The short trips not having enough time to replenish that which the starter used to start the engine, is largely horse hockey in this day and age of quick startng fuel injected gas engines.
Now if the battery was not fully charged then short trips will do little to increase that level of charge.
I measured about 45 seconds for amps to taper to the same level as they were at 14.7v before and after engine starting an overnight cold engine. Mine cranks less than 1/3 the amount time when it is warm, compared to overnight cold.
I've charged a few maintenance free flooded batteries inadvertently discharged to sub 11 volts according to Mex's prescription, which was 15.0 vabs, until amps taper to near zero. I did find it getting hot fairly quickly with 40 amps available so lowered the voltage to keep amps under 20 and rose it in a few stages to 15v.
In fact I've done this to the same battery 3 times over the last 5 years. His radator fan sometimes stays on, or comes on when parked and runs the battery dead.
I think it too is a group 48 in a BMW, mounted in the trunk.
