Clive

Hi, I think I have phrased the question incorrectly. Thanks for all attempts at help. The loss of 4 Ahrs a day was arrived at using a multimeter for voltage Plus a derivative of Peukert's Law. My understaning of a 55 Ahr battery is the rating is based on 20 hrs, ie. 20 hrs at 2.75 A discharge. Thanks again Clive.

amp discharge a day, based on Trojan Battery guide (USA } this gives % of charge based on volitage at rest after discharging surface charge. Voltage after 2 days is now 12.47, (78%). I use Trojan Batterys on my yacht.

Clamp meter shows discharge of .03 A after 30 or so mins , is that sleep mode ?.

Hi, Any advice on replacing a Din 55 battery with a Din 66 battery ?.On a 2007 120i. The battery is 2 3/4 years old with no known history, Jap import. 3 months ago. Alternator is fine, discharge at rest after 40 mins is app 30 milliamps, but battery is loosing charge at app 4 amps a day !. I only do 2~3 thousand ks a year ,so car its in garage for up to 2 weeks.