Minimun amp rating of and esc for 2s & CMS7700
 

To match up an inexpensive esc with the cms7700 motor on 2s. What would be the min amp rating of the esc to look for?

This one suck current like russian drink vodka. Mamba max is the cheapest solution out there. If you don't like it try Speed passion GT or Tekin R1pro

Thanks. I still would like to know what the minimun amp for an esc could be. What's BrianG been doing lately? :whip:

This should be on his calculator web page under the heading 'All the crap that Gee doesn't know how to figure out his self." That would not be a small page either.

I'm sure BrianG page has all the information I need to get my answer. Just don't know how to.

The amp draw depends on the load placed on the motor by what you've got it in. So you cant really know unless you put a meter on the system and find out.

I'm not sure, but I do know the 7700 is a hog. The MM esc will get quite warm while pushing any 1/10th off-road with the 7700 motor. 1/10th on-road might be ok. I'd guess you'll be in just under the 100A range pretty easily if it's in a decent sized vehicle, but that's a wild guess.

Like mriccucci said, it depends a lot on the application and load on the motor. Perhaps if someone is running a similar setup as you will be running and is using the same running gear you can get some input from them. We'll need to know what your plans are though.

J.

Sounds like a job for the MGM 8012!

Okay, I guess I will have to give it up. I know there's better setups and the villian isn't stable at higher speeds and all the kinds of different motors that would be better. But I am not asking of those questions. Just so I don't get bombarded with post telling me which boat would be better or what not. I think you know what I getting at there. Just looking for what min amp esc to run in this configuration.

Here is what I am working with because it sitting here not being used. 2 - CMS7700 motors. Villian IV and 2s batteries. I was searching for 2 inexpensive esc to run in the villian. I came across these esc and I liked the features and water cooling built in. The prices are not that bad either. I would be getting water cooled jackets for the cms7700's and keep the villians gear boxes to adjust the setup with different size pinions. Ofcourse I was hoping a 25amp esc would get by in the setup.

http://www.himodel.com/electric/Seak...ng_system.html

They also have a 35amp and a 60amp esc.

So with the setup what do you think about the amps.?

Aha, and now we get to the point! Discussion could have been much more accurate if you had mentioned you were running this setup in a villain to start with. There can still be no definitive answer as to what amps you'll be pulling, but a 60-70A ESC might very well be OK, if it's decent quality. Cooling won't be so much of an issue, and load should be relatively low compared to 1/10th off-road.

J.

My bad. I'll will be more up front in my questions from now on. I just didn't want to get all the responses telling me the othe motors I should use, or scrap the whole thought and get the SB27. But then again this is RCM. That don't happen here. No matter how whacked out our projects can get. We're all supportive. Family, gotta love em. Thanks for the help.

So it sounds like a 60amp would be a minimum to try. Any thoughts on the type of esc I linked to?

Exactly. The best you can do is figure out the minimum possible current (0A when off :smile:), and the maximum possible current (very high current at stall). The running current will be somewhere in between. :smile:

Not trying to sound sarcastic, it just depends greatly on weight, gearing, etc.

Didn't take is that way brian. I suppose using too low of and amp esc would just burn the esc up. If I remember correctly. Running at half throttle is actually worse on things then running at full thottle. So even thinking I would not need full throttle with that setup. Still doesn't get me in the cheaper seats.

How about....

It sounds like you guys feel the load would be lighter then a rustler for example. If I am running two motors and two esc to push this thing. Using a low gearing setup for each motor. That should help lighten the load that is put on each motor. Right.?.? I'm sure my math isn't going to work here. If each motor would be doing half the work. I could take the 70amp esc that I might get by with and divide that by two and run two 35amp esc. What are the odds the esc(s) would last until the LVC cut in for the lipos?

id say just buy a sidewinder, add a fan, ubec and capacitor and call it a day... it MAY work great, but i dunno, seems to run the 5400 max... but with a ubec and capacitor it would take the load off, and you would have programming options :)

OR spend the money on the Mamba max esc and not worry about it blowing up, but that isnt cheap i know! (cheaper than buying a cheap esc for $50 then buying a mamba max when it blows up :lol:)

I have the mm's (not laying around their in other rcs) I could put in it, but then I would need to try and water cool them also. That's one of the reason the model of esc that I linked to above was appealing to me. They had the water cooling already set up. Has the fwd/rvs brakes, and can handle the 2s lipo. The cheapest one, the 25amp is only 32.00. So blowing up two of them wouldn't be that expensive. If it is a sure fire explosion running the 25amps. I wouldn't get them. If the odds are 50/50 or better that a 35amp esc might not blow up. I might gamble the 84.00 dollars for two of them. Once it starts getting into the 120 dollar range. That's a little different for some reason to me.

The sidewinder didn't come to mind for an esc to use. Two of them would be a bit of money plus the water cooling for them. I did notice last night when I was on the cc looking for amp info. They don't recommend the sidewinder with any of their motor above the 5700. I guess that should of have given me a better clue of what I was getting into.

This was just an idea to throw in the villian, make the long trip to the lake and try it. I rarely get a chance to run it now. If I lived on a lake or was at one alot. There wouldn't even be an issue about what to get for it. The best I could afford.

why not try 2x mamba max and 2 batteries and use a y adapter? im not even sure how the steering works on those boats though (whether it decreases one prop or has a rudder)

also i forgot u were using a boat LOL.

but the mamba maxxes shouldnt get too hot inside a boat, perhaps adding a alloy sheet that they stuck to would be a good idea?

Ok, I'm going to go out on a limb here and I'm going to say a 120A speed control or above. The 25amp unit will melt. The 7700s pull some serious amps. I generally have to gear way down just to get the mamba to 180 degrees on my offroad vehicles. In my opinion the 7700s are for on road only. At 2S you are looking at 56k rpm about double what a boat would normally pull. I think you are going to smoke some esc with this one. I think the 7700's will work on 3 or 4 nimh cells each. The villain also doesnt have any prop choices so you are stuck with whats on it right now. The only way I think you could get it to work is if you could prop way down. If you can gear it to about half of what the titans normally geared at you may have a chance on this one, but even at that I would recommend an 80A speed control min.

EDIT.
check out the cheap esc thread. They have 100A speed controls for 28 bucks.

EDIT
I'm a big fan of my villain since the last time I took my supervee to the lake the water was to rough to get on the plane.

I have to disagree, boat have very high amp requirements, as the speed goes up, so does the load. I would not be suprised for a 7700 on 2s in that boat to pull 80amps or more, each. I have a supervee, and a few other boats. The sv27 can produce almost 700watts, so on 14v (4s lipo under load) that is 50amps. Of couse, motors running half the voltage will have to pull twice the amps... The only way boats get by is due to water cooling, even a feigao will run cool in a boat with a decent water cooling system. It will still not be effecient, but will run cool.

I would run a pair of 80 amp escs (water cooled) with the 7700 motors. And try to gear them down as much as possible smaller pinions) , as they will run quite a bit faster than the stock brushed motors. You should most likely step up the props a bit, but testing on the stock props should be fine. I have no idea how stable the hull is on the villian, 40mph may be all it can handle.

I got my sv27 up to 44mph, running stock motor and esc with a pair of 3600 12c 2s lipos in series. The batteries were limiting the boat. It was fun, the only thing in the water was half og the prop, and the last little bit of the trim tabs. We could see daylight under the hull...

Buy yourself an octura x642 prop, polish and balance it, and enjoy. Adds about 4-8mph and greatly increase the speed out the hole. Use good lipos though... nimhs will not cut it in this boat. No way nimhs can produce 60+ amps continuous...

Thanks hemiblas. That was a helpful post. I had no idea what the amp draw of the motors would be. For that mater any motors. I opened up the Medusa instruction sheet today and behold they have a table in it with some info concerning the amp draw of their motors. That table gave me some good references to go from also. The highest KV motor 4800 was list as 97a cont. That helped me put things into perspective also. I've seen that table before (RCM store for 1) but didn't understand the abreviations that were used in the header. Even if I don't attempt this with the 7700's I've once again learned somethjing new and useful. Thanks for helping me figure things out RCMers

I like playing around with crazy combinations like that atoo and think it would be a nice build, but people (Me included) have smoked many a speed controller doing stuff like this. I understand why you didnt post what you were trying to do originally. Every time someone with a villain get on the forums its always the same comments about limitation on the hull etc etc. Realistically if all you want is 35mph or under it makes a great boat in rough waters and then you get the extra speed to boot.



Ideally to make this work you would want to know the rpm of the titans and then regear so its up 10 or 20 percent if thats even at all possible. Even then an 80A speed control would still be a minimum I would use, with watercooling.

FYI I just bought a pair of the great planes 600 motors for my villain. It was either that or 2 brushless motors with speed controls. To keep things in perspective the supervee motors are like 1900 rpm/ volt and its a 45 amp speed control on that one.

I bet a pir of sv27 motors and speed controls would really wake up a villian, on 4s. IIRC the octura m447 props work well on the villians, just havve to buy a normal and a counterrotating. Steven at OSE sells the whole thing as a kit, with the upgrade stub shafts to fit 3/16 props...

Sweet, Yeah I have thought about a couple of sv27s, 45 amp speed controllers and throwing it all into the villain with a couple of 4S lipos, but it would be extreme overkill. The villain couldnt handle one of those motors, but 2 would just be uncontrollable even at half throttle.