Another sick puppy type of question - second battery? :D

[V6er]

Yello!
Since I am lazy and can't decide on new battery, but have one spare... so - for now I have jumpercables and spare battery in cargo - if battery will go below ability to start the car - I can jumpstart myself.
But there was this idea - can I conect in more civilized way that battery to be able to start?
for example

we have A - power socket in the back.

if we look at schematics -

t32-cargo.power.socket.schematic.png (36.7 KiB) Viewed 2715 times

seems that it is connected via fuse to battery.
so - if I make little cable with male connector for power socket (sorry - my English is so bad that I don't remember how to call this plug). then - when needed - I can just plug it there, without opening hood and using jumpercables (and not needing to put them back after).
am I correct or I am missing(don't understand) something?

[itsa300zx]

Do you ever wonder why booster cables are such heavy gauge wires?
Needs to carry hundreds of amps to boost a car. Even if your trick did close the loop to the battery, you’re looking at burnt wires, or you might get lucky and blow the 20A fuse first. Go buy yourself one of those lithium ion booster packs, they are small and powerful.

[V6er]

jumpstart cables - heavy gauge for a reason.
booster pack - who needs heavy gauge...?

my idea is using that second battery as booster pack.
plus - starter is 1500w. with 12v that is 125Amps TOTAL. ok, few amps for fuel pump, injectors... I am guessing - less than 150Amps, not hundredS.
and that current is going to be had for few seconds.

though wiring/fuse _might_ be thing to think about. thanks for a critics

[VStar650CL]

my idea is using that second battery as booster pack.
plus - starter is 1500w. with 12v that is 125Amps TOTAL. ok, few amps for fuel pump, injectors... I am guessing - less than 150Amps, not hundredS.
and that current is going to be had for few seconds.

Every DC brush motor has a "stall current", which is the amperage drawn if the motor is stuck and can't spin. It's inherent that every motor draws stall current for a short time when it starts up, which then tapers off as motor RPM increases. Depending on motor design and load, stall current is usually 2~4 times the rated current. So for the first several milliseconds, your 1.5kW motor could be drawing as much as 6kW. That's why the 250A main fuse on, say, one of my Altimas will blow almost instantly if the engine seizes or hydrolocks and can't spin on startup.

[V6er]

ok. now I am educated enough... thanks, guys!
will have to rethink my "fantastic" idea