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Old 03-20-2009, 08:58 AM   #1
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Default 7.4v 2 cell lipo on a 1/12 scale?

Is there a reason no one is testing out 2 cell lipo on the 1/12 scale? After reading all the necessary adjustments you have to do to run a 1 cell 3.7v I'm still unsure. To me 7.4v lipo would be just plug and play.
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Old 03-20-2009, 09:19 AM   #2
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Is there a reason no one is testing out 2 cell lipo on the 1/12 scale? After reading all the necessary adjustments you have to do to run a 1 cell 3.7v I'm still unsure. To me 7.4v lipo would be just plug and play.
None of the currently available 7.4v LiPO packs in hardcases would fit in a 1/12 chassis for starters... One of the guys at my local treack was experimenting with smaller 7.4v sofpacks, I think he got some 2000 or 2100 mah to fit. He was running small 1/18 scale motors in the car to go with the higher voltage. THe car was crazy fast even with the tiny motor. I don[t think any of the current motors we use would make run time on a 2000mah pack.

It's really not any big deal running the 3.7 pack... I know guys running with no booster or receiver pack, there are some speed controls out now that work fine without them. Minie needs an rx pack or booster, but it's hardly a bother.

Before I drove the single cell 3.7 setup I was pretty against the idea, but after running it, I can definitely say I'm a believer. THe lighter car drives a LOT like a mod car from the early '90's, it feels light, slightly edgy, and a LOT of fun to drive. In another thread, Scottrik described the difference as like drivinig a sports car versus a dump truck, which in my opinion is a VERY good analogy... I would NOT want to go back to the heavy feel of a 4 cell car after feeling the 3.7 LiPO on the track.

To be honest, I was probably the most vocal critic of the 3.7 pack, but one day on the the track has completely changed my opinion. I tend to resist change, but this is a good change.
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Old 03-20-2009, 09:22 AM   #3
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I don't understand the people, which are trying with one cell driving. When you want drive relative slow, choose a motor with high turn winding. When you want to pay relative low to a battery, choose a lower capacity battery. High voltage + low current makes life easier for all components. You don't need a voltage booster for servo and receiver. Your motor operates at lower temperatures and your esc operates lower temps too.
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Old 03-20-2009, 09:23 AM   #4
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Some of us have tried it. A few swear that it's the "future".

2 cell will require extremely high wind motors or completely different smaller motors to work well.

Single cell isn't bad, some are using their current electronics with no modifications. Simple as plug and play.

Worst case you need to wire in a voltage booster and that's not very hard either.

I tried 2 cell LiPo in mod a couple years ago and it wasn't all that great. Runtime was a huge issue and whatever cell we end up with it needs to be able to work reasonably well in stock and mod.
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Old 03-20-2009, 10:52 AM   #5
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Is there a reason no one is testing out 2 cell lipo on the 1/12 scale? After reading all the necessary adjustments you have to do to run a 1 cell 3.7v I'm still unsure. To me 7.4v lipo would be just plug and play.
I know many people, who uses 2S Lipo or LiFePo. Most people use 1800mAh or more. A motor with 10.5 turns is as fast as 4 (Nimh-)cell modified, but tire wear is less.
Probably it's more a european thing. I heard US-tracks are a lot smaller and tighter than european tracks.
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Old 03-20-2009, 11:01 AM   #6
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+1
High voltage + low current makes life easier for all components. You don't need a voltage booster for servo and receiver. Your motor operates at lower temperatures and your esc operates lower temps too.
My 3.7/13.5 comes off the track at 98F-114F. I don't think temperature is an issue with the single cell.

Lower current and higher voltage don't necessarily mean lower temps. Wattage is volts x amps. Raise the voltage and lower the current, the wattage stays pretty much the same. IF the wattage goes down, the lap times get slower... if lap times are to stay the same, the temps will stay pretty close to the same.
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Old 03-20-2009, 03:40 PM   #7
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To be honest, I was probably the most vocal critic of the 3.7 pack, but one day on the the track has completely changed my opinion. I tend to resist change, but this is a good change.
I am and have been a big supporter for a cell change either to a lipo or LiFe-po. I just received my booster(a must have for the Tekin esc running 189) and am looking forward to trying out the 1s lipo. I have tried LiFe-po and love that, also very lightweight and much easier to fit in a t-bar car. The only drawback to either type of cell is that on a bumpy asphalt track(like we have here) the lightweight car tends to get upset very easily and can be quite a handfull to drive at times. Its in conditions like I face here that the extra weight of the nimh cells help to keep the car planted on the track.
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Old 03-20-2009, 04:08 PM   #8
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I use 2S2P LiFePO4 cells in saddle configuration (2x1100mah A123 cell) : http://www.rctech.net/forum/5539929-post7174.html. I like it very much, car feels very light and goes fast on asphalt.

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Old 03-20-2009, 04:13 PM   #9
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Is there a reason no one is testing out 2 cell lipo on the 1/12 scale? After reading all the necessary adjustments you have to do to run a 1 cell 3.7v I'm still unsure. To me 7.4v lipo would be just plug and play.
There's no reason. It's actually been explored and discussed ad nauseum. This thread was raging not more than two months ago:

http://www.rctech.net/forum/electric...uture+1%2F12th

I run 13.5/1S and am liking it just fine.
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Old 03-20-2009, 04:26 PM   #10
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I have been running 2-cell 21.5 in my BMI for about the last 6 months. I love it. Yes, it is much faster than 1-cell 13.5 or 4-cell-nimhl 17.5 if you choose to gear it to the limit. However, it can be gear to feel and drive exactly like the other options. Im using a 2000 mah 20c soft case pack.
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Old 03-20-2009, 04:43 PM   #11
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None of the currently available 7.4v LiPO packs in hardcases would fit in a 1/12 chassis for starters...
It can be done...



I would love to get into 12th but the added expense of having to buy new packs and potentially boosters/receiver packs is putting me off. I reckon there would be others in the same boat.
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Old 03-20-2009, 10:41 PM   #12
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I think a 2 cell smaller pack is the way to go. I am sure a 3000 or 4000 mah pack could be squeezed into a SMC single cell case. If we go 2s we do not have to go through an electronics cluster mess with the single cell pack.

Has anyone tried to have a 23.5 turn BL motor wound for something like this?
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Old 03-21-2009, 08:36 AM   #13
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speed is why.......it's cool if you are all by yourself on a track..because your wreck dosen't affect anyone but you.....add a few buddies with 1-12th scale missiles that are faster than they can control....you've got problems.
Plus there is never going to be a this = that concerning cell number and motor winds....more problems
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Old 03-21-2009, 08:40 AM   #14
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It can be done...



I would love to get into 12th but the added expense of having to buy new packs and potentially boosters/receiver packs is putting me off. I reckon there would be others in the same boat.
that car is plain ugly........is it a Tyco or a Hai Boxing??
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Old 03-21-2009, 08:43 AM   #15
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I would love to get into 12th but the added expense of having to buy new packs and potentially boosters/receiver packs is putting me off. I reckon there would be others in the same boat.
1/12th scale has been around longer than any other electric class. I've been involved since the first 1/12 scale cars came along. A LOT of evolution aloing the way to get what we have now. If you are interested in getting into 1/12, I'd respectfully suggest that you try it as it is... you won't be disappointed.

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I think a 2 cell smaller pack is the way to go. I am sure a 3000 or 4000 mah pack could be squeezed into a SMC single cell case. If we go 2s we do not have to go through an electronics cluster mess with the single cell pack.

Has anyone tried to have a 23.5 turn BL motor wound for something like this?
I'm pretty sure you can't get a 7.4 400 mah into the SMC 3.7 case... I dojn't see it geting much smaller than the existing 7.4v 4000mah LiPO's out there now.

1/12 used to be a 6 cell class. 7.2v was the norm for years. 4 cell came along in the U.S. when we started racing on small tight indoor carpet tracks in the winters. Summertime came, we went back outdoors and back to 6 cells. Europe ran 6 cell year round... Eventually, we evolved into a 4 cell only class. I don't see any logical reason to go back to higher voltage...

7.4 LiPO in 1/12 scales could be done, but it makes more sense to run single cell. A 23.5 would still be insane fast in a 7.4v 1/12 car. We'd need special 1/12 only motors to get the speed right... I'd guess something around a 26.5 or so. Now you'd need to buy a special motor (going rate for brushless motors is $80 neighborhood) that you'd only be able to use in 1/12th.

The single cell pack solves this problem elegantly... at around $50, the single cell pack is an easier buy-in than a new 1/12 only high turn motor. You only need one pack to go racing. Some speed controls run with no booster or rx pack. You can get a booster for under ten bucks if your speedo needs it, and it's plug and play. No complicated wiring. Most people who first get in to 1/12th scale say the cars are too fast... On the single cell, your existing 17.5 in a 1/12th chassis makes a VERY nice package... a little slower and a lot easier to drive than the 4 cell 17.5, not at all intimidating. Lightweight, less crash damage in an impact, hardly any tire wear. 13.5's on the single cell run about the same speed as current 4 cell stock 1/12ths, but again, less damage in an impact and greatly reduced tire wear.

The single cell really is the logical next step... I was not at all in favor of it when it first came along, but I was wrong. IT's hard to argue against something that works so well.
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