Mavic Pro Factory Battery Controller Mod

[beanbubba]

OK, just did a preliminary flight and hover tested dual 5200LiHv's for 15 minutes and the sport mode percentage indicator leveled at 62% and remote RPM's stuck at 750 for the run. All 4 motors were pretty hot, but not any worse than I have seen after a typical range test. I think this is probably right at the outer limit of take off weight the mavic can ever handle.

@CyberNate, what was your takeoff weight on your record run?

 

[CyberNate]

OK, just did a preliminary flight and hover tested dual 5200LiHv's for 15 minutes and the sport mode percentage indicator leveled at 62% and remote RPM's stuck at 750 for the run. All 4 motors were pretty hot, but not any worse than I have seen after a typical range test. I think this is probably right at the outer limit of take off weight the mavic can ever handle.

@CyberNate, what was your takeoff weight on your record run?

View attachment 19756

I'll have to check. I only have the batteries, xt60 connectors, and dual lock tape. I'll weigh it later.

 

[CyberNate]

OK, just did a preliminary flight and hover tested dual 5200LiHv's for 15 minutes and the sport mode percentage indicator leveled at 62% and remote RPM's stuck at 750 for the run. All 4 motors were pretty hot, but not any worse than I have seen after a typical range test. I think this is probably right at the outer limit of take off weight the mavic can ever handle.

@CyberNate, what was your takeoff weight on your record run?

View attachment 19756

Right around 1550 grams. Unfortunately my scale only goes to 500 grams, so I'm assuming mavic without it's battery is 743 grams per online specs.

Edit: it's exactly 1322.51 grams. Took propellers of and body was just under 500 grams without battery.

 

[CyberNate]

OK, just did a preliminary flight and hover tested dual 5200LiHv's for 15 minutes and the sport mode percentage indicator leveled at 62% and remote RPM's stuck at 750 for the run. All 4 motors were pretty hot, but not any worse than I have seen after a typical range test. I think this is probably right at the outer limit of take off weight the mavic can ever handle.

@CyberNate, what was your takeoff weight on your record run?

View attachment 19756

So my setup is slightly lighter than yours, but I have 1440mah more than you. You will need those dual 7000mah titan batteries with this mod to better the record. The titan batteries are significantly lighter than the 5200s.

 

[chazz]

So my setup is slightly lighter than yours, but I have 1440mah more than you. You will need those dual 7000mah titan batteries with this mod to better the record. The titan batteries are significantly lighter than the 5200s.

Just because the Titian batteries can run to a to lower Voltage how do you know the bird can? And why do you think this mod will give different results from what others have seen with them? Its still using the batteries control board only the cells are changed. Maybe I'm missing something...

 

[Kilrah]

View attachment 19661

This shows the controller learns the correct battery capacity, so you should be able to have accurate percentage measurement if you do a full discharge/charge cycle. The caveat is you likely have to charge through the controller as well and probably should never disconnect the cells from it or it may reset to standard.

 

[beanbubba]

Can one make a linear assumption like this correlating volts to battery percentages? And from your experience, will a battery drain in this linear fashion (assuming constant load for the flight)?

 

[Kilrah]

Would be easier if you posted a graph... but no, lipo discharge is anything but linear, and that's the reason why mAh count is used instead of voltage.

There are voltage->capacity approximations around, but they're only valid at rest (no current drawn) and even then you'll find many different voices.
Examples: Can someone tell me LiPo Voltage vs Percent Charge? - HeliFreak

Under load it can vary so much from one battery to another it just makes no sense.

 

[beanbubba]

Can we narrow the discussion to this example (LiHv)? Does anyone have a rule-of-thumb dataset to map volts/mAh/percentage for LiHv and/or Lipo? Is there an expert that could give guidance and help me create this chart if one does not exist?

My apologies, I am new to the battery game and have no foundation to leverage in making estimates.

 

[chazz]

Hey beanbubba i wish i had the answers to your questions but the closest thing i have with mah and voltage percentages is a flight-log i got off my phantom using DatCon...Its for a 4 cell lihv 4480 mah so i dont think it helps but here ya go..

 

[beanbubba]

I have a ton of telemetry data from testing several configurations that I am still compiling, but one that popped out was a hover test of dual 5200LiHv's with the mod'ed battery controller. All was going great until 26:36 into the flight and started getting max motor rpm messages nonstop. I landed after a minute because this is what happened when I had the motor melt free from the bird.

We are for sure at the far outer limit of take off weight. I would surmise that if this was a real flight and not a hover test that the wind would have cooled the motors for some additional flight time, but this is just a guesstimate. But we can for sure say the actual limit is somewhere in-between Cybernate's 1323 grams and my mod'ed 1357 grams. You can take that to the bank if you are testing and need to know the max. takeoff limit for an extended range flight.

 

[Kilrah]

I am new to the battery game and have no foundation to leverage in making estimates.

The whole point is that with a lithium battery anytime you try to do a voltage-percentage curve it WILL be a (very rough) estimate, as can be seen with the link I posted where 3 different attempts at doing so give very different results.
There's simply no getting anything reliable with this method, and under load is even worse.

 

[mavicpro1000]

So almost doubling the Auw gives you a duration of what? Thanks.

 

[daivatam]

I have a battery with fw upgrade failed...2 middle lens lighted...but the battery still powering mavic...then the battery discharged under safe limits...now the battery is locked...even if I cut it open and recharged directly...then this appear correct that it is having an circuitry that disable it if something bad is happening...like a deep discharge...and appear that this circuit will not reset...

 

[chazz]

Sorry Bro but the board you sent me is toast...Tried everything i could think of for over an hr.,,,even re-soldered the balance lead from another battery board and nothing...But you did inspire me to try this mod myself..I thought i could get 4.35Vper cell but when i charge the dji battery cells to that voltage as soon as she fires up it drops to 4.32 or 4.33V...A little more work to shorten all the leads and ill be ready to test it...Maybe I'll get some time this weekend if the weather permits...

 

[Mavman]

This is awesome! Great job bubba. I look forward to replicating your work, this seems awesome if you can charge using the regular DJI charger with this....

 

[Progenite]

Bubba and Chazz, I am impressed with your work and thank you so much dedication and documentation on your progress. I hope this will encourage more Mavic users to continue improving their Frankybateria and its configuration in the DJI Go4 application.
I as soon as I can start to try with one, now you have to choose which external batteries to use to find the best result.

I insist, thank you for your work. Great Bubba.

 

[lolo780]

I have a ton of telemetry data from testing several configurations that I am still compiling, but one that popped out was a hover test of dual 5200LiHv's with the mod'ed battery controller. All was going great until 26:36 into the flight and started getting max motor rpm messages nonstop. I landed after a minute because this is what happened when I had the motor melt free from the bird.

We are for sure at the far outer limit of take off weight. I would surmise that if this was a real flight and not a hover test that the wind would have cooled the motors for some additional flight time, but this is just a guesstimate. But we can for sure say the actual limit is somewhere in-between Cybernate's 1323 grams and my mod'ed 1357 grams. You can take that to the bank if you are testing and need to know the max. takeoff limit for an extended range flight.

I run max motor RPM for 10 min+ at a time going straight up and draining around 7Ah out of the batteries in ~13 min.
Dual 5200's is a lot of weight though to hover for 26 min. My record altitude run was around 997g.

Motor cooling mods:
Official Mavic Range Leaderboard

 

[MacIak]

Finally found time to go thru this thrad. Doin' all kinds of stuff but no flying, both birds at repair centre....having tough luck with mavs lately.
Thanks a lot for all this Bub! You're doin a great job (and you know it!)

 

[MacIak]

Screwing around with an open mavic i managed to short it at battery pin level, bird side. Smoke came out. Don't ask...doin a rush-job.
Damage: gimbal ribbon cable fried, core-board fried. Repair cost €400. Stupidity comes with a price.
Happy modding!

Edit: this message is intended for 1 reason only...WARNING: DO NOT SHORT MAVIC, ALL KINDS OF BAD THINGS HAPPEN.