Battery drain reassurance

[G60jet]

Right so I set my alarm on my tx to go off when the lipo onboard my chopper hits 14.2v. (Yes I got telemetry baby) and altimeter

Now I have fitted my gimbal my alRm goes off much earlier into the flight yet now I';m only putting back about 2600mah back into a 3850mah 4s.

Does that sound normal given extra weight and power need to lift said weight.

I';m going to try dropping the alarm by .1v each flight till I get back up to charging the pack at 3000mah.

[guest325]

And????????

[G60jet]

Where the hell did the rest of that post go. Frigging ios8

[G60jet]

Right. Edited the first post lol

[flybywire]

Well, I';ve said it many times, you can';t rely on voltage alarms on their own!  Especially given that in my experience using lipo';s for several years (and loads of different brands at that) the cells lose voltage quicker over time (but not necessarily capacity), so will set off a low voltage alarm falsely. That goes for telemetry (which I also have).  There';s no easy-peasy way, it';s down to experience, and a certain amount of confidence in your lipo';s.
THat said I always bring my beasts back slightly on the early side, but that';s just common sense.
THe best gauge I';ve had so far is the ezosd mAh consumed indicator, that was pretty spot on, and the only thing i miss using DJI osd.   

[guest325]

If you go through what you said at the end of the op then you can';t go far wrong with landing at 35% ish capacity, it gives you a bit of room for things going wrong.

[DebianDave]

I';m putting 1100 mah back into my 1500 (25% leeway) Zippy';s and 1600 into my Turnigy 2200s on low voltage alarm. Assuming the charger is accurate! I find actually going out an flying then marking the batteries to compare flight time vs charge put back in is the best method. Aside from that, I try not to think too much about it. Then again, my batteries are ~£8.50

[Biffa]

I stopped using voltage buzzers the day I fitted my first one. They are great at telling you when the voltage sags but obviously are no good for capacity which is really what you want

I just rely on timing and capacity put back in the pack.

[kilby]

The charger gives a higher value than it actually puts back into the battery as it';s not a 100% efficient process.

Also of you check a battery straight after a flight and again 20 minutes later you will also find that the battery ';recovers'; be quite a bit (believe the later reading is the true stater of the battery)

[G60jet]

I am also factoring in the the voltage monitor goes off underload not resting

[Ben Kenobi]

I';ve done some ';tests'; on mine to determine a voltage trigger point, that point is the voltage I can go to and still have the battery voltage in each cell return to 3.2 volts when resting, seems to work OK. I have telemetry and an Open Pilot based controller though so this is fairly easy to do. Not much point having a flashing LED you can';t see or a buzzer you can';t hear - telemetry is the only way to go  ;D

I was forced to do it by the OpenPilot failsafes which are a tad ';over enthusiastic'; if left at the defaults.

One thing that I have noticed on a couple of batteries is that the voltage looks OK overall but some cells ';sag'; more than others under load so the overall voltage looks OK - but from a single cells voltage perspective it is far from it. I now work each battery based on ';worst case'; cell voltage because once they start to fall through a certain point they seem to drop like a stone.

[guest325]

One thing that I have noticed on a couple of batteries is that the voltage looks OK overall but some cells ';sag'; more than others under load so the overall voltage looks OK - but from a single cells voltage perspective it is far from it.

If you have got batteries that are doing that it';s a sign of them getting worse for wear - if it we me I would be pensioning them off!