Just wondering why when I'm using a battery that is fully charged and 97 % life I only get 3 minutes of flying time.   I bought a new battery that on assistant says I have 100% battery life and get 15 minutes of flying time.   Is it mormal to get only 3 minutes of flying time with a battery that has 97 % life left in it?

Short answer is no...

Not normal at all. There has to be an issue with the battery itself... Lipo battery can do that when are getting old, have overheated, have built up gases, or have been discharge too much and the cell no longer retain the charge... So it will show you that they are full, but will discharge very quickly, as you have already found out..

Different question...

What heli is pictured in your Avatar? Is that an Align?

Burt37 Posted at 9-2 13:51
Short answer is no...

Not normal at all. There has to be an issue with the battery itself... Lipo battery can do that when are getting old, have overheated, have built up gases, or have been discharge too much and the cell no longer retain the charge... So it will show you that they are full, but will discharge very quickly, as you have already found out..

yes I agree there is something wrong with the battery, but why is it showing 97% life when in reality its probably more like 5%?   I would expect it to show 5%.
   

The heli is a kyosho nexus.

donut Posted at 9-2 14:55
yes I agree there is something wrong with the battery, but why is it showing 97% life when in reality its probably more like 5%?   I would expect it to show 5%.
   

Because as far as the BMS interpretation, the battery is fully charged (voltage)... The issue is that the battery simply no longer retains the charge when under load... Same kind of thing happen when a car battery has one cell that has lost performance... If you check the voltage it will say still 12 volts, but if you check the voltage while a load is applied you get to see the true voltage...

WOW... A kyosho Nexus...

We are going back in time here... My first heli was the Ergo 60 from JR

Burt37 Posted at 9-2 15:06
Because as far as the BMS interpretation, the battery is fully charged (voltage)... The issue is that the battery simply no longer retains the charge when under load... Same kind of thing happen when a car battery has one cell that has lost performance... If you check the voltage it will say still 12 volts, but if you check the voltage while a load is applied you get to see the true voltage...

WOW... A kyosho Nexus...

yes, I understand that the voltage can be normal but drops under load when the battery is  used up but if the battery is used up, that that should be reflected in how much life is left in it.   For example, in my case the battery when fully charged only has about 3 or 4 minutes of flight time because voltage drops under load, however, on assistant 2 the battery show it has 97% of life left in it when in reality, the battery is practically useless and should have a 5% rating.   Rating this battery at 97% implies that the battery is almost new and has plenty of life left in it when in reality its junk.   I am frankly surprised no one else has pointed this out.

Check the number of cycles the battery has gone through.

donut Posted at 9-3 06:45
yes, I understand that the voltage can be normal but drops under load when the battery is  used up but if the battery is used up, that that should be reflected in how much life is left in it.   For example, in my case the battery when fully charged only has about 3 or 4 minutes of flight time because voltage drops under load, however, on assistant 2 the battery show it has 97% of life left in it when in reality, the battery is practically useless and should have a 5% rating.   Rating this battery at 97% implies that the battery is almost new and has plenty of life left in it when in reality its junk.   I am frankly surprised no one else has pointed this out.

That's not what I said at all... Let me explain...

The BMS will read the voltage and because the voltage is correct when there is no load it thinks the battery is full or in your case 97%...

The soon you apply a load (in your case starting to fly) the voltage drop to its real value and that's why you get only few minutes of flying time... The battery no longer hold the charge...

The 97% that you read, doesn't mean anything as far as your battery current capacity. The BMS can only read the voltage, not the actual capacity left of storing energy...
Think of it as an elevator in a building.. You can see by the lights at which floor the elevator is, but you can't tell how many people actually are inside the elevator...

It is not the voltage your issue here, but the actual capacity of storing energy that has gone down in one of your cell in the battery pack, that gives you the problem...

Another common issue with standard LIPO is when the cells in a package are no longer balanced (as they all have the same voltage)... But the BMS in the DJI battery should take care of that, making sure that all cells are at the same voltage.. Doing this, ensure that all cell take the same charge

Normally, a LIPO battery capacity (not voltage) decrease as times goes by until it no longer take any charge... What ever the reason it maybe in your case, (age of the battery, number of charges, left it too long without charging it, overheating, dropped on the ground...), your battery is no longer good for flying...

yes I understand all of that.   What is the meaning of % of battery life?    What does it mean?   Does 95% battery life mean the battery  is almost new and can still be used for flying?

donut Posted at 9-4 12:25
yes I understand all of that.   What is the meaning of % of battery life?    What does it mean?   Does 95% battery life mean the battery  is almost new and can still be used for flying?

It means that according to the BMS in the battery, you have 95% out of 100% (100% = 4.0 to 4.2 Volts per cell) Voltage available...

You can try this:

Put the battery in the drone and turn both drone and radio on. Then go to the screen where it shows the battery voltage per cell and look at each voltage available..

Now start the drone and just hover in front of you.

Now quickly go back to the screen where it shows the cells voltage and see what your readings are now..

Take a picture of both screen and post them here...