iOSD mini question..

[07QPSPGT]

Hey guys, 1st timer here. I've been learing a lot browsing this forum, just a few things I need to pick up on.

Im thinking of installing PMU and an iOSD mini for my Phantom 1.1.1.

Yeah all the heads up info would be awesome, but the main reason I want this is to monitor battery life without having to use a timer or having to find it in the sky to look at the blinks.

I've seen some youtube vids showing the on-screen and there are 2 different set ups I saw.. One showing only voltage and one showing the actual percentage of battery power left. Is this something in the software available to all Phantoms w/ iOSD? If not, how can you determine battery life with just voltage reading?

 

[Pilot_FML]

A few words of caution...

If you want information that tells you how much time you have before you have to begin a return trip home, the remaining battery voltage is important but its only part of what you need to be aware of.

Battery voltage by itself won't give you all the information you need. You'll need to factor in a lot of other considerations like how aggressively you've already flown, the wind direction on the return trip, the age of your battery and how much time you typically get out of that particular battery when flying normally.

Look at the remaining battery voltage as a worst case situation and give yourself some leeway when deciding when to start returning home.
To make that decision you need to consider each battery differently and factor in all the above every time you fly.

P.S. Any program that tells you what percentage of battery is left is almost worthless in my opinion. At best it makes assumptions that could be close to right or at worst very far off. Everything depends on healthy the battery is and that depends on well you've cared for it.

 

[ScouseMouse]

Hi and welcome to the forum. I think your desire to fit iOSD comes from a very responsible attitude but I tend to agree with Pilot FML's comments, another 'layer' of helpful tech is just that - another piece of tech that may lull you into a false sense of security. Battery condition (i.e. individual cell performance) is key to remaining safe so monitor your packs carefully before flights and never be tempted to push them beyond a time/distance figure that will give you plenty of leeway to RTH. As I understand it, the voltage of a fully-charged LiPo cell is 4.20V, nominal voltage is 11.1V (3.70V per cell in a 3 cell pack), dropping to 3.00V per cell when FULLY discharged so you can use voltage display to monitor flight times should you so wish. The danger in doing so is that if a cell goes down on you it will drastically affect the pack as a whole. BTW charging higher than 4.20V and discharging beyond 3.00V are definite NO-NO's

 

[gianni_BT]

Hey guys, 1st timer here. I've been learing a lot browsing this forum, just a few things I need to pick up on.

Im thinking of installing PMU and an iOSD mini for my Phantom 1.1.1.

Yeah all the heads up info would be awesome, but the main reason I want this is to monitor battery life without having to use a timer or having to find it in the sky to look at the blinks.

I've seen some youtube vids showing the on-screen and there are 2 different set ups I saw.. One showing only voltage and one showing the actual percentage of battery power left. Is this something in the software available to all Phantoms w/ iOSD? If not, how can you determine battery life with just voltage reading?

There is a relationship between voltage pack and percent of power left: at 3.7V/cell(11.1V) you are about at 50% of your battery pack capacity. At 3.3V/cell(9.9V) you are basically at the end.
Unfortunately there are some issues: the 11.1V can be reached with umbalanced cells (e.g 3.5,3,7 and 3.9): in this case you risk the lowest cell to drop below the safety voltage even if the overall battery pack voltage is showing a safe value. In addition the percent of remaining battery pack does not give a unique indication of your remaining flight time: it depends how long your battery pack took to reach that percent, how you fly etc.
If your problem is essentially the battery voltage monitoring, there are very cheap devices like this

Remote Control Helicopter Multicopter Spare parts Lipo LiFe LiMn Li-ion Battery Monitor Alarm Low Voltage Buzzer Alarm Indicator 1S-8S-1.58 Online Shopping| GearBest.com

that can monitor the voltage of the single cells of your battery pack and give you an audible early warning alarm if a single cell voltage drops below a programmable set.
I have one mounted on the cover of the battery compartment that gives me a warning if any cell drops below 3.6V and I can hear the sound up to about 200mt in a quiet environment:I know that is the time to start to go back without being in hurry. Then, when the bird is close to me, I check the red LED indication.

 

[07QPSPGT]

Hey thanks for all the info!!

You guys are obviously pro's, so being new to the hobby I understood maybe half of what you guys were saying lol. (give me time, quick learner

Just act like you are speaking to a 10 year old kid...

Hypothetical: I have a brand new battery ready to fly. 4000mah.. I now understand there are a lot of factors to calculate flight time as mentioned above.. But I just really want to know how it "works". When I start her up what voltage should it read? When Its halfway what should it read? when its time to come home what should it read? Are there fluctuations I should be watching out for etc.. Any extra help besides the blinking light and calculating based on a timer would help greatly once I put them all into use together. I've seen vids on youtube of the iosd in use.. I see some with an actual %, I assume are the Ph 2 w/ the PMU already in, but the others are just volts and I want to know how he's calculating flight time (just looking into the "volts on screen". not taking into consideration the other factors)

 

[Pilot_FML]

Your last sentence gives me the impression that you still believe flight times can be calculated by primarily relying on what the screen shows for remaining battery voltage and/or remaining battery %. You're going to get into trouble if you continue to do that.

To see why, you need to understand how your LiPo battery begins weakening over continued use. These types of batteries drop in voltage at a fairly even and slow rate until they reach a certain voltage and then they almost loose all their remaining voltage almost immediately. How fast you get to that quick drop off point completely depends on all the "other" factors mentioned earlier.

As a pilot you have to consider BOTH how close you are to that drop off point AND all the same "other" factors when deciding when to turn back. If you get too close to that battery voltage drop off point on the way back you'll quickly loose power and crash.

Rely on the battery voltage to give you a rough idea of how close you are to the voltage drop off point and then turn around early enough to compensate for all the "other" factors that your facing for that particular return flight.

 

[gianni_BT]

Hey thanks for all the info!!

But I just really want to know how it "works". When I start her up what voltage should it read? When Its halfway what should it read? when its time to come home what should it read? Are there fluctuations I should be watching out for etc.. Any extra help besides the blinking light and calculating based on a timer would help greatly once I put them all into use together. I've seen vids on youtube of the iosd in use.. I see some with an actual %, I assume are the Ph 2 w/ the PMU already in, but the others are just volts and I want to know how he's calculating flight time (just looking into the "volts on screen". not taking into consideration the other factors)

When are not loaded (e.g. on a table) the battery pack fully charged has a voltage of 12.6V(4.2V/cell), when half of capacity 11.1V(3.7V/cell) and fully discharged at 9.6V(3.2V/cell, optimistic value).
These values are valid even when you are flying, but they do not give you a precise value of the remaining flight time.
The flight time depends on the current that your bird is sinking and that causes the battery voltage drop, but the current sink depends on external conditions (wind etc, ) the way to fly (hovering or full speed) and the internal battery pack resistance that starts from 5-6 mOHM/cell with a pretty new and good quality battery, but can increase 2,3,4 times with battery use and/or low quality batteries.
As much is the sink current as much will be your battery pack voltage drop and shorter your remaining flight time.
This is the reason because the simple voltage monitoring can give you many troubles: it must be weighted by the fly conditions and the flight time in your last flights with that battery pack.
This is the reason because I suggested in a previous post to increase the distance between the 2 alarm levels in the Naza low voltage monitor settings and a further third level pre-alarm (that can be also the IOSD, even if very expensive if used for this purpose only).
My early warning is set to 3.6V/cell for new battery packs and 3.7 for older battery packs: when I reach this alarm level I know I have approximately 2 more minutes +/- 15 seconds to safely come back.
But these values are valid for my Phantom configuration, with my gimbal, my camera and accessories and my battery packs and I arrived to these values with a step by step approach measuring the time and the final battery pack voltage at the end of the flight.

 

[ScouseMouse]

Rather than work from voltages for fully/partially charged batteries I would suggest that you start actually flying in an area which is open enough for you to see and recover/land the bird as and when you need to start off with. Go through a variety of flight manoeuvres (hover, circle, out-n-back etc) to put some load through the batteries and THEN measure how much charge is left in the flight pack. This is easier to do if you use an independent charger (I use Imax) rather than the stock unit. This will then give you a better idea of actual potential flight times with YOUR packs, rather than relying on theoretical values for new packs.

 

[lake_flyer]

There are cheaper OSD's that don't need the PMU. I have a Chinese mini OSD (BangGood) installed in my FC40 that I converted to P1. Works great and was as cheap as 10$. There are 2 little Chinese characters that I can't program away, the rest is English. But who cares. Nice thing is that next to all the info the Mini IOSD gives, it displays the GPS coordinates, total time since motor start, and the distance flown. The DJI Mini IOSD lacks that.

Here's a snapshot from the Mini IOSD on my P2.

 

[ScouseMouse]

Lake_flyer, do you have a link to that mini OSD?

 

[lake_flyer]

Here's a link i found but doesn't mean it's the cheapest place. It's gone up a bit in price but still worth it. Search for the N1 OSD. FPV Flight Controller N1 OSD Module for DJI NAZA V1 V2 NAZA Lite GPS $19.67 Free Shipping @GoodLuckBuy.com