quick question

[Crownvicon28s 10+ year member]

at my alt full tilt the voltage drops to 13.5. at my bass amp it drops to 12 volts. is it normal for these voltages to be this different or is something wrong? the voltage at my back batteries drops to 12.9 from 14 volts. sorry for the sloppy post at work posting on my phone.

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[IDSkoT 5,000+ posts]

at my alt full tilt the voltage drops to 13.5. at my bass amp it drops to 12 volts. is it normal for these voltages to be this different or is something wrong? the voltage at my back batteries drops to 12.9 from 14 volts. sorry for the sloppy post at work posting on my phone.

Yes. Check your grounds.

 

[Crownvicon28s 10+ year member]

I have a ground run from front to back of 2/0 gauge and both batteries are grounded to the chassis in the back. The guys at a local audio shop said my grounds in the trunk are good. My alt is fine the guy at the alt shop tested it and said it was putting out 220 amps at 1200 rpms.

 

[Plutoman 10+ year member]

Do a run of negative from the front to back. The chassis ground is not ideal.

 

[Crownvicon28s 10+ year member]

Already did that.

 

[Crownvicon28s 10+ year member]

I played a constant note, voltage dropped to 12.2 with the trunk closed, but only dropped to 13.6 with it open. Why is this happening?