brushless conversion questions
 

hi guys
im looking to convert a buggy to brushless and hopefully race it as im geting fed up the the unreliability and hassle of nitro engine and the slowness of my brushed rustler:lol:

im hoping to get it done within a month or two(when i have enough money)
i was very impressed with the rc monster products like the motor mount, battery mount and pinions so i think i will use those to make it a bit easier, i have not yet picked a model to convert i will just see what comes up on ebay or forums.

its the brushless and lipo setup i was hoping you guys could help me with, as i will be racing in the nitro class i would like a setup which has similar performance to a nitro buggy(or even better:mdr:) my budget isnt massive but i will spend what it takes to get the right setup
i have had a look around a few shops but cant realy make sence of all of the numbers, so if anyone is able to explain what it all means and suggest some good brushless setups, lipos and chargers that would be great :wink:
thanks, sam

Best bet is to read up on this and work up a budget...
http://www.rc-monster.com/forum/showthread.php?t=5115

thanks, was an intersting/confusing read
so i think a 4s battery would be best? unsure of what mah i would need though
realy all i know is that i would like it to get a 1/8 buggy up to around 45mph and atleast 15 minutes runtime(is that reasonable? i have never run brushless and lipo only brushed and nimh and i guess lipo and brushless should last longer?)

the 1/10 mamba systems seem reasonably priced, will they offer a similar package with the 1/8 monster max? or could i find somthing cheaper? the Feigao motors seem very cheap

also what is a BEC?
thanks

There will be a MMM esc & motor combo for about $300, so that would be ideal for you really- saves the hassle of guessing which esc and motor to buy.

Run that setup on 4s, and it will easily keep up with the nitro buggies- run it on 5s, and it'll blow them away (and you too I bet!). As for which lipos... rule of thumb I stick by:

Anything that can provide at least 80-100amps continous for a vehicle this size weight really (mah capacity x C rating = continuous rating). Plenty of brands to choose from, have a read around to see what others like & recommend.

BEC - Converts higher voltages to a lower level - normally to 5/6v for servo's and RX to work.

I just sold my setup (financial issues) and it was purely a racing setup

4s Neu 30c packs
Neu 1515 1y/f
Mamba Max with the usual mods
BEC set at 7 volts ^_^ fast servos are the #&!*

Car really doesnt matter all that much... i found that kyoshos had a ton of room to play with... it took me a week or so of fidiling to find a CG i liked with battery / esc setup and all as well as the setup i used

8k front diff oil, 50k center, 3k rear

fiegos are cheap but they run hot (very hot I guess)
-Go with the MMM controller (castle has taken preorderes so I have to assume they will really release it when they say they will (end of may?) But I think the MMM motor is still in waiting. I don't follow castle, so I could be wrong.
-For racing 4s is sufficient, you could run 5s, but it would only be giving you more top end speed (which isn't what you really need on a track in my opinion).
-Most people go 5000mah to 6000mah, some go high (8000mah or more) to make absolutely sure they will have enough juice for anything. But a larger pack will add weight and slow you down.
-find an inexpensive roller, BUT it would be in your best interest to make sure a local hobby store sells spare parts for that brand/model.

thanks for the advice, looks like i will wait for the MMM
unfortunatly my lhs is very bad and overpriced so i dont shop there often, mostly buy my parts online... so the upside is that i dont have to worry too much about what chassis i buy
although i do like how the 8ight has the steering servo and receiver box way at the front which would make mounting the receiver easier/neater

will i need a BEC or a low voltage protecter if i use the MMM controller?
and what sort of runtime would i expect with a 4s/5s lipo pack?(unsure of mah yet need to have a look around... maxamps are cheap are they any good?)

No external bec required with MMM as it has a switching one - mixed results on maxamps with 5000 cells on 1/8th cars. Enerland / polyquest / Neu are nice at 5000 4s/5s. ATB

My lhs is overpriced as well, but there were weekend when I would break something on my T4 and I could drive up and buy the overpriced part so that my weekend was not ruined (instead of waiting till midweek for parts via internet).
Whereas I bought my mp777 roller before checking to see that none of the 3 hobby stores in town carry kyosho parts, so if it breaks on Saturday (practice) I am out of the game on Sunday, unless it is one of the parts I have spares of. Although I always seem to break something I don't have any extras.

Edit:
Maxamps aren't very well liked on this board. I have some and they seem to run great, but I don't have much experience with them yet. Additionally you can't be quoted a runtime without picking the mah as runtime is dependant on mah.

hmm well if i go for an X1CR or a hyper 7 i already own nitro versions of them so i have a few spares, although the hyper 7 is a bit old for racing

i tried the calculation for continuous rating (mah capacity x C rating = continuous rating) i picked one at random its 4s 6000mah 20c(what does the C stand for?) so i get 120,000 does that mean 120A continuous?
then there is a 5000mah 25C version which works out at 125A continuous :neutral:

one other thing is a charger, do i need a seperate balancer(right word?) and charger or do they come in one
does anyone have any recommendations?

When you do the calculation, remember that 1000mAh = 1Ah. So yes, 120,000mA = 120A.

Some chargers like certain Hyperions and FMA have built-in balancers. Personally, I like outboard ones for a little more versatility...

C is the dischare or charge rate.
1C =1xstored energy
aka if you have a 5000mah battery
1c (you usually charge rate) = 1x5000mA =5A
or 20C (battery discharge rate) =20x5000mA = 100A
Most batteries will post multiple C numbers for discharge: the most common is the continous, but they may also post a peak or burst or susutained or whatever other word they feel like using. But Continuous is the number you would care about most of the time.

is it possible to talk to any of you guys on MSN messenger about lipo batterys? as i have been looking around and im now very confused and have lots of questions which would take a lot of forum posting:sarcastic:

Trouble with that is that no one-person has all the answers, so its cool to just post up a long list, and number each question. That way, people can chime in and answer as many questions as possible :yes:

ok then :)
well i went onto maxamps.com and was looking around
and i saw that alot of the batterys are 2S2P or 4S2P.... and im a bit confused with the 2P part, so could anyone explain that please?

i was looking at other peopls conversions and was amazed at the runtimes people were geting 30-45 minutes on one pack is brilliant, if i could run 3x 5minute qualifiers and then a 15minute final(30 minutes in total) with just one battery then i could afford to spend more on one good battery rather than two not so good ones

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!

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

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:)

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.

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

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?

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.

Ok, given my experience, I would suggest to use a MMM, and a medusa 36/60/2000, in the V2 line. Run that on 5s lipo and you will have a cool running system with plenty of power for a buggy. I run a 36/60/1500 on 6s lipo in a hyper8 buggy and it does fine. Very nice motors for the money. I would stay away from maxamps, as there are other battery choices that will perform better and cost about the same.

So my suggestions, with links:

MMM : http://www.rc-monster.com/proddetail...steresc&cat=21

Medusa 36/60/2000, found on this page: http://www.medusaproducts.com/motors...MR036060XXXX-5

Battery : http://www.rc-monster.com/proddetail...5S_3700&cat=18

The rcmonster store can also provide you with the motor mount and battery tray, plus the pinions and other odds and ends that you need. You could buy a neu 1512 motor from there instead of the medusa, but the medusa is on special right now.

yes i do plan to get the motor mount and battery tray from rc-monster
are there any similar motors that are available through rc-monster so i could make the whole purchase from one shop as i imagine shipping to UK and customs will cost me alot
what runtimes do you get with that setup? i was expecting to need a higher mah battery

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

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