Help Wanted With DJI F550

[CeilidhKeith]

I have just rebuilt a DJI F550 after a very bad crash three new arms, then did a upgrade with E300 motors and new props. Have had it flying but not for long about 5 mins then red led starts to blink and it will try to land, after connecting it back up to my pc and going through the Naza-M Light assistant when i get to the voltage protection page i am stuck as i do not know what to set. Can anyone tell me what these settings should be when setting it up for 4s lipo's. I have just joined this site have had a quick look through but cannot find anything relating to this. Can some one give me the figures please any help will be appreciated.

 

[John Doecliff]

Dont know the numbers for a 4s but are you sure the settings are off? Do you think there too high?

 

[CeilidhKeith]

I have always run on 3s but after doing an upgrade of E300 that include six new motors six new esc and six new props i now need to run my F550 on 4s.
As it is i have to turn off the low voltage protection as i do not know what the settings should be.

 

[John Doecliff]

Lipo battery individual cell voltage is 3.7V per cell (nominal). Times that by 4 (4S) and you get 14.8V. A fully charged lipo should read 4.2V per cell so thats 16.8V. Never fully discharge your lipo's it's very bad for them. 3.5V per cell would be a good number to go down to just to be safe (at 3V it's probably wrecked). Times that by 4 and you get 14V. Another way to look at this is to see what the default setting for a 3S is on the battery alarm page in the phantom GUI. I forget what it is but just divide that number by 3 and you get the individual cell voltage that you should not go below. For instance if the default was 10.5V divided by 3 (because it's a 3S battery) would be 3.5V per cell. Clear as mud right?

 

[John Doecliff]

Just looked at the Naza GUI and it's second level of low voltage protection is set for 14.8V or 3.7 per cell. It's a selectable setting in the dropdown menu on the voltage protection page just select 4S.

 

[John Doecliff]

Just to clarify. 3.7V per cell is minimum. don't use that 3.5V number I gave you, that was bad advice.

 

[CeilidhKeith]

Thank you John for all your help i will give it a whirl tomorrow if this wind drops.