What do you think about "e-soaring"?

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addaon

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As a side note, I’d wager that the first charger you describe would run fine on single-phase 220V, unless they really cheaped out on the bulk capacitance or put in software to detect and disable it. It’s also quite possible it would work as-is (or with software changes) on 240 V three-phase and 120 V single-phase… 144V is right at the limit for a 170V intermediate voltage, but that sort of architecture for 100V or 60V batteries is pretty close to “universal by default”.
 

John.Roo

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As a side note, I’d wager that the first charger you describe would run fine on single-phase 220V, unless they really cheaped out on the bulk capacitance or put in software to detect and disable it. It’s also quite possible it would work as-is (or with software changes) on 240 V three-phase and 120 V single-phase… 144V is right at the limit for a 170V intermediate voltage, but that sort of architecture for 100V or 60V batteries is pretty close to “universal by default”.
I think you are right - reason why they "split" 400 V into 3x 220 was probably "spread out load" of each phase. In old hangars you never know on what phase are some appliances (fridge etc.).

Anyway.... it is sure I have to focus myself to composite work on airframe. Detailed electric propulsion system (incl. motor, controller, battery and charger + proper wiring) must be consulted with expert. Maybe better done by expert....

A friend of mine (from Ireland) often uses the term "PFM" when he sees how something modern works that he doesn't understand.
It stands for "Pure Fucking Magic". I used to laugh at him, but I guess I'll start using it too....
 

John.Roo

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As a side note, I’d wager that the first charger you describe would run fine on single-phase 220V, unless they really cheaped out on the bulk capacitance or put in software to detect and disable it. It’s also quite possible it would work as-is (or with software changes) on 240 V three-phase and 120 V single-phase… 144V is right at the limit for a 170V intermediate voltage, but that sort of architecture for 100V or 60V batteries is pretty close to “universal by default”.
If possible - I would like to ask you for your opinion about voltage 🤔
At the beginning we were planning to stay arround 50 V.
For two reasons - safety and price.
51,8 V (14S) is +- border between RC models and light electric flying machines. Geiger Engineering is offering wide range of products based on standardized battery pack with 14S and two different capacities. Prices are higher, but you pay for good service and quality.
Freerchobby producer has also wide range of affordable products - prices are really low but I have no personal experience with quality.
Negative on low voltage is high current necesary to get reasonable power.
To get 15 kW you need 300 Amps and "cruise" power of 5 kW still require relativelly high 100 Amps. Wiring designed for high currents is also heavier - especially when batteries are far from controller and motor.

Second "reasonable" voltage I have experience with is 99,9 - 103,6 V (27-28S).
Controller (for excample MGM Compro 280120) has higher price (still acceptable) and currents are lower.

I don´t expect that for light one seat self lauch glider (or light motorglider) we should go to higher voltage like 350 V or more.

In your opinon... what is better way?
 

addaon

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The constraints for voltage are (a) safety — either you’re below 60V or you’re treating it as a whole HV system with two contractors etc; (b) current — higher voltage generally leads to lighter systems, as you mention; (c) vendor support; can you do single BMS IC (up to 16s or so) or, if not, how high a strong can you build, can you wind your motor with thin enough wire to use a higher voltage; can you use MOSFETs or are you going to be pushed to GaN or SIC?

The sweet spots really are 14S - 16S (depending on cell chemistry) and then 400V, driven by industry support. If you can get motors that fit your specs wound for 400V it might be interesting… but honestly 60V is probably the right answer for a sailplane; and anything carrying less than a couple hundred pounds of batteries. 300A isn’t that bad, just requires strategic placement to shorten copper runs. Aluminum bus bars can help here, but even without, you’re talking a few pounds — about the weight of the contractors you’d need at HV, and at HV you’d /probably/ need a second LV battery anyway (instruments).
 

John.Roo

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The constraints for voltage are (a) safety — either you’re below 60V or you’re treating it as a whole HV system with two contractors etc; (b) current — higher voltage generally leads to lighter systems, as you mention; (c) vendor support; can you do single BMS IC (up to 16s or so) or, if not, how high a strong can you build, can you wind your motor with thin enough wire to use a higher voltage; can you use MOSFETs or are you going to be pushed to GaN or SIC?

The sweet spots really are 14S - 16S (depending on cell chemistry) and then 400V, driven by industry support. If you can get motors that fit your specs wound for 400V it might be interesting… but honestly 60V is probably the right answer for a sailplane; and anything carrying less than a couple hundred pounds of batteries. 300A isn’t that bad, just requires strategic placement to shorten copper runs. Aluminum bus bars can help here, but even without, you’re talking a few pounds — about the weight of the contractors you’d need at HV, and at HV you’d /probably/ need a second LV battery anyway (instruments).
Thanks for your opinion 👍
I had the same feeling. Simplicity = safety and in this case = affordability.
400 V request a lot of cells even in 1P configuration. Also BMS config is far from simple.

In my case is the only complication problem you mentionned.... length of power wiring.
Roughly measured would be cable length around 3,5 m (battery position must be near CG).
Phoebe - fin prop version.jpg
I definitelly agree to have one independent 12 V battery for instruments 👍
 

blane.c

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Thanks for your opinion 👍
I had the same feeling. Simplicity = safety and in this case = affordability.
400 V request a lot of cells even in 1P configuration. Also BMS config is far from simple.

In my case is the only complication problem you mentionned.... length of power wiring.
Roughly measured would be cable length around 3,5 m (battery position must be near CG).
View attachment 129098
I definitelly agree to have one independent 12 V battery for instruments 👍

Nice sketch! Could the forward sweep be reduced by placing the batteries closer to the motor? And/or lengthening tail boom a "tich"? I know you are not concerned so much about forward sweep but I think it would be more attractive with less, especially when painted in bright balloon colors!
 

John.Roo

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Nice sketch! Could the forward sweep be reduced by placing the batteries closer to the motor? And/or lengthening tail boom a "tich"? I know you are not concerned so much about forward sweep but I think it would be more attractive with less, especially when painted in bright balloon colors!
Quick draw with original wings....
Phoebe with e-motor.jpg
 

John.Roo

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Nice sketch! Could the forward sweep be reduced by placing the batteries closer to the motor? And/or lengthening tail boom a "tich"? I know you are not concerned so much about forward sweep but I think it would be more attractive with less, especially when painted in bright balloon colors!
But even with no wing sweep it will save me only few cm of cables....
So... I have to accept long cables and small weight penalty.

Bright colours are OK for me ;)
 

addaon

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Al wiring can be fragile. At 300 A you’re looking at something closer to a solid bus bar — worth checking it out.

Personally, I’d be comfortable running instruments off a DC/DV from a 60V battery as long as I had one instrument with independent backup (G5 or similar). It’s higher failure than a lead acid battery, but it’s a a single failure (converter), not like at high voltage where you want to disconnect the battery in the case of many other failures.
 

John.Roo

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Al wiring can be fragile. At 300 A you’re looking at something closer to a solid bus bar — worth checking it out.

Personally, I’d be comfortable running instruments off a DC/DV from a 60V battery as long as I had one instrument with independent backup (G5 or similar). It’s higher failure than a lead acid battery, but it’s a a single failure (converter), not like at high voltage where you want to disconnect the battery in the case of many other failures.
I thing that independent 12V battery can run all instruments without any problems.
Maybe at least this 12V battery could be "recharged" with small solar panel - this is system already succesfully used on gliders.

1661351488620.png
In this case is weight penalty acceptable ;)

It is funny.... sometimes we "fight" for few kg and difference between light and heavy pilot can be up to 45 kg (65 kg min. / 110 kg max) :D
 

blane.c

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Al is too fragile.
It has to be high quality Cu cable.
?

I guess I think of Aluminum as ground or Negative polarity and not stranded wire but bar or structure. Positive is Cu. Aluminum connections get "the lube".

Current flows Positive to Negative through the source and Negative to Positive through the circuit. Current flow is useful in plating, if you want something cadmium plated or chrome plated etc., so it is easy to see that if you do not want something Aluminum plated you need a barrier.
 
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John.Roo

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?

I guess I think of Aluminum as ground or Negative polarity and not stranded wire but bar or structure. Positive is Cu. Aluminum connections get "the lube".

Current flows Positive to Negative through the source and Negative to Positive through the circuit. Current flow is useful in plating, if you want something cadmium plated or chrome plated etc., so it is easy to see that if you do not want something Aluminum plated you need a barrier.
Well... I need to lead +, - and data (BMS) from battery to controller.
So I have to go to the end of fuselage, up via leading edge of fin and than to controller. My idea is to use "goose neck" tubes along fuselage sides.

Aluminium is "getting old". I have been removing old aluminium wiring from house and it was possible to see that old aluminium wiring was really fragile.

It is possible to buy very good quality well protected flexible Cu wiring so in this case I prefer to spent a bit more money for high quality ;)
 
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