Would it be possible to change the "Power" left on the throttle?


#1

Hi!

I don’t know a lot about LiPo but have been reading tons and checked with forums, seller specialists etc and most of them say it’s not good to run the batteries dead while using them (So you leave them at a charge before landing).

I saw that in the first video where this project got announced the throttle had a “power left” on it https://i.imgur.com/SyqxOY4.png

The people and specialists I have been talking to says it’s around an 80/20 rule on LiPo to keep them for the longest time (So you only use 80% of the charge and leave 20% when you land).

My question is if it’s possible to modify the throttle so it would only show “80%” battery as 100% so when the throttle shows the last dot of power it’s actually only at 80% and not 100% used making so we always land safe with 20% storage left,

I hope this made sense?

Thanks!


#2

Yes. Your right with the 80/20 thing and Lipo. Draining the batteries to zero in-flight would not be a good look.
While I don’t know the spec of the ESC’s being used for this project, many of them come with a programable Low Voltage Cut Off. So say when each cell reaches 3.5 volts (42V for 12S), the ESC will cut power. Close throttle and open again, power comes back. Castle Creations HV series ESC’s do this
While it may be problematic to have sudden, total power loss, perhaps 2 of the speedies could be programmed to do this as an indication to land now, while still providing some thrust.
Voltage sag, under high load and other variables come into it, you will quickly develop an intuition for where your pack is at before it hits LV cut off. This is the way I plan to deal with it anyway, without any instrumentation or telemetry. That stuff is just a bonus.
Or, kick it old-school with Lipo buzzers on your batteries while the electronics is further developed.
Just thinking out loud over my morning coffee, getting stoked over the discussion.
“Trust in The Force Skywalker”


#3

In many countries, it is obligatory from the outset to see the state of charge. no matter if it’s an electric bicycle, e-bike or e-ppg. also a warning shortly before the end (usually 15 -25%) depending on the akkutype. just at eppg you are without telemetry of the state-off charge otherwise in the “blind flight” on the way. if you flee only 5 minutes at the airfield circles it does not matter. But as soon as you fly longer distances you should know exactly if you reach your destination or come back home. After many hundreds of flights it has turned out to me that it is ideal to have the following programming: state off chareg is set to display the bargraph of 0-100%. so I can visually see exactly how the state off charge is. The battery has as an example 37 Ah. The balancing suit is set to 30 Ah. So 7 Ah remain in the battery. as soon as I have used up 29 Ah, the engine does not matter if I’m holding full throttle or less on 50% power for 3 sec. so I know that it will soon be over. I can also use more than the 30 Ah, but only with reduced power. consumed at 32 Ah then the drive switches off. Of course, many other options are coupled as temp. sensor, etc. But that’s a different topic. Now something important:If the battery loses capacity later ( after 2-3 years ), I simply set 30 Ah as an example 26 Ah and so I have an exact battrie tank indicator again.


#4

I see, So in best scenario is that OpenPPG has a chip that will detect when the batteries is going low and cut the power?

Could this be possible @pdwhite ?


#5

Yes, it is possible and its what is going to happen with the BMS and FC systemes.


#6

Yeah and since we’ll be monitoring cell voltages as well, we’ll be able to set cell level alarms as well. And more importantly, notify the operator of an impending shutdown BEFORE it happens so the pilot can react. It should also allow us to do something like reduce total throttle to 50% or something like that to give the pilot some control in a low voltage state without a complete shut down.


#7

Just thought I’d throw this one out here.

If your looking for some electrical metrics in the cockpit, There is an off-the-shelf solution already present and easily adaptable to this project. It’s now in it’s 3rd generation so been around for a while.

http://www.ebikes.ca/product-info/cycle-analyst-3.html

While it is more relevant to the e-bike world, there’s some pretty good battery monitoring features in there. State of charge, Ah used, temp sensor with programable cut off etc.
The software is pretty open and flexible.

There may be some cool microprocessor / app stuff being developed in the background but thought this may be worth a mention as a ready-to-go adaptation


#8

A situation may arise that one is willing to trash the batteries to save his life.
I think it would be wise to add this possibility.
We are flying, you know…


#9

I don’t see it much differently than traditional gasoline paramotors. When your gas tank is empty then it’s empty. As the pilot in command it ultimately is your responsibility to know how much fuel you have left.
At least with the OpenPPG we make it easy, just look down at the screen, no mirrors required.

Of course users are welcome to modify their own flying machines however they want. That’s the beauty of FAA part 103. However for numerous reasons by default we’ll need to have a safe limit for battery discharge.