brushless conversion questions

[rcsammy]

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

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) 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
thanks, sam

[Arct1k]

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

[rcsammy]

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

[suicideneil]

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.

[Arct1k]

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

[mwry13]

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.

[rcsammy]

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?)

[Arct1k]

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.

[rcsammy]

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

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?

[BrianG]

Originally Posted by rcsammy

...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

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.

[rcsammy]

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

[suicideneil]

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