mamba monster on 7s

Ok first I know it voids my warranty but will the mamba monster run 7s with a external bec?Its for 132ft 1/8 buggy racing.I KNOW IT VOIDS THE WARRANTY!!!i need good indepth tech knowledge from the best technological guys here! help

[Arct1k]

I think it will go into over voltage mode and not work.

A friend accidentally took my 4S packs which he thought were 3S and hooked them up to his E-Revo. He even ran it for about a minute until I saw his mistake. Not sure what sort of long term damage he might have caused but it did run. You could get lucky and it will work fine or it might go puff as soon as you connect the batts. Either way I wouldn't do it. I hate destroying things for no good reason at all.

Have you considered an plane/heli high voltage ESC. As long as you don't need reverse you could make the whole thing work with a use of a PISTIX. Plane ESC can usually be had much cheaper than a car version so might be worth going that way.

mind you 7s is 25 volts only what are the mosfets rated for on the monster i think 30 volts and with the bec disabled should be ok small spurts im still scared!! oohh i added capicitors too.

[BrianG]

Actually, 7s is 29.4v fresh off the charger. Granted, the voltage doesn't stay there long, but voltage is what breaks dialectric/insulator materials which then allows current to flow and burn stuff.

Even if you get 7s to work, you will surely blow the TVS device. The TVS helps to shunt high voltage spikes to an acceptable level during braking. Once that blows, there is no more protection. So then all those brake spikes are free to wreak havoc. A while back I was doing some playing around and recorded ~30v braking spikes when using 4s lipo. On 7s, you could get into the 60v range.

[snellemin]

7S is 29.4V charged up and 25.9V at rest when nearly depleted.

For dragracing you have the wrong setup. You want to reduce weight on your vehicle, so adding more batteries will just weight you down and loose the race. Acceleration is key here and not top speed. You are not doing a 300ft speed run, but a 132ft dragrace.

Get rid of you 51t spur and swap in the 47T. Launch control is key to winning with these big cars and not the abundance of power. Remember it's only 132ft. My A123 "low powered" GTP kept up and won races against more powerful cars and buggies.

Originally Posted by BrianG

Actually, 7s is 29.4v fresh off the charger. Granted, the voltage doesn't stay there long, but voltage is what breaks dialectric/insulator materials which then allows current to flow and burn stuff.

Even if you get 7s to work, you will surely blow the TVS device. The TVS helps to shunt high voltage spikes to an acceptable level during braking. Once that blows, there is no more protection. So then all those brake spikes are free to wreak havoc. A while back I was doing some playing around and recorded ~30v braking spikes when using 4s lipo. On 7s, you could get into the 60v range.

now we're getting somewhere i did not know this.so BRIAN G its actually 29.somthing huh thanks !

Originally Posted by snellemin

7S is 29.4V charged up and 25.9V at rest when nearly depleted.

For dragracing you have the wrong setup. You want to reduce weight on your vehicle, so adding more batteries will just weight you down and loose the race. Acceleration is key here and not top speed. You are not doing a 300ft speed run, but a 132ft dragrace.

Get rid of you 51t spur and swap in the 47T. Launch control is key to winning with these big cars and not the abundance of power. Remember it's only 132ft. My A123 "low powered" GTP kept up and won races against more powerful cars and buggies.

i need consultation from you.i was going to try use a delrin 46 but did not know if it could last accelerating or under braking?

[RC-Monster Mike]

I know guys that run the Mamba Monster on 7s for 300ft drags(2650 motors, too). They use mechanical brakes, though. And they go through ESCs occasionally in their quest for bragging rights.

Originally Posted by RC-Monster Mike

I know guys that run the Mamba Monster on 7s for 300ft drags(2650 motors, too). They use mechanical brakes, though. And they go through ESCs occasionally in their quest for bragging rights.

wowww!! im itchin to try it.did they use a ccbec?hey Monster mike if i use a ccbec and disconnect the monsters internal bec and run a small lipo battery for my servo will this allow for more speed since the monsters not working so hard and using my main battery to steer?

[RC-Monster Mike]

Yes, they use an external bec(hv). In a speed run, the minimal amp draw the steering servo draws won't have a noticeable impact on power(carrying an extra pack will likely hurt more than it helps in this regard). Any of this stuff is at your own risk, of course - the MM is intended for 6s max voltage and the 2650Kv motor is intended for 4s voltage. :)

[Pdelcast]

Originally Posted by RC-Monster Mike

I know guys that run the Mamba Monster on 7s for 300ft drags(2650 motors, too). They use mechanical brakes, though. And they go through ESCs occasionally in their quest for bragging rights.

Yeah, electronic brakes will kill the ESC on 7S.

Shouldn't use 7S -- it's over voltage for several parts, and will void your warranty.