PPRuNe Forums - View Single Post - 787 Batteries and Chargers - Part 1
View Single Post
Old 30th Jan 2013, 21:10
  #324 (permalink)  
syseng68k
 
Join Date: Jun 2009
Location: Oxford, England
Posts: 297
Received 0 Likes on 0 Posts
rottenray:

First, according to the securaplane website, battery history is recorded
by the chargers - not the BMS co-located with the battery cells.
I had a look at the securaplane website few days ago and couldn't find
any detailed info re: where the logging is done. This may depend on
particular system requirements. Can you post a link to the relevant page
for the actual 787 charger system ?.

To summarise the discussion re: battery data logging:

1) In the charger, which I originally suggested, but that leaves the
problem of what happened to that data ?. It should provide an audit
trail of the events leading up to the failure and would expect it to
be the first thing examined. Yet, no word about this.

Also, it makes the exchange of either battery or charger more inconvenient
since the logged data no longer matches that for the battery. That is,
there needs to be a process to download, store the data from the charger
and ensure that it's tagged to the battery that's been removed. Hence,
the suggestion that the data may be stored in the enclosure. There's
a lot of electronics there and while they may just have made a meal of
it, it does suggest further functionality.

2) Internal to the battery enclosure, which makes more sense from a
maintenance pov, but such data would be unlikely to survive a fire
using the present layout.

It's worth noting that this, too, apparently worked as advertised as there
was a "drop to near zero" recorded on the batt of the ANA aircraft.
Sorry, but a drop where ?. The associated dc bus, in the fdr, or what ?.

Putting the BMS inside the battery case makes it easier to calibrate and
more reliable. You are dealing with DC levels into the millivolts, and
at these low voltages even the best connectors can add undesired and
unpredictable resistance.
What was being discussed in context was the data logging: where it takes
place, what parameters are stored (timeline ?) and where that data is
now ?...

Regards,

Chris
syseng68k is offline