DJI mavic battery repair - Page 1
Forum section: electronics / repair

author: lartsu
author_rank: Contributor
timestamp: July 17, 2018, 10:34:03 am
content: My current project is DJI Mavic battery.The battery was not working because the cells were not in balance. Now the cells are in balance (3.7 V/cell).For some reasons the DJI mavic charger is not charging the battery. When connected to charger the battery is repeating the following sequence: the LED1 is blinking ~16 times in 6 sec. and then ~7 sec break.Do you have any ideas how get battery back to charge and life?Some of batteries have printed labels on back side of it. What they are and are there any use for them (RST)? (image from mavicpilots forum).

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 10:47:44 am
content: First you need to know if the problem is in the battery or in the charger.To you have a DC load to test how the battery performs in discharging?And do you habe a Lab power supply to check how the battery performs in charging?The DC load can also be used to check the charger.A second known ok charger or battery can also be helpful.

author: wraper
author_rank: Unknown
timestamp: July 17, 2018, 11:05:16 am
content: I see there is BQ.... controller on the PCB. Once fault is detected, it gets locked. You cannot simply reset it.

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 11:15:15 am
content: Quote from: wraper on July 17, 2018, 11:05:16 amInteresting.Looked at BQ24703 and BQ24650 datasheet, I could not find such a lock feature.How do you unlock it?

author: lartsu
author_rank: Contributor
timestamp: July 17, 2018, 11:21:48 am
content: The charger is fine - it charges other batteries.The chips are bq30z55 and MSP430.

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 11:59:42 am
content: Use the DMM with a good and and the bad battery to understand where the difference is under charge.90% the battery is bad, and there is no fix for it.

author: wraper
author_rank: Unknown
timestamp: July 17, 2018, 12:05:50 pm
content: Quote from: zucca on July 17, 2018, 11:15:15 amBy stolen authentication key.http://www.ti.com/lit/ug/sluu852/sluu852.pdfQuote

author: wraper
author_rank: Unknown
timestamp: July 17, 2018, 12:12:30 pm
content: AFAIK there is expensive software to reset this chip in laptop batteries but I doubt they support DJI batteries. In any case it's not cost effective in low quantities.

author: lartsu
author_rank: Contributor
timestamp: July 17, 2018, 01:41:53 pm
content: Thanks for providing more details.BTW - Do you have any clue what RST contact on back is used for?

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 02:14:06 pm
content: picture?

author: lartsu
author_rank: Contributor
timestamp: July 17, 2018, 02:23:38 pm
content: In the first message ( battery.jpg).If the chip is replaced to new does this clear the situation?

author: wraper
author_rank: Unknown
timestamp: July 17, 2018, 02:36:10 pm
content: Quote from: lartsu on July 17, 2018, 02:23:38 pmIt needs programming

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 02:56:45 pm
content: https://www.eevblog.com/forum/repair/asus-laptop-battery-bms-reset-ti-bq30z55/msg649902/#msg649902

author: lartsu
author_rank: Contributor
timestamp: July 17, 2018, 04:17:39 pm
content: Any ideas what are these test pads on the circuit board?

author: Zucca
author_rank: Unknown
timestamp: July 17, 2018, 04:26:27 pm
content: Those are test pads for production. By connecting the board with the line production equipment they make sure the board is ok.

author: james_s
author_rank: Super Contributor
timestamp: July 18, 2018, 12:38:57 am
content: Sounds like one more reason to avoid DJI. My multirotors use standard "dumb" LiPo packs, nothing in them to prevent me doing whatever I please. Of course the safety responsibility is strictly on me too.

author: wraper
author_rank: Unknown
timestamp: July 18, 2018, 01:02:42 am
content: Quote from: james_s on July 18, 2018, 12:38:57 amDJI is not a small company located in garage, you can be pretty sure that shit will fly the first time when it burns someone's house. Actually it does a darn good job in this case. Preventing using battery with problem in the cells.

author: james_s
author_rank: Super Contributor
timestamp: July 18, 2018, 01:04:56 am
content: Generally it does, although I saw a video from a of a DJI battery that was sitting on a workbench back behind some guys who were filming a video on another topic spontaneously catching fire. By the time somebody noticed the smoke and turned around the thing had burst into flames. Stored energy is dangerous, no way around that.

author: lartsu
author_rank: Contributor
timestamp: July 21, 2018, 11:20:33 am
content: Now the Battery Pack Manager (bq30z554) has been bypasses. The battery leads have been connected directly to external connector. Also the battery type have to change to non DJI battery via DJI assistant software. You will need the older version from DJI assistant to switch the debug mode on to change the battery type.The battery manager is still sending at least the cell voltages and temperature to the remote controller.Probably it's not the safest to charge battery from DI charger... I added separate connector to external charger.

author: ronimarquestc
author_rank: Newbie
timestamp: April 02, 2020, 01:34:42 pm
content: what software do you use to unlock batteries together with the ev2300?

author: nospam2000
author_rank: Newbie
timestamp: May 21, 2022, 06:30:48 am
content: Quote from: ronimarquestc on April 02, 2020, 01:34:42 pmI know this answer comes late, but it may be helpful to others finding this thread:Youtube video:Github repo with the software:https://github.com/o-gs/dji-firmware-tools#comm_sbs_bqctrlpyIt uses a Raspberry Pi, but probably a USB=>i2c cable on a PC/Mac can also be used. The tool is written in python.Unfortunately the P3 batteries need a specific unseal code which is not publicly available. Only commercial software like UBRT (with the Red_Label_DJI license which is USD $200 per year, seehttp://ubrt.com.ua/prices.html) has the needed key.Michael