Opinions please?
 

Ok guys, as some of you know, I am in the slow process of rebuilding my E-Revo. V3.0 will have the batteries on the right side with the motor on the left, were the stock nitro motor went. It will use a Revo 3.3 tranny with a center diff and rear brake kit so I can tune the brake bias as well as not be so hard on the speedo and keep the 2 speed. What I can't figure out is the battery situation...Its either 4S or 5S with a Mamba Max esc and a Neu 1512 or 1515. 1512 only because of weight, etc. because this is gonna be a all out racer. What are your opinions? I am not really concerned with running the MM on 5S by the way....

Sounds like a good project. Personally, I'd go with the 5s and the motor to go with it. For a given speed, you'd get more runtime with a higher turn motor with higher voltage. Of course, if you use hi-cap cells, like 8Ah-12Ah, the runtime point is academic. Just my $0.02.

Yea, I plan on going with 8000mah packs, maybe 12000 or 16000mah....I dunno about that yet, but what motor would you choose? A 1512, or 1515? I was kinda thinking about 4S just for the weight/size factor but...I'm not sure....

wow..that is some really high mah lipo's....got a link to them...would like to check them out

Well the 12000mah would be 4000mah TrueRC cells, and the 16000mah would be the 8000mah cells would be from TrueRC as well, but there one of the major namebrand cells. I just can't remember who makes em...It use to say on there website. Here is a link to the 8000mah cells. The MAJOR disadvantage with them is the width...

cool, thanks...squee

No problemo...

are you really gonna try 5 Cells with it.... I have a feelin' it will fry...

Chances are I will try it...A rep form CC told one of our members its ok...http://www.rc-monster.com/forum/showthread.php?t=4417

really?... wooah...mine's comin' in this week....

Yeah, runtime shouldn't be a problem then. :dft008:

I think a 1512 will work, but I'd go with a 1515 for the extra torque of the bigger motor. That's just me though - I tend to overengineer stuff...

Me to...I will probably go with the 1515. That and the Mamba should be a nice setup. I just don't know if I should go for 4S or 5S...

With a single battery on the right side, I would think that anything over 8000mah would be too tall and heavy.

I've ran 16 cells w/ mine, no probs. My 5s lipo from TrueRC should be here Mon or Tues, so I'll LYK as soon as I run it. I'm really not worried about it. :)

Thats why I was thinking of 4S2P 8000mah instead of 5S. My 3S2P pack looks right at home in there. It can be a decent bit taller without problems...I was also thinking of going with 2 packs so I can run them in something else.

The 1512 2.5d motor works nice on 4s. It has a kv of 2000. I have tested it
on 6s as well. It was pretty quick. I ran it on a 80b quark to.

CC Mamba Max is awesome, if it can run 5S..... best price ESC... awesome...

I've been using the 1512 2.5d/f motor in my truggy, and it has plenty of power. If you are trying to save weight, then I don't think you need the 1515 for racing. It will be overkill, imo.

So your saying that my 10XL on 6S LiPo is overkill for racing? :p I think I'm gonna go for the 1512 for several reasons:

A. It's lighter
B. It should be more than enough power for 4S
C. My favorite, its cheaper

I would really love for you to try it on the 5s. I don't have a MM or I would try it.

But.... 4s is plenty if you are building a full on racer. 5s just adds weight and you wont use the extra power.

The I have both the 1515 and 1512, and the 1512 pushes my trucks just as well as the 1515. I can't really tell a differeance in the torque. You cant use all the torque that either one makes. Just get the 1512. Its cheaper, its more than powwerfull enough and its lighter. All good reasons in my book.

The 1512-2d seems like the PERFECT 4s motor.

I run the 1512-2.5d on 5s and its ridiculous. I actually like it much better than the 1515-2.5d I also run on 5s.

The middle comprimise motor would be the 1515-1y. At 2200kv it would be plenty fast for a track on 4s and still able to run at silly speeds on 5s. Thats the Motor mike runs in his emaxx. He runs it on 4s for racing, but I saw him run it on 5s when he was in the area for a trade show and it was amazingly fast.

Thanks for the input! I will probably try it on 5S just for kicks once or twice since I have 2 3S2P 8000mah packs for my BPP LSP. Sombody else is gonna run a MM on 5S as well. I think my mind is made up on the motor. I'm thinking a 1512 with a KV of about 2200 like the 1515/1Y (not sure which one).

4S2P 8000mAh packs are over 1.6 pounds.
5s-6s will run more efficient than 4S with less weight.
I am going to run the Neu 1515 2.5d/F on 6S for racing.
The 1515 may be a bit too much but I like the power :017:

Yea...5S or 6S will be more efficient, but...the weight is a factor. Remember, the batteries are gonna be all on one side with everything but the controller on the other side. With 4S, it would have a better weight distribution.

:027:

A 5S1P 4000mAh pack will give you a better weight distribution than a 4S2P 8000mAh pack. you'd have 3 less cells with the 5S setup.
The question is, will the 5S 4000 mAh pack get you through your Mains. Unfortunately, the only way to tell would be to test it. :030:

I bought TrueRC lipos, they are poor, I got 4000mAh, not sure if the higher capacity use better cells but you get what you pay for. Having to buy MaxAmps.

That's from my experience using them. Dans good though, if somethings wrong he'll help you out to the end, just living in the UK, I don't have the time and money to keep shipping things back and forth, so I just want to move on quickly and get some new cells.

Nick, The trueRc cells are only 10c cells. at 4000mah thats only a 40A cont. 60A burst discharge. Thats not enough. Thats probably why you are having problems. The 8000mah TrueRc packs are fine. 80A continuous and 120A burst is fine.

Starscream, If he goes with the 5s1p pack, he will need much higher quality cells to supply the amps needed. A 4000mah pack would need to be at least 20c cont. 30c burst. to be effective. While they are lighter, they will cost just as much as the 8000mah 10c cells and only give half the run time. Its all a trade off. You are right though... For a pure racer, that may be the better solution, unless he has 20 minute mains to get through.:D

Yeh, well he said they were the same as the Maxamps ones, which led me into buying them. When I found out they weren't after a topic on this forum. Arn't the Maxamps 4000mAh 10c to? Well, 12c I think.

I believe the TrueRC 4000mAh cells were the old cells Maxamps used to use.

Yeah, they are most likely the older Maxamps cells if they were at all the same. Even the old Maxamps 4000mah cells should not have been used in 1p for most purposes.

Racing, being what it is, is not cheap so price is not a factor for me. Since we're specifically talking about racing, weight plays a major factor in the performance of the vehicle so your best over all performance would be achieved by running the lightest and most efficient system. Yes, at 1P you must use 20C Lipo cells. I never stated what C cells to use as I would asume 20C would be used in a 1P application.
I can race 20+ mins on 6S 20C 3200mAh so a 20 min main would not be a concern. I may run into problems though, if the mains were 25+ minutes.
My point being that
4S2P 8000 mAh maxamp pack = 1.6 lbs
my 6S1P 20C 3200 mAh pack = 1.2lbs
a comparable 5S1P 20C 4000 mAh pack ~ 1lb

The key is to determine how long you need to run so that you can adjust your mAh choice accordingly. Why race with more weight if you don't need the mAh...

The only reason to race with larger cap batteries that I can think of is to get the most out of the batteries. When you discharge close to the max continuous rating of the batteries, you don't get the full capacity, Ah-wise, that you would if the batteries were discharged at, say, half their max C discharge.

For instance, if you have some 4Ah batts rated at 15C (60A) and you discharged close to 60A, you probably won't get 4Ah out. Whereas if you had 4Ah batts rated for for 30C (120A) and you still discharged at 60A, then you'd get closer to 4Ah out of the batteries, which would translate as extra runtime.

Either way, we're only talking about a couple minutes extra at most in the example above.

In your case, since you are racing times so close to the runtime of the battery, it could mean the difference between finishing first or last if they die 1/2 lap left to go. Differences in ambient temps and slight changes in how much you gun the throttle can change the runtime too. Personally, if I was running that close, I'd go with 6Ah to be safe, but that's just me.

The run times I quoted are actual run times not estimated from mAh. But, you are absolutly right, you need to run the appropriate mAh for you race duration or you could end up going from 1st to worst :027:
I know from experience what mAh I need for my system for a particular race duration at my local track. The reason I run 6S is so that I do not have such a dependancy on current thus I am not as concerned with the need for excess mAh. I said I needed 60AMPS but its probably closer to 50AMPS. In any case, thats just another reason to run higher voltage so that you don't have to run excess mAh to provide the current as you mentioned above.

I need at least 8000mah....Thats why I said that. Our mains at your big races (points races; the ones that matter) are 30 minutes and some of the really big nitro races run 45 minutes....Thats why I said I will probably go for 8ah, but maybe 12 or 16,000mah... I think 12,000mah would get me 45 minutes...I guess I will find out soon enough...Anybody wanna buy a 9920 :p.

Is the 9920 in good condition?

Yea. Just needs to be reshrunk with some heatshrink tubing....It was smooth as butter last time I used it...

Yikes, thats a lot of weight to run for 30-45 minutes.
A quick pit solution would make life a lot easier and give your truck much better performance.

Yea. I have thought about that as well...Only thing is I need more than 40 amps continous and 60 amps burst...To be honest, my 3S2P 8000mah pack isn't really that heavy. I can't imagine 2 extra cells making alot worse...

The only problem is, you would need 3 more cells instead of 2 ;).

How so? 3S2P is 6 cells and 4S2P is 8 cells...

Oh, woops. I misread your post. I thought you were referring to making the 3s2p pack into 3s3p for more runtime, in response to starscream's post. Sorry 'bout that!