Mavic Pro Battery Mod

[mnoutdoors]

So who is going to be first to set a litchi waypoint mission just past the current distance limit?? I would but weather is horrendous here.

I would have tried it already but can not figure out how to get litchi to fly the bird above 500 meters it does not allow it. And my route heads out over the mountains at 6-7000 feet about 4K higher than takeoff. I’ve programmed it before and it flys fine till it reaches 1640 feet then if I would let it go it would flown right into the mountain.

 

[chazz]

I would have tried it already but can not figure out how to get litchi to fly the bird above 500 meters it does not allow it. And my route heads out over the mountains at 6-7000 feet about 4K higher than takeoff. I’ve programmed it before and it flys fine till it reaches 1640 feet then if I would let it go it would flown right into the mountain.

Does it slow down at each waypoint?

 

[mnoutdoors]

Does it slow down at each waypoint?

No, it just keeps going,if you don’t program a function for that waypoint. I have found though if I program 32 mph in the program and it seems it always runs slower than what’s programmed

It will keep going even if it was to loose signal with the RC but you better hope you have good GPS because that’s what its flying with

 

[efowler]

cybernate turned me on to this unit. I have 3 and they work perfect and support over packing LiHv's.

View attachment 31860 View attachment 31861

Nice - Thanks for the tip!!

 

[Deadleg]

Hey Deadleg, That's great stuff!
Yeah i just go in order and from the neg side (Cell 1) and leave off the positive side (Cell 4). IDK if it matters... DJI Go shows Cell1- 4V Cell 2- 4V Cell 3- 4V and total volts 16V. Also It seems one cell (cell 1) drops faster then the others for some reason but not too bad and that's the one it shows on the main screen...Keep us updated on how things go...

Thanks Chazz. It's good to hear that it works that way. You connect the power wires directly to the pins on the multi-pin connector. I want to wire the 18650 battery the same as the original Mavic battery, i.e. connect the power leads directly to the board. I think if I wire it the same as you I may short out batteries 1 & 2 - see attached diagram. I might give this a try - unless you can see a problem with this.

If this doesn't work, I'll do what you have done and wire directly to the multi-pin connector.

 

[chazz]

Thanks Chazz. It's good to hear that it works that way. You connect the power wires directly to the pins on the multi-pin connector. I want to wire the 18650 battery the same as the original Mavic battery, i.e. connect the power leads directly to the board. I think if I wire it the same as you I may short out batteries 1 & 2 - see attached diagram. I might give this a try - unless you can see a problem with this.

If this doesn't work, I'll do what you have done and wire directly to the multi-pin connector.

View attachment 31917

Just be careful i think you have the pos and neg switched on the board in that drawing.
I do have mine hooked up the way the original battery was but i put jumpers to the pins too. I explain why here Mavic Pro Factory Battery Controller Mod

 

[Deadleg]

Just be careful i think you have the pos and neg switched on the board in that drawing.
I do have mine hooked up the way the original battery was but i put jumpers to the pins too. I explain why here Mavic Pro Factory Battery Controller Mod

You're right . . the pos & neg are the wrong way round. I've looked at your mod details and tried to draw a schematic of your system. You have effectively by-passed the battery switch. What worried me was the possibility of a link on the board between the battery connectors and the positive balancing pin . . but I guess if you didn't get a big bang, then there isn't one! Please let me know if I have the circuit right this time.

I would still like to use the start button, so I will start by leaving out your by-pass jumpers, and see if that works first. (I don't yet know if the board is ok)



On a general point I have always wondered why you need the pos and neg wires on the balance cable. You already have these connections on the main power wires, so they seem to be redundant. If someone could enlighten me I would be most grateful!

 

[Deadleg]

You're right . . the pos & neg are the wrong way round. I've looked at your mod details and tried to draw a schematic of your system. You have effectively by-passed the battery switch. What worried me was the possibility of a link on the board between the battery connectors and the positive balancing pin . . but I guess if you didn't get a big bang, then there isn't one! Please let me know if I have the circuit right this time.

I would still like to use the start button, so I will start by leaving out your by-pass jumpers, and see if that works first. (I don't yet know if the board is ok)

View attachment 31936

On a general point I have always wondered why you need the pos and neg wires on the balance cable. You already have these connections on the main power wires, so they seem to be redundant. If someone could enlighten me I would be most grateful!

STOP PRESS! . . I have just put a meter across that link and it shows zero resistance - so the link does exist . . at least on my board. So what's going on here? When you connected your 4s battery Chaz, why didn't battery 1 short out? You should have had a big bang, but you didn't, so what is wrong with my diagram?

 

[beanbubba]

STOP PRESS! . . I have just put a meter across that link and it shows zero resistance - so the link does exist . . at least on my board. So what's going on here? When you connected your 4s battery Chaz, why didn't battery 1 short out? You should have had a big bang, but you didn't, so what is wrong with my diagram?

Hey guys, great work. Don't let this derail you but I remember one significant issue that stumped me a while back. Depending on the version of battery controller, the balance wires are flipped from what it appears to be. So if you are wired 1-2-3-4, it is in reality 4-3-2-1 (again depending on the controller variant). Hope this possibly helps.

 

[Deadleg]

Hey guys, great work. Don't let this derail you but I remember one significant issue that stumped me a while back. Depending on the version of battery controller, the balance wires are flipped from what it appears to be. So if you are wired 1-2-3-4, it is in reality 4-3-2-1 (again depending on the controller variant). Hope this possibly helps.

Yes, it can be a problem . . but on the Mavic battery controller it seems fairly clear which is which. The pos balance pin and the pos power pin are connected in the board, and the negative pins are also connected, as you would expect. The problem comes when you go from a 4s battery to the 3s battery board. It seems to me you have to wire the pos and neg balance leads from the 4s battery to the pos and neg balance pins on the board, or you will short out one of the batteries . . but Chazz seems to have found a way round that, so I need to solve this mystery!

 

[Deadleg]

Battery connectors, plugs and sockets soldered. Used 2 XT30's instead of one XT60 to make them easier to unplug. Next job spot welding the nickel strips . .

 

[Memphis3]

The problem comes when you go from a 4s battery to the 3s battery board!

Yes your right
8S battery wired to 4s using a 3s charger. If any 1 of the 8 cells gets a low charge or becomes out of balance it will never be able to fix itself. The 4s battery will stay unbalanced.
Fix
Use a 8s connector and balance charge the 8s battery. They make 8s balance connectors.

 

[Deadleg]

Yes your right
8S battery wired to 4s using a 3s charger. If any 1 of the 8 cells gets a low charge or becomes out of balance it will never be able to fix itself. The 8s battery will stay unbalanced.
Fix
Use a 8s connector and balance charge the 8s battery. They make 8s balance connectors.

This is not an 8s battery, it's 4s2p and will be charged and balanced with a 4s charger. Parallel cells are self-balancing.

 

[Memphis3]

This 4s2p and will be charged and balanced with a 4s charger.

Ok
Mavic charger can not charge a 4s2p properly. Mavic battery board trying to use it on a 4s2p will cause battery balance problems.
and
A 4s charger needs to see a 4s (5 wire) connector to balance the 4 parallel battery banks.

Like the drawing bellow shows a 4s2p battery and 4s charger requires one more wire (purple) which the 4s2p battery the Mavic battery board and Mavic battery charger do not have.

 

[Deadleg]

Ok
It sounds like your in the know.
Then
A 4s charger needs to see a 4s (5 wire) connector to balance the 4 parallel battery banks. Like the drawing bellow it requires one more wire (purple) which the Mavic battery board does not have.

Correct. The Mavic board does not need this, but the battery pack does and it will have a 4s balance plug for charging. The drawing only shows the battery connections to the Mavic.

 

[efowler]

Very cool, I did not know that. Thx for sharing.

 

[efowler]

beanbubba - Question for you (or anyone else on the thread). I have 3" long cables that go from my antenna to my controller. What would happen if I put 50' or 100' cables between my antenna and my controller??

On another note - Have you tried out Litchi yet?

 

[chazz]

Yes, it can be a problem . . but on the Mavic battery controller it seems fairly clear which is which. The pos balance pin and the pos power pin are connected in the board, and the negative pins are also connected, as you would expect. The problem comes when you go from a 4s battery to the 3s battery board. It seems to me you have to wire the pos and neg balance leads from the 4s battery to the pos and neg balance pins on the board, or you will short out one of the batteries . . but Chazz seems to have found a way round that, so I need to solve this mystery!

If i did find a way it was truly by accident. I just plugged the 4s into the control board and it worked. The only time i ever saw sparks from this thing is when I plugged the battery into it first and then into the Mavic and didn't have the terminals lined up properly. I'd like to say i learned my lesson and that ill never do it again but id be lyin. I think i'm going to do another but this time I'll try without the jumpers first...

 

[Deadleg]

If i did find a way it was truly by accident. I just plugged the 4s into the control board and it worked. The only time i ever saw sparks from this thing is when I plugged the battery into it first and then into the Mavic and didn't have the terminals lined up properly. I'd like to say i learned my lesson and that ill never do it again but id be lyin. I think i'm going to do another but this time I'll try without the jumpers first...

Thanks Chazz! . . it's still a mystery. Your photos look the same as my diagram, but the diagram says it won't work! Anyway, I decided not to take the risk so I connected the pos balance wire to the pos power connection. I connected it all up today and pressed the start button. Sure enough all 4 lights came on and then went out as normal. Then I did the short + long press and the Mavic sprang to life . . but only for a few seconds and then the battery shut down. I tried this several times and got the same result each time. So what's causing the battery to shut down? Maybe the board senses that the voltage is too high. If anyone else has had the same behaviour trying to run with a 4s then please let me know. I have a feeling that the board is still working ok, but cant prove it yet.

So only partial success . . at least the board didn't appear to blow up. The main button and battery lights seem to work as normal, and the Mavic powered on, if only for a few secords. The next step tomorrow is to try your jumpers. That way at least I can get it flying and see what the battery levels look like in the app. (Any other ideas gratefully received!)



Spot welding complete:



Battery weight 435 g.




Mavic fired up ( but only a few seconds!) :

 

[chazz]

View attachment 32126

I got a chance to test my 18650 4s4p today but I’m having the compass issue. So, I only flew for a few minutes because I suck pretty bad at trying to control this thing in the wind without positioning. It’s actually pretty comical to watch. But yeah, I think the issue may come more from actual battery then the motor wires running under the compass or maybe both. Before I added the 4 batteries I was able to re-position it forward a little to stop it from interfering with the compass but now the batteries pretty big and I really have nowhere to go with it. I should have thought of this and IDK what to do really. I wonder if I wrap it with copper tape? Is that dumb? I guess we’ll see because I just ordered some (Online ordering is way to easy). I thought this thing has two compasses shouldn’t at least one of them work?

I tried a few things to stop the compass issues I’m having…I started looking into it and noticed it said compass error in the go app and the RC said “Mag Interference”. Also in the go app a warning kept coming up “Compass redundancy switch” (I think that means its switching between compass 1 and 2 IDK) so I looked at the compasses in the sensors and both of them had an error “Abnormal Compass Dire”…I bought a spare compass with the intentions of seeing if I can modify the wiring and moving the position of it but before I started that I decided to try wrapping the battery in foam and copper tape. At first when I hooked it back up the error wasn’t there and I was thinking it worked until I wrapped the Velcro zip tie to the battery to pull it tight to the Mavic then it came back. So that gave me an idea and I noticed when I pulled the battery away from the bottom of the bird the compass error would go away and when I got it closer it would come back. So ultimately putting a 5mm thick piece of foam between the bird and the battery was enough to get rid of the error. I may take all the copper tape and insulation off and add another piece of 5mm piece of foam to give it a little more distance away from the bird…