brushless conversion questions

[tom255]

2S2P is 2Series2Parallel.
Check BrianG Page to understand better
http://www.scriptasylum.com/rc_speed/_lipo.html

Nothing is ideal in our world, runtime depends from ton of factors. From Motor, weather, count in track style, track surface and etc.
In realtively small track where I am usualy run I get with 5000mAh pack 12 min in race condition. In this weekend I ran it on faster track with loose surface and i got 7min of running. 5min less I recorded 1600W peaks in my system.
All comes through experince!

[mwry13]

In breif,

say we have 2 7.4 volt 5000 Mah packs

If we have both packs in Series, the MaH stays the same but the voltage is doubled to 14.8

if we have both packs in para, the voltage stays the same but the MAH is doubled to 10000 Mah

[rcsammy]

ok, thanks thats alot easier to understand than how the guy on the maxamps chat thing explained it
so what difference does more or less voltage and more or less mah make to the performance of the car/battery? then hopefully i can work out which batterys to go for, im sure you guys could probably just suggest one but it would be handy to know why its the best:)

[Motoman]

Basically, if you kept everything else constant (like motor,gearing,...), then more voltage means more motor rpms so faster speeds. More mah or capacity, means you have more disposable energy and so the vehicle will run longer on a single charge.

you need to find the right balance of both voltage and capacity that works best for your application. Consider size, weight, voltage, capacity, expected speed, expected runtime, brand, and price. Usually 1/8th scale buggies run great on 4s. A light setup in 4s would probably be around 4000 - 6000mah, but some people use bigger batteries like 8000mah. The 8000mah batteries are great but as I found out they are too big for an 1/8 scale buggy both size and weight.

hope that helps.

[mwry13]

Also cant forget about amp draw...

Lipos are rated in terms of there C rating. The higher the C rating, the more amps that pack can produce under high stress conditions.

say for example you want a motor that will spin about 30,000 rpms which is a good starting point.

If you use a 4s pack with a 2200 kv motor you'll spin about 32,560.


if you want something comparable to 30,000 rpms on a 5s setup you'd have to run about 2000 KV motor

The RPMs in the end will be about the same but using the higher voltage of a 5s pack will yeild less amps drawn and when less amps are drawn... less heat is generated.

so in short, you can get a setup for any RPM range you want, it really depends how much you want to spend on a speed control, that decides it imo...

High voltage Speed controlls (anything over 5s ) are usually expensive and exotic... aka mgm

Lower voltage speed controlls are reasonable but you usually generate considerable heat when using them... aka mamba max

[rcsammy]

i think aslong as the price is reasonable it will be a MMM

so what sort of packs should i be looking at from here? www.maxamps.com
so far from the info everyone has given i know i need 4/5s atleast 100A continuous
personaly i would like similar performance to a nitro buggy amd runtimes long enough to make a 15 minute final(so around 20 mins to be safe) and at the moment it looks like im going with a MMM

or even better would be if i could buy just one pack(even if it is more expensive) that will last me 3 qualifiers and a final so 30 minutes(35-40 to me safe)

are either of those acheivable with the kind of setup im looking at?

[Arct1k]

i'd be looking at a Polyquest / Neu 4500 5s 30c or 5000 4s 25c - They would fit the bill nicely.

IMO my 5000 maxamps cells seem to be more suited to 1/10th scale than 1/8th.

[Arct1k]

Coming to the UK in two weeks - happy to post it for you in UK...

[rcsammy]

thanks for the offer but i dont think i will have enough money by then