I tried, undercharging my batteries (to about 8.0v) was by far the most effective and natural feeling. It's what got me thinking about reducing the voltage even further, and then maybe motoring up as needed. I suppose 1S could be an option, but that comes with the added hassle of powering your electronics somehow, and I don't know if there are any full-size 1S packs out there.
Going to 1s with a lower-turn motor isn't going to solve the problem. The torque curve is still the same shape. But if you want to try, buy a saddle-pack and wire the cells in parallel. That's what I do on some of my loaner cars; I can run them all day without charging!
Originally Posted by syndr0me
(Post 14231099)
The thinner wires are an interesting idea. Does that added resistance cause the ESC to run hotter?
Many ESCs for brushed motors had a dedicated, hardware current limiter. This made a huge difference in the feel, since the torque curve was essentially flat all the up to a certain speed, like a kart with a slipper clutch. You can get this effect, and virtually any other torque curve you desire, via the software approach. But it ain't a small project! |
Originally Posted by syndr0me
(Post 14231099)
Car looks reasonably powered for sure. That's such a nice, big open track compared to what we're running on here. I would think bigger motors might be easier to control with more space, but perhaps the opposite is true. Here's what we're running on right now for comparison: https://www.facebook.com/CORtrack/vi...7520841986103/.
I definitely haven't tried all the possible combinations of mild mod motors with boost, but I did experiment quite a bit with boosted 6.5 and found it was possible to calm things down somewhat through the ESC. I'm not sure if it's laziness or what, but I don't love tinkering with ESC settings as much as I probably should. I really like stock racing in that regard. Just set your drag brake and go. The software part sounds interesting, but without an open hardware project that provides some sort of SDK, I'd be out of luck. There are some open ESC projects out there, but I don't think any of them are intended for sensored motors. Some ESCs do a decent job of smoothing out throttle input, like the Orca. But of all the things I tried, undercharging my batteries (to about 8.0v) was by far the most effective and natural feeling. It's what got me thinking about reducing the voltage even further, and then maybe motoring up as needed. I suppose 1S could be an option, but that comes with the added hassle of powering your electronics somehow, and I don't know if there are any full-size 1S packs out there. The thinner wires are an interesting idea. Does that added resistance cause the ESC to run hotter? What about 10.5 or 13.5 boosted, at least you'd already have the 13.5's to play with? |
Originally Posted by Skiddins
(Post 14231149)
What about 10.5 or 13.5 boosted, at least you'd already have the 13.5's to play with?
Howard, I'm not sure how to change the torque curve of a motor. Less timing? Less powerful rotor? |
Originally Posted by syndr0me
(Post 14231157)
This is what I've been considering recently. It's possible I can get what I'm looking for by just adding some turbo on the straight.
Howard, I'm not sure how to change the torque curve of a motor. Less timing? Less powerful rotor? |
Originally Posted by Chris Adams
(Post 14231171)
Charge your lipo to 8.00. Its got plenty of mah to handle it being charged less. Makes a pretty big difference.
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Originally Posted by syndr0me
(Post 14231157)
Howard, I'm not sure how to change the torque curve of a motor. Less timing? Less powerful rotor?
For DC motors with field coils, one can play all sorts of games. But we don't use those in RC. The software approach lets one do fun things, like put maximum torque somewhere in the middle of the speed range (as for an internal-combustion engine). One could even put a little "kick" in the response, so a nitro guy would feel like his 2-speed transmission shifted. :) Thanks for letting me ramble! |
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