Motordavid did not say I put charger on for two weeks, just 10 to 18 hours. Our use of x5 will be low miles often on level ground. I would like to know if we may deeply discharge the battery this way or not.

So my plan is to manually charge at 1 then 2 and 3 month intervals. If manual charging time increases in like linear pattern then I will know we can face deeply discharging the battery.

I know once a battery has less than 50 percent charge the voltage it provides drops. If lower voltages cause systems to get flaky then I want to avoid that..

Seems nobody really knows what the algorithm of battery charging is so I am left to discover in part by this experimental manual charging.