Volts and Amps - Numbers you look for when Flying

Hi everyone, I looked and looked before creating a new thread, and I hope it might be merged into another post like the “User’s guide”

For me, batteries are the most “dangerous/unknown” in the system (coming as a Free-flyer/fixed-wing-aircraft pilot)

For anyone that received a ready-to-fly from OpenPPG assembled kit, having performed a training on a regular 2-stroke engine course, I think the questions you might ask yourself is :

READ this ! => OpenPPG Open Guide

But, I am missing stuff…

For a pilot it is important to know it’s endurance. I sadly do not get any % on my device/controller. (I have a nice constant 0, enevn though I customized to 6S via the online setup-soft)

I read the Voltage you have when fully charged (25,2/6Sbatt = 50,4V displayed on the controller), the one when discharged (Don’t discharge below 3.5v/cell says GliderPilot here : https://community.openppg.com/t/storage-of-unused-batteries-bonkas)

but what about the readings during flight?!

When flying/under load, with a high amp-draw, from 80 to 210A draw reading on the remote control on my setup for instance…) the Voltage is a lot less than the one without draw.

So… when to stop? How to evaluate when is it safe ton continue and when to stop? What voltage do you usually stop requiring full throttle/reducing the use to go for a safe landing/ from your OpenPPG so spare your batteries?

Thank you for your inputs or to direct me to the adequate topic…
Have nice flights

ps : I Flew first time this summer… see : This Video
Tank’s to the owners, it took me quite some time to get in the air (fried board), and I’m dying to fly again…
Flew with a Ozone Swift 4 (PG glider size MS-24m² - 70kg naked, so 85kg flying weight with wing and setup) and 2 6S batteries, a few short flights…(many flights with 4 batteries total, 2 at a time) did not even discharge below storage level, that’s why I’m looking for more accurate numbers…and the SD-Card did not record the flights… a faulty card…(France is locked-down))

Nice flight. Cool to keep it low like that when you have some room.
My % does get displayed and I fly to about 5% or maybe less when under full power. Off the power that bounces back up to 20% or more maybe. Mostly however, I watch the clock! I try to arm the motors just before launch and I manage my flights by time not the voltage readout or % estimate.
I know the batteries (four 6s packs) are good for a maximum of a 20 minute flight in perfect conditions and just flying level. I don’t have that of course. My field is small and I must climb out of it unless I just want to do laps at the tree tops. I tend to spend most of my time either climbing under full power then gliding around or gliding back. I think my batteries would last a maximum of 8 minutes under full power the whole time. I want to save a couple of those minutes for a go around if my approach is poor.

Here’s what I’m doing:

  1. I want to be gentle with my batteries so I charge to 4.15V/cell, not 4.2. This is reported on the chargers as 95%. Generally I try to schedule the charging so it’s done shortly (an hour or so) before I go to the field.
  2. Setup and ready to launch. I used to do a ‘run up’ like regular aircraft but I’ve stopped doing this. I really think it’s a waste of energy and we don’t have energy to waste. If power is not adequate I abort. My field is small so the decision gets made quickly.
  3. Arm the motors and launch. Good thrust = airborn. Fly the aircraft. Sufficient clearance I get seated, check the amp draw, and note the time. I’m looking for >240amps on my setup. Yours may be less. If I see a lot less I’d probably already have aborted but it’s a nice check.
  4. Climb for 3 - 5 minutes into the wind. Glide and enjoy the scenery. Check for traffic, keep an eye on the alternate landing spots and glide slope.
  5. Check % while gliding and climb some more or cruise around watching the clock. I want to arrive over the field at a pattern altitude with not more than 10 minutes on the clock.
    Sometimes I just do practice approaches for fun. Climb, glide, climb, glide, etc. I just watch the clock and check amps each climbout. 10 minutes = land unless the approach is really poor.
  6. Approach to land. If my approach sux I go around. If I really feel comfortable and on my game I might go around just for fun. Otherwise just land.

My flights are just around 12 minutes. Longest so far is just over 14 minutes. At home the chargers show 14-35% depending on how many go arounds. I’m putting 16-18amp hours back into the batteries to fly the next day.

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I’m in the same boat, the controller does not display a percentage.

So I’ve been recording my numbers for each flight. :slight_smile:

I usually fly till voltage drops to 40V (approximately 150a running). That ends up with a resting voltage, when all is cool, of 3.6 V per cell in my 6S batteries.

There is a couple of times when I had to push it a bit to get back home and ended up with a power on voltage of 36V which ended up being a resting voltage of 3.2V per cell. Don’t really want to go that low.

The thing you need to watch is that the volts drop off RAPIDLY once you get below 40V.

I fly an Advance Epsilon 6, 26. Loaded in the middle of the range.

To 42V, I get 15 minutes with 4 batts, 33 minutes with 8 batts.

my tip: just use an isie cockpit v2. since you can connect all the sensors you need. you can set everything you want to evaluate. also adjust a state off charge display exactly to the battery. everything is saved as a csv file. you can use the normal rc model version. I got the rc version myself in 2012. today i use versions specially programmed for eppg. (shouldn’t be advertising, I don’t want to sell anything). you can also use the gps functions then the vario, altitude, motor data for example. fade into a video. https://www.iisi-rc.com/IISI-RC/Products.html

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Thank you grejen711, assiegordon and “bratwurst”:wink:

These numbers are nice to have, and I really thank you because I did not find them anywhere else.

The isie-cockpit v2 seems to be a nice way to monitor every cell, but you need 1 transceiver per battery+the display if I understand correctly?

I am going through the hole forum searching ot the correct way to update in the hope of geting the % working again (did connect and use the online-tool to change the settings to my 6S batt, but I was unable to enter or force the “reboot in update mode”)
And as I have a batch 6 hub+controler (I think?red pcb with the over-voltage feature…;-)) due to them beeing fried due to an over-voltage some time ago, I don’t see any update for them in particular…

And as I see Voltage and Amps and so on, and that it is just the % that remains at 0, I guess the telemetry connectors are well connected, but maybe there is a change from batch4 to batch6 in the way to connect the hub that I am not aware of…?

Anyway, THANK you all, and have nice flights!

unfortunately i don’t understand why you want to see the volt of individual cells?

This is the killer part, the low voltage on one cell that should stop usage in order to avoid damage, don’t you agree?

I have only now seen that you fly with lipo. there is a simple solution. just take 2 lipocheckers and build a long cable for them. switch to it, then you can view individual cells. however, i expressly distance myself from lipo technology when flying with eppg.

I think I understand the disadvantage and added risk of LiPo vs LiFe. Do you really think the added risk is not worth the extra capacity and punch vs LiFe? I’m not monitoring the cells in flight at all really. In a 10 or 15 min flight there isn’t much time or point. If a cell goes bad under load what would, or could, be the result?

clearly the risk to me is : uncontrolled fire and or explosion strapped to your back. Depending on how fast you can make an emergency landing and un-strapp yourself, you could get badly hurt at best.
I do fly with it, but I like to know how close to the limits I am, in order to estimate my “safety margin” and I was opening the discussion of the amount of safety margin one likes to fly with. (and how you read the numbers to know how close to it you are)

Thank you for anybody else to share the values you fly with and when you stop!
Have nice flights!

A “vent with flame” event for these batteries is almost exclusively due to overcharging and/or overheating. I’m well within the margins in that regard. The other cause of a catastrophic failure is mechanical damage, specifically a cell puncture. This is only a potential risk in a tree landing. In that case puncturing myself is much more likely.

I know I have a different point of view. I use eppg for flying like with ppg or xc-pg in thermal. I fly very high, far and long. it is not comparable to flying a few minutes at the sports field at a low altitude. therefore we have a completely different perspective on the subject of security. as a husband and father of 2 children, I certainly think differently about risks than sometimes young men. li-ion have a higher energy density than lipo and about 3 times longer life.

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Or older men?
Unless I go to an ice motor I’m thinking to build a 21700 pack. Also there is an ev charge station right at a field I’ve flown from. Hmm…

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i am 46 years and a few days old. i don’t think it matters what i am. i wanted to express my sense of responsibility. But I know you understand what I’m saying all good:-)

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Ha. I was referring to my own nearly 6 decade old self! :grin: yes I fully get that your mission is very different from mine.