[TinyStego]

How would I be able to read current levels of the battery? I've seen posts of people advising not to do it because it isn't worth it, but why?

I would love to be able to see how much I have left of the battery so I know when I need to land it. I've been doing 5 minute flights because I'm afraid that the voltage is too low, but I have no way to check it. I'm going to get a second battery, but I want to know when I can fly high, and when I should return it to home.

[Mateusz]

There is no such thing as current level of battery. You have voltage level of battery, and current which is amount of electricity drawn from it.

Current sensor is not very precise, even after calibration. You could use AttoPilot current&voltage sensor on the leads between battery and pdb.
This sensor scales voltage down, so max does not exceed 3.3V, and that is the maximum that AnalogToDigital converter(ADC) on Revolution accepts.

GCS or telemetry in OSD could display current voltage and how much your spinning motors draw. In theory it should be possible to predict how much battery is left, maybe it's done, I dont remember, but I guess it wouldn't be very accurate either.

Though it's better than nothing. You can also use cheap $~5 voltage alarms, that you set to 3.7V and they beep when they reach that level under load (motors spinning), then you land and in rest (motors not spinning) it bumps back to 3.8V which is perfect storage voltage.

I think voltage on OSD is more important than current, though I display both on mine.

[TinyStego]

Would a voltage alarm be audible if I was flying high and far away?

When you say you use voltage and current on your OSD, does that mean you use a sensor? If not, how else would you be able to do it?

BTW, you've been helping me so much tonight, you freakin rock!

[Mateusz]

Would a voltage alarm be audible if I was flying high and far away?

Depends, it might be enough if you dont fly far. You should also have Lost Plane Alarm bound to accessory if you fly FPV and far.

When you say you use voltage and current on your OSD, does that mean you use a sensor? If not, how else would you be able to do it?

Yes I use sensor.

I use AttoPilot sensor (like this https://www.sparkfun.com/products/9028) in the middle of my cable that I connect to battery (attachment).
Of course this sensor has 90A limit, but I have small copter which does not draw more current than that.

So yes you need additional sensor. Revolution has only Analog to Digital converter with max voltage 3.3V. What sensor does it measures current and voltage and outputs that in a renge of 0-3.3V so your revolution can convert that into numbers.

I also had to solder JST SH 1.0 4 pin cable that fits into Revolution ADC port and connects sensor to Revo. You can get those from ebay easily as well http://www.ebay.com/itm/20-SETS-Mini-Micro-SH-1-0-4-Pin-JST-Connector-with-Wires-Cables-100MM-/251979895512

[TinyStego]

That might be something I would have to invest in at a later time. I can set a timer right now for 10 minutes and hope all is well. I'll most likely get the warning buzzer as well.

I have some more hardware upgrades to look forward too haha

[@marc]

I am using this ("standalone"): http://www.banggood.com/2-x-2-in-1-Lipo-Battery-Low-Voltage-Tester-1S-8S-Buzzer-Alarm-p-973987.html

and this (with GCS and/or android app): http://rctimer.com/product-1096.html

More info: https://librepilot.atlassian.net/wiki/display/LPDOC/Configure+a+Current-Voltage+sensor

[Mateusz]

I am using this ("standalone"): http://www.banggood.com/2-x-2-in-1-Lipo-Battery-Low-Voltage-Tester-1S-8S-Buzzer-Alarm-p-973987.html

Exactly, those work really well, and are cheap It's good to get bunch of them, but dont leave them connected to battery forever, they also drain power

[f5soh]

Exactly, those work really well, and are cheap It's good to get bunch of them, but dont leave them connected to battery forever, they also drain power

Datasheet says the quiescent Current is 60µA typical / 125µA max so current draw per sensor itself is not significant.
Do you want to do the time calc for a 2200mAh battery ?

[Mateusz]

Datasheet says the quiescent Current is 60µA typical / 125µA max so current draw per sensor itself is not significant.
Do you want to do the time calc for a 2200mAh battery ?

From my experience, leaving similar buzzer connected, drains only one of the cells, while other also measured cells stay at similar level. If you leave it at storage voltage 3.8V and one cell drops further, it not only becomes unbalanced, but one cell is hurt. I fly 800mAh or 1800mAh 3S at most.

Might be that alarm I use has bad design or is faulty one, but it's safe to check specs like f5soh did with his buzzer