M300 Batteries... Looking for Community Input

For all you lidar lovers who fly the DJI M300, I have a question…

Scenario: You are on a multi-battery mission. The M300 returns home at the appointed time, lands and you spring into action! You grab your fresh set of batteries (each pair is considered ONE unit, they are not mismatched), go to the M300, carefully remove one old battery and install the new battery, repeat… But now your drone won’t take off!! Why? Well, you “fresh” batteries happen to have a voltage mismatch (damn self discharge feature). My left battery was at 91%, the right battery was at 89%… the voltage difference was too much for software, therefore, I can not fly. (remember, your time is limited when the R2A is running on the ground, at the first sign of distress, perform R2A shut down so you don’t corrupt the data you have)


So what are the options? This is where I am looking for community feedback…

  1. We could turn on the self-heat but the batteries are already warm and we are nowhere close to freezing. A hot battery working hard is a bad idea.
  2. We could place the batts in the charger (but I’m in the field and I did not bring my charger, nor do I currently have the facilities for mobile recharging)…
  3. Could I bleed off the full battery with a dead battery on the other side? Would it eventually bring down the full one, closer to the it’s twin? I know it won’t fly, but how else does one match batteries in the field? :thinking:

What would you do?

As it turns out, I had to return to base, recharge/grab new batteries, return to field and refly. The concern is that one day we will be in the middle of nowhere with this problem.


I always charge batteries the night before a mission so that they are as close to equal as possible. If you let them sit, you are more likely to encounter this behavior. Not much you can do besides run the higher battery down until the % and voltages match. Just keep the aircraft powered with only the higher battery installed until the voltage is closer to the other one.

For this reason amongst others I like to think of every RTH as though it could be the end of the mission, and therefore make sure to fly home with the same behavior every time no matter what. That way if you need to end the capture you’re not chancing having an improper final high velocity calibration.

FYI: The max time you want to have the R2A sitting on the ground is 5 minutes. I usually cut it before then and just start a new capture if I know that I’m going to have to wait any longer than a normal battery swap. After all it only takes about 3-5% of your battery to do your convergence maneuvers and be back to capturing your mission.

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from our in-the-field experience, we always take a charging station and portable generator…cuz you never know when you may need to charge batteries…even though you may think you have enough to fly your mission. This way, you have a backup scenario to avoid leaving your project site, only to return again. Time is money so being fully prepared always C.Y.B.!!!

as long as we keep max time of the R2A on the ground (recording) at 2 minutes or less, we’ve never had an issue. couple times around the 2 minute mark we’ve experienced processing issues.

We haven’t encountered this issue yet but I do pretend each segment is our last even if I intend to do a battery swap.

I’m nervous to just continue past the battery swap as I have had corrupt data more than once after a hot swap.

This is a totally suitable practice, however you shouldn’t be afraid of battery swaps and continuing to run your R2A. As long as you adhere to standard procedures you should have no issues whatsoever. We have had luck with doing missions as long as 6-10 battery swaps that still output great data.

That being said, there is no issue at all with stopping after each flight and then starting a new mission. All the .las or .laz files can be uploaded to a single project anyway and they will all align perfectly as long as you use the same base station RINEX file, or at the very least set the base station up in the exact same position and use the exact same values when prompted for them in PCMaster.

Ellipsoidal Height.

We ran into similar issue. To solve, we have installed a stickers on each battery (1 Green / 1 Red) that are numbered in pairs. 1 / 1, 2 / 2, 3 / 3, 4 / 4. We always charge all batteries the night before. When I come in the next morning I turn the charger off for 10 minutes then turn it back on just to top off any batteries that may have discharged overnight. They are put in the battery case with Green sticker up to indicate they are fully charged then we always keep them paired together. In the winter we keep the batteries in the heated cab of the truck to help with cold weather discharging. Once we fly those batteries out then we put them back in the case Red sticker up to indicate discharged. We also alternate the battery pairs we start out with to distribute the usage. No more battery issues.

Leads down, Charged. Leads up, burnt.

Pairing batteries is good practice, but actually isn’t necessary with TB60s

Have a pure sine wave inverter or battery pack generator at all times if possible. Saved me before with this issue

I recommend putting a 110v Power Inverter in your truck or SUV and having a RV or Camper shop install it. You can get a really good one on Amazon for like 350$ and it runs the Charging Station suitcase perfectly.
Also, you should always have at the very least, one extra set of fully charged batteries from what you think you need from your pre-programmed flight plan. Charging the batteries in full the night before is always a must, or wake up 3hrs early from your takeoff time and start your charger and go back to sleep if you are worried the weather may hold you off and you dont want to fully charge your batteries until you know you are a go on your mission flight.
I have had to do things in the field such as leave only 1 single battery in the M300 to wear down a bit so the voltages match up but if you do that, you should make sure younrun a battery maintenance on that set of TB60’s after that days mission.
That low of a voltage difference shouldnt keep you from taking off with the new firmware update from DJI as well. They are smart enough to pull more juice from the higher voltage battery to put them even prior to flight.
Lastly, you should be able to run the R2A as long as younneed on the ground as long as you pull those images and data collected out on your post processing in PC-Master with the start and stop measurement trajectory data section.
Good luck with your flights and if you ever get into Aerial OGI Inspections with your M300 my company has a custom built OGI Epa Certified and 0000a Certified OGI-Camera thats built and integrated into the M300 drone platform and is fully operational through the DJI Pilot 2 app. We can also built the camera onto any other UAS platform amd integrate it onto any other drone platform and into any other video format that’s needed such as .ts, .mov, .mp4, and plenty of others. Thanks and good luck with all your flights and data collections!