Vince G32

I don't need to know about long battery wires and capacitors. I just quoted someone else on a different forum (not my work) and accidentally started a third party debate. Lesson learnt don't copy and paste other peoples work.

Going back to the first question. If you run two LiPo's in parallel and a number of ESC's in parallel you can share the load between a number of smaller connectors. You can't do this with 1 LiPo and a number of ESC's in parallel. Or two Lipo's in parallel and one ESC. Or as is the norm with a single engine model, one Lipo and one ESC.

Just theorizing (too much time). We are both looking at this from the electronics point of view. If you were running a low voltage, high current system, with different long wire lengths and diameters the resistance of the wires may vary? Hence each ESC will detect a different voltage, the RPM may differ? but that would be impossible to detect. I think I'm feeling very subtle changes of frequency more to do with the vibrations coming down the control line wires to my hand? The next two paragraphs are not my work, they are copy and pasted from another forum. "If there is a significant distance between the battery and the motor, it is MUCH better for the controller to be as close as possible to the battery, with the three motor phase wires being the longer section. In an effort to reduce voltage ripple and voltage spikes that result from being forced to have longer battery wires, it is sometimes helpful to add capacitors to the red/black pos/neg right next to the controller. This is because the motor can absorb quite a bit of voltage ripple and voltage spikes, but the controller is much more sensitive. The key metric is to use Capacitors with a low-ESR. A physically larger capacitor with high capacitance doesn't hurt, but it also doesn't help either. A capacitor has two leads, positive and negative. Simply connect the two leads to the two battery cables, in a place near the controller." Back to me. If there was a dry joint somewhere? that would cause major issues.

You have a very good point about setting the max/min range of the ESC's (didn't know it was called spanning). So easy to forget to do that the first time you connect it all together. Ohms law tells me higher voltage is better. But as you say small motors are normally designed to work on a lower a voltage (high KV). It's all a bit of a compromise. My motors are 1100KV, not ideal, I need to use very small props 7x4 to get the power down to 200w. 4max sell a 870kv 35/35 size motor that would be a better. But I already had the 1100KV motors, so its a done deal.

Talking about motors running at different speeds. I've only noticed that happen on an electric control line model. When you do a loop you put a little more load on the propeller, that in turn increases the current. Due to the internal resistance of the battery the voltage will drop a little. The ESC algorithm will reduce the RPM slightly, its very subtle.

I've bench tested the motors, they are all 200w, give or take a few watts. I've never had issues with motors running at different speeds. Difficult to see how that could happen if all the motors are from the same manufacturer, the same KV and all four ESC's receive the same voltage from the LiPo's. Should have said, the LiPo's are connected in parallel within the XT60 dual adapter. I've tried to standardise my Lipo's. I use one 14.8v 2200mAh in small models like the Marlin EDF. Then connect two in parallel to power my 40 size models and three in parallel to power 60 size models.

For what its worth this is my setup. Each motor is 200w (14.8V) (13.5A) giving a grand total of 800w (14.8V) (54A) to power a 72" Tony Nijhuis Avro York. I prefer to have short battery wires and long motor wires (there are advantages/disadvantages for both setups). The 5.5A SBEC within the 40A ESC powers the receiver and 5 mini servos. The 5A UBEC powers the retracts only. The 4A BEC's withing the 20A ECS's are redundant.