[disoriented]

Is that not the point of in flight readings as that battery is low on 1 or more cells and is all the power available to you at that time. It is also a vulnerable time for the battery as drawing large current now can damage the cell.

There are two fundamentally conflicting requirements:

1) A discharge curve which is as flat as possible. Ideally, a LiPo cell would stay at 4.20V until it was say 80% exhausted, at which point its voltage would rapidly fall off a cliff to 3.7V. That ideal is still unachievable, but the more technology advances the flatter the discharge curve becomes.

2) The ability to sense remaining capacity based on cell voltage. This is effectively impossible with the idealized stays-at-4.20V LiPo, and it's getting ever harder even with real life battery packs. They all tend to exhibit the fall-off-a-cliff discharge behavior, to one extent or another, unlike traditional NiCd and NiMh chemistries.

The more rapid the discharge, the worse the problem. An EasyStar puttering along at 25W motor power may be able to say aloft for 20 minutes or more, and voltage sensing is a relatively accurate way to deduce how much is left in the pack. On the other hand an EDF or high-powered heli setup which exhausts the battery in 3 minutes is not a good candidate for voltage-based alarms. Mere seconds separate the point where the cell hits 3.7V under load, and the point where the thing falls out of the sky or damages the LiPo through overdischarge.

Wish we had a decent weather weekend so we could all go fly instead of talking about it