Car will not start sometime as if the battery is dead, hookup cables to jump it off it startup i though it was the starter, or just a bad battery so i had it checked and it was good.

I call that chatter and means the starter solenoid
sees only 8vdc from the battery , cranked.
there are 6 causes, due to 6 things(parts) make cranking go.
why do all that,and not do jumper cable jump starts first. if works then battery is NO GOOD>in car.

posted this 100s times.
both cable ends (x4) not loose or rusty.to bat.
1: battery good means alternator not bad too.
load test the battery or jump cable jump it.
we know the starter is good, last words of your post.
2: then key switch good, and ST pin sends 12vdc
to the PRNDL switch.
3:PRNDL on/in the tranny must work in park and neutral both so all techs and tow truck mean test neutral cranking next or gets egg in face.
4: next up (it is a series path of DC ST )
the starter relay closes, called energizes.
and sends 12vdc to the soleniod and starter cranks.
5: starter bad , no it is not.
6: wires bad.(and or connectors)
did not jump start your car
did not charge battery and load test it. oops

comments:
NO 15 year old battery is good, my 50 year record is 10 years life, (and not common)
did not crank in N neutral PRNDL.
did hot wire starter and starter is loaded for bear (good)
and wires. yes can fail #6
so all techs know that and out pops Mr./ DMM set to volts to find where the path fails easy.
normal cranking voltage is 11vdc.
the 1 volt loss is battery internal resistance at 300amps load.
8vdc the solenoid chatters like mad. a huge key fact.
it only takes a voltmeter to find this failure.
after jumper cable jumps fail,
if not fail Jumped, the battery is bad,(or rusty lugs)

good luck , be happy for 6 and not 50 engine failures and lots of tests. that.

we charge the battery first then load test it , a tool..
or have shop test your battery ,even walked in.
or find a good battery out of 2nd good car. TRY IT.
or jumper cable jump start your car off 2nd running car just like AAA Auto club tow trunks do endlessly.
day by day.
or the voltmeter across battery terms (clean) show 8vdc cranking is a bad battery.

not withstanding driving car the battery dicharged dead , alternator dead.

Mitsubishi Grandis , year not old, no engine size told or VIN.
2003 to 2011 made, sure.
starter failing for any reasons is a simple thing, (unlike bad engines 50 ways to fail)
Battery must be good, load tested, did you know batteries can even be intermittent a hard fact of life, good ,back,weak or intermittent or simple not charged up.
or 10x more often battery lugs loose ,or rusty or BOTH>?>???>
jumper cables ,jump start any dead starter car>?????????
ok Jumps fail so we do what? now.
Your car has an automatic transmission. but some are 5speed manual transmission,s for sure. so I answer 2 times blind, sure
A/Tbox
the PRNDL switch bad for PARK cranking, we shift them all to N
to neutral and crank if this works PRNDL ,P switch is bad
car #2
if M/T tranny, the clutch switch bad kills the starter dead.
no sound means starter motor is dead , the tests are simple
one can have a car battery load tested for free in most shops and vast stores here in USA,did I say FREE, I did.
learn to use jumper cable
learn to start in N
if clutch pedal car, learn to short the 2 clutch pedal top switch wires and the starter motor goes BACK to working again or

if all tests fail we hot wire a starter motor, ask
and if that fails a new starter is replaced. (battery NEG lug pulled first)

I want to be sure I understand.
You changed the starter and the alternator but the engine still will not crank over.

There are relays that activate the starter. If a relay is bad it doesn't matter if the battery and starter are in good condition, it will not crank over. You will need to check the manual to find what relays activate that starter. Put a finger on the relay, It should click when someone
turns the key to start. If not, that is your problem. If it clicks repeatedly you have a dead battery or bad connections.

If you tried jump starting but it still wouldn't start, it could be the battery is bad or the battery terminals are corroded. It happened to my Jeep.
The battery posts are lead but the cables are steel. It can corrode and you can't even see it. I suggest pull the cables off and use a battery cleaning brush on the cables and the battery. Work on them till they are shiny. If they were corroded maybe that is all that's wrong. Connect charger or jumpers to battery and wait a few minutes till it has some charge. A totally dead battery sometimes will not let you jump start.

I sure hope that helps.

do you have power even if lights go on dosent mean there is enough power to start ,did you try jump starting to get it to crank over

Could be a bad battery,Aytozone will test for free,here's a link on how to remove the starter,then take to Autozone to test,also test alternator,you can do this with it on vehicle.

If the car doesn't start with a jump you might have a bad alternator. The alternator supplies voltage to the car once the engine is running. If the battery is dead, and the alternator isn't putting out sufficient voltage, the engine cannot run. Then again sometimes a car with an extremely dead or internally shorted battery WON'T start with a jump. Replace the battery and try again.

Could be several things, I would replace the battery first, sometimes the cables get corroded which could cause a bad connection.Try cleaning the cables or check to see if the cables are tight. If you are having to jump the car all the time that has to be a bad battery. OR a bad alternator that wont hold a charge on the battery.. worse case scenario is fuel pump, though I dont think its that.
If you have an Autozone in your area, take the battery in and get it tested. They can figure it out pretty fast

Sometimes dirty battery posts cause this issue. Get a wrench, remove the cables from the battery, scrape posts and cables shiny clean and re-install

Have you tried jump starting it? If it will start this way, then either your battery is going bad, or the alternator is not working properly.

If it will not start (not even turn over) with a jump, then the starter may be bad. Good luck...Chris

run another test on the starter...they are about 20/80 bad/good right out of the box!

bad silonoid on starter
the actual cable on starter is bad even though you replaced the positive battery connector the whole cable could be bad
also your new battery might not be a heat battery example= a battery that cannot handle heat and will die on you this indicates a dead cell in battery
bad alternator not charging battery
bad ignition coil
scorched spark plug wiring
dead cell in battery even though the battery can show good it can still be bad
battery's these days are usually refurbished battery's practically every one recycles batterys so its a chance that you got a bad battery try a jump then while vehicle running disconnect the positive post of battery if vehicle dies its the alternator

i myself had to do a battery swap 4 times before i got a refurbished battery without a dead cell this something that is a pain but once you get a good battery then everything should work