Voltage steadily dropping off at idle

[KingCobra07]

Hey guys, so I've got a voltage drop issue happening to my heavily modded 07 GT500.

Cruising, the car sticks around 13.6 to 13.8 volts, but as soon as I come to a stop, voltage drops down to 12.6 and will slowly drop a tenth of a bolt at a time, until it's down in the low 10's and my factory navigation starts resetting. If I turn the car off now, because the voltage is so low it won't restart. Idle is set to 900 and tune calls for 14v at all times.

I have a brand new PA 200 amp alternator, their 4 gauge lead wire, and a new oem motorcraft battery.

Amperage using mods are a triple 465 hat with lethal wiring harness, dual 11" spal fans, mezeire 55gpm intercoolet pump, lund n gauge, n2mb wot box, wideband and map, and a rule 2000 in my ice box.

Anyone have any insight on what I can do to make my car idle and not consume the voltage? Thanks!

 

[scotsam]

Do a voltage drop test between positive terminal and the alternator also between ground terminal and engine/ body etc.. try to do it running while there is a load on it also. Sounds like a bad connection/ground if all else is ok.. did this start after the alt or were you chasing voltage issues before the alt?

 

[ShelbyGT5HUN]

Do you have the stock pulleys? With all those high amp mods, I'm not surprised at idle, you are dropping voltage. Might need a dual 12V battery or higher amp battery. This all assumes the alternator is good.

 

[ashleyroachclip]

I would think as was stated , if the alt. Is chatging properly

 

[RedVenom48]

Alternator might not be up to the task if pullied down. if stock pulley that 55GPM IC pump could be drawing a ton of amperage. At idle speeds, the alt probably cant keep up with the demand. Add the rule and dual fans along with main fan... i could see and issue at idle.

How new is the alternator? May need a larger capacity battery.

 

[69b302]

You need to put two of the 465s on a Hobbs switch. You are heating up the fuel and drawing lots of amps when not needed. I had a similar problem until I added a Hobbs switch. Just a bad idea to run three pumps full time, especially if you are at idle in traffic. Maybe a track only car, but not a part time car. You are running to much electrical at idle, and need to reduce the load.

 

[ShelbyGT5HUN]

If your car is DD, and you are running all that load all the time, the OEM battery is the problem. Throw an ammeter on the battery, at idle, with everything on, including the stock rad fans, A/C on, and the interior blower motor running.

Just my interior blower motor on, nothing else on, car off / not running, pulls 10 amps on high. The stock battery has the same CCA's as a Miata.

 

[KingCobra07]

Wow! Thanks for all the great responses guys. I'm definitely going to look into a hobbs switch, and maybe add the IC fans to the stock rad fan.

The alternator is brand new, and all connections are good everywhere. I added the 4G lead wire to assure it can get all the power to the battery. The alternator was put in because my PA 160amp wasn't keeping up, so i was hoping 200 would do it.

All pulleys are stock size, but to spin to 7k+, I had to put the PA 2.6" alternator pulley on. Stock it came with was a 2.3".

Bigger battery may be a good idea also. The oem motorcraft one is oddly small CCA. It's under 600 I believe...

Thanks!!