Mavic Pro Battery Mod

[MacIak]

Certainly the wind cuts down the flight time drastically, but it's the voltage after the flight that tells me there's an issue. The voltage on the external should be relatively close to the Mavic battery voltage at the end of the flight. If you are seeing 50% on Mavic battery, well 4.04V per cell on the external is more like 78-80% remaining. That means you didn't get the proportional amount of energy out of the external batteries. This is usually a sign of resistance in the connection and in some cases also internal resistance of battery. I'm never had an issue with internal resistance with LiHV batteries from Multistar.

Very true. The voltage does not make any sense. At some stage during flight i saw the percentage remaining decrease faster than earlier during that flight. The multistar used was the same i ran down to almost zero before. It charged and balanced well, maybe still something wrong with it. Cannot troubleshoot for now due weather so it has to wait a couple of days.

 

[CyberNate]

Very true. The voltage does not make any sense. At some stage during flight i saw the percentage remaining decrease faster than earlier during that flight. The multistar used was the same i ran down to almost zero before. It charged and balanced well, maybe still something wrong with it. Cannot troubleshoot for now due weather so it has to wait a couple of days.

Having a high voltage remaining in the battery would not be caused by battery issue unless it has high internal resistance. I doubt that is the case. As mentioned, I saw another post where a guy saw poor external battery performance when using modded Mavic battery connection. Anyway, you'll just have to try again. Perhaps do a hover test. In that case the wind shouldn't matter so much if it's less than 25mph.

 

[digdat0]

Tried to open up one of the batteries...tried. I find the glue very rigid and when trying to break it the seams bend and deform.
@digdat0 : how hard was it to get it opened? Are you able to put it back together nicely?

Dude it was a pain. If those tabs weren’t glued, it would have been super easy. I am gonna try pulling the side out and putting a drop of acetone under there to see if it will loosen up. drilling is probably easier to be honest. While I did a decent job removing, it’s not perfect and I wouldn’t wanna offer as a service as the side will get all bent up, even if ya do a good job. I’ll put back together and take pics of the sides later so you can see.

 

[MacIak]

Dude it was a pain. If those tabs weren’t glued, it would have been super easy. I am gonna try pulling the side out and putting a drop of acetone under there to see if it will loosen up. drilling is probably easier to be honest. While I did a decent job removing, it’s not perfect and I wouldn’t wanna offer as a service as the side will get all bent up, even if ya do a good job. I’ll put back together and take pics of the sides later so you can see.

Thanks a lot for sharing the experience. It indeed did not feel right trying to pull it apart. Then again, so did the remote but that one does not mind being cracked on a regular basis.

 

[cruzroy]

Oh. Ok, i will leave it for now then. Did not feel comfy to use more force trying to seperate.
Pff. Still not able to fly the coming days. I need to figure out what's wrong with the mod i did. Red to red, black to black...fool-proof..i solder/re-solder heavy battery wires for years, never had a single bad connection.
Maybe it's the wind (25-30mph) that drastically reduced the flighttime. I ll only be able to figure out when it calms down in some days.

yes its all about the cell level in the backup lipos......if they exceed the mavic lipo, what happends the mavic lipo thinks its in charge mode....if that makes sense

 

[cruzroy]

Dude it was a pain. If those tabs weren’t glued, it would have been super easy. I am gonna try pulling the side out and putting a drop of acetone under there to see if it will loosen up. drilling is probably easier to be honest. While I did a decent job removing, it’s not perfect and I wouldn’t wanna offer as a service as the side will get all bent up, even if ya do a good job. I’ll put back together and take pics of the sides later so you can see.

dji and apple engineers work in the same place.....LOL

 

[MacIak]

dji and apple engineers work in the same place.....LOL

THIS IS FOR EVERYONE!!! And specific questions to you.
I need you on this: you have direct battery mods..does it extend your flighttime?
What you say about the cell levels : i have successfully used the LiHv cells charged to 4.3v/ cell with the battery adapter. Anything above that and the main battery switches off and you get errors, logical.
I had charged the external to the same level for my first test run...FAIL. Today the winds calmed down to about 20mph and i took my chance to try again. Discharged the LiHV to 4.28v/cell to make sure. Used a different main/external combo. What are the chances that i screw up 2 battery connections (as said before: i never had any bad connections, ever). By the time i arrived at the field the dreaded wind picked up again but i decided to continue.
THE RESULT IS ALARMING! (Sorry for the capitals, not screaming...)
-13 min with the 5200LiHv, flew the main down to 2%!!!! And still 3.91v/cell in the lihv! This is not good (high wind, p-mode)
- did another with the modded battery i used during the first test but without external. Higher wind, combined p and s mode. Ran it down to 10% and got 16 mins ( this is normal with this flightstyle and wind getting ridiculous).
When logically thinking im afraid that i cannot fool this smartass battery if i tap into it before the mavic. The pins is already mavic so that works. The direct mavic mod also works. Something happens between the battery leads and the pin connectors but then again i cannot say what. People have modded the batteries before me, i just made different holes ending up with the same cable BEFORE the pins.
Pfff frustrating days these are..

 

[digdat0]

here's what the sides look like after i put back in place. I'm gonna try acetone on another battery and see if it will open easier.

 

[digdat0]

THIS IS FOR EVERYONE!!! And specific questions to you.
I need you on this: you have direct battery mods..does it extend your flighttime?
What you say about the cell levels : i have successfully used the LiHv cells charged to 4.3v/ cell with the battery adapter. Anything above that and the main battery switches off and you get errors, logical.
I had charged the external to the same level for my first test run...FAIL. Today the winds calmed down to about 20mph and i took my chance to try again. Discharged the LiHV to 4.28v/cell to make sure. Used a different main/external combo. What are the chances that i screw up 2 battery connections (as said before: i never had any bad connections, ever). By the time i arrived at the field the dreaded wind picked up again but i decided to continue.
THE RESULT IS ALARMING! (Sorry for the capitals, not screaming...)
-13 min with the 5200LiHv, flew the main down to 2%!!!! And still 3.91v/cell in the lihv! This is not good (high wind, p-mode)
- did another with the modded battery i used during the first test but without external. Higher wind, combined p and s mode. Ran it down to 10% and got 16 mins ( this is normal with this flightstyle and wind getting ridiculous).
When logically thinking im afraid that i cannot fool this smartass battery if i tap into it before the mavic. The pins is already mavic so that works. The direct mavic mod also works. Something happens between the battery leads and the pin connectors but then again i cannot say what. People have modded the batteries before me, i just made different holes ending up with the same cable BEFORE the pins.
Pfff frustrating days these are..

Yeah i too ran into the overcharge issue. I just let them run the camera for a minute and try turning on the battery again. Few mins later it will run down to the point of being equal, it sucks but i live with it

edit: i'm off my rocker

 

[digdat0]

i was going to solder mine onto the unswitched and put the two holes here,not much room for exta wires in there.

 

[digdat0]

I'm getting itchy to try a "clean" mod like I did on my p4 ... maybe with some smaller connectors. Seems like DJI is getting closer and closer to the magic weight / flight time ratio

hey kyle - where can i get one of those? wanna see the backside to see how much room it will take, that would be a cool mod.

 

[MacIak]

i was going to solder mine onto the unswitched and put the two holes here,not much room for exta wires in there.

Ehh .. to be honest i do not really understand this. The "switched and unswitched" you refer to are exactly the same cables. There is nothing in between?

 

[digdat0]

Ehh .. to be honest i do not really understand this. The "switched and unswitched" you refer to are exactly the same cables. There is nothing in between?

well i do think im crazy, never mind that. i just looked at the pics again, it has to go through the board to hit the power contacts either way. nm this crazy guy

 

[MacIak]

well i do think im crazy, never mind that. i just looked at the pics again, it has to go through the board to hit the power contacts either way. nm this crazy guy

Meaning there is no way to mod the battery itself like this?
Crazy minds are the most brilliant and pleasant ones to deal with on my planet ;/ .
I do really need @cruzroy to chime in on this one before everyone starts butchering batteries. There was someone else before reporting something similar (did the mod at the points you thought were good, also unsuccessful).
I really should have tested the actual endurance before i posted something here when modding. Just checked "all functions normal when switched on". Weather has been impossible last week and when it was good..all work no play.

 

[CyberNate]

Meaning there is no way to mod the battery itself like this?
Crazy minds are the most brilliant and pleasant ones to deal with on my planet ;/ .
I do really need @cruzroy to chime in on this one before everyone starts butchering batteries. There was someone else before reporting something similar (did the mod at the points you thought were good, also unsuccessful).
I really should have tested the actual endurance before i posted something here when modding. Just checked "all functions normal when switched on". Weather has been impossible last week and when it was good..all work no play.

It is strange. If those leads you soldered the xt60 connector to are direct to magic lihv cells, then there is no way any smart circuitry could cause this behavior. It has to be the soldered points. Please disconnect your external batteries and measure the voltage across the xt60 connector. Do it both with smart battery on and battery off.

 

[digdat0]

Meaning there is no way to mod the battery itself like this?
Crazy minds are the most brilliant and pleasant ones to deal with on my planet ;/ .
I do really need @cruzroy to chime in on this one before everyone starts butchering batteries. There was someone else before reporting something similar (did the mod at the points you thought were good, also unsuccessful).
I really should have tested the actual endurance before i posted something here when modding. Just checked "all functions normal when switched on". Weather has been impossible last week and when it was good..all work no play.

i think it should still work, saying my theory of why it wasnt is debunked. I cant test this till I order my xt60's i better do that.

 

[MacIak]

It is strange. If those leads you soldered the xt60 connector to are direct to magic lihv cells, then there is no way any smart circuitry could cause this behavior. It has to be the soldered points. Please disconnect your external batteries and measure the voltage across the xt60 connector. Do it both with smart battery on and battery off.

You mean to measure it with battery plugged into mavic?
Besides, have no meter...will borrow one tomorrow.
In the mean time: anyone with a working battery mod?
Edit: this is a smart battery right? Do these cells individually have a "signature" ? As in: Mavic is asking, battery is delivering. So when mavic asks, the main batt delivers from the cells it "knows".
If the external is plugged in after the battery you just force-feed and the main still delivers but not as much as before cause mavic is also receiving from external, you get load-sharing and they drain parallel.
When the external is plugged before the battery "smart part" the main delivers from its own cells since the externals are not known, they do not have a compatible "signature" making it a dumb battery. All it does is trying to charge the main, reason why there is some drain. But in this short time it cannot keep up charging and main runs out before. The charging does not help much cause the extra weight and drag...
All the above assuming that solder is ok
Just a minor brainfart, really late. Should be sleeping.
Oh and: the main does not switch off cause it is being charged before the smart part..it parasites without knowing. Egad! Almost sounds plausible.

 

[MacIak]

Also want to share my experience in "landing mode".
So when battery modded mavic runs below 10% the landing mode kicks in " critical battery, landing". And the mavic initiates autoland, starts descending slowly. Making a climb input you can still keep altitude though. What also happens is that speed is reduced and the yaw becomes hypersensitive. (It is also reported that it starts spinning, hard to control) This gives the impression of loosing control but you just need to make micro- inputs on yaw which is hard because you also make a climb input with the same stick which is less responsive. Did this 3 times now and it always reacts the same. Maybe other mavics react different so IF you anticipate using those 10% i suggest you do a couple of testruns nearby over a grass field to get the feel and pulse reponse.

@digdat0 , also thanks for the pics on the reassembly of your battery.

 

[cruzroy]

My record is 37 minutes hover

ok you got 37 min hover, did you test flying around from about 5 - 10 mile per hour, cause all drones get better time flying then working hard in a hover, you should get over 40's easy, can you write down specs of your mod for everyone,
1. lipo or lipos
2. mount
3. connecto
4. mod or type
etc....
etc...

 

[afastboy]

THIS IS FOR EVERYONE!!! And specific questions to you.
I need you on this: you have direct battery mods..does it extend your flighttime?
What you say about the cell levels : i have successfully used the LiHv cells charged to 4.3v/ cell with the battery adapter. Anything above that and the main battery switches off and you get errors, logical.
I had charged the external to the same level for my first test run...FAIL. Today the winds calmed down to about 20mph and i took my chance to try again. Discharged the LiHV to 4.28v/cell to make sure. Used a different main/external combo. What are the chances that i screw up 2 battery connections (as said before: i never had any bad connections, ever). By the time i arrived at the field the dreaded wind picked up again but i decided to continue.
THE RESULT IS ALARMING! (Sorry for the capitals, not screaming...)
-13 min with the 5200LiHv, flew the main down to 2%!!!! And still 3.91v/cell in the lihv! This is not good (high wind, p-mode)
- did another with the modded battery i used during the first test but without external. Higher wind, combined p and s mode. Ran it down to 10% and got 16 mins ( this is normal with this flightstyle and wind getting ridiculous).
When logically thinking im afraid that i cannot fool this smartass battery if i tap into it before the mavic. The pins is already mavic so that works. The direct mavic mod also works. Something happens between the battery leads and the pin connectors but then again i cannot say what. People have modded the batteries before me, i just made different holes ending up with the same cable BEFORE the pins.
Pfff frustrating days these are..

Same here, modded battery with 1800mah turnigy bolt, less then stock flight times.