charging issue, alternator, battery

[rsmartin]

'85 300SD, 269K

the following occurs randomly, as i have not found a particular set of circumstances causing it..

i go to start car, turn key, glow plugs turn on and the lights go very dim and car will not start, as if dead battery.

hook car up to charger for just a minute, and car starts instantly, BUT is takes a few minutes for all the lights and electric to work... then all of a sudden everything brightens up as if some switch turned everything on..

so i hooked multitester up to cigar lighter and noticed that when the car is first started, only get about 11 volts, then after a few minutes all of a sudden voltage jumps up to 12.2 and climbs to 13.5+.. so i thougt voltage regulator, replace that.. no difference.

so I thought alternator... so did the guys at the auto store.. bought alternator (rebuilt bosch unit by duralast).. installed alternator.. same thing still happens.

i have replaced battery at least 3 times in the last 2 years.. cannot find any current draw when car is off by hooking up multimeter between negative battery terminal and negative cable.

this has me perplexed.. any help out there??