DC-DC converter requirements

What will the loads be?

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Rated Amp draw	Current 12V systems	Current fuse size	Notes	Exists
Not installed opt.	1 Washer nozzle heaters	10	Empty slot
	2 Turn signal lights	10		10
Not installed opt.	3 Fog light relay	5	Empty slot
	4 License Plate Light	5		5
	5 Comfort System, cruise control, Climatronic, A/C	7.5	?	7.5
	6 Central locking system		Empty slot
	7 Back-up lights, speedometer vehicle speed sensor (VSS)	10		10
	8 Open		Empty slot
	9 Anti-lock brake system (ABS)	5		5
	10 Engine control module (ECM): gasoline engine	10	?	10
	11 Instrument cluster, shift lock solenoid	5	?	5
	12 Data Link Connector (DLC) power supply	7.5		7.5
	13 Brake and tail lights	10		10
	14 Interior lights, central locking system	10		10
	15 Instrument cluster, transmission control module (TCM)	5	?	5
Not installed opt.	16 A/C clutch, after-run coolant pump	10	?	10
	17 Open		Empty slot
	18 Headlight high beam, right	10		10
	19 Headlight high beam, left	10		10
	20 Headlight low beam, right	15		15
	21 Headlight low beam, left	15		15
	22 Parking lights right, side marker right	5		5
	23 Parking lights left, side marker left	5		5
	24 Windshield and rear window washer pump,windshield wiper motor	20		20
	25 Fresh air blower, Climatronic, A/C	25		25
	26 Rear window defogger	25		25
	27 Motor for rear windshield wiper	15		15
Removed	28 Fuel pump (FP)	15	N/a
	29 Engine control module (ECM): gasoline engine	15	?	15
Not installed opt.	29 Engine control module (ECM): diesel engine 10A		N/a
	30 Power sunroof control module	20	Blank
Not installed opt.	31 Transmission control module (TCM)	20	Blank
Removed	32 Injectors (gasoline engine)	10	N/a
Not installed opt.	32 Engine control module (ECM): diesel engine 15A		Blank
Not installed opt.	33 Headlight washer system	20	N/a
	34 Engine control element	10	?	10
	35 Open	30	?	30
Not installed opt.	36 Foglights	15	N/a
	37 Terminal (86S) on radio	10		10
	38 Central locking system (w/pwr windows), trunk light, fuel door, trunk release	15		15
	39 Emergency flashers	15		15
	40 Dual tone horn	20		20
	41 Cigarette lighter	10		10
	42 Radio	25		25
	43 Engine control elements	10	?	10
	44 Heated seats	15	Blank
	SUM	530		400
	Add 12v battery as load on converter
	New 12V systems
	Power steering pump
	Vacuum pump
	Water pumps
10	DMOC 645
	SUM	530		400
	New 400V systems
	A/C compressor
	Winter cabin heat
	Removing 12V systems
	Fuel pump	15
	Fuel injectors	10
	A/C clutch	10
	Starter motor
	Spark plugs
90	Alternator rated output

Apparently the manual transmission version should have a 90amp alternator in it.  They say something about the manual having 3x10amp coolant heaters used to bring the engine temp up faster, but the automatics use excess heat from the transmission to heat the coolant. We have never heard of this, anyone know where these heaters are located? Can we use them for winter heat in the cabin?

Obviously the alternator could not keep up with all the fuse ratings, anyone know what rule of thumb they use for rated use vs. rated fuse?

Initial guesstimate, if the standard alt. is 90amp, and the coolant heaters cause the 120amp system, then based on the 530 and 400amp sums above, and we have removed many components we should be close to even except for the new A/C pump.

We need to find out about these coolant heaters since in the winter we could be running the coolant heaters and the A/C to defog.

UPDATE March 22,2020
We measured the amp draw on many components of the new system individually and simultaneously.  It appears that the OEM fuse size is roughly double the peak in most instances except the rear defroster.  We were able to create peak 80A@10.9V draw with a few components still missing.  Therefore we believe the 90 amp OEM alternator to be a good capacity to match for the new DC-DC converter ~800-1000 watts peak and the battery can absorb the rest.  Normal night run conditions should be around 400 watts peak.