booman311

lately when my eld is engaged my voltage drops to 11.8 v and with a load 14.3 v. ive read people getting 13.5 v when drops so what do you think it could be. ive upgraded all grounds off batt. including the one from body to motor. upraded to 4 gauge on alternator. i have 0 gauge running to batt in back and a 10 farad cap. kinetic in back and duralast gold series in front. any help would be appreciated. just had my alternator and battery tested and tested fine but 11.8 dont feel right in my bones...

jordan1794

How much wattage are you pulling and what year are you?

Alternators on this car are small; if you have a system trying to pull anything more than 30-40 amps the alternator won't keep up(at idle, at speed you might be able to see a 50, MAYBE 60 amp system supported)

Alternators are rated somewhere around 100 amps; but that is at the best RPM, at idle you only get 50, and 20 of that goes to run the car.


30 amps at 12 v translates to 360 watts(not a lot in car audio terms.)

My 2014 can only get 30 amps to my Alpine MRX-M110 pushing my 10" type R, a set-up fully capable of pulling close to 90, or even 100 amps.
(Test slip for my amp was nearly 1200 watts RMS)


Your capacitor means nothing if you are exceeding the amperage of your alternator by very much; the capacitor still has to be charged by the alternator, and if your alternator is sending all it can there won't be any power left over to recharge the capacitor.


My amp detects voltage drop, and will start clipping before it empties my battery, even so if I'm playing a bass heavy song I sit between 11.75 and 12.25 volts.


I covered my testing and big 3 upgrade very well here:
https://www.civicforums.com/forums/1...014-civic.html

booman311

it does it with stereo off. if i turn stereo on it sees a load and charges 14.3 steady. stereo off, ac off, and lights off it charges at 11.8 most of the time its a 2006

jordan1794

Although e-zone could be typing this same thing as I type;

Might be time to get a new battery; most testers can pass a bad battery under certain circumstances.

How old is the battery, and how much abuse has it seen?(Ever run it dead and need a jump? Almost dead to where it barely started? etc.)

Honestly 11.8 with no big load sounds pretty normal, these cars are built for fuel efficiency and are designed to keep the alternator off as much as possible.

I'm sure if you turn the AC on it will kick up to a higher voltage and stay there.

jordan1794

If you have a meter measure the amperage going from the negative battery to the chassis; It SHOULD read nothing.

If everything is working correctly, the only thing providing power once the car is on is the alternator.

Try hooking a voltmeter between the top of the alternator, where the power cable connects the alternator to the battery, and the other side to the chassis of the car.

This will tell you what the alternator is charging at, if it's 11.8 as well then your alternator is choosing to run at 11.8

booman311

i will try that tomorrow man thanks... no batt never ran down and its about 8 months old.