# Thread: How do you guys determine actualy voltage going to the car .

1. ## How do you guys determine actualy voltage going to the car .

the lipo says 4.2v at end of charge , I turn on telemetry and its at 25V .. Now for my 8S setup Ive been doing calcualations over and over and ppl are saying that youll blow this motor or the other .. my LHS employee whos their so called guru always does the math with 4.2v times whatever kv times how many cells to get the figure for rpms or such .. Now im wonderin how much is actually goin to the car because me and my buddy are at odd about it and he claiming that once the power goes through the drivetrain and whatnot the car is only getting about 3.8v usable power respectivly with the car planted on the ground compared to having wheels freespin off the ground .. Not sure how it goes but can somone exlain it a little better

2. reminds me of flywheel hp compared to wheel hp discussions and drivetrain loss factor... Its like saying i put in 115 octane and my car is only using 93 octane.... when you use 8s its 8.4 volts more than 6s 2 more cells at 4.2 volts so 33.6v for 8s compared to 25v ....for 6s ...

3. The 4.2v right off the charger will quickly fall to 3.5v or less under a heavy load. also depends on the lipos used how low they will sag under high amp draw. A eagletree or similar equipment will tell you exactly the voltage throughout the run.. I think most people would be suprised how they drop.

4. Originally Posted by phildogg
The 4.2v right off the charger will quickly fall to 3.5v or less under a heavy load. also depends on the lipos used how low they will sag under high amp draw. A eagletree or similar equipment will tell you exactly the voltage throughout the run.. I think most people would be suprised how they drop.
at 3.5 under load wouldnt running a 2200kv on 8S keep the motor under 60K rpms ?

5. Originally Posted by BennyG6
Not sure how it goes but can somone exlain it a little better
No lipo can discharge at it's claimed "C" rating, nor can they discharge at a constant 4.2V...if either of these scenarios were possible then most packs would last only seconds before recharging, and this is without the added restricting factors like wire gauge or plugs

6. Originally Posted by BennyG6
at 3.5 under load wouldnt running a 2200kv on 8S keep the motor under 60K rpms ?
. I've seen a 2200 on 10s in a tc before. I think your fine with 8s but heat may be a prob.

7. Originally Posted by phildogg
. I've seen a 2200 on 10s in a tc before. I think your fine with 8s but heat may be a prob.
Well after readin this I dont feel as bad for the motor to run it on 8S . How did the TC perform on 10S ? . How many passes you think itll be good for before the rotors come apart ? im thinkin if Yoloer" hit 80's on 4S 29tooth gear on 2200 the 34 tooth gear on 8S should send the xo-1 into orbit lol
I personally am more concerned frying my XL2 could care less bout the motor as it only \$100 after 2 xo-1 and about \$200 in backup parts for anything that could go wrong whats a \$100 motor ..

Also came across a Neu 1512 thats rated for 60K rpms and can handle 32volts and 1850KV .. its made for a heli but Im thinkin might be enough power to get this car past 125 for under \$125 lol

8. Well the tc went into the 150's, he used to be a member on rc-isc, hermes. it was in a schumaker mi 4 ,no i woldn't go with the 1512 too small a motor. I would try a leopard in a 40/82 or 40/92 size. and the best kv you can get. check out offshore electrics.

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