787 Batteries and Chargers - Part 1

[RR_NDB]

Individual cells monitoring (AND also CONTROL) during recharge

hetfield,

Ideally the charging would be controlled to each cell. (because they are not identical. And Temp and Aging are extra factors). In the config of the Thales battery the charging current SEEMS TO BE THE SAME* for all cells). The control of the voltage just allowing a derating during the charging (extending the time). But when discharging (APU start, etc.) voltage control is useless. Just for recording, if so.
If the internal data recorder is not properly designed we may never know what led to BOS and TAK incidents.

The plane FDR certainly is not used to look inside a battery. Should be. If airliners would use these batteries for HIGH CURRENTS. It´s relatively simple.

This comment is also to answer A33Zab question on my concerns on other Li Ion applications in 787 and 380. Problems are much likely with high current (specially charging). Trickle charging (to keep the cells "floating" to a safe value is not dangerous.

There are other considerations on the use of Li Ion on an airliner. Location can be critical, in case of a catastrophic failure.

I actually have objections on the positioning of them in the 787. Specially the APU battery. (Nearby electronics).

(*) There is a possible charger architecture with controlled currents (closed loop) for each cell. It allows quick charge "respecting the personality of each cell during her aging and under different temperatures". I will assembly it for my electric bike pack. I would like to know if what A33Zab commented on A350 was with this concept. We may find this in Patents Database. (USPTO, SPACENET, etc.) The concept is one charger for each cell. I assume the designers put everything possible (for safety) in the 787 subsystems design. The same i imagine in A380 Li Ion application and A350 (that will benefit from 787 teething issues).