Installing 2nd alternator in Jeep Grand Cherokee

 

Silver Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 180
Registered: Jan-05
I have upgraded (twice) from a 90amp stock alternator to a 205amp alternator and still get dim lights and see the voltmeter on dash dip.

I have upgraded the wiring from alt to battery from 8g to 4g.

i have added a second ground from battery.

i run 0 gauge to a rear distribution block then 4 gauge from block to amps (tricky with RF amps).

i have installed an Orbital Select 34DC-48 battery (nearly identical specs as Optima Yellow top 34d series which i couldnt find anywhere the day i wanted to buy a new battery)

I have an Orion 2500d and 2 Rockford Fosgate 301x amplifiers.

I have 4 .5 farad caps wired into 2 pair feeding each power connection to the 2500d (which as 2).

From my research i have discovered 205a is about as big as you can get without modifying the alternator case or mountings.

If i am going to do that why not just install a second alternator. i have seen many vehicles with 2-25 alternators (cant recall if its JVC or JBL that has a blazer with alternators installed in a ring around the radiator but there were close to 25).

My Question: Has anyone installed a second alternator in a ZJ or similar chrysler/dodge vehicle?
Was there anything special beyond the obvious?

Any ever installed a second alternator in any vehicle? what were the results?

thanks
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10854
Registered: Dec-03
does the voltage dip momentarily or does it drop and stay below 12 volts?

are the capacitors wired together in series or parallel?

 

Silver Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 181
Registered: Jan-05
it dips from 14 to about 11 when at red lights and i am listen some what loud...

the caps are wired series to give 1 farad to each power input of the 2500d
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10864
Registered: Dec-03
actually two problems:

1: the alternator doesn't help when at idle. rev the engine above idle to about 900RPM or higher and current output increases as does voltage. problem will stop.

2: capacitors go in parallel. In series, you are actually reducing their output.
Capacitors are just the opposite of resistors like that.
resistors go in series to increase resistance. capacitors go in parallel.

have 1Fd of capacitance for every 1Kw of power.
 

Silver Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 183
Registered: Jan-05
ok...
when i am at stop and see the needle dip i can rev engine to about 1000 rpm and needle does climb back up to 14v

.5 caps are wired together in 2 sets ( thus = 1 farad per side of 2500d input (claiming series may have been mistake on my part.)


what would you recommend to ensure optimal power to system?

i am thinking about removing caps altogether (from what i am gathering from research caps do no good unless 10 farads or more regardless or watts output...) your thoughts?
 

Silver Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 186
Registered: Jan-05
 

Silver Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 189
Registered: Jan-05
 

Silver Member
Username: B101

Queen City, NC USA

Post Number: 320
Registered: Sep-05
" have upgraded the wiring from alt to battery from 8g to 4g."

BIG PART of your problem!
That wire needs to be 0ga.
U have a 205 amp alternator
4ga wire can handle 150amps

I would upgrage big 3 to 0ga!!

what kind of HO alternator u have? and do u know the idle amperage?
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