Leighton,

Where do you find a recommendation for constant potential charging Concorde RG batteries at 13.8 volts?  The following is a quote from the "Instructions for Continued Airworthiness, Concorde Valve Regulated Lead Acid Main Battery" document at http://www.concordebattery.com/otherpdf/IFCA1.pdf

"b. Recharging a single battery on the aircraft:
...
Caution / Warning: Only constant potential charging may be done
on the aircraft. Ensure the charging area is well ventilated. DO
NOT constant current charge a battery on the aircraft. There may
be a serious risk of injury to personnel and / or damage to the
aircraft and aircraft systems.
...
ii. Set the charger for 2.35 volts per cell (14.1 volts for a 12 volt battery, 28.2
volts for a 24 volt battery)."

Tom Thibault


Leighton wrote:
...Adjusting the voltage down to the recommended 13.8 solves the problem.