I suppose it would depend on whether you are a 1 or 2 battery equipped aircraft?
The QRH is not particularly helpful, giving no actions to undertake.
If the Ni-Cads are into thermal runaway, then it belongs on the ground ASAP, but there again we have no information as to diagnosing such a runaway til the smoke starts or the bits begin to burn up?
Reading the UPS 747F Dubai report will chill the bones and may influence our subsequent actions, better safe than sorry. Maybe some research into Ni-Cad runaways would be useful.
Otherwise keeping an eye on the systems, the weather, your location and maybe continuing to destination or suitable commercially desirable diversion where the defect can be rectified, if the craft continues to function normally, would be the other option.
I am presuming the 60 minutes endurance on the "fully charged battery" applies in the event of a further failure involving loss of generating ability, so we're looking at a double failure case.
If Mr Boeing regarded this as a LAND ASAP option, I presume he would have stated thus in the QRH?
It will be an interesting tea (no biscuits) discussion with Fleet Management if one diverted because of a Batt Discharge light with no other adverse symptoms.
Thanks for the post, it will stimulate me into ferretting around looking for further guidance!
