Battery pulse rating mech3/1/2023 ![]() ![]() C rate is only the amount of current that a battery can deliver at one time, it has nothing to do with the esc. Then make sure your battery has enough c rating to handle the amp draw of the combined demand. Think about the current (amp) demand of your motor/prop combo- then size your escs accordingly to handle the max amperage and then some. I think you are missing part of the equation. A 20 amp esc with only 10 amps flowing through it will not overheat, however a 20 amp esc with 30 amps flowing through it most likely will overheat which is the main cause of escs failure. Zippy compacts are a good example of a battery that will work great until you start charging it at a high C-rating.Ĭurrent flow is the main concern. I always stick to the rule of thumb that you should charge your batteries at no more than 1C even if they are rated for a higher Charge c-rating. It is also important to consider C-rating when charging batteries. ![]() I will be posting real life data to this site soon. You can find Amp draws on propeller manufacturers websites. So we would need a 1.6A (1600MA) or larger 25C battery in order to get the discharge amperage required for these motors. So it would make sense to bump up our 1300mah 4s battery to a 35C rating.Ģ5C batteries cost less than higher C rating batteries, but in order to use a 25C 4S battery at with Cobra motors at 10.4 amps, we would need to up the battery capacity to 2000mah or more. We could achieve this by either increasing our battery capacity, or increasing our c rating. This means that ideally, we would need a battery capable of a continous current at or near a 40 amp discharge. If we use the 2000KV motor for a 4S build (recommended) we can calculate it out: It is a little bit more efficient at full throttle. The 2000v Cobra motor draws about 10.4 amps at full throttle. The cobra motor draws about 13.3 amps with a gemfan 5030 on 4s. If we decide to go with a steeper pitch prop such as a 5045 or a a larger propeller, then we would need to reconsider this battery as it would not be adequate. ![]() So a good rule of thumb is to engineer about a 20% margin into your calculations to make sure that you are well within spec. The burst C rating should handle any current overages that are incurred.īattery manufacturers lie. The Gemfan 5030 draws about 8.4 amps total with a Cobra 2300kv motor on 3S, so I am within the design limits so long as I am not building this quad to be at full throttle all of the time. Acrobatic maneuvers & full throttle pullouts tend to use much more amperage, so you could use this battery on a craft that draws 8a per motor in full throttle, and then know that burst will cover acrobatic maneuvers. We should use this battery on a craft that draws no more than 8.13 amps in most circumstances. That is 16.25 amps per motor at the burst capacity of the battery.īurst is usually considered in 15-20 second increments, so in my designs, I like to make sure that I mostly stay within the main C rating. These Nanotechs are rated with a burst capacity of 50C-Īgain, Doing the math, but this time for a 50C Discharge rate, Looking at this chart, I would think that it would be ok to use the nanotech battery in this application. Looking at the graph of the current draw of 2300KV Cobra motors on 3s with 5030 props, we can see that the motor current draw is somewhat linear until about 80% throttle, after which it becomes logarithmic the efficiency of the motor drops off and the current really rises. When engineering a new quadcopter, we have to consider the amp draw of the motor/prop combination, and the max battery size we can fit on the quad to determine the right battery for the job.Ĭobra 2300KV motor current on gemfan 5030 prop and 3s The C rating is inversely proportional to the battery’s capacity, so as you move up in capacity, you can move down in C. The C rating is important when it comes to choosing a battery for high performance multi rotors because our multi-rotor motors draw high amounts of current (amps) and it is very easy to choose a battery that is not properly rated for our current draw. This is very important when you consider battery choices for Quadcopters and multi rotors because these machines draw very high amps from the motors and it is easy to choose a battery that can’t handle the currents required by brushless motors and steep-pitched props. The rating is combined with a battery’s capacity to find determine the maximum discharge. If you need to read up on some basic battery theory, read this post first.Ĭ rating is a rating of how quickly energy can be discharged from a battery. ![]()
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