Bad ESC?

[aerogator]

Hi guys, we built the Tiny Trainer 6 weeks ago but for one reason or another haven't. Even able to fly until now. Today I connected a fully charged battery and nothing happened. When we buoy the plane we installed a battery to center the servos and test everything out. It all worked fine then. I disconnected the battery and the plane has been just sitting. Seems to me the power goes though the esc first so if it's gone bad, that would affect everything, am I right? How do I trouble shoot this?
Thanks, Jake

 

[cranialrectosis]

When you connect the lipo, does the ESC chime? Most should sing out a few beeps to let you know it has power.

Is the receiver bound and working?

Most receivers will have an LED showing that it is receiving signal. If the receiver isn't receiving signal, nothing happens.

How are the batteries in the transmitter? If the transmitter batteries are dead, so is your receiver and so on.

 

[JimCR120]

ESC's with a BEC have 3 wires in the connector to the receiver. Some ESC's don't have a BEC so they only have 2 wires in the connector on the receiver.

Most likely you have an ESC with a BEC. If you've powered up your receiver to center the servos using the ESC then you have the right kind.

Do you get any lights on your receiver when you connect the battery to it through the ESC?
Are you sure your battery is fully charged?

 

[aerogator]

No lights, no chirp, nothing this time. It did all that before and yes it has three wires so yes to bec.

 

[JimCR120]

In that case I would check your battery and inspect the wiring. What do you have to check the voltage of your battery?

 

[aerogator]

One battery is 4.35 and the other is 8.36. what should they be? Transmitter works with other plane so batteries should be OK. That brings up another question: Transmitter is Spektrum DXe and has just been bound to other plane maybe I need to rebind to Tiny Trainer?

 

[cranialrectosis]

Lipos should be considered discharged at <> 3.3v PER CELL.

A 3S lipo is fully discharged at <> 9.9V. A 2S lipo is fully discharged at 6.6V.

Be aware, discharging a lipo below this level may kill it or may make it dangerous to re-charge.

I recommend you ALWAYS balance charge and charge at 1C (a 1300mAh should be charged at 1.3A).

Once a lipo is damaged (over discharging can damage lipos) I recommend charging outside in a fireproof bag/box. A quick youtube search on the term 'lipo fire' should be all the incentive you require.

 

[aerogator]

Yes, I've seen the vids. Lipos are completely new to me. I've ordered a charger/discharger to help with this.
So, are both of these batteries discharged? Is that the problem?

 

[cranialrectosis]

That depends but it's very likely root cause.

You haven't stated what those lipos are yet, 1S (s stands for cell count 1S is 1 cell), 2S, 3S, 4S...I suspect you aren't running any hotter than 4S.

Once you drop a lipo cell below 3.3V there may be no way to recover it safely and you should ALWAYS forever after consider it 'iffy'.

 

[aerogator]

The lipo's are "20c 800mAH 2cell 7.4v". One of the batteries shows about 4v per cell, so it should be rechargeable, right?
Next question: if I charge but don't use for several days, what happens to the battery?
Do you guys check the charge after every flight?
Thanks

 

[cranialrectosis]

4v per cell should be fine and you should be able to power that plane.

Once you charge a lipo you should use it. If you sit it on a shelf for days/weeks at a time, you will increase internal resistance and decrease the life of the battery. A good charger should also allow you to discharge to a 'storage charge' level.

I test my lipos in the air in real time using telemetry or a lipo voltage alarm. When the voltage hits 3.5V I land.

 

[aerogator]

Thanks guys for all the help! My batteries are charged but still no joy. I have ordered another esc (maybe should have ordered 2), so I will see what happens.
Meanwhile, I also bought an IMAX B6AC charger but have not been able to use it yet because it does not come with XT30 connectors for the output leads. Are XT30's generally hard to come by? I live in Atlanta and HobbyTown does not carry them. I have ordered some to make my own leads but this seems unusual since they are so common with Flite Test products. We'll find out how good my soldering skills are after 50 years. I probably should practice a little first
Thanks again everyone!
Jake