Battery Discharge with Battery Mod

jsa1742 · Jul 20, 2018

Hi everyone, something quite curious began happening when I first tested a battery adapter mod I handmade on my Mavic Pro. I turned the MP on with just the adapter plugged in, everything was fine, powered it down. I plugged in one of the two Li-Po batteries I have and the lights turn on, but it's not powered on. In fact, with the lights on, I held down the power button and it powered up. Once it powered up, that's when something confusing was going displaying on the controller. The MP battery was discharging at a rate of about 1% per 15-20 seconds. Is this normal, or is something very wrong?

Dronason · Jul 20, 2018

Can you clarify with picture/video what you are really doing?
For how long is the 1% discharge?
Are you putting batteries in parallel? If yes there will be some time so their level adjust.

jsa1742 · Jul 20, 2018

Dronason said:
Can you clarify with picture/video what you are really doing?
For how long is the 1% discharge?
Are you putting batteries in parallel? If yes there will be some time so their level adjust.

That's the adapter in the photo. It went from 100% to 90% in about 3-4 minutes, this is with only one 3S 11.1V battery. Is it possible that the MP battery is charging the Li-Po batteries?

Dronason · Jul 20, 2018

jsa1742 said:
That's the adapter in the photo. It went from 100% to 90% in about 3-4 minutes, this is with only one 3S 11.1V battery. Is it possible that the MP battery is charging the Li-Po batteries?

What you measure is the Mavic battery. If it discharge, it means the Mavic battery charge the other battery until the Mavic battery output is same as your extra Lipo.
Most probably, as soon the motors turn on, then all batteries will be discharging. You can measure voltage at your added connector without the extra battery and the extra battery voltage. If same, there should be no discharge.

jsa1742 · Jul 20, 2018

Dronason said:
What you measure is the Mavic battery. If it discharge, it means the Mavic battery charge the other battery until the Mavic battery output is same as your extra Lipo.
Most probably, as soon the motors turn on, then all batteries will be discharging. You can measure voltage at your added connector without the extra battery and the extra battery voltage. If same, there should be no discharge.

That makes sense. I bought the battery so recently that I don't have a charger for it yet, but I should have it in the next 3 days. As soon as I get it, I will fully charge both batteries and see if that changes, so they're all at 100%.

Dronason · Jul 20, 2018

jsa1742 said:
That makes sense. I bought the battery so recently that I don't have a charger for it yet, but I should have it in the next 3 days. As soon as I get it, I will fully charge both batteries and see if that changes, so they're all at 100%.

That should go better that way.

jsa1742 · Jul 27, 2018

Dronason said:
That should go better that way.

I haven't forgets about this, I promise lol. I will get to it this weekend and update this post.

SkyNinja · Aug 1, 2018

One thing to remember if your external batteries or regular Lipo, not LiHV they are starting voltage will be less them the Mavic stock battery starting voltage. Meaning that they will start off by charging the external batteries until the voltage is equal. The stock battery cells start off at 4.35V and regular LIPO batteries start off at 4.2V

jsa1742 · Aug 1, 2018

SkyNinja said:
One thing to remember if your external batteries or regular Lipo, not LiHV they are starting voltage will be less them the Mavic stock battery starting voltage. Meaning that they will start off by charging the external batteries until the voltage is equal. The stock battery cells start off at 4.35V and regular LIPO batteries start off at 4.2V

Yeah i became aware of this when I first plugged it in and had a mini heart attack lol. I'm waiting on the mavic battery mount right now to test it. Should arrive tomorrow. I'll update with results.

SkyNinja · Aug 1, 2018

jsa1742 said:
Yeah i became aware of this when I first plugged it in and had a mini heart attack lol. I'm waiting on the mavic battery mount right now to test it. Should arrive tomorrow. I'll update with results.

What battery mount are you waiting on?

jsa1742 · Aug 1, 2018

I ordered one from MaxxUAV.

SkyNinja · Aug 1, 2018

The MaxxUAV looks nice. Only downside is it at 34g of and weight. Most of the guys n the mavic range leaderboard that fly with the batteries on the side of the Mavic use the 3M duel lock velcro. I personally fly with my battery is underneath held on by a rubber bracelet.

jsa1742 · Aug 1, 2018

34g is not much when you realize the batteries can weigh in the 200g-350g range. I'm also not trying to max out flight time, just trying to add a few minutes. In my case I have two external batteries so I'm going to try the maxxuav mount, if it weighs too much then I might go to one battery.

SkyNinja · Aug 1, 2018

If you’re only trying to add a few minutes extra flight time the 34g doesn’t mean anything.[emoji106]

But if you ever decide to become one of the crazy long distance flyers like myself you will want to Shed those 34g. The 34g would keep you from flying out to the Mavic’s hard limit of 58,825ft( controller automatically disconnects when mavic gets 58,825 feet away from the controller) and get back to the home point.

jsa1742 · Aug 3, 2018

I have the first results of the battery mod. Not successful.

The battery was detected, but it seems that the extra weight overwhelms the fact that it has more batteries. I was using a 5000mah (381g 155mmx48mmx24mm) battery and when hovering, it cut my flight time in half (13:20 approx.). I get the feeling that maybe it's not taking the second battery in to account in the displayed flight time, so I'm going to continue attempting it to see if I get different results. I also have two 1500mah (129g 74mmx34mmx27mm) batteries that are much lighter, so I'll try that and come back with results.

Also should note that the Maxx UAV battery mount is made for smaller batteries. The 5000mah battery I purchased didn't fit into the mount; I had to velcro it to the bottom, which can be dangerous because it blocks the take-off/landing sensor. I had to manually land it and it would drop altitude very quickly near the ground.

SkyNinja · Aug 4, 2018

So your goal is to increase your flight time correct? What type of flying are you doing, a lot hovering, flying fast, slow, combination of all ?

The 5000mah battery you are using is way too heavy for the amount of mah. Only providing you about 13.2mah per gram of weight. I try to stick to batteries that provide a minimum 15.5mah per gram.

When I purchase batteries I always divide their power rating by there wait to determine if the battery gives me over 15.5mah per gram

I would recommend you get one Turnigy Multistar Lihv 5200mah = 318g. Mount it on top using a rubber wristband making sure wristband does not block any of the sensors underneath the Mavic.

Or get 1 or 2 ProTek RC 100c LiHV 3600mah = 221g / x2 = 7200mah = 442g. Using one battery mount it on top using a rubber wristband make sure the wristband does not block the sensors underneath the Mavic. Using two batteries mount them on the side you seen 3M duel lock.

With one ProTek RC 100c LiHV 3600mah you should be able to fly 30+ min. With two I can fight out 50k feet and back fly at 32mph.

enrico.fedi · Aug 6, 2018

There is something to do ... when I plug my Smartphone/Tablet (all Android), they ask for what to do with the incoming charge, and I reply "nothing", so the controller supports 5-6 flights. Otherwise, I have two controllers, and I use them, sometimes, one to fly and the other one to control the camera ... when I'm alone, I live the charge of smartphone/tablet (4 batteries) but I have the second one to go on, with a bit of time to recharge the drone batteries and the ended controller ;-)