Unsure when to charge // voltage fluctuating

[SkyHighFlyGuy]

Hey gang, I'm out flying again for the first time in a while. Stock battery, full charge. I fell like it drained awfully quick... I was down to 14.7 in a matter of like 2 minutes. Probably 50-80ft up there, no crazy wind. I did tinker around like 10 minutes on the pad with some camera settings, but I didn't think this would drain it much.

Then once landed it quickly returned to 16.2 until I fly again. I'd been advised to power down at 14.6 or face the risk of diminishing long-term battery life. I've flown probably 50 times since it was released and usually drain to 14.8ish then charge overnight and store.

Are my batteries f'd? When's the best gauge of true battery life.... the voltage mid-air, or once off and and on the ground?

 

[PatR]

I prefer to check the voltage under load, when the H is in the air. That value is what's still available. The unloaded voltage on the ground is always higher but what it is flying is what's critical. If the battery is losing voltage very quickly when being flown normally there may be a problem within the battery. They drop voltage very slowly when on the ground with the motors off.


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[Rayray]

Going from 14.7 under load to 16.2 with props off is not normal. Jumping to 15 or 15.2 is OK.
However, I fly to land at 14.3, first warning. Then it jumps to 14.6 or 14.8.

If you start at 16.8, 16.7, the voltage will drop fast below 16, but usually hold in the 15's and then 14's much longer.
My opinions of course.

 

[Steve Carr]

If you drain the battery to 14.8 then you should simply store it at that voltage rather than recharge before storing. Storing a fully charged battery will shorten the life.

One possibility with a sudden drop in voltage when you start the motors would be some oxidation at the battery connections either inside the H, the battery or both.I use a tiny bit of die-electric grease on the terminals. Just put a bit on an old toothbrush and apply it inside the battery terminals. That will stop any oxidation and maintain a better connection.

 

[Rayray]

usually drain to 14.8ish then charge overnight and store.

Oh my...I overlooked this at first, but Steve caught it. Never never ever charge overnight. That will ruin your batteries. Smart chargers may cut off
but a Lipo Rule is never leave on charge unattended. As Steve said, store at 14.8 or so.

 

[PatR]

Missed that too. Don't over night.


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[QuadBart]

Based on a few thing in your OP...

Been using lipos since they were first available for R/C use. I too would not recommend leaving a battery charging overnight for the simple "safety" reason. In that charging or soon after is when most fires happen with lipos (short of being damaged in use). I've left batteries charging overnight in the past with no ill affect. These were smart chargers though...

ALWAYS base how much "charge" you have left with a load on the battery meaning when you are using it. So if it read 14.7v during flights that what it is...

Never run your batteries down completely that will definitely damage them. On most lipo using vehicle I've ever owned, I'll run them down to 15%-20%, let them "rest" then charge them back up to between 50%-75% and store them. On my TH I'll run the batteries down to 14.3 and land at that point, let the battery rest and before bringing it back up the 50-75%.

 

[John339]

Here is a helpful little chart. I didn't make it but I do follow it.
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