Battery level setting

Can I set my critically low battery below 10 percent

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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!

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

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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.

25% for my DJI batteries which is the default

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?

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

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

Thanks.

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%ā€¦ in fact its much less. see chart. It is this fact that often catches pilots out, leading to that gut churning, butt clenching panic.

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Thanks for confirming what I said,

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

Would have thought around 3.3v per cell.

Well - yes and no, actually.

Indeed - the curve is not straight ā€¦. but with the DJI ā€œIntelligentā€ 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 batteryā€™s voltage isnā€™t falling as rapidly as the newer battery toward the end ā€¦ 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 didnā€™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 Iā€™ll check to see if it has deteriorated further.

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

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You shouldnā€™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.

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Yeah - indeed - but there will be a limit and Iā€™ve no idea where that is.

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Perhaps the more critical voltage is the whole MP controllerā€™s available voltage ā€¦ when it gets to the ā€œEff this - Iā€™m just gonna switch off!ā€ voltage. :wink:

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I think the intelligent batteries work independantly and itā€™s that which shuts off when charge is low.

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

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Makes sense.

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Shame theres not an emergency override.

ā€œIā€™m nearly down, I donā€™t give a fuck if I kill the batteryā€ mode.

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I think thatā€™s where additional batteries come in. :wink:

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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 heliā€™s. Whilst the voltage was very accurate the % quoted did not take account the ā€˜naturalā€™ 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.

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@Beano1978ā€™s not replied to this thread since the day he started it - a week ago now :man_shrugging:

Are you still around mate?