I am trying to hit higher and higher speeds on the street using an RC8.2E. Currently I have the RTR version with Tekin RX8, on 5s lipo, and I am moving to a 6S pack.

Since the voltage and amperage drop during a speed run, Ithought about something. What if I added a small 2S pack in a place Ihave found it to fit, connected it by some type of relay, and when the vehicle reached top speed, Icould use the 3rd channel on my M11 tx to activate the voltage in the boost pack, which would only be used for 2-4 speed runs as to not deplete the pack.

Is this possible to do? Say with a pair of large capacitors between the two voltage sources?

The goal here is for a nitrous/turbo effect on the car. The car doesn't need the weight of a big block engine (8S or [2x 4S]) pack weight, the main pack is still decently large, the small pack doesn't add much weight, and it dumps itself quickly in contribution to the top speed of the short run. I got the buggy cheap and track racing is not my thing yet, so Iwent the max speed route for fun.

are you trying to figure out a way to add the 2s lipo power threw the ESC....or direct to the motor?

Direct to the motor would be impossible due to the ESC programming and timing of a brushless motor. So Iam basically just trying to trick the ESC into taking in more voltage/amps during a full-throttle speed run. The ESCs voltage detection would not be in effect on the maximum end Idon't believe while under full power delivery. So Ithink it could be tricked by a small "boost" of 1S or maybe even 2S that only initiates during the maximum throttle value range say after 4 seconds of full throttle, programming would throw in the smaller pack, and cut it when throttle dropped. My only other option is to run a 4S pack in the car, and a duplicate cell type 2S pack mounted down under the rear custom wing that we just made from 4 layers of carbon fiber. This would be really awkward as you could see two cells mounted back there, and might throw the balance of the car all aroundIdon't know, but it would be an option for a speed queen.

whats the voltage limit on the ESC?
If you are trying to go above that, even for a short burst and only while wide-open-throttle it still may cause the ESC to emit black magic smoke.

You normally use a "Y" harness to connect 2 batteries in series.

I suppose its possible to make a modified "Y" harness, with a bypass for when you want just the main pack, and a switch to include the 2nd lipo in the series.
Thing is, I dont see how you could make the swtich off the bypass quick enough for there not to be a momentary loss of power.

I dont think a small 2s lipo pack will like having that current draw drawn through it from the other batteries....

im sure there would be a way to do it, but there is simply just better options out there that will give u more speed

agreed,
unless its a really high "C" rated battery.
I mean, a 50-100 "C" rated 2000mah pack might be OK. Even then, you risk puffing up the pack.

It would likely be easier to swap to a system made to handle more voltage and 1 battery.
You dont have to run duel packs. There are 6,8 or 10 cell lipo packs.

Even tho that means some $$$, you wont be risking burning up or damaging your existing lipos/esc.

you will smoke your ESC if you hook it up in series by putting 8S into it, and cause the electronics to kick out cause the relay would have to swap over.
if you hook it up in parallel you will probably cause the battery to explode(not joking) as there is a reason when you hook up batteries in parallel that the voltages match.

best option buy a 8S capable ESC, but then the motor probably won't be able to take it

Iwas thinking the relay idea is complicated after this all bearing in mind. But, in things like motherboards for PCs, car audio amps, they use larger capacitors on the switching lines to deliver smoother sine waves and to keep and maintain smooth DC power, as do caps have an effect to even out the sine waves in an A/C to D/C converter circuit, by varying steps of capacitor sizes. The smaller the cap, the quicker the discharge, and faster the wave falls before the next peak. So if the caps start large and then get smaller, they can make the output almost like a plateau sine wave. But that's just garble now.

I have an 8S 1/5 scale ESC. It has twin fans and is rated for 200amp continuous 34V x200A = 6,800 watts = 7HP that might get to the ground if you could ever pull 200A which means 6HP might be doable. The ESC itself sounds louder than a PC running at 5V on a BEC, and at 6V the fans are just loud! It's giant in an 8th scale buggy but Icould always use a sedan body on the buggy and extend the body mounts, get rid of the side chassis guards and outhang a carbon plate for bigger battery and ESC. It would need to be mounted where the motor is, and the motor swung up above the center differential, then you could fit an 8S pack under the body, and run a longer or fatter motor with larger pinion under or inside the body cab area since it would be the only room for the motor to swing to. Iwould have to bore the pinion out on a lathe and make a custom motor mount. But it could be done. Imight have to think about how many sacks of potatos Ican weigh the buggy in before it's considered overkill.

back on the motor/esc you have now....
do you own a temp gun?
there may be some gearing left in the motor, especially if you are just doing speed runs.
Ive run brushless motors as high as 190 degrees without damaging them. If your motor is only hitting 150 or so then you could gear up.
But dont try it unless you have a reliable way to measure the temps, IE, a temp gun.

lets say the ESC and motor or lipo don't blow up. what sort of power boost is going to occur. will it be enough to do anything or will it be to much of a boost. i messed around with ni-cd batteries years ago and when adding extra cells to a moving motor it was a massive jump in speed. (never tried on a moving RC car as i only had a basic 2 channel setup.)