loosing a half of volt

[king ranch 5,000+ posts]

from the front battery to the back battery i am only loosing about .2volts at full tilt at idle front battery was around 12.5-12.7 back battery was 12.25-12.50 at the amp however it was 11.75-12volts the lowest was 12.5 at the front 12.25 at the back battery and 11.75 at the amp, those were the lowest readings i got on the song put on.

so i figure its not a bad voltage drop from front to back battery but why am i loosing a half volt from the back battery to the amp just curious.

I am running a stock gold duralast 1000amp battery upfront with both grounds done on the big 3 but no alt to battery done yet, i then have a stinger spv70 in the back grounded to the front battery with 1/0 and 1/0 power to the back battery from the front battery. I am running a zx1500 and 2 channel of a zx850.4 so roughly 1850-2krms

my test were with the truck warm and at idle with headlights on at full tilt.

any ideas why i am loosing a half volt from battery to amp but only loosing maybe .2-.4volts from front to back battery

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[99grandprixGT 5,000+ posts]

when r u ever going to do that alt run. youve been putting that off for a while now.

 

[king ranch 5,000+ posts]

idk man yea i keep putting it off i had the wire 6ft of 2/0 and the fuse holder and terminals and ended up selling it to a buddy of mine who needed it worse than me haha.

I am curious if i ground the back battery to the frame as well as grounding to the front battery if will help the voltage a little.

and also how much more increase could i see by doing the alt to battery upgrade stock wiring is like 4 or 6 guage its not super small

 

[2000LaDe 10+ year member]

make sure u have a solid ground in the rear.

 

[king ranch 5,000+ posts]

make sure u have a solid ground in the rear.

the amp is grounded to the rear battery and the rear battery is grounded to the front battery and the front battery is grounded to the chassis with knu 1/0 and the engine to the chassis is grounded with 1/0 kicker wire, my power wire from front to back is knu 1/0 my ground from front to back is kicker 1/0 and my amps power and ground is kicker 1/0

 

[2000LaDe 10+ year member]

ground the rear battery to the chasis

 

[MmatsDude 10+ year member]

ground the rear battery to the chasis

x2.

Try that. Then let us know what happens.

Edit.

And I am ussually loosing around .4 from front to rear battery. Although my voltage stays the same from rear battery to amps.

 

[king ranch 5,000+ posts]

yea i asked on here and people said it didnt matter since it was grounded to the front but i figure it will bring up my voltage at least .25 volts maybe a half volt

but for the most part at full tilt at idle with lights on the voltage at the amp sits around 12.25-12.50 only for a split second it hits the 11.75-12 volt mark and then jumps back up and sits around 12.25-12.5

so doing a ground in the rear and the battery to alt pos upgrade i should gain around a half volt possibly right

 

[2000LaDe 10+ year member]

people on here are stupid id does matter.

 

[MmatsDude 10+ year member]

yea i asked on here and people said it didnt matter since it was grounded to the front but i figure it will bring up my voltage at least .25 volts maybe a half volt
but for the most part at full tilt at idle with lights on the voltage at the amp sits around 12.25-12.50 only for a split second it hits the 11.75-12 volt mark and then jumps back up and sits around 12.25-12.5

so doing a ground in the rear and the battery to alt pos upgrade i should gain around a half volt possibly right

Well, I have my rear battery grounded to the front battery and chassis, and that increase my voltage by .4 so yeah go for it.

 

[Rashaddd 5,000+ posts]

0 gauge per foot = 0.0000983 ohms

0.0000983 x 15 feet lets say (from front to back) = 0.0014745 ohms

.0014745 ohms x 200 amp current draw = 0.2949 volt drop

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[king ranch 5,000+ posts]

0 gauge per foot = 0.0000983 ohms
0.0000983 x 15 feet lets say (from front to back) = 0.0014745 ohms

.0014745 ohms x 200 amp current draw = 0.2949 volt drop

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

yea thats about right because they are both 15ft runs plus the fuse holders so 15ft basically so thats about right bc i am only loosing .2-.4 volts at the most but its only really around .2-.3 volts

but i am confused on how i am loosing almost a half volt from the back battery to the amp.

 

[Rashaddd 5,000+ posts]

yea thats about right because they are both 15ft runs plus the fuse holders so 15ft basically so thats about right bc i am only loosing .2-.4 volts at the most but its only really around .2-.3 volts
but i am confused on how i am loosing almost a half volt from the back battery to the amp.

Oh, well if thats the case, there's a power transfer issue directly between the two, make sure all wires have perfect connections, one could easily be somewhat loose. In fact, I can't think of any other possibility than a poor connection between amp and battery

 

[king ranch 5,000+ posts]

Oh, well if thats the case, there's a power transfer issue directly between the two, make sure all wires have perfect connections, one could easily be somewhat loose. In fact, I can't think of any other possibility than a poor connection between amp and battery

yea i figured that myself it has to be a bad connection at the amp because the connection with the ring terminals and at the back battery are all good i mean only loosing .2-.3volts from front to back isnt a issue at all its just the back battery to the amp.

Also grounding the back battery to teh frame as well as grounding to the front might help the voltage right, and adding the alt to battery the last thing i need to do on the big 3 should help it out as well. With those voltages do i risk damaging the amp it drops below 12 only with headlights on at full tilt at idle and only for a split second on certain notes rest of the time its above 12

 

[jrwalte 10+ year member]

The probable reason connecting a negative to the chassis may help is because your single line of 1/0 negative would be choaking and the chassis helps 'share' the negative run. The chassis is not a better conductor than an OFC 1/0 wire.

You may also try adding a 1/0 negative directly from alt to front battery (not using the engine block). I had a voltage increase when I did this from 12.7 to 13.2 when I connected my rear 1/0 negative directly to my alt, which has a grounding bolt on the alt chassis. Running yours from alt to front battery would do the same thing since you already have a 1/0 negative going to the rear at your front battery. But you could always test to see if moving the rear negative line directly to the alt improves voltage.

In my case the weak point was my negative from alt to front battery, which is going through my engine block to battery and chassis both with 1/0. When I connected my amps negative run directly to my alt I saw the big increase. But this may be due to the HO alt I have and wouldn't help as much on a system with a lower amperage alternator.

We have about the same wattage, too. I'm running 1900RMS total with a 180a Excessive Amperage alt and 1 Kinetik HC1400 up front.