Lipo questions
 

I have an Emaxx with your 9L/9918 combo and am considering going with lipo cells,I see in your ad for the Warrior 9918 it says "useable with lipo cells" exactly what does this mean?

I am not sure "exactly" what it means, but I will forward this question off to BK directly and post a reply when I have a clear understanding of what this means.

While we'er waiting I have more questions.I've been asking around at local hobbies shops about a lipo setup for an Emaxx,but with very little success.They either have no idea or are strongly against it.I understand the dangers involved in both charging and bashing relative crashes but the extended runtimes and lightweight keeps me interested.What little I've learned is a company called ThunderPower makes a Lipo pack that has a built-in device that cuts the power before the cell runs down to low and damageing it self otherwise there is a regulator that can be bought and manually added to the pack.Is this accurate?

I already bought a charger that can charge Lipos.I currently run GP3300s,two 7 cell packs(14 cells=16.8 volts)and dont want to give up the excellent power,but I've heard that with lipo two 7.4 packs(14.8 volts) when fully charged is equal to 16.8 volts,thus no power loss.Am I hearing accurate information?

This supplier is cheaper than ThunderPower:

http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MEWA:IT

All of the concerns you mentioned are valid concerns. Care must be taken when using these cells to avoid costly and/or disastrous repercussions. Having said that, I too have been bitten by the lipo bug! I haven't gotten my hands on the safety device for avoiding over discharge, but I am careful not to overwork the cells. I have played quite a bit with the lipos in my tc3 and absolutely can tell you they are awesome. I did run some in my e-maxx a few times as well, but the packs I have aren't truly up to e-maxx duty, so I have been very careful. A 14.8 volt lipo pack, of the right configuration (strong enough to discharge at a high enough rate) will definately feel more like 14 cells than 12 cells (nickel cells). They seem to hold their voltage better and have excellent punch. The 11.1 volt lipos (Kokam 2000mah) that I use in my tc3 (used two packs in parallel -so 4000mah and 11.1 volts) seemed every bit as punchy or maybe even a little more punchy than my 12 matched, high voltage gp3300 batteries in the e-maxx! The 12 cell gps topped out a little faster (as voltage came back), but the lipos are impressive. The two Kokam packs also weigh about as much as 5.5 3300 cells, so the truck lost over a pound and had 4000mah worth of runtime! I will reserve my e-maxx for some better lipos in the future (some day, I will stock them in the store), but my budget and time hasn't allowed me to get the bigger cells. I would also try to attach the batteries in the truck in such a way that they are not prone to damage (from rocks being thrown by the spinning tires or bottoming out on a rock in the back yard, etc.). I have seen a 7xl motor run on 22.2 volts and it was about as crazy as you could imagine. The batteries put out a bit over 2000 watts in this truck (over 3hp!) and was pretty insane. The guy ended up overdischarging them on a run (ran too long) and ultimately destroyed the cells 9$$$ out the window). I say go for it, but be aware of the downfalls and take steps to avoid costly mistakes. Proper charging is another story, but it sounds like you have done some research already. Just be careful. I know I plan to keep using them!

Hey Mike thanks for being so prompt in your reply.MMMM,have you had any lipo/Emaxx experience as of yet? I'll take info you have to offer.

I haven't had a personal experience with lipos myself. I've just spent a lot of time researching them. The amount of mAh these things can have is amazing! I've seen 10,000 mAh packs!

Here's an overdischarge protection circuit for lipos. You'll need it if the pack doesn't already have one built in.

http://www.newcreations-rc.com/Produ...number=Lisaver

In order to keep the costs from getting to out of hand I was looking for something in the 6000 mah area.Its been awhile since I saw these numbers so correct me if I'm wrong,a stock Emaxx with Titans and 14 cells draws 30-40 amps continuiously and can have bursts of up to 70 amps.When looking for Lipo cells in a brushless setup will these numbers vary much?I've seen Lipos that can handle 60,90 and 120 amps,which is right for me? THX

What voltage are you gonna run? On 14.8 volts, I would look for something that can handle at least 60-80 amps continuosly and peak over 100 amps. A heavy truck with big tires and high traction really draws power on acceleration. You may get away with a weaker cell, but it will be pushed and will not last as long. The 6000mah packs you mentioned: what rate can they discharge at (12c? 15c?)? Got a link to them?

The Thunder Power Batteries list the discharge rates:

http://www.thunderpower-batteries.co...batteries.html

The 6000 and 8000 mAh batteries discharge at 8-10C with 15C bursts. The 6000 mAh batteries are rated for 48-60A continous and 90A bursts. The 8000 mAh batteries are rated for 64-80A continous and 120 A bursts.

I personally wouldn't buy less than the 8000 mAh lipo.

The 8000mah packs are the safer batteries for sure. There are other batteries with 12-15C discharge rates, and Kokam is said to be releasing some 30C discharge cells!

Thanks MMMM for listing the link,that is where I was looking.Because my charger can only charge 3 cells max I would have to go with 2 cell packs.2 packs of TP8000-2s4P 8000 mah at 7.4 volts.I didnt hear about Kokam but I did hear that Hitec was releasing some lipo packs though.I may have to hold up a bit to see what they have to offer.

I hope the prices come down. Right now they're just too expensive!

I spoke to Alex of BK Electronics at great length today. Basically, the voltage cutoff is 2.55 volts per cell when using lipoly cells. This is a little low if you talk to most people, though. Their next generation of controller will have a fully adjustable voltage cutoff, but they are a few months out. They are also working on a pair of controllers designed to work on low cell counts and up to 12 cells for cars. These new controller should be at or below the warrior controller prices, but will function better than the warrior on low cell counts (warrior has a 5.5volt bec cutoff, which causes problems on takeoff), while the new controllers will have a 3volt bec cutoff. This has been tested by some famous onroad guys in a touring car so far, and I should get one for testing in a few weeks. These won't be available for a few months, but it sounds as if it will be a great option for low cell counts at warrior level pricing! The 60 amp version will be released first, followed by a 95 amp version! They are working on some new motors as well that are said to perform as good or better than the Lehner motors at a lower price point. I will be sure to keep you posted on the availability and performance of these items as they arrive.

sounds interesting

95 amp version
 

put me down for one of dem 95 amp mamma jammas - for my XXXS - those nitro guys wont have any idea what hit em - :D

If they work well during testing, I will stock a bunch of them. they sound great and the price should be pretty reasonable as well. They are a couple months away at the least, but summer is a couple months away!

Get the polyquest packs. I have the 4s3500 packs and they're about 7 cells worth of subCs but can delivery about 1 HP continuous. For stock emaxxes, get the 4s3100 packs. They fit in stock trays and can handle 12C continuous and 16C for 10 second bursts. You can get 4s3100 and get two and parallel them for 6200 mah and peak out around 100 amps w/o too much probs. Great for run time and light weight. I went with 8s3100 and went with a slower motor to lower amperage, reduce heat, increase efficiency. Always use the highest voltage possible, get a slower motor and you don't have to worry about heat again... plus more run time.

BTW, I can bash for over 20 minutes when running my 6s3100 pack on my emaxx! Bashing means mostly 35 mph in first gear and occasional 50 mph bursts in second gear. :) WAY TOO MUCH SPEED.

I have looked at the polyquest packs and will probably stock them when I pick up a Lipo line. I have some Kokams (2000mah, 15c discharge) that I use in my tc3 (and occasionally in the e-maxx). They are a little light for maxx duty, but I ran them in 6s on an xl2400 and it ran very well for a good bit of time (around 8 minutes before I stopped the run, geared for around 30mph). Eventually I will pick these up, as well as a charger or so capable of charging them.

I've used the 2000 mah kokam 11.1 volt 15C packs in my TC4 with a Hacker C4012s (3500) geared about 10:1. I've also used 14.8 volt same pack. Those batteries on my TC peak out around 40 amps on a carpet track with rubber tires. Tops speed is 30 or 40 depending on how many cells I'm using - obviously, I'm geared very short (small pinion) so I can reduce amp draws. It makes for a very lightly TC - and because the CG is actually higher, more prone to traction rolling... but lighter so everything seems to react a little faster and crashes don't break as many parts. I don't intend on going more than 4s with my TC4. I did make a 6s pack, but I have yet to use it on my TC4. Besides, beyond 60 mph, it's pretty hard to control. Anybody interested in a Kokam 22.2 volt 2000 mah pack that fits into the stock TC3/TC4 chassis? Never used - I did take it apart and reroute the wires so it would be shorter so it wouldn't cause voltage spikes into the controller and destroy the capacitors.

BTW, I've pushed one 2000 mah pack and got over 100 amps from it!!!!! I had it in my TC4 with a lehner 1515 5 turn motor (that motor is like 11,000 rpm/volt!!!!) The batteries got damaged by that experimental run so I don't recommend 50C for a 15C pack. :)

I run the basic 4200 in my tc3, with two 11.1 kokams in parallel. It flies and runs for quite a while. I ran the same batteries in series in my emaxx with an xl2400 for a run or so (geared for around 30mph). The runtime was good, the power was great, but I haven't run it like that lately, because I don't want to wreck the batteries (I use the batts in the tc3 normally). How do you like the tc4? It seems remarkably similar to the tc3. Is it worth the upgrade?

I don't know - I've never had a TC3! I had a pro4 previously and hte TC4 seems to be a little more forgiving to drive and easier to drive out of the box (I could never get used to the one way front diff). The parts quality isn't quite Pro4 - but then again, it's not a factory team. I don't need to run a 4200 in my track - it's only 70 feet by 40 feet. There really is no use going ove r30 mph cuz the track is so small. In fact, when I'm using 4s, it's too fast for that small track. Going 0-40 in 1 second gives incredible torque steer - almost no front traction also. In addition, after about 10 minutes, the diff outdrives start to melt - even if they're REALLY tight to start with. So, now I've got metal outdrives.

Mike, you should really use a smaller rotor motor for TC's. Get a 400 series motor. The "spool up" is way quicker. When comparing the basic 3600 vs. a c4012s, (3500), the Hacker is quicker and more responsive. Same top speed. With 1/10 tc, the limiting factor is traction. There is no way you can put down 700 watts of power to the ground on a 3 lb TC. Doubling up on the batt is definitely a good thing - with the 4200 geared approx 10:1, you'll be pulling about 50 amp peaks. Geared just a tad taller, you'll pull 60 amp peaks easily. Good thing you're doubling up on the 11.1 volts.

Lipo
 

Well it seems that the time has come for me to prepare for a lipo/brushless for my XXXS graphite TC - Which setup would be a good setup for me - i tend to be a little hard (understatement) on the throttle. I dont want any problems - My track usually has quite a nice long back straight with a couple hairpins in the infield - I have no idea what is what with lipos - I will get all my stuff from Mike - All of your input is welcome......

Young,
I have a hacker c40 8s that I have been thinking of putting in the tc for a while, but I just haven't gotten around to it. I have experienced the same thing as you, though. The smaller motors spool up quicker (same principle works on the e-maxx). I also have similar drive issues with the tc3 (torque steer, hard to hold under pure acceleration). I should be getting some high rpm outrunner motors in soon as well, which will have to be tested, but one motor reaches 7500 rpm/volt. It should fly in a TC!

Mike, I've had one motor go 11,000 rpm/volt and another go 9,500 rpm/volt. It doesn't matter how fast a motor spins. It'll only spin so fast before it's breaks. Those high KV motors are way less efficient too. The high KV motors are only good if you are absolutely limited to running only with 6 cells or other low voltages. Since you're using lipos, high KV really just doesn't matter - in fact, it'll just run hotter and destroy controllers and batteries.

If you want to run 11.1 volts, get a polyquest 11.1 volt 4400 mah pack. Fits in a standard 7cell location - just a tad taller so you'll have to back up the threads just a little. Or, you can go 14.8 volts 3500 mah. Both packs are the same size. These packs will deliver 1HP easily (700 watts). Just be VERY careful charging them and read about all their safety stuff before you get into it.

talk about high kv motors;

I've got a mini-t with a mamba 8k, it sure is one fun ride, if i had place for a 6S (and if the controller was able to handle it) i would also drop in a 4200

http://www.serum.demon.nl/mini-t/CIMG2331.JPG

Not a monster, but one fast little bugger.. (on 3 S it is rather quick (understatement))

I run it with the 1650mah maxamps.com 3s packs

I had a mini T with the Mamba 8000. I ran it 3s and measured top speed at 39 mph with 13 tooth pinion. Definitely fast - but not very controllable due to it wanting to do too many wheelies - so I sold it.

That is a sweet lookin' mini! HotnCold has a rc18t with the 8000kv lipo. I am waiting for the outrunner system for my rc18. I never dug the mini t, as I pretty much am mostly interested in 4 wheel drive (although I still like my stampede).

You can lower it real good, not to much wheelies now..

(roaduse) chassis is about 1 cm above the road.

I drove it a few days ago, not one single flipover.. fulspeed, nice long speedrun... And suddenly.. there he was... That monster..

My sisters Berner Sennen.. hit the poor monster at full speed.. The only plastic piece making part of the frame shredded in pieces..

And the dog didn't move a mustle.. He's affraid of my savage though.. (good for him to..)

And yes, 4wd is an easier ride! Just love the 2wd little nervous thing. Reminds me of my old tamiya frog.. Good oll' frog!

Lipomaxx,

I have been playing around with the lipos for a little while, and I have read a ton of info and safety stuff regarding them. I also completely agree with the high voltage, low Kv motor practice. I just happen to have the hacker c48s already. I really like the basic 4200 in the tc3, but I have been interested in the smaller rotor motors to see if becomes more tractable/driveable. I have also thought about running the cells in series on a basic 2100 motor. Performance should be similar (well, on paper, the performance would be identical), but I woder if the setup would run cooler for longer than the 4200 and parallel cells. Have you tried similar setups in your TC? I know you have a data reader and wonder if you have graphed any similar testing information. I am certainly interested in this info.

Actually, I've done test on a c406s (7000) with 2 cells vs. a c4012s (3500) with 4cells. The 12s is much more efficient than the 6s. Theoretically, RPM should be the same, but because there is less voltage sag, the RPM is higher with the slower motor and higher voltage. In addition, everything did run MUCH cooler and did not thermal the controller.

I don't believe you'll gain much going slower than 3000 rpm/volt. It seems that the small RC motors seem to peter out around 90% efficiency. So going 6s on 2100 isn't going to be much of an improvement vs. 4s on the 3100. But definitely an improvement over 3s on the 4200.

Going with a smaller lighter rotor doesn't make the car more driveable - it makes it more BALLISTIC! Acceleration is instataneous.. snappy... no spool up. When comparing the B506s (like a Feigao 6s), it was actually slower and pretty lazy on the track in my XXX-S G+. Going to the basic motor, it was definitely faster and still kinda smooth. Going to the c40, it was even quicker - so quick! I wish I had a vid. of my tc4 with 4s with the c4012s motor. Geared only 10:1, top speed is around 40 mph but it'll get there sooooo fast. If traction wasn't such an issue, I'm pretty sure I can do 0-40 in 1 second. I think I read the last RCCA and the TC4 did 0-40 in like 2 seonds with the 12 turn motor (if I remember correctly).

Another reason I have a hard time justifying going above 4s in a TC is packaging. It's hard to find a 6s pack to fit into stock TCs - the Kokam 2000's do fit - but you have to have them end to end and they barely fit. In addition, I really like the U-Force 75 for my TC4. I used to use the 12.97 fwe but that was difficult to place. The Hacker Master was kinda jerky and for some odd reason, there was always a slight lag at startup - not cogging, but literally a lag of about 1/4 to 1/2 second when I hit the gas.

I have had the same experience with the Hacker controller. I have an 18.97 in the tc3 now (not the kw/kwf - no heatsink) and I can't complain. I think the smaller motors have a slight advantage in acceleration, but the setup I have now is definately no slouch(don't think I need it to be any quicker!)! I have heard good things about the u-force, but I haven't tried one. Schulze is not famous for warranty backing (in fact, they always find a reason it was the users fault!). They are slow to turn things around, too. But that is partially because they are so far away. BK is definately quicker and seems to back their product pretty well, too (not that Schulze doesn't have killer stuff, but when it fails, it gets expensive - and they aren't cheap to begin with!). I have heard good things about the mgm controllers, too.
i am set up as a dealer with them, too. I just haven't had the budgetary means to add them to the lineup yet.

The 18.97 is a great controller no doubt, but the lack of BEC makes it difficult to package into a TC. In addition, the U Force 75, even though it's has less amperage rating, I believe can probably run more constant current due to the heatsinks. also, the controller is just about watertight too. The U Force can also be adjusted - one of the aggravating things about the "future" is that they really can't program any kind of drag brake unless you really fool around with your controller. Makes it kinda hard to drive. With the U Force, you can actually setup drag brake, min. voltage, and has unfortunately a 5.0 volt BEC... but it's still built in. I had a Micro1895 about 2 years ago or so and it was okay, but it cogged and wasn't quite as smooth as Schulze - plus they cost more! I might try the MGM if I hear a lot of good things... but I'm waiting for a 50 volt 100 amp version from Castle Creations for a 14s lipo setup on my emaxx!!! I'm going to need a 1200 kv motor soon!

Castle is currently working an a new mamba, but they will sell it in combination with a motor. They are currently looking for a motor that is more efficient.. (they tried all sorts of different brands/types) The controller was ready, that's what i understood.

BK is also working on a pair of controllers that are said (By BK) to be designed with the 1/10 car in mind. I spoke with Alex and he said the low cell count cogging is gone. There will be two versions (60 amp and 95 amp), both rated for 12 cells. The 60 amp version will be out first. I should have one for testing in a month or so. The 60 amp version has already been tested in a touring car by a big name on road racer and is said to be very smooth at all speeds. I hope they are as good as they sound. The price will be around the warrior price range or slightly less as well!
I agree that the u-force could likely handle more continuos current. I actually think the 18.61 with a heatsink ("k") can handle more current, based on trying them both in my e-maxx.

Petty they are only for 12 cells..