Checking actual voltage

[shizack2000]

How could I "activate" a Mini 2 battery to check its actual voltage? As I've stated in other posts, I do not trust blinky lights or "auto" discharge.
If I have to rig one up that's no problem. I'm pretty handy with a soldering iron. Ive made several charge cables for lipos to be used with my smart charger and helicopter batteries ranging from 1S to 6S.
I use a Hanatora charger so I already have four cables with a battery socket on one end and a barrel plug on the other. I only have two batteries so I can sacrifice at least one cable for this. The battery "sleeps" almost instantly when the plug is taken out of the charger so using a DMM on the barrel or the battery pins is useless.
I have some ideas but they're kind of convoluted so I wanted to check here before I rig up a Rube Goldberg cord.
Thanks.

 

[Yorkshire_Pud]

The Mini 2 equivalent of this perhaps? Note, it is shaped to fit the battery case so will not fit the Mini 2.

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[shizack2000]

Something like that. Im trying to avoid spending more money on a solition, though. I have seen something like that which shows voltage for Mini 2 batts but it's a whole charger for about $40. Besides, I kind of need to scratch my crafting itch. That's the thing I miss most about doing helicopter stuff - the DIY thing.
Good idea though and I thank you for the suggestion.

 

[Yorkshire_Pud]

Wel,l if you got the pinouts for either the Mavic Mini battery or the Mini 2 battery and a suitable connection block you could alway make up you own voltmeter with a similar display. That sort of voltmeter/display unt is relatively cheap.
Alternatively and with fine probes and care, just used a normal multimeter.

 

[Yaros]

Wel,l if you got the pinouts for either the Mavic Mini battery or the Mini 2 battery and a suitable connection block you could alway make up you own voltmeter with a similar display. That sort of voltmeter/display unt is relatively cheap.
Alternatively and with fine probes and care, just used a normal multimeter.

I attached the image of the DJI Mini 2 battery pinout below. If you want to measure the voltage of the battery output (all cells together) then it is quite easy, but you can't measure the voltage of each cell because it isn't like the balance lead on a LiPo, cell balancing is done by the BMS inside the DJI Battery, and it uses the data terminals (C and D) to transmit it to the drone in some digital format (probably). Also, I don't know how about the mini 2 battery, but the air 2 battery needs to be turned on to supply voltage, but it has a button, the mini 2 doesn't have a button, so I don't know about that. Before making it you might try to measure the voltage using a multimeter and see if it works.

DJI Mini 2 Pinout:

 

[Faster]

I have the same problem as the OP. Coming from the RC world where you are able to charge your batteries to the values you like (usually you want 100% of capacity) These DJI smart batteries are a PITA. As all lipos they start discharging immediately but if you want to recharge them to 100% again they won't let you do it if they are at not more than 95%. Example, if the battery is at 97% you are not able to recharge it to 100%, you need to discharge it to less than 95% and the recharge it to 100%. Iknow that because I bought the charger from post #2.

 

[db4476]

Something like that. Im trying to avoid spending more money on a solition, though. I have seen something like that which shows voltage for Mini 2 batts but it's a whole charger for about $40. Besides, I kind of need to scratch my crafting itch. That's the thing I miss most about doing helicopter stuff - the DIY thing.
Good idea though and I thank you for the suggestion.

If you are into the DIY thing, check out this Github post: Mavic Mini Battery Tester.

I did something similar with different processor, code and display. Or you can just get the connector and solder the leads to a board and use a Multimeter.

Cheers!

 

[BethanyFerrell]

One caution: the voltage provided by a battery that's not connected to anything but the measuring device, which is made to draw as little current as possible, will be substantially higher than one that's providing significant juice.

I have a lot of DeWalt power tools in their so-called "20V Max" line, which claims a voltage of 20 volts (surprise). I suppose that's to make them seem better than measly old 18-volt tools. In fact, when a load is placed across a fresh 20V Max battery, due to losses from internal resistance its actual voltage drops to… well, about 18 volts. The fine print points this out but I'm sure few potential buyers bother with that.

That's not to say DeWalt tools and batteries aren't really good — they are! Just that marketing and tech aren't necessarily on the same track.

Given the unique connectors of drone batteries it wouldn't be trivial to make a rig that pulls current similar to what an operating drone requires, so you could measure real-world voltage. Something to keep in mind, though.