80 Amp ESC for 3900 KV???

[tlo1360]

I want to put this set-up in my 1/10 Ruckus just to go to a brush-less system for now but I want to put max power to motor along with adding led lights later on.
I don't want to give up motor power not even for one light. I am basing all this off of my knowledge of power and power draws in full scale, I want to prevent this in my 1/10 scale. Any help would be appreciated.

Waterproof 3650 3900 KV Brush-less Motor with 80A ESC and programmer

 

[Fabio casa]

A 60 amp esc is pretty standard with the 1/10 scale size brushless motor

 

[tlo1360]

I finally found the spec sheet on the 3900 motor I was looking at and its max draw is at 69 amps. So, if I want to run the headlight taillight combo down the road the 60 amp wouldn't give me all the power I would want to have on the 2S lipo's that I do run. I go with the reaction brand so far it's a 7.4v that I ran on the 540 brushed system and got good results out of just my first pack. I have already got at least 8 hrs of run time through the battery plus a minimum of 4 hrs test time setting things up on esc and swapping motor already from a 15t to a 20t

 

[Steve g]

Fyi, the power drawn from the esc for the lights and servo and receiver is separate from 80 amp output of the esc. That 80 amp rating is strictly motor output. There is a bec inside the esc sends power at a lower voltage through the receiver wire. Those Chinese esc's bec are rated at 2 amps, though its probably even less. If you notice the esc is getting hot while driving, installing an external bec and not using the one in the esc will help keep it cool. I have a couple of these systems, and the best way to keep them alive, is to run a bec, install about 1000uf cap on the battery wires close to the esc case, and dont trust the factory waterproofing. You may not have any issues at all, but if you do, that will solve them.

 

[tlo1360]

with running the 1000uf will I need just one to connect both positive (+) and negative (-) wire?
will do I need to run One on each wire individually for best results?

As for the waterproof the most water that I have put my truck through is a light rain, not enough to even put mist on the electronics. I run mostly dry, dusty areas, or concrete. so no worries their. Only question on that is it better to use a can of compressed air on the esc or is using an air compressor OK once in a while instead?

 

[tlo1360]

I found this spec sheet for the 80 A Esc

80A CES specifications:
Continue current: 80A
Explosion: 480A
Battery: 2-3 S li-po / 4-9 S Ni-Mh Ni-Cd
BEC output: 5.8 V / 3A
Power supply plug: male T plug
Motor plug: 4mm banana plug
Dimension: approximately 43 * 31 * 32mm / 1.7 * 1.2 * 1.3 inches
And the motor specs show a 69A draw so I wouldn't be able to run the motor at full capability regardless of the BEC running the lights because, the 60A Esc won't put out a 69A draw current. But, I understand you on watching the BEC now for aux components on the truck. What would you recommend for a program setting to run on the BEC for a good avg pull from RX, servo, and lights?
I know that with some esc you can program a different level BEC on them, I currently use 2S lipo on my brushed system and I am thinking of running a 3.0 LVC alarm.

 

[Steve g]

With the capacitor, you only need one, (or 2 or more smaller ones that add up to about 1000) and you hook the positive side of it on the red wire, and the negative side on the black wire.
As for the 80 vs 60, im with you on the 80. I bet they exaggerate the ratings, so the 60 probably would fry if you had a motor that had a amp draw close to 60. I also think the motor would probably only draw its max amp on its max voltage. I've seen reviews for the goolrc 60amp esc combos where people say it worked great on 2s, then fried when they used 3s. But these same people didn't do the research you did, seeing the motor draws more then the esc can handle, then blame the esc when they max the voltage of it. I have a 3900kv on a 60, probably the same motor you are talking about, and i wont be using 3s on it. Been great for over a year or 2 now, I'm sure if i used a 3s it'll fry. Wish i went with the 80, or even the 120, but it was a sweet deal for the combo.
The bec setting depends on what the ratings are what its powering. Most recievers are rated at 6v, as are stock servos. So 6v is safest, unless you're sure everything can handle higher voltage and you need the higher voltage, then you can go up to the max ratings. 3 out of 4 of my setups are rated for 7.4v, but i only have 2 of them set to 7.4. They are crawlers and benefit more from the higher voltage and stronger servos, my bashers i keep lower because i dont need the max torque and speed of the servo, and hopefully that will make everything last longer.
As for lvc, 3 is a little low. Usually 3.4 to 3.6 is more common. You can go a little lower, say 3.2, if you have the type of lvc alarm that plugs into the balance leads of the battery. Those monitor individual cells, where as the esc monitors total voltage of all cells together, so if you have a weaker cell in the battery, it'll drop lower then what its set to, potentially causing premature failure of the battery.

 

[tlo1360]

Thank you very much for that bit on the LVC I haven't done that much research into that I have heard over a multiple extension of videos where all of them are running in low 3's for their LVC. So I figured I could run about the same as them, but i will only be using the LVC interfaced within the ESC itself so good to know on that one. As for the moor combo you can tell through the reviews that some of these people did not resaerch what they wanted they just wanted the cheapest and they payed for it but I take into account all measurements I can now that I have done all the rookie mistakes ( 200$) worth of learning so far. HAha the misses wasn't happy about all of that So now I learn as much as I can before hand. do you know of a good brand of exterior LVC or BEC alarms that work better than the ESC internals?

 

[Steve g]

I bought a few of the bx100 lva from china off Ebay. Same internals as the venom and turnigy ones, but cheaper. Can get them with or without a case too. I got the cased ones and glued them to lipo batteries i run in the car with the goolrc esc. Sometimes after a hard crash it can some unplugged, so good idea to check it if you crash or have a bad landing. With a good esc, like castle or tekin or hobbywing, etc, it's not needed, but not a bad idea to use as backup. I have a tekin rx8 in one of my cars, and the lvc on that i had set to 3.4, but on that particular esc, you need to select your battery size, 2s,3s,4s,etc, and one day I set it to 2s so my young son could use it, and the next time i used it, i used a 3s battery, and forgot to select 3s on the esc settings, and i didn't realise it untill the voltage dropped to about 2.7v per cell, ruining my battery. Now most escs have autodetect, meaning it knows the cell count of what you use, so that wont happen. Had i had one of these lva as backup on that truck, it would have saved a battery. Well theres one in it now, so it won't happen again.

 

[tlo1360]

now I am debating using one of those as well. I usually only run the truck for about 30-40 min when it was brushed on 2 separate 2 s 5000 mah lipo battery. I wasn't temp checking motor either, but nothing ever felt too hot too touch after running.both batteries are 7.4 v by the way. I plan on running a new brand of 2 S to see if I can get either run time or performance out of them might go one of each. LHS was explaining something about so many mah counts towards run time or something like that but the one i have has been through some really hard hits and even dragged a few 100 ft or so and still gets full charge and has no problem delivering power when needed to the brushed system. But after reading your earlier post I re-thought my idea of running a 3.2 LVC to about a 3.7 no more than 4 total because it is fun to bash as long as you can but, batteries by far are not cheap for what they are.