Select an RC High Voltage or High Current Setup
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- Опубліковано 8 вер 2024
- High Voltage or Current in a Power System
The scope of this topic is going to be achieving the same power level in all comparisons. For example a 6s battery at 60 amps will provide the same power output of a 3s battery at 120 amps, about 1300 watts. Which setup is best?
There’s a 2 part answer to this question
Part 1 - If you have no limitations when building your power system, and are new to selecting power systems: it can be easier, safer and more reliable to run a higher voltage then a higher current.
Part 2 - For the rest of the setups out there a reliable setup can be had of either a high voltage or a high current setup. In many cases a higher current setup may be required and this is OK.
This is true as one would be able to select the appropriate components to suit the specific setup. If you have a high voltage setup, select the correct components that match the voltage specs. If you have a high current setup, select your power system to match the current. When power systems fail, the most common cause is too high of a load placed on the power system or a battery that is not suited for the task. This is where it appears that a higher voltage setup is the way to go. The difficult part about a high current setup is that it is not as predictable due to current being related to the load placed on a power system.
Factors that Contribute to Power system selection:
- Racing Specifications
- 6s to 8s LiPo Limit on ESC’s suggesting higher costs to run a higher voltage setup.
- There’s no weight advantage to either solution. 6s 45C 5000 (max amps 225) equal in weight to a 8s 45C 3750 (max amps 168.75A)
I prefer high voltage setups with larger motor size at low kv. Its win win! because esc,battery and motor runs cool and lasts longer
Super correct, Ryan helped me with this, I had to return two RC boat motors of 800kv and get the 400kv version.
Luckily I happened to have a friend who flew to China so all that procedure of returning them and getting them replaced went smooth.
Thank you
Also high voltage and low current have less loss on whires and connectors, less heat, is more eficient.
What is the down side is usually more cells are batteries are more expensive and If one cell fail all battery fail.
For example I have ldark et 115 2s version and on the market is also 4s version. The battery for 4s version is almost double expensive than mine. The flight time is the same. Perhaps 4s version have much more power, I dont know.
Aniway when is about performance more voltage , better.
Forgot that the lower voltage higher amperage all connectors have to be so much bigger. As more weight and all the other hardware because of that. So you save on weight on everything else.
I think high voltage is always better, low resistenc, tinner kable, no fan on esc, better stall torque
What about selecting the correct gearing for your motor/esc/battery, and vehicle type & weight.
So if I use high voltage but dont change the motor to a low kV one, the torque will suffer, since torque = current and the high higher voltage pack wont be able to push the necessary current? Even though both packs can push the same total power if the load is right?
That is correct if the battery can not push the required current for the load.
So I have an 80 amp esc with a 1300 kv motor I was thinking of putting a 2650 kv motor which is bett
Motor: SSS 3674 2075KV brushless motor for tfl zonda boat 120 seaking esc,what lipo battery can I use for it plz cos I'm just starting to get into this hobby. Thank you ur help would be grateful
thank you!
You're welcome!
I have a xlx esc and a1450 kv tp power brushless motor for the kraton 8s. Is this a good convination? Or should I get a different esc? Thanks for the great videos
Although I haven't used it, the XL X ESC is a beast and would fair well with your setup.
great video series thank you. question, why does the high voltage set up have to have a lower mah then the low voltage?
Great question. The high voltage setup does not HAVE to have a lower mAh battery pack. However, if you were to match the same 5000mAh pack you will now face a weight disadvantage. The EDF where that example came from would not be able to handle a heavier setup without a sacrifice in slow flight performance.
Thanks for that answer. I purchsed 2*4s gens ace 5000mah battery 50c , and a tp 4070 , 1440kv and a flier 300a 2-8s esc . I hope that will be a good setup for my df 35 boat ?
I have a question on this subject. Another RC youtuber(french language) claims that 1/5th scale, heavy (20kg) cars will have a longer runtime with high voltage setups?
Lower voltage systems have higher currents, which result in bigger heat losses.
For example, the Losi DBXLE 2 has a factory 8S system. Changing this setup to a 12S system, reduces heat losses and increases runtime.
Is this statement correct?
And 2nd questions: Does C-rating influence heat losses in the 8S setup? Will a 100C lipo stay cooler then a ,same capacity, 25C lipo in the same setup?
Hi Manu D, this video should help answer that question as it explains that exact idea in detail.
If you are expecting to run the same power output (watts) with different voltages but a different Kv motor to maintain equal output RPM and all else equal, it won't matter so much. If you are going to try and make more power by going up to a 12s Pack, this will make life so much easier.
To counter the problem with higher current leading to increased losses, a suitable motor with a lower internal resistance must be selected. Going up to 12s vs 8s will require a motor with a lower Kv thus a higher internal resistance. The higher internal resistance and the lower current draw cancels out when compared to a higher kv motor ran at higher current and lower voltage.
Most new hobbyists would be better suited to use the higher voltage setup as it is much easier to manage lower currents vs higher.
To answer your question - Changing this setup to a 12S system, reduces heat losses and increases runtime.
This is a huge simplification of a complex problem. Changing the system out can improve efficiency completely independent of 12s vs 8s. One could state, changing out the stock 8s setup to a more efficient one can increase efficiency as well. At the end of the day the power system should be selected based on how much power is required then go from there.
Yes a 100C LiPo will run cooler than a 25C LiPo with all else equal.
@@RCexplained Thanks! I
ua-cam.com/video/uRZlX6t7Xv4/v-deo.html.
But in this video you show that 9s system is 20% more efficiënt then 4s system?
In this video I show its a lot easier to select a power system for efficiency based on a higher voltage. It's also a lot easier to manage lower currents for newer hobbyists.
The difference in efficiency is not 20%. It's actually approximately 92% vs 93.5%. This translates in to about 1.5% increase in run time running at these specific conditions. Nearly negligible.
Now if you want to increase the efficiency of the lower voltage setup, increase the motor size, select a motor with the same kv or slightly higher to increase the RPM output. The internal resistance will drop making it easier to surpass the efficiency level of the example in this video. The difference will be you won't need to completely swap out the entire power system.
Thank you for these videos, i've learned a lot. I have one question that i hope you can help me understand if you find the time. Does a typical RC ESC demand speed or torque from the motor, based on the input from the receiver? For example: Say we have a 7.4V system powering a 2000Kv motor, and we pull the throttle to 50%. Will the ESC provide max voltage until 50% of top speed is reached, or half of max voltage continuously?
Thank you Jan for your comment.The ESC will simply switch power to the motor on and off very quickly. Lower throttle is possible by chopping this signal. The ESC will provide full voltage.
@@RCexplained That is interesting, and answers my question. Thanks!
@@yvindholgernes8950 Excellent!
Excellent videos.really learning alot.I just wanted to know if I got a 2000kv motor on a heavy boat(26 pounds) and I change from 3s to 4s without changing prop will the current draw go up or down.also how much more watts will be produced.thanks
Thank you for the comment Thakrim. Current will increase. Depending on the setup it's possible to easily see more than 60% increase in power output when voltage increases by 30%. Make certain your power system can handle the additional load. To see what the actual increase in power is, you must measure it. Take a look at the video I have of a cub running on 4s vs the power running on 6s. Difference was big.
@@RCexplained thanks alot for the reply.will check it out
Current will increase. Motor have the same resistance.
So a higher voltage is faster for a rc car?
A higher voltage offers so much more potential.