stock battery mod

[Texas Mavic]

Yes sir

 

[Texas Mavic]

 

[Former Member]

So, if I remember, you were first having trouble with the Mavic wanting to land at a certain altitude, correct? Then you did a hove test, and it puffed you DJI battery. No damage to the external batteries?

 

[Texas Mavic]

No, that was sprtbkrydr
I believe he was having a 250 ft altitude landing issue.

 

[Texas Mavic]

No the externals look fine. I believe I let it get way too low in voltage. And hot as hell.

 

[Jeffm912]

Cell 2 **** the bed. Did those voltages come up after letting it sit for a few and cool down?

Jeff

 

[Jeffm912]

I can't believe these things pull so little current. Even some of the 150 size racing quads I have built were over 80A constant between all 4 esc's. Nothing like draining a 4S 1A pack in under 4 minutes.

Jeff

 

[Texas Mavic]

Cell 2 **** the bed. Did those voltages come up after letting it sit for a few and cool down?

Jeff

This is IMMEDIATELY after landing. I fought the landing till it got as low as it did. Just tried to get as long a fly time as possible. In a super tight spot, so I had to have manual control the entire time. So this is the clip, two 3000mah 10C LIHV’s. With xt60’s. Mavic battery is on the charger and seems to have lost most of the swell. **** near has stretch marks if that makes sense. The temperature was super high, the Mavic battery seems to leave room for this type of temperature swell. However I will not try that twice. I have some 2700 lipos, gonna give them a whirl and not push down to 2% just to get 30 minutes hover. If that causes me issues I’m building my own lipos.

 

[Jeffm912]

Glad it went down some. May have been just the temp when it got so low causing that. Hope it isn't permanent. I had that on a few regular lipos that flew fine and lasted another year that way before I decided not to press my luck any longer. I like the strectch marks part. My youngest daughter was nearly 10lbs when she was born, gave me a visual of the ex wife, a decade back and a quick chuckle.

Jeff

 

[Former Member]

No the externals look fine. I believe I let it get way too low in voltage. And hot as ****.View attachment 69196

I am extremely happy the drone landed and it didnt fry anything inside the drone. 69°c is 157f, and cell 2 dropped down to 2.48v. I would use it as a bench battery if it allows you to charge it again.

This is great info for future modders. You can keep the battery window open to make sure the temps and VPC are within specs. You can also monitor the external cells with an RC telemetric monitor attached to your controller.

It also proves that the internal LVC (low voltage cutoff) of the Mavic battery does not always measure accurately when adding external cells. The fact that it let the battery drop to below 3.0vpc is disturbing.

Man, Im happy you got it back.

 

[Former Member]

Another thought. Maybe raise the low battery warning to 40% and the critical to 20%. It should auto land at 20% if the voltmeter in the Mavic battery is working right.

How old was that battery before you started? I wonder how it got so out of balance?

 

[Texas Mavic]

Another thought. Maybe raise the low battery warning to 40% and the critical to 20%. It should auto land at 20% if the voltmeter in the Mavic battery is working right.

How old was that battery before you started? I wonder how it got so out of balance?

It had about 60-70 cycles on it. I lowered the battery warnings, and I did all this foolishly. Astros games 4 days then the President came to town... I had been waiting a week to do the hover test, and I was desperate to get 30 minutes. I could have ruined the bird. Let the battery cool down, the swelling subsided but it’s obvious that it puffed at one point. It charged up like a champ but I haven’t put it back in and checked it. This evening hopefully. 1st test I attempted was a failure, the LIhv’s fully charged immediately began to charge the Mavic battery. So I back the charge down to 12.5 across the board(externals), and then yesterday was the result.

 

[Former Member]

It had about 60-70 cycles on it. I lowered the battery warnings, and I did all this foolishly. Astros games 4 days then the President came to town... I had been waiting a week to do the hover test, and I was desperate to get 30 minutes. I could have ruined the bird. Let the battery cool down, the swelling subsided but it’s obvious that it puffed at one point. It charged up like a champ but I haven’t put it back in and checked it. This evening hopefully. 1st test I attempted was a failure, the LIhv’s fully charged immediately began to charge the Mavic battery. So I back the charge down to 12.5 across the board(externals), and then yesterday was the result.

I think it was a success. The world was not built in a day, and you are breaking new ground for yourself, so really no harm done. There is a learning curve to all of this.

Im sure that given time, you will find all the sweet spots.

 

[Texas Mavic]

My guess is the middle cell, sandwiched between the other two cells, due to heat, took a dump. I am assuming that if I brought it down at about 15%, instead of down to 2%...it wouldn’t have been as ugly of a reading.

 

[Texas Mavic]

I think it was a success. The world was not built in a day, and you are breaking new ground for yourself, so really no harm done. There is a learning curve to all of this.

Im sure that given time, you will find all the sweet spots.

Agreed. I think round two, same batteries and all is in order. Just wiser settings and bringing the bird down before dead zero percent. Thanks for the encouragement!!

 

[darknet]

Any video or picture on stock batteries mod yet please share

 

[BobDoLe]

No the externals look fine. I believe I let it get way too low in voltage. And hot as ****.View attachment 69196

what was the voltage reading on the external batteries?

imo, if the dji battery dies this puffy death and the externals are fine, those externals are no good for this application.
the new hyperion g8 lightweight batteries are great. the protek lihv batteries are good also, but have relatively less actual capacity than advertised. both are the lightest, lowest resistance lihvs you're going to find.