test running on ground
 

Hi,
Is it OK to run through an entire battery on the ground to test everything and check run-length? I know that you cannot run full throttle continuously (even in the air)... I would just do half throttle.

I was just thinking about the fact that the prop cannot unload on the ground... so would that cause overheating or damage?

I was thinking of leaving off the cowl as well, so everything will have plenty of exposure to air flow.

The set-up I want to test is a Park 480 (1020 Kv), 2100mah 3 cell LiPo, and APC 11x5.5 E-prop. ESC/BEC is an Align RCE-BL35X (from a heli, but set to airplane mode).

Thanks

RE: test running on ground
 

I would recommend using very short test runs using a wattmeter or ammeter to measure the maximum static current draw of your setup. If you are drawing too much (or too little) current, you'll know immediately and can make the necessary adjustments. With this information you can determine about how much thrust is being generated and your probable flight duration. You can use a timer set for your calculated flight duration for your first flights to avoid LVC. I think you are right to be concerned about overheating under static conditions, even when current draw is within a motor's specifications. The airflow is not as good as under flight conditions.

RE: test running on ground
 

Ok thanks. Better not risk it then. I don't have an ammeter. I guess multimeters do that? Would need to learn how to use one first... those things are confusing.

Another reason that I was considering a full-length test is because my ESC instructions say to never connect a partially drained LiPo, because then the ESC can mistakenly over-drain the pack (if it runs long enough in total). Since I'd rather not toy with that possibility, then that means it's better to do just ONE short test run.

IF I need to do another test, then I should recharge the LiPo back to FULL charge. From what I understand, it's OK (but not great) to do that with LiPo's... like only use 10% of capacity, then just briefly charge back up to 100% when you need to use the pack. That's correct right?

Thanks for help

RE: test running on ground
 

You will be OK if you connect a freshly charged battery as instructed and then run a few short tests without disconnecting the battery. Your ESC must use the initial voltage of the battery as a starting point to calculate LVC (low-voltage cutoff). During these brief runs, you can make your current measurements. There are many inexpensive multimeters that can measure 10 amps continuously and up to 20 amps for 15 second intervals. That might do the trick for you if your current requirements are in this range. A dedicated wattmeter is probably the best solution.

Without a meter, you should be OK if you use the setup recommended by the motor's manufacturer. It might be a good idea to use one prop size smaller initially, just to be on the safe side. As you hold on to it (hold on tight and anchor everything behind the prop :) ) when you briefly run it up to full power you'll get a very good idea if you have enough power for flight. See how warm the motor gets after these runs. You want to avoid very high temperatures that can damage the wiring insulation and/or the magnets. During the first flights, manage the throttle for comfortable flight and reasonable duration. If your easily getting 10 minute or longer flights, you're probably in the ballpark, and you can make incremental adjustments to enhance performance.

RE: test running on ground
 

I've done some very short test runs. I wasn't calculating anything for the moment... just making sure everything works and that my soldering was ok, etc.

The motor is the spec motor for the plane and the LiPo is to spec. The ESC is 35 amp and the spec requires 25 to 40 amp.

I'll be ok for a while with lower settings, so I can leave settings like "throttle response" on easy-on-the-motor, low settings. The only thing I might play with a bit is the battery protection level to get a little extra flight time, but currently that is set at a safe "high cutoff" (but I'm aware that flight may be pretty short). I may start looking at multimeters or wattmeters to get more info on how it's working though.

I didn't throttle up to max, but up to like 75-80% of power and only for a few seconds at higher rpms. The Park 480 packs a punch :)

Cheers

RE: test running on ground
 

You won't regret the money spent on a Wattmeter - it will save you motors and packs in the long-run!

RE: test running on ground
 

You can run a motor system at full throttle for about 10-15 seconds, but nothing more than that. Usually, before I fly, I run my motor system to full, just to check that it is working properly. It's only very quick though.

I have seen people, and have read of people running a motor system at full throttle (brushed and brushless) for the entire battery on the ground, because they said they need to break the motor in.

Some tests I have read about state that the break in period for a brushed motor is not needed, as it only yields about a 5% effecieny increase-time that could have been spent in the air breaking the motor in.

Oh, and the people who ran brushless systems at full throttle overheated the motor and ESC, and caused them to go out. Just to show that you do NOT need to break in brushless systems, which is where the term "Plug N Play" came from ;)

RE: test running on ground
 

A wattmeter will pay for itself in short order. For instance, a motor may be recomended to pull 10 amps sustained full throttle. You choose a prop to get as close to that # as you can without going over. without the wattmeter you may be way underpropped and not getting the full poop out of your motor, or if you go over, you may toast the motor.