voltage drops at 2nd batt

[bumpingrandamgt]

Installed a 220a ho alt, big 3, a kenetik HC 1200 blu, at the second Batt my voltage is 13.8-14.2 (i know that's kinda low my front Batt needs to be replaced, at the second batt it reads 12.6-13.0, thinking i need to Change my grounds, any other ideas?

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[Savackz]

Is that with car running? And make sure to scrape the grounds and connection from pos to neg from front to back battery is a solid run. Crimping is all good and firm.

 

[massivespl]

Installed a 220a ho alt, big 3, a kenetik HC 1200 blu, at the second Batt my voltage is 13.8-14.2 (i know that's kinda low my front Batt needs to be replaced, at the second batt it reads 12.6-13.0, thinking i need to Change my grounds, any other ideas?

How can the second battery read 13.8-14.2 and 12.6-13?

 

[Justin braaapp]

How can the second battery read 13.8-14.2 and 12.6-13?

I was thinking the same lol

 

[Savackz]

Yeah, might get a dud battery.

 

[negolien]

Did you charge up both batteries before putting in the 2nd and the alt?

 

[Savackz]

Check voltage with car on (engine on) and car off with a dmm at the 2nd battery.

 

[bumpingrandamgt]

The battery I have under the hood was reading 13.8-14.2.

The battery in the trunk was reading lower at like 12.6-13.0 both tests while car is running

And yes I charged both batteries before hand,

 

[shammyhavik]

Check if the battery is swollen at all on the sides

Where did you buy the battery was it used if it's used how old is the battery and was it charged regularly

 

[bumpingrandamgt]

I bought it new from sonic electronix, I honestly think my front bat is fried and I don't have good enough grounds, gonna check both battery voltages when the car is off and see what it is

 

[adulbrich 5,000+ posts]

What gauge wire and is your run to the back fused? If so, check your fuse. If it's loose or partially blown, that could be an easy fix.

 

[bumpingrandamgt]

0g 250 amp fuse from alt to bat, 250 amp fused 0g to the second battery, all fuses are tight connections all secure,

 

[Jduane]

When you installed the grounds, Did you scrap the paint off the metal until it's l a mirror.

When you upgrade + wires you need to upgrade - wires, power flows - to +

Mabey it hasnt fully charged yet, how long has it been in?

 

[bumpingrandamgt]

Only a couple days, charged it before installed too

 

[wew lad 5,000+ posts]

Are you using a battery isolator or relay? You might need to. Running dissimilar batteries in parallel is a bad idea