Battery level setting

#1

Can I set my critically low battery below 10 percent

1 Like
#2

I understand that 10% is the lowest level if you have a DJI quad. Have to say I would never want it that low! as it is surprising how quick the battery power drops - nearly lost mine as a result!

2 Likes
#3

But it was an excellent butt-clencher video. :wink:

5 Likes
#4

While it may be different with the DJI intelligent batteries, when it comes to my usual LIPOs I aim for 20% capacity left when I land.

#5

25% for my DJI batteries which is the default

#6

There might be a parameter mod for this? :thinking:

I know you can disable battery-condition forced landings.

What drone is this for @Beano1978 and which firmware version?

#7

Hi Andy / @Beano1978, and welcome to GADC. :+1:

If you have a moment, perhaps you’d pop over to #introductions and tell us a little about yourself?

Thanks.

#8

When considering the % you wish to set, remember that the lipo discharge curve IS NOT a straight curve, unlike other battery types. That is, the voltage drop between say 70 and 60% is not the same at say 15 to 5%… in fact its much less. see chart. It is this fact that often catches pilots out, leading to that gut churning, butt clenching panic.

2 Likes
#9

Thanks for confirming what I said,

1 Like
#10

Anyone know what zero percent on an intelligent battery is in terms of voltage?

Would have thought around 3.3v per cell.

#11

Well - yes and no, actually.

Indeed - the curve is not straight …. but with the DJI “Intelligent” batteries I was 99% certain that they do report % as a straight line (when the usage is constant).

Curious about this (and anticipating a near limit flight over water!) I went out to tinker, this morning.

Two batteries - hovering @ 6ft - auto land set @ 10% - kept in the air until 5% (without any problem) - landed @ 3%.

Battery 1 - one of my original, 30 month old batteries.

Battery 2 - a new replacement battery about 20 months ago.

It was early - it was cold (about 7C) which explains the initial voltage drop until the usage warms them up.

But, whilst the newer battery’s voltage isn’t falling as rapidly as the newer battery toward the end … both curves are as expected, and cell difference minimal.

But, for both, the reported % is absolutely linear.

Obviously, the maximum power available will be less with less voltage - and that will be more the case with the older battery. But both were more than happy to maintain flight and even do a (brief) climb without a problem. (Kept it brief only because I really didn’t want to take it below 3%.)

However - with an even older battery - there is a chance that the earlier voltage drop-off toward the end could mean that the loss of maximum available power might fall below enough to maintain height.

I have a third battery I’ll check to see if it has deteriorated further.

I’m not inclined to intentionally take them below 3% to find out. Best to try and be home by 5%. :wink:

1 Like
#12

You shouldn’t lose much power as the voltage decreases.

The ESCs use vector control and should output the same power through the full range of the Lipo.

1 Like
#13

Yeah - indeed - but there will be a limit and I’ve no idea where that is.

1 Like
#14

Perhaps the more critical voltage is the whole MP controller’s available voltage … when it gets to the “Eff this - I’m just gonna switch off!” voltage. :wink:

1 Like
#15

I think the intelligent batteries work independantly and it’s that which shuts off when charge is low.

It’s a safety mechanism to avoid damaging the battery by over discharge but not very handy if your still in the air.

1 Like
#16

Makes sense.

1 Like
#17

Shame theres not an emergency override.

“I’m nearly down, I don’t give a fuck if I kill the battery” mode.

1 Like
#18

I think that’s where additional batteries come in. :wink:

1 Like
#19

Great work! The whole volts vs % issue was one that I first came across a long time ago with one of these lipo cell (fuel) meters that used with my RC planes and heli’s. Whilst the voltage was very accurate the % quoted did not take account the ‘natural’ lipo voltage curve, so it was never accurate enough to rely on. Anyway, it is reassuring to see that DJI have got it about right with regards to the % / voltage relationship, which given the price of the batteries is what we ought to expect.

2 Likes
#20

@Beano1978’s not replied to this thread since the day he started it - a week ago now :man_shrugging:

Are you still around mate?