E-Revo with Twin Force Tranny

I've try to find Twin force parts on the web, but..............NOTHING.
Tower, A Main, flebay, nothing
I would like to have this twin force chain drive system, but as i can see, any hobby shop have the twin force parts in stock.

[Lonewolf039]

Originally Posted by t-maxxracer32

how were you charging these?

at how many amps and all that?

I have been charging them on my Triton2 at 4.2 amps using a y adapter to charge both batts at the same time. I am now trying to slow charge them at 1 amp, but the stupid Triton has a 90 minute timeout feature, so I have to keep resetting it.

Hopefully a slow charge will perk them up. If not, maybe individually charging them will help. They are both the same temp after charging at 4.2 amps, so I figured they were charging evenly. They have always been used in a pair, so they should be close.

[Lonewolf039]

Originally Posted by david lamontagn

I've try to find Twin force parts on the web, but..............NOTHING.
Tower, A Main, flebay, nothing
I would like to have this twin force chain drive system, but as i can see, any hobby shop have the twin force parts in stock.

Sorry, I forgot to mention that Kyosho parts are hard to get. The only place I have seen to order online is Kyosho America, but they only ship within the USA. Here is a link to the Mad/Twin force parts.http://www.shopkyosho.com/index/410....5411.25465.0.0

[johnrobholmes]

Are you using your packs hot off the charger? I never found IB4200s to be a stable cell, and 30-50 cycles is all I can ever seem to get out of sub-C anymore. I have started to really dislike anything but lipo lately. It is cheaper in the long run and there are less cells to go bad in a pack!

[Lonewolf039]

Yes, I run them hot off the charger. I have been reading up on these 1b4200 cells, and they sound really fragile. Sounds like you are only supposed to run them 1-2 times per day, and even then they are only good for a few races.

I got these so I wouldn't have any worries running in the snow for winter, but now I guess I should have got lipos. I have had really good luck with lipos in my 3d planes, and I run them as hard and often as I can.

Flightpower, here I come.

[johnrobholmes]

2 cycles a day is what I hear too. Anything above about 3700mah in a sub-C jacket is fragile IMO. The nice thing about lipo is that they can just make the cell taller for more mah. No worries about cramming too much in.

[Lonewolf039]

OK, I figured out how to reset the safety timer on the Triton charger to 720 minutes, and I did a 1/10 C slow charge last night. I repeaked the batterys at 4.2 amps just before heading out. Performance was the same, run time slightly longer, so the slow charge might have equalized the cells a bit, but didn't restore any voltage. At 1 minute into the run, I got 55.5 amps peak and 11.1 volts minimum, for 616 watts peak. I also got the same numbers at 5 minutes. At 8 minutes, voltage was down to 10.2 volts under load. At 9 minutes the batterys started to dump, 3600 mah used. At 10 minutes, end of run, the lowest voltage recorded was 7.6 volts, 3900 mah used. Performance was rather weak throughout the run.

I ran the numbers through the top speed calculator:

Differential Ratio: 2.8461538461538463
Transmission Ratio: 2.36
Other Ratio: 1
Spur Tooth Count: 54
Pinion Tooth Count: 15
Total Voltage: 11.1
Motor KV: 4400
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor Current Draw: 55
Motor coil Ω: 0.0073
Spur/Pinion Ratio: 3.6 : 1
Total Ratio: 24.18092 : 1
Tire Circumference (inches): 18.22 inches (462.82mm)
Total Motor Speed: 47073.4 RPM
Vehicle Speed: 33.59 MPH (53.96km/h)
Effective Speed Rate: 3.03mph/V (4.86kmh/V)
Effective KV Value: 4240.85
Motor Torque: 0.09 ft-lbs
Final Torque: 2.13 ft-lbs

Top speed of 33 mph looked about right. When the batterys were new, the voltage stayed up around 12.5-12.6 under a load of 70+ amps. The higher voltage in the speed calculator puts top speed at 37 mph, which was probably pretty close. Now they can barely put out 50 amps. If I had know how crappy the nimh batts were, I would never have even bothered with them. I really did not think I was abusing them. Oh well, live and learn. I am now charging them at 5 amps, so I'll see if a bit of torture will wake them up. I really don't care if they blow up now.

[Lonewolf039]

Well, run 2 was a little better. At 1 minute the voltage was 12.82 volts at 54.38 amps. At 5 minutes, voltage was down to 11.84 volts at 55.48 amps. Pack dumped at 3700 mah. So the higher charge current did raise the voltage up for a bit, but these batterys are on their last legs.

Anyways, there haven't been any pics for a while, and I know we all like pictures, so here we go.








And my highly scientific measuring method A whatts up meter in a baggie zip tied on.

[Lonewolf039]

I got the battery holders done tonight. Turned out not too bad. I wish the Revo didn't have that hump on one side of the chassis. It makes the one battery stick out 1/4 inch more than the other one. I've been thinking about cutting up a chassis and tigging in some holders that are nice and centered.

[suicideneil]

I see what you mean about the bump, but it does look like like you could 'cut and shut it' to make the trays more sysmetrical. I cant weld myself, the sparks scare me too much....

[gasshead]

holy clean wireing batman...looks gread dude makes me want some kyosho stuff

[Revracer]

wow thats amazing... im pissed that i just ordered my tekno conversion now... wish i had spent the money on that instead. looks awsome. very compact

[Lonewolf039]

I actually put the twin force tranny back in the twin, I only wanted to see if it would work. Besides, the twin was broken, and my 3.3 pullstart kept freezing up, and then I boke my carb, so I took 2 broken trucks and made 1 good one.

Check here for the next phase of the Revo project.
http://www.rc-monster.com/forum/showthread.php?t=9722