Battery Charging - Performance Tips

[The Editor]

When I fly and want to setup the battery for storage, I fly until 23.3v and land at 23.1v. That puts the 6 cells at 3.85 volts. Perfect for storage.

BlueSkies

Yes - although watch this because the cell voltage will be lower under load, so if you fly to that voltage and land, the pack voltage can actually recover to around 0.5 - 0.6v after rest putting your storage charge at 3.95v per cell.

 

[Larry Hurley]

According to DJI, they don't give a minimum to fly the battery down to that I have found but I fly it down to around 15 to 20% every flight. I then recharge it to 50% after the flight and fully charge it to 100% when I fly it again. After 20 flight's I fly it down to 5% or 3% and recharge it to 100%. You should be notified to do this in the software after 20 flights.

 

[MacDyver]

Sorry but this is VERY VERY wrong! If you are storing your Lipos for a prolonged period the absolute best environment for them is a colder storage - A fridge is ideal. You do not need to store them this way if you are going to use them again in a few days but for prolonged storage - say longer than 3 weeks cold is better to prolong their life.
Perfect conditions would be at around 3.86v per cell at approx 4 degrees. DJI packs are nothing special in the Lipo world and rely on a chemical reaction to release their energy the same as every other pack.
Packs degrade over time whether they are being utilized or not but if you want to slow down that degrading process then the best way to store them is as I stated above. However, the caveat being is you MUST bring them back up to room temp BEFORE charging.
Stores in this way your pack will only lose circa 2 - 6% of their capacity over a 12 month period. Storing Lipos in a warm environment can mean they lose up to 30% of their original capacity in a year! That means your 4,500mAh pack is only going to give you 3,150mAh and then you should only fly to 80% of that which mean 2,520mAh !

Also... yes, you should allow your packs to cool back down to ambient temp after a flight before you recharge them. Charging warm packs is not good for them.

I've actually posted on another thread here http://www.inspirepilots.com/threads/lipo-discharge-threshold.707/
as I'm curious to know how DJI have set their discharge/empty levels for their packs.

When I am in the field I use a Honda 2K generator to recharge, in order to lower my turnaround time as soon as I land I place the batteries in front of a fan, do you think this "quick cooling" is detrimental to battery life sir?

 

[The Editor]

When I am in the field I use a Honda 2K generator to recharge, in order to lower my turnaround time as soon as I land I place the batteries in front of a fan, do you think this "quick cooling" is detrimental to battery life sir?

I would think that should be fine. You are simply moving the air away from the packs as they cool back to ambient. I wouldn't put them in front of an A/C air vent but a fan on them should do no harm.

 

[MacDyver]

I would think that should be fine. You are simply moving the air away from the packs as they cool back to ambient. I wouldn't put them in from of an A/C air vent but a fan on them should do no harm.

I truly appreciate you sir!
In fact as I'm discovering at this moment charging them under the cooling fan significantly reduced charging time also.

 

[Kevin Cabral]

I find flying it down to 5% doesn't work for me. Doesn't calibrate the battery. Flying it down to 3.3v and land when 3.3v appears. Once landed, I allow the batt to cool and wait for it to shut off completely. Once that is done, I allow the battery to cool some more, and charge it to 100%. After that, all is well and it's calibrated. I hear it hurts the batt doing this method, but at least it's calibrated and it's done every 20 charges. I wait for the app to tell me to do it though. In case I forget when I last did it and what cycle it was performed.

 

[The Editor]

I find flying it down to 5% doesn't work for me. Doesn't calibrate the battery. Flying it down to 3.3v and land when 3.3v appears. Once landed, I allow the batt to cool and wait for it to shut off completely. Once that is done, I allow the battery to cool some more, and charge it to 100%. After that, all is well and it's calibrated. I hear it hurts the batt doing this method, but at least it's calibrated and it's done every 20 charges. I wait for the app to tell me to do it though. In case I forget when I last did it and what cycle it was performed.

Who told you it 'hurts' the battery? It doesn't.
The packs have an LVC built into them to prevent damage.

 

[Kevin Cabral]

Who told you it 'hurts' the battery? It doesn't.
The packs have an LVC built into them to prevent damage.

I did notice that in the history for the battery. 'Low voltage protection'. Just been reading around and some people I know said it's never good to drain a battery completely. My 1 battery told me to deep cycle 2 days ago. So I drained it to 3.3v and landed. I believe it landed at 3.28v :S. So I had it grounded and the volts jumped to 3.4v. Allowed it to sit there till the battery turned off. Charged it to 100% and all seems fine so far. The total capacity went up a bit. It was at 5400 mah. After calibration it jumped to 5570 mah I think. Not bad... Just worried I hurt the battery. The way I'm deep cycling it, is that fine to do?

 

[Kevin Cabral]

Here is a tutorial Lynh Phan put up. He doesn't say to drain the battery until it shuts off though. I assume we have to? Unless we land at 3.3v and turn off the battery ourselves?

How to calibrate your DJI batteries