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Discussion in 'Pro/Adv Discussion' started by 30secs, Oct 16, 2015.
The higher output/ faster charging of the p3p... Does it shorten the life of the batteries?
It is still in the realms of a trickle charger - it isn't that fast!!!
The batteries don't even get warm.
The way I see it is the charger is dumb, all it does is supply current 16.8v I think (typical Lipo 4S current) the balancing of cells and shut off happens inside the battery itself.
This is unlike most Lipo Charger systems in the hobby where the chargers have both a power lead and a balance lead. For 4S batteries this would be an additional 5 leads to the balance part of the charger. This makes the charger much cheaper but all the batteries more expensive. This is also why you sometimes have to update the FW in the batteries. All charging and balance management happens inside the smart batteries.
You will notice the 4 extra connections to the Phantom itself, this is so the phantom can keep track of the individual cell voltages, a very good thing. The App will warn you if the battery goes out of spec, that is cell voltages get very uneven.
All in all I am very impressed by how DJI is simplifying battery care with built in balancer and discharge circuits. With normal Lipos you have to put the battery into storage mode yourself between uses. DJI is taking the headaches out of Lipo management.
I think it is still a good idea to fly the batteries down to about 50% when they will not be used for the next 24 hrs. Storing fully charged Lipos will age them prematurely.
I'm not so sold on their implementation.
Most people will have only 1 charger but multiple batteries. So will buy th balancing/shut off circuitry multiple times when once would have done.
As you say the extra connectors that would be needed in a typical charging setup are still on the batt so the phantom can read the individual cells (I agree, a great thing).
Also I prefer it if the batteries were kept as light as possible to increase fly time, I appreciate were not talking about a big weight but I'd prefer the additional circuitry stay on the ground to not add weight.
Thank you. What about the discharge to 8% every 20 cycles? Do you believe it's needed or no?
That is a bit strange to me. Maybe someone from DJI can expand on this topic.
I have about 120 Lipo batteries. I have about 40 models I fly, everything from 1s indoor 3D planes to 7' Giant scale balsa models flying 6S 6000's. And S800 flying double Lipo 6S 6000's. Most of my Lipos are 3-5 years old and still charge up to 95% or more.
I never fly them below 30% unless I make a mistake or have some kind of emergency, like people on the runway when I have to land, or a few times dogs chasing a plane as I am trying to land. 20% is OK, but that is why I always aim for 30%, after that I consider it imperative to land.
If I am not going to use my Lipo for 24 hrs I fly it down to 50% or so, anywhere from 35% to 70% is OK for storage. I always use balancing chargers, my favorite chargers are Hyperion, they also have storage cycles and breaking in cycles available. I break in a new Lipo like a motor. Fly slow w/o full power and only down to 50% the first 5 cycles. Or use the gentle breaking program on the charger. Never charge a hot Lipo and I always check that cels are even before flying. DJI does a lot of this for you.
I know some batteries have a memory problem if they are not discharged every so often down to 10% or so, but Lipos are not one of them as far as I understand it.
I agree that weight saving is very important on any aircraft, but I can see why DJI is managing these complex batteries as simply as possible. It is quite a chore when I fly my S800 to charge up 12 6S 6000's make sure they are matched pairs and after flying get them all into storage mode. It adds hrs the night before and the night after flying.
I see the Phantoms as a very user friendly product with many aspect we used to have to do automatic. I think this is the direction we are heading in in this hobby. Some of us old guys may grumble, but it does help bring new pilots into the hobby and that is a really good thing.
If you Google managing Lipo batteries you will find lots of in depth articles. These battteries can actually be quite dangerous and have caused many fires. I have personally witnessed 2, they burn like magnesium, very hot and almost impossible to put out. At our AMA field we have buckets of sand for putting out these and Nitro fires. And I always have a fire extinguisher in my truck when I fly. I also use Lipo Safe sacks when I charge Lipos in my truck. At home I charge Lipos on non combustible surfaces with lots of room around the charger and Lipo.
I hope this helps a bit. It is a good idea to become familiar with the battery chemistry you are using.
Fly safe and have a great weekend.
Another important reason to have the smarts in the battery itself is for the smart discharge feature. They are selling these machines to people of all skill levels from first time RC flyer to the pros that have been flying for years. For that reason, they had to make it as simple as possible to avoid as many possible issues they could, and battery maintenance is one of the more serious ones.
Re. the 8% discharge after 20 cycles - I'm disinclined to do it unless you are seeing reduced flight times.
Running that low is itself somewhat bad for the battery.
Presumably the main purpose is a form of calibration.
With the P2 I did the proceedure with one battery and the next time it was used it started auto-descent on about 50%.
This became a common issue last year, and was 'fixed' (i.e. hidden!) in a later firmware update.
... but what is 8%? if each cell is at 3.3 volts per cell, then all should be ok.