6 Cell mod with AAA's question...

[momofx]

I am attempting to do the "6 Cell Mod" with AAA's and I am using all Duracell 1000 mah cells in series, so it adds up to 7.2V. Will this be safe on my R8?

[BART]

Yes, and will also be the most significant upgrade for the money performance wise.

[momofx]

Hey I have another question - how does the 6 Cell AAA mod compare to a Lipoly 2S2P 450mah? Still a day and night difference? Just wondering...

[mycrors4]

lipo will give more of a punch, because it has a higher discharge rate

so if u want kinda like a punch, get lipo, but if not, use the 6cell upgrade speed wise, it should be very close as the lipo=7.4v and the 6cell=7.2v

[Action B]

Originally Posted by momofx

Hey I have another question - how does the 6 Cell AAA mod compare to a Lipoly 2S2P 450mah? Still a day and night difference? Just wondering...

Handling wise, day and night. 2 batteries up high on the body doesn't really help with your center of gravity.

Straight line acceleration will be considerably faster with lipo

Top speed is pretty similar.

[PingPong]

On the dyno, the 6cell will be a huge upgrade to stock but I can't say anything about the lipos since I haven't found a motor that would work with them yet. However, I hated the handling of the 6cell EVO I have. Strait line speed was epic! but the handling was very sluggish from the extra weight on top. Totally different from a regular EVO.

[lol]

Strap down the extra batteries so it wont swing around, throwing off COG. Try to center it as much as possible. If done correctly, should improve handling a bit.

[Action B]

Originally Posted by PingPong

I can't say anything about the lipos since I haven't found a motor that would work with them yet.

What do you mean by this?

[fast tim]

i need ideas for a rear wing for my gtr

[lol]

Originally Posted by fast tim

i need ideas for a rear wing for my gtr

This is very related to our discussion. (: Look up designs online and try to replicate the one you like most.

And all motors work with Li-Po except ones that burn out really fast because of heat and power. :P

[reaper]

my experience is that 6 cell is good for drag or dyno runs , but due to the extra weight and limited choice of battery placement its not very practical for track cars
i found a fifth cell tucked into the rear bumper gives a good increase in speed and keeps the cog and overall weight down

[PingPong]

Originally Posted by Action B

What do you mean by this?

They always end up "smoking" when I run them with my lipo cars. I don't have much time to mess around with them however.

[momofx]

Okay I was looking at these Lipo batteries that work with the Xmods and most of them rate at 7.4v and approx. 500mA - now what I do not understand is, how come this is more powerful when 6 x AAA that are rated at 1.2V 1000mA x 6 = 7.2v at 6000ma or 6A ??!

I do not quite understand how the Lipo setup can be more powerful than that - can someone explain to me - Thanks!

[Howlsatmoonlight]

Originally Posted by momofx

Okay I was looking at these Lipo batteries that work with the Xmods and most of them rate at 7.4v and approx. 500mA - now what I do not understand is, how come this is more powerful when 6 x AAA that are rated at 1.2V 1000mA x 6 = 7.2v at 6000ma or 6A ??!

I do not quite understand how the Lipo setup can be more powerful than that - can someone explain to me - Thanks!

While the voltage is roughly multiplied by the number of batteries, the mAH is not. 1 AAA, or 1000, its still 1000mAH. Also with lipo you can keep your center of gravity low, and they discharge much faster; As said before it is much faster acceleration than AAA, but the same max speed. Something else to consider is AAA rechargeable's have a pretty fast power drop off, while a lipo maintains its max power output much longer. As an example, after maybe 5 minutes of continuous driving, your AAA's have dropped from being able to discharge 7.2V max, to maybe 6V max. After 10 minutes it drops significantly lower. A lipo keeps its continuous discharge of 7.4V until about 5 minutes before the battery dies.

As for lipo burning up motors, there's something else going on there, because a lipo pack will not burn up any motor. All my chassis run on lipo, and even the one with a stock stage 1 motor doesn't have any problems ( I use the same lipo pack in them all, just switch it out in a new chassis when needed). A motor is limited by the amp draw it is capable of pulling from the batteries, and a stage 1 motor draws about 1.4A, a stage 2 around 2.2 if I remember correctly, and on up from there. It won't burn up the motor until the motor itself is built to draw more than 7.4A, but those motors all need stacked FET's anyway, so a battery pack still wouldn't be an issue.

For the person that tried to hijack 3 different threads asking for wing ideas in topics nowhere even remotely related to your question, something tells me this wing is perfect for you.

[momofx]

Thanks you hit it right on the money

[dreamingISdrifting]

Well set out Howls, just to add on to that.... but the mAH is really determined by how the battery pack is wired out, it can be wired in a series form which is when the batteries are wired positive to negative so the initial voltage would be raised per battery, for example the xmod has a 4AAA holding tray and they are hooked up in a series. So if you were using say, 4AAA 1.2V 750 mAH rechargables it would have an end result at 4.8V@750 mAh. However the other way to wire it is parallel, this will raise the initial amount of mAH but keep the same voltage, so if you ran 4AAA in a parallel form with the same batteries the end result would be 1.2V@3000mAH, the mAh may seem outrageous but the voltage is not enough to power the board. The mAH stands for Milli-Amp Hours, so it represents how much runtime you should be getting, how to calculate the runtime is by multiplying 60(minutes) by (BP mAH/1000) / amp draw. So the formula looks would be "60xAH/AD", with AH being your mAH/1000 and AD being your motor's amp draw. So if you could run 3000mAH with a stage [email protected] the estimated runtime would be about 128 minutes, but since that is not possible to run it with 4.8V+ with less than 6 cells. But lets use something more reasonable like 4.8V@750mAH Nimh it would be "60x.75/1.4" you would get a runtime of about 32 minutes. But the formula is not 100% true, you will still have to incorporate the forces of friction and drag, so that will bring the runtime down, along with incorporating the servo voltage and board consumption, not to mention discharge percentage which is based on the rate of discharge (which is a headache just thinking about). So as an end result you might get around 21-26minutes of run time off 750mah Nimhs. But if you used LiPos or LiIon the discharge rate is much greater than that of Nimhs so it would boost your run time by about 6-9 minutes because the discharge rate is higher allowing for a higher efficiency rate so the motor isn't working as hard to draw amps from the battery. So as already stated Lithium batteries should not fry up your motor unless you are running a motor with a beastly amp draw rate such as a Chili or a Lightspeed X2.

Well I hope all of you enjoy reading this, it feels like i am typing my 8th grade report on electricity all over again..... lol

[momofx]

Right on the money again! Wow, you guys are really tryin to shut me up! lol j/k

[mycrors4]

lemme try putting this in a sentence instead of a paragraph, for those lazy people who dont like to read..(like me ) lol

mah doesnt determine power, voltage does

Mah= run time
Voltage= power
C rating= rate of discharge


so for example

Lets say u have a lipo

2s 10c 500mah(just an example)

so you have 7.4v discharging at a rate of 10 currents for 500 milliamps (if that makes sense)

bigger scale r/c like 1/10 or 1/8 uses a lot stronger batteries for example

6s 40c 5000mah lipo (this is the extremely strong one, usually use in 1/8 buggies and truggies) lol, and yet, they keep going ever stronger than this O.o)

so you have 22.2v discharging at a rate of 40 currents for 5000 milliamps

the more "c" you have the faster the car can accelerate, but too much "c" can burn out your esc/motor

the "c" is basically the "punch" of the battery

mah= run time, so more mah= more runtime

v=voltage=more power, so the more voltage the faster the car will go(speed wise)


err.. i just noticed i wrote another mini essay lol

[momofx]

Wow, I was watching videos on youtube of Lipo's going "bad" and ****, these things just burst into flames when there is a malfunction?!!

How long does a Lipo pack last in terms of charge cycles? Makes me wonder if I DO end up going Lipo, will I have to keep the xmod in a fireproof safe lol? Hey that does not sound like a bad idea huh - since I am gone so often from home...

Honestly, I am kinda confused now what to do power wise - 6 Cell sounds very safe but Lipo sounds mad power - I've been reading all over the net how Lipo is so powerful on the Xmods, etc. etc. - wow what to do what to do...

[mycrors4]

Originally Posted by momofx

Wow, I was watching videos on youtube of Lipo's going "bad" and ****, these things just burst into flames when there is a malfunction?!!

How long does a Lipo pack last in terms of charge cycles? Makes me wonder if I DO end up going Lipo, will I have to keep the xmod in a fireproof safe lol? Hey that does not sound like a bad idea huh - since I am gone so often from home...

Honestly, I am kinda confused now what to do power wise - 6 Cell sounds very safe but Lipo sounds mad power - I've been reading all over the net how Lipo is so powerful on the Xmods, etc. etc. - wow what to do what to do...

lipos last a loooooooong time, ive heard they last over 100 charge cycles

i was the same way you were, it made me paranoid, and now im still paranoid about lipos, im always afraid my car is just gonna burst into flames, but if you treat them well, its gonna be fine, just, treat them a lot battery than regular AAA's, pretend its a shelf queen, and you should be fine