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Old 10-17-2008, 11:05 PM   #76
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I used to think 1/12th was the cheap class to run. Now with rubber on carpet and LiPo and BL TC, I am sick of 1/12th. Come Christmas I am going to run TC. $30 a week for tires and NiMh that need replacing every 6 months to stay competitive... not for me. Especially at 15 with no job.
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Old 10-17-2008, 11:52 PM   #77
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This discussion is going to go sideways in a heart beat. Take a breath.

What Roland is proposing is cheaper from a "start up stand point". And yes, it will cost less in the end. I have already done the math. It would take a customer with nothing but a transmitter, about $750 to put a 380 sized car on the carpet track which then would cost pennies to maintain from that point forward. To put that same scenario together with a current 12th scale, is $1000 minimum plus a series of maintenance parts and batteries after that.

There is no question that lipo and brushless is going to be more cost effective then turning coms, brushes and buying new nimh every few months to stay fast.

Still, the bottom line is that it needs to work on all surfaces: carpet & asphalt. I don't mean to pee on the parade, but go test on the asphalt and see if it's still a viable idea.
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Old 10-18-2008, 12:12 AM   #78
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These are things I used to set up my car, where to get what, and how to put them together.

Motor and motor mount:
In the attached pictures, you will see the parts you need to mount the Momba motor on the motor mount of a 1/12 scale.
You will need:
2 3mm x 12mm screw
2 2.5mm x 4mm screw
4 split washers
2 washers
2 3mm nuts
1 aluminum plate
1 1/8” plastic tube, some antena tube will work fine. And if it's too tight, cut a slit on the tube.

You can use momba 5400kv motor, with 1.725" tires, I use 16/88 ratio.
You can also get this motor here:
http://www.hobbycity.com/hobbycity/s...idProduct=4215
I have this coming my way, it's a slower motor:
http://www.hobbycity.com/hobbycity/s...idProduct=4216
I've also try Momba 6800kv, it's like mod speed, but very hard to gear though.
You have to use very small pinion and tires.


Battery:
Just a few days ago, a 1800 mah became available on the ebay, click the link :http://stores.ebay.com/seemmy999
In the battery category, you will be looking for:
7.4V 1800mAh 25C Lipo Battery for 1:18 RC Car Truck
It comes as 2-cell 7.4 v.
I used a 2400mah pack like this:

http://www.rk2trade.com/rk2trade/pro...roducts_id=161
It came as a 3-cell 11.V, I had to use my Dremel. Both are perfect in size. The 1800mah is lower in capacity, but higher C rate. It should provide more than 10 minutes run time. After 8-minutes qualifier with the 2400mah pack, I plug it into my charger, it showed that I still had 45 % capacity left in the battery. l did not feel any drop in speed for 12 minutes with this battery.
This set up is the best thing happen to 1/12.

ESC.
It’s also available on www.hobbycity.com, here:
http://www.hobbycity.com/hobbycity/s...verse_programm.
Or better yet, it's cheaper here, the same place you can order the 2400mah battery:
http://www.rk2trade.com/rk2trade/pro...roducts_id=190

I use this esc without the fan, I don't think it's needed for the tiny motor. This ESC will allow you to use it in 1/10 scale down to 9T motor, but in sensor less mode.
Attached Thumbnails
The future of 1/12 scale-103_0078.jpg   The future of 1/12 scale-103_0080.jpg   The future of 1/12 scale-103_0088.jpg   The future of 1/12 scale-103_0089.jpg   The future of 1/12 scale-103_0101.jpg  


Last edited by Roland S; 10-18-2008 at 09:18 AM.
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Old 10-18-2008, 12:29 AM   #79
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No offense intended to others who have or are testing the small motor 2 cell option intended here.

All of the testing I have done with sensor-less motors at stock speeds has left me wanting for a better start up. I couldn't find a way to get rid of the cogging and weirdness when hitting a board and rolling backwards or stopping. It is difficult to take someone else's word for some of the proposed ideas without an idea of what they consider acceptable for racing. I have seen people from my local track post on RCTech about different solutions and products claiming they run great, but when I drive their car at the track, or watch it I would definitely not say the same. Not that I am a national A main driver, but I think we all agree that there are different opinions when it comes to what "works" and what "works well" etc.

I'd like to think I am a rather objective thinker and am looking at what will work best on asphalt, carpet, for rookies, veterans, pros, stock, mod, national races, and club races, and everything in between.

Rather than pointing at what we disagree about here's where I feel we are mostly in agreement.

1. 12th scale is a great class worth investing time and money into ensuring it will be around for years and years to come.

2. Lipo's are more cost effective and simpler to maintain than NiMh's.

3. It is likely we will see a change in availability or performance of NiMh's

4. We need a motor/battery package that will allow for the varying speed needs of pro's and total rookies by only changing the wind of motor and not relying on rollout restrictions.

The main obstacle I see to the 2 cell option is . . .

I have yet to test a motor that is slow enough to allow rookies to run it on 2 cells and not cog. I don't know enough about the math, kv/rpm and such to theorize with y'all, but even the slowest motors I found were way to fast when run on 2 cell lipos and geared for racing 8 minutes. This is where I hope not to insult. I could see a basher testing a smaller motor on 2 cell lipo and under gearing it to get similar to stock speeds and then posting here that its a viable solution.

For all of 12ths history the only thing different between it and other classes' power packages has been the battery source, if anything: 4 cells instead of 6 cells. Considering 12ths track record and longevity (pun intended) I feel this is a safe template to model in the imminent shift to newer technologies: same motor as other classes with a reduced voltage battery.

PS: As for the weight I feel this is a moot point as the weight could easily be added back into the car where ever its needed. I could see steel pods (that don't bend!) being used to replace the weight of the motor if we did go the small motor route

Roland_s

What was the motor temp on the smaller motors you've tested after racing for 8 minutes?
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Last edited by andrewdoherty; 10-18-2008 at 12:46 AM.
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Old 10-18-2008, 03:30 AM   #80
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The only future is A123 batts not lipo, lipo is a short term solution for a long term problem.
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Old 10-18-2008, 12:03 PM   #81
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Since everyone wants to toss in a smaller motor into their 1:12, do additional comparision test with 3-Cell NiMH and a RX pack. Do one test with a small motor at 3.6V and another test a 13.5 or 10.5 Brushless at 3.6V.

If you do not own a RX pack,

make a short trip to Wal*Mart and buy a 4-pack of AAA rechargables and a AAA 4-cell holder from Radio Shack or Ebay. A 4.8V AAA pack would be roughly 22mm x 22mm x 45mm or about the same size of a Sub-C battery if soldered together. If using the battery holder, 23x23x54mm. That is funny, going to 3-cell NiMH frees up the perfect spot for a RX pack and the weight does not change but yet provides a compromise for LiPO's to join in the fun as 3.7V pack.

Last edited by trailranger; 10-18-2008 at 12:53 PM.
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Old 10-18-2008, 08:28 PM   #82
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Quote:
Originally Posted by bs6ef View Post
The only future is A123 batts not lipo, lipo is a short term solution for a long term problem.
Show me how you fit a 65mm battery in a space designed for 63.5 (old 6 cell chassis is the biggest I found in my stash) and then place weight around it.

Technically this is actually possible within the current wheelbase rules if you don't mind trashing a chassis for a longer one. All my WB measure right about 196mm (7.75"). Max wheelbase is 222mm (~8.75). It would also require manufacturers to come out with new bodies so the rear wheels are not hanging out back past the end of the current bodies. Guess thats when the thicker body rules could go in effect too.

I don't particularly care for a one battery OEM either.
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Old 10-18-2008, 09:42 PM   #83
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I used to be big on LiFePO4, AKA A123 cells. The conclusion I came to is that unless that technology catches up LiPO in power density, it will be hard to market to racers who want the biggest and best.

LiPO's offer pretty good capacities and not many racers would want to trade a 6000mah 7.4V lipo for a 4000mah 6.6V LiFe pack for sedan use. LiFePO cells could have some chance at being a replacement for 5-cell racing, but not 4-cell racing as the motors in use right now are pretty fast and adding 1.8V more will make them even faster. Going to 7.4V with the current motors would just be too fast which is why 1:12 made the step from 6-cell to 4-cell many years ago.

For those reasons I fell 3.7V LiPO would be a good start for replacing the 4.8V NiMH batteries in the near future. Allowing 3.7V Lipo in 1:12 racing could be a the hot ticket for attracting new racers that are looking at the 1/14 scale Recoil and even AE 18R for second classes. There is no dispute that a 1:12 compared to a RTR TOY is the better choice due to lower ownership cost in repairs and little upgrades are needed since 1:12's come fully loaded with the best option parts. If 3.7V LiPO was allowed in 1:12 the ownership cost would reduce as NiMH do not last as long.

NiMH is not going away over night. I highly doubt that NiMH will disappear at all since many tool and toy companies will use the batteries. Racers that do not want to run LiPO can run 3.6V NiMH with the 3.7V LiPOs just as 6-cell NiMH is allowed with LiPO's in Sedan and Off-Road. Giving the racers the choice between LiPO or NiMH would be a revelation in 1:12 and pan cars. Many of the die-hard racers will most likely stick to NiMh as that is what they know and they may not want to but new Chargers/Balancers/ Charging Sacks. Once again 3-Cell NiMH would not force racers to buy new parts or batteries. A budget racer can use current battery packs once a one cell is soldered off.

Since by default all 4-cell 1:12 cars today can fit a 3-cell NiMH pack and the link cars can fit the purposed SMC 3.7V LiPO cell it should be the clear choice that 3.7V LiPO / 3-Cell NiMH should be the recommended change to 1:12 in the near future. 3-Cell NiMH would be much easier and lest costly to implement than changing the motor and chassis along with a 7.4V battery that racers would have to buy new.

In the distant future: I would like to see a smaller motor in 1:12 class but designed to run on 3.7V battery so that changes are kept to a minimal to the 1:12 class over the next decade.

I am not advocating that 1:12 should change to 3-Cell NiMH / 3.7V LiPO because the option is available. I am suggesting it to help return the speeds of Stock 1:12 to pre-2000 speeds and allow more racers to experience racing in their level of drivers confidence. Mod racing with 3.7V will still be very very fast!
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Old 10-18-2008, 10:01 PM   #84
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Quote:
Originally Posted by trailranger View Post
I used to be big on LiFePO4, AKA A123 cells. The conclusion I came to is that unless that technology catches up LiPO in power density, it will be hard to market to racers who want the biggest and best.

LiPO's offer pretty good capacities and not many racers would want to trade a 6000mah 7.4V lipo for a 4000mah 6.6V LiFe pack for sedan use. LiFePO cells could have some chance at being a replacement for 5-cell racing, but not 4-cell racing as the motors in use right now are pretty fast and adding 1.8V more will make them even faster. Going to 7.4V with the current motors would just be too fast which is why 1:12 made the step from 6-cell to 4-cell many years ago.

For those reasons I fell 3.7V LiPO would be a good start for replacing the 4.8V NiMH batteries in the near future. Allowing 3.7V Lipo in 1:12 racing could be a the hot ticket for attracting new racers that are looking at the 1/14 scale Recoil and even AE 18R for second classes. There is no dispute that a 1:12 compared to a RTR TOY is the better choice due to lower ownership cost in repairs and little upgrades are needed since 1:12's come fully loaded with the best option parts. If 3.7V LiPO was allowed in 1:12 the ownership cost would reduce as NiMH do not last as long.

NiMH is not going away over night. I highly doubt that NiMH will disappear at all since many tool and toy companies will use the batteries. Racers that do not want to run LiPO can run 3.6V NiMH with the 3.7V LiPOs just as 6-cell NiMH is allowed with LiPO's in Sedan and Off-Road. Giving the racers the choice between LiPO or NiMH would be a revelation in 1:12 and pan cars. Many of the die-hard racers will most likely stick to NiMh as that is what they know and they may not want to but new Chargers/Balancers/ Charging Sacks. Once again 3-Cell NiMH would not force racers to buy new parts or batteries. A budget racer can use current battery packs once a one cell is soldered off.

Since by default all 4-cell 1:12 cars today can fit a 3-cell NiMH pack and the link cars can fit the purposed SMC 3.7V LiPO cell it should be the clear choice that 3.7V LiPO / 3-Cell NiMH should be the recommended change to 1:12 in the near future. 3-Cell NiMH would be much easier and lest costly to implement than changing the motor and chassis along with a 7.4V battery that racers would have to buy new.

In the distant future: I would like to see a smaller motor in 1:12 class but designed to run on 3.7V battery so that changes are kept to a minimal to the 1:12 class over the next decade.

I am not advocating that 1:12 should change to 3-Cell NiMH / 3.7V LiPO because the option is available. I am suggesting it to help return the speeds of Stock 1:12 to pre-2000 speeds and allow more racers to experience racing in their level of drivers confidence. Mod racing with 3.7V will still be very very fast!
Dude, trailranger, who are you? Your posts on this topic are very articulate and thoroughly thought through -- not the typical forum monkey!

When I started racing sedans I purposely built an underpowered car so I could actually learn to race and drive smoothly. I ended up finishing ahead of a lot of "faster" cars. I think when I build my 1/12 scale car in the coming year I'm going to run the SMC 1S lipo and just run with the 4-cell guys in our club. Everyone here is mellow enough not to care about the deviation and perhaps "slow is fast" will work again.
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Old 10-18-2008, 10:24 PM   #85
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reenmachine, if you go with the 1S setup, inform me. I REALLY would like to see that and compare my pan car to yours or anyone elses at the club that goes the lipo route.
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Old 10-19-2008, 09:12 AM   #86
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Future of 1/12th is a smaller lipo with a hotter motor.

I know, I know, sounds 'crazy'. mark my words here, this is the way it will be. Debate, argue, come up with pages of arguments or complaints.... but I tell you this now, it is the wave of the future in 1/12th and it will solidify one of the most stable and still popular classes in the history of our sport.
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Old 10-19-2008, 09:28 AM   #87
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Quote:
Originally Posted by bs6ef View Post
The only future is A123 batts not lipo, lipo is a short term solution for a long term problem.
There are so many new cells being worked on out there that it's hard to keep up. I've heard the whole A123 argument for years now and they still refuse to build a sub-c sized cell (at least last time I checked).

I do have sub-c sized LiFeP04 cells (not A123) and they work fine. They won't handle the current we need for mod as a 4 cell pack wired to 2 cell voltage. They do seem to work ok on single cell voltage though.

The "A123" stuff is an option and it makes some sense for the t-bar guys but there are no readily available cells.
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Old 10-19-2008, 09:53 AM   #88
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I experimented some last night after our local club race. We raced WGT and 12th on carpet yesterday. After the racing was done I made a 1 cell lipo out of an 1800 25c 2 cell lipo I had laying around. I bought it off e-bay for about 20 dollars shipped. It is now a 1 cell 3600 25c pack. Just for grins, I taped it into my WGT car and plugged it in just to see what would happen. Guess what . . ? It worked. I DID NOT use a receiver pack, I did not add weight. Heres my electronics set up.

Futaba 9550 servo
SpeedPassion LPF ESC
Standard Spektrum receiver
Helios with standard Spektrum module
Novak 17.5 and 13.5
MRT PTx transponder
88/35 gearing
Speedmerchant Formula 10

I dont have any caps on the receiver or the esc other than the one the LPF came with.

I immediately went out to the track and set the car down to see if it would work under load. During racing that day my fast lap for a 17.4 WGT car on 4 cells was a 12.7. I had a buddy time me and I just pulled the trigger for 5 minutes simulating a race. I went another minute past the 5 minutes and then handed the car to my buddy for another minute or two. The car never stuttered, never shut down, and felt just like my 17.5 4 cell car other than it was a little slower; about a second per lap. My transponder counted every lap as well!

I temped my motor and it was about 120*. During racing with a 4 cell it was coming off around 150.

So I went back to my pit, recharged the lipo on my TC1030, swapped the 17.5 out for a 13.5 and went back out to the track. Again I "raced" for 5 minutes+ with no problems. Only this time the car was exactly the same speed as my 17.5 4 cell car. I had the same fast lap, 12.7 and my average laps were a touch better with the lipo, I suspect from the lack of traffick and the flatter discharge curve of the lipo.

Both times when I recharged the lipo I only had to put in about 1500 mAh's. The voltage had dropped down to about 3.8 volts at rest. I would guess that under load it may have dipped to 3.4 or so.

I ran out of time but next time I will see if theres any room to gear up since the motor temps were a little lower.

I considered the possibilty that I had luckily just stumbled on a magical combination of electronics. I didn't have enough time to track test all the speedos I have, but I was able to bench test the following escs.

Sphere-Did not work
Sphere TC -motor and servo worked well
4 cell GTB-motor and servo worked well

The sphere, the sphere tc, and the gtb were bench tested using a JR 3650? 12th servo, a micro spektrum receiver, the same helios and spektrum module, a 17.5 novak, and no receiver packs.

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Last edited by andrewdoherty; 10-19-2008 at 01:34 PM.
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Old 10-19-2008, 12:02 PM   #89
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A standard AMB transponder won't work well on single cell LiPo. Novak does make a booster for the transponder (about $10 in parts can build one).

Some of the guys testing single cell are saying that the steering can get a little goofy on the straight without a receiver pack but I've never run without one to confirm.

I do like the fact that all you have to do is simply run a single cell (and maybe a receiver pack) and you're done. Nothing else to buy or modify.
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Old 10-19-2008, 12:07 PM   #90
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reenmachine, if you go with the 1S setup, inform me. I REALLY would like to see that and compare my pan car to yours or anyone elses at the club that goes the lipo route.
You bet. It'll be interesting to compare, to say the least. It will certainly be brushless as well.
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