ive seen a number of threads recently about batteries that shouldnt be bad (few cycles, relatively new, not 3rd party, well stored and cared for, fully charged, etc) but that are simply 'going dead' midflight.  i know i have seen a minimum of 4-6 posts on it just in the past week.

many of the posts speculate if other non-battery factors were at play (accidental CSC, motor failure, esc, and so on) and im sure there are plenty of times there are.  but in some threads the sense i get from what people recall doing points to the battery being the most likely culprit.

this got me to thinking about the other two threads we talked on about

a) how hard it is to put them in especially when both craft and batt are new and
b) how hard they are to get out wihtout throwing things across the room (LOVE the two wrist approach now, my fav thing i have found on this board)


well this weekend, i noticed that every 2 or 3 times i put a battery in (i have 4), that the form factor of the plastic 'head' (the part with the hardware, button, lights, etc) is sometimes a millimeter out of being fully seated on either the top side or bottom.  it is usually not both and IS NOT repeatable (meaning one battery will do it once and not the next time, and so on).  i believe this is because the plastic head is not rigidly attached to the plastic charge housing.  


i wonder what you all think about whether a millimeter off could potentially allow the tiny reciprocating leads to connect at startup and launch, but come off enough midflight to simulate a battery failure (maybe due to vibration or whatever, not sure).


whenever i see the millimeter gap, i always remove it and reseat it again until it feels perfect on both sides.  but honesly after reading posts and looking at the tiny gap, im not certain everyone would naturally look at it and not think it is fully seated (particularly given how hard the damn things are to get out haha).


just something i was curious what you guys thought...

Besides being clean, the electrical contacts must have what is known as "follow up". This follow up is achieved by having sufficient spring tension on the contacts and from the point of initial contact sufficient further movement towards the contacts so as to maintain a connection under tension. Put simply the contacts should make contact before the battery is full in.

I think 1-2mm for the small contacts should be sufficient. Having said that the only way without drilling a hole in the side of the Phantom to view those contacts to check would be to measure from some point the travel of the battery from where it is (before closing) to where it would be in the fully closed position and the distance between the Phantom spring loaded contacts and the battery contacts. The distance between the contacts (battery and Phantom spring loaded contacts should be less by a mil or two). Maybe DJI can give us this follow up distance as a benchmark.

The main contacts are a very different story. There is no real way of checking how good the contact is. Making sure the blade contacts on the Phantom are clean and no obstruction in the battery contacts is about all that can be done.

If the battery was not so hard to pull out one could gently pull at the battery with it on and see at what point power is lost or monitoring is lost. One would hope the battery could be pulled out a few mil before contact was lost.

Does anyone know what would happen if a battery was on before inserting it? If nothing untoward then that would be an easier way to check how much sooner contact was made before the battery was fully home.

In time the spring loaded contacts on the Phantom will have to be replaced and one would imagine the blades as well. We don't need to worry about the battery contacts apart from keeping them clean because they don't last long apparently.

Regards

Guy MacDonald

there is always a tiny gap between the battery but i cant influence it, i always but the battery in with force and the gap is there and when i put it in without much force its still the same. The two main contact prongs holding the battery very firmly in place.

gnixon2015

I know what you mean, I have also seen this, but the difference is I only have the one battery so for me at least it is me not pushing it all the way home, even though I press on it hard.

I also once crashed it in to a tree and the battery fell out, so I know I have flown with an incorrectly seated battery on at least one occasion.

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

test reply  (it keeps letting me reply and the post shows up but when i leave the thread and come back, the reply is gone...)

dan, mine doesnt 'always have a gap'.  i can put it in one time (see the gap) take it out, put it back in (maybe see the gap maybe not), take it out, put it back in (maybe see the gap maybe not), etc.  i can also 'minimize the likelihood' of the gap by sliding it in/out/in/out gently before it 'pop it in' sort of like priming the grooves (not a technical term of course).  ive found that doing that i can get it perfectly in about 8 or 9 times out of 10 but it still occasionally does it.  but to me, the fact that the gap exists means that i think it is at least possible that vibrations midflight COULD separate leads (whether flight or data leads IDK) so was just throwing that out there as something for folks to look at on preflight checklists since there seems to be higher frequencies of unexplained battery failures than one would anticipate.

Interesting line of inquiry.  So I took my four batteries and lined them up with a straightedge across the top and backlit to see if there was any significant difference in their length. A smidge yes but not more than about a half millimeter between the shortest and longest.  I then tested each one in an empty Phantom shell I had lying around to see if there was any noticeably different "feel" as they locked into the battery box.  Unfortunately, I didn't have a set of battery contacts installed in the shell so I could see whether a minor gap between the battery and the box would make an difference.  I plan on ordering that part and then repeating the test.  The difference in sliding the different batteries in and out of an operational Phantom is somewhat subjective and I was probably more conscientious than normal about getting a good "snap" when the locking tabs engaged.

yes, gil, i am very conscientious about getting perfect fit because im afraid of a midflight battery issue.  nice approach tho interesting info.