On Sunday, December 13, 2020 at 2:49:43 PM UTC-8, Matthew Scutter wrote:
On Monday, December 14, 2020 at 12:02:14 AM UTC+10, Moshe Braner wrote:
On 12/12/2020 11:53 PM, Matthew Scutter wrote:
On Sunday, December 13, 2020 at 2:31:33 PM UTC+10, Eric Greenwell wrote:

Once I get to about 40% remaining, I can only get ~15kW instead of 22kW. Around 30% it warns me to reduce power below 8kW to prevent battery damage, but doesn't prevent me from continuing. I need about 3.5kW for level flight and 8kW is a ~200ft/min climb. Haven't discharged past 20% yet but it was still able to achieve 8kW at that level.
The default charger is 1200W, so even at 110v 10A should be fine, I also purchased a small 600W 'travel' charger that fits more comfortably in the cockpit with me if I outland at a remote airfield and wanted to recharge overnight, or to tour with.

So since the power (and voltage?) decreases as the batteries are
partially discharged, when it says XX% remaining, what is it a
percentage of? Amp-hours? Energy? Altitude it can climb? And how
accurate is that prediction? (As we know it was disastrously wrong in a
rooftop in CT.)
That glider looked (relatively) intact so I hope the logs from the aircraft will provide some insight when the accident report comes out.

7.2.3 Battery packs available energy and consumption
Each of the 10 battery icons on the screen represents 10 % of the total available
energy. The number of displayed battery icons represents the remaining energy in the
battery. It is calculated by comparing the total theoretical available energy of the battery
packs (3,8kWh) with the consumed energy per unit of time. The actual consumed energy
depends on power setting and the duration of powered flight.
Calculation is quite accurate at lower power settings. At high power settings,
voltage drop in the battery packs is larger, and thus usable battery capacity reduced.
Because of this reason, a yellow warning message: “Low Voltage! Reduce power!” might
appear, even if a few battery icons are still displayed.

How far you will need to self-retrieve depends upon the flight, not the glider. A Mini-Lak was the glider involved in the case I cited, and the pilot was attempting a 750k record flight. And the oft-quoted self-retrieve distance is way too optimistic - I would cut it in half, and that might be too generous (having to clear a mountain range, for example).

Arguing about the circuit amperage is nit-picking (20A is pretty much standard, but 15A may do as well): you have to have a dedicated circuit is the point.

These electric gliders will perform, just realize that the manufacturer's are not giving you the entire picture on their limitations, particularly regarding safety.

Tom