jetta low voltage with ho alternator

[soulnomad 10+ year member]

okay ive already troubleshooted a lot but heres the equip:

-220 HO Alternator

-G34 Optima Yellowtop upfront (added one in rear but still low voltage)

-3700 rms (dont feel like calculating current demand atm)

-Voltage with old 90A dying alternator (13.3V idle max 12.2V resting car off)

-Voltage with NEW 220A alternator (15V idle mas 12.2 resting car off)

-Big 3 Done over 3 times with 0/1 wiring sanded all grounding areas

-All amps grounded back directly to front battery.

-Car struggles to start also

on long transients my voltage dips all the way down to even 8.7V no lie and my speakers fade out. can anyone help diagnose this problem i think i may have deteriorated my battery fromt he old ****** alternator, thanks guys!

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[MONSONwarrior Premium Member]

Well are the batteries charged? How many runs of 1/0 do you have?

 

[soulnomad 10+ year member]

the battery (one in the front atm) is charged by the alternator with car off its at 12.1V i have 1 run of 0/1 to the back its all i can really fit.

 

[soulnomad 10+ year member]

and also my car struggles to start with the old 90A alternator and the new 220A alternator even

 

[MONSONwarrior Premium Member]

the battery (one in the front atm) is charged by the alternator with car off its at 12.1V i have 1 run of 0/1 to the back its all i can really fit.

Well 12.1 is pretty damn low for resting voltage. throw it on a 2 amp trickle for the night and see where it sits in the morning. Your old dying alternator may have taken your battery with it. And 1 run of 0 gauge is border line acceptable for that amount of power. OFC is rated at 300a so running 3700 through it is tight.

 

---------- Post added at 09:49 AM ---------- Previous post was at 09:48 AM ----------

 

and also my car struggles to start with the old 90A alternator and the new 220A alternator even

your battery is shot.

 

[soulnomad 10+ year member]

ill try and pick a charger up and hopefully solve this 6 month long headache and actually im tripping lol. i have 2 pos runs or 0/1 to the rear.

 

[MONSONwarrior Premium Member]

ill try and pick a charger up and hopefully solve this 6 month long headache and actually im tripping lol. i have 2 pos runs or 0/1 to the rear.

Then you should be okay, your battery is just shot, and that means it's also straining your new alternator.

 

[crucial24 10+ year member]

I know some Honda vehicles got something called ELC which stands for electronic load controller which tells the alternator to only put out full load if A/C or headlights are on maybe your vehicle has a similar technology!

 

[MONSONwarrior Premium Member]

I know some Honda vehicles got something called ELC which stands for electronic load controller which tells the alternator to only put out full load if A/C or headlights are on maybe your vehicle has a similar technology!

I work on a friend's 04 Passat pretty regularly and his doesn't have this problem. I'm pretty sure it's just the batt.

 

[hispls 5,000+ posts]

Any parts store will load test your battery for you. Are you running at 15.0V? Over voltage on batteries will kill them quicker than anything.

 

[soulnomad 10+ year member]

im going to go to get both batteries load tested and ill post results incase anyone else is having similar problems.

 

[soulnomad 10+ year member]

update:just realized radiator fan cut through my 0/1 run alternator pos to batt pos wire going to swap that now and see if this improves anything.

EDIT:switched wire out... same problems lights are dimming like crazy but even with ac on full blast/circulation and every single accessory on voltage drops only .2 until i turn on and play my stereo and then its down into 9V-10V.ugh

 

[soulnomad 10+ year member]

UPDATE:checked inline fuse for one of my power runs...fuse is gone since i grounded out my wires and threw 2 300 amp fuses forgot about this one.running to get replacements will post results.

EDIT:fuses replaced no improvement...i used to run the same equipment with a 90A alternator with slight dimming but i could play full tilt for about 3 hours straight due to heat...wth is going on!!

 

[09civic 5,000+ posts]

make sure grounds are good

 

[soulnomad 10+ year member]

amps are grounded back up to the front battery.about to check the stock battery ground location since i ran big 3 with the stock wiring..