Voltage Drop Help?

[SWFL 10+ year member]

My electrical consist of

242 max 178 at idle amps DC Power Alt

big 3 in 1/0 doubled up

duralast gold upfront.

2 power runs of 1/0 klmx to the back

2 ground runs of 1/0 klmx to the back

back batteries are 3 C&D 135AH batts all connected in 1/0 and 1/0 to the amp

The amp is a RD D9. I dont even have it giving full power. The amp is playing at .8ohms.

However the front battery is at 13.3-13.5 full tilt at idle. At the amp its at 12-12.25. I am losing 1-1.5 volts somewhere. Why would this happen?

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[Crownvicon28s 10+ year member]

My electrical consist of242 max 178 at idle amps DC Power Alt

big 3 in 1/0 doubled up

duralast gold upfront.

2 power runs of 1/0 klmx to the back

2 ground runs of 1/0 klmx to the back

back batteries are 3 C&D 135AH batts all connected in 1/0 and 1/0 to the amp

The amp is a RD D9. I dont even have it giving full power. The amp is playing at .8ohms.

However the front battery is at 13.3-13.5 full tilt at idle. At the amp its at 12-12.25. I am losing 1-1.5 volts somewhere. Why would this happen?

Man I'm having the exact same problem. If I figure it out I will let you know.

 

[loudsw2 10+ year member]

if anything is in line it will do that are they straight runs of 0 gauge or do they have fuses in line? or anything of the sort

 

[SWFL 10+ year member]

yes two fuses per run of 1/0 a fuse upfront right after the front battery and another fuse at the back right before the back batteries and then another fuse on each 1/0 run to the amp from the batteries.

 

[loudsw2 10+ year member]

ya im having the same issue right now with my single 0 gauge with a fuse up front but im doing double 0 runs straight with no fuses but i have noticed that i am dropping a volt from front to back and my friend has two runs with 1 fuse in each line and he is dropping almost 2 volts, i would say do a little test, take a small piece of 0 gauge (like a few inches) put O ring terminals on both sides and just replace ur fuse with the 0 gauge to see if it fixes the problem

 

[SWFL 10+ year member]

yea i am gonna meausre the voltage before and after the fuse holders and see what happens gonna go do that now and try to test my grounds as well

 

[njaykaplan 10+ year member]

Do you have your back batterys wired to your alternator or to your duralast gold? Hopefully off the alternator, but i would get rid of that durlast gold. Maybe even loadtest the C&Ds in the back. You check your grounds as well? Having a good charging wire and ground to the back batterys, i dont see why you'd drop that much, but then again that is a 5k watt amp. 13.5 isnt a bad drop either, but thats because you have upgraded. Check what i mentioned though and let us know.

 

[loudsw2 10+ year member]

let me know cause i am curious lol, this is actually my most recent testings too, was gonna run the wire today/tomorrow to find out for sure but def let me know what u get (shoot me a pm if ya could) =)

 

[Crownvicon28s 10+ year member]

I will be definetly be watching this thread. Im in Houston right now. I will be doing some testing when I get home tomorrow. If no solution is found by then hopefully I could come up with something when I get back.

 

[pawn man 10+ year member]

4 more runs of o gauge

 

[tez4life Premium Member]

Do you have your back batterys wired to your alternator or to your duralast gold? Hopefully off the alternator, but i would get rid of that durlast gold. Maybe even loadtest the C&Ds in the back. You check your grounds as well? Having a good charging wire and ground to the back batterys, i dont see why you'd drop that much, but then again that is a 5k watt amp. 13.5 isnt a bad drop either, but thats because you have upgraded. Check what i mentioned though and let us know.

True, but with that amp, voltage drops should not be that bad. Friend of mine had a RD pushing (2) BTL 15s in his Crown Vic, had a big class AB Rockford pushing the mids and highs (around 1000w total). His electrical was a pair of Alts, (POS db electral, and a Mechman 250) and a pair of G31s in the trunk, (forgot what he had up front) 2 runs of 1/0 gauge, and he was charging at 14.4, never dropped below 14v and that was idling...

Seems like the OP has a very sufficent electrical system for the amp, not sure why he is having the drops like he does.

 

[Crownvicon28s 10+ year member]

Do you have your back batterys wired to your alternator or to your duralast gold? Hopefully off the alternator, but i would get rid of that durlast gold. Maybe even loadtest the C&Ds in the back. You check your grounds as well? Having a good charging wire and ground to the back batterys, i dont see why you'd drop that much, but then again that is a 5k watt amp. 13.5 isnt a bad drop either, but thats because you have upgraded. Check what i mentioned though and let us know.

I agree 13.5 isn't that bad of a drop, but me and the OP are measuring 13.5 at the alt and front battery, but 12.5 at the amp full tilt at idle. He is trying to figure out why his voltage is dropping so low at his bass amp and not at the alt. I was doing some brainstorming and I might be wrong. If your batteries in the trunk are wired parallel with your battery upfront, the amp is drawing more off of the batteries in the back and the least off of the batteries in the trunk. Maybe since the battery closest to the alt isn't really having that much of a draw the alt isn't charging at its fullest potential when there is a draw at the back batteries. Maybe a diode isolator would help eventhough you would lose ~.4 volts if I am correct. Or maybe run the power wire back to you rear batteries directly off of you alt if its not already this way. Thats about all I could come up with.

 

[SWFL 10+ year member]

well just got done playing around with it. playing juice box which is the most steady bass line and is constant so works good for voltage test. The front battery is around 13.2-13.35 at full tilt at idle. The back batteries are at 12.35-12.45. So roughly .75-.90 volt difference. I tested the voltage before and after the fuse holder on the two front holders that go to the back and same voltage on either side. I measured the back fuse holders that go to the batteries and its the same on the input and outout so the fuse holders i dont believe are taking any power if so its slight maybe but i dont see it.

Then at the back batteries its 12.25-12.5 roughly and at the amp with short runs and fuses between the amp and batteries the amp sees 12-12.25 so loosing a 1/4 of a volt in that small run. Only thing i can think of is the fuse holders possibly or i need another few runs of 1/0 front to back and i am going to do direct grounds to the frame off the batts in the back as well.

All connections seem fine. The two runs of 1/0 to the front are connected to the copper busbar that is connected to the front battery where the two runs of 1/0 from the alt are connected to.

 

[loudsw2 10+ year member]

hmm ya im a street a competitor so i don't have any batts in the back but i am dropping a volt from the batt up front to my amp, only thing in line is the fuse, hmm thats interesting

 

[SWFL 10+ year member]

I think i dont have enough runs of 1/0 only thing i can see. According to BCAE1.com on the votlage thing i will be dropping .8-1 volt and thats right bc i am dropping that much. I might add some more runs over the truck when i order some more and see if that helps if so then i will be running more power wire.