2nd battery/isolator questions

[filtor1 10+ year member]

woo hoo. I have 2 trickle chargers at my disposal. This should knock down the time frame by a few hours. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I will wait until I get home from class tonight and hook them both up.

 

[filtor1 10+ year member]

One thing I neglected to give is I have never seen anything under 14.4-14.5volts at the rear distribution block since the system was installed in Feb. Don't know if that is important. I would typically see the voltage drop to 12volts at full tilt. Now I have seen it drop to 8-9volts when playing music.

I decided to do some more testing. Before I did, I disconnected both batteries grounds as well as the amps grounds and sanded down the ring connectors and the chassis contact points. They all looked fine so I just did it to eliminate that as a possibility. I also checked the voltage with different accessories on as well.

With the car running and no accessories. #1. 13.9 across the front battery. #2. 12.8 across the rear battery. #3. 13.8-14.1 from the factory alternator wire. I will use the #'s to indicate the corresponding reading and specify what accessory was on when tested.

#1. 13.7 with the headlights on. 12.3-12.6 with the A/C on.

#2. 13.7 with the headlights on. 12.0-12.3 with the A/C on.

#3. 13.9 with the headlights on. 13.2-13.4 with the A/C on.

These reading were consitant after running the car for 10 minutes.

I just wanted to see a 14.4-14.5 at the rear distribution block again. I do not have the ability to check the voltage drops while playing the stereo loud at this time. I will see if the stereo looses volume as it is increased on my drive to class. I am sorry for obsessing, but I miss how strong the system sounded just a week or so ago.

I appreciate the responses. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bri487 5,000+ posts]

isolators are junk. if the second battery, the auxillary one is too dead (like completely dead), the isolator cant click over to the good battery. a much safer way to go is with a perko switch. you can pick them up at like west marine or local boat shops. also, if you decide to go with either one, i would charge it at night, or after extended play, because a stock alternator wont put out enough to really charge it back up to where it should be.

 

[filtor1 10+ year member]

perko switch?

 

[knukonceptz 10+ year member]

12.3 - 12.6 seems low to me with headlights and A/C on. What year and make car is this again?

Now one thing I notice looking at your numbers, the Alternator's voltage is a full volt higher then either battery with a draw. As you see the alternator is working (only a 0.5V loss with accessories at the back of the ALT) so that leads to either a wire problem (high resistance, a section may be "green") Or it is a ground issue. Since both batteries are effected by this (both have low voltage), it could be the factory ALT wire or Ground (most are grounded from their mounts though...)

Start with charging the batteries for a 6-8 hours on a trickle charge. Make sure they are in fact good batteries. After that it would have to be cabling

 

[bri487 5,000+ posts]

perko switch?

look it up on google. it is known quite well with anyone with boats.

 

[filtor1 10+ year member]

12.3 - 12.6 seems low to me with headlights and A/C on. What year and make car is this again?
Now one thing I notice looking at your numbers, the Alternator's voltage is a full volt higher then either battery with a draw. As you see the alternator is working (only a 0.5V loss with accessories at the back of the ALT) so that leads to either a wire problem (high resistance, a section may be "green") Or it is a ground issue. Since both batteries are effected by this (both have low voltage), it could be the factory ALT wire or Ground (most are grounded from their mounts though...)

Start with charging the batteries for a 6-8 hours on a trickle charge. Make sure they are in fact good batteries. After that it would have to be cabling

It is a 01" Nissan Maxima

What does "green" mean exactly?

I played the stereo on the way to class and it didn't fade like before. It also doesn't seem as strong either. At least it doesn't fade out. Could I have discharged the yellow top too many times? I suppose I mean to the point where it cannot be recharged or no longer operates at full capacity.

It is raining and has been all day here so I will have to charge them Friday. How would I go about checking them to make sure they are still good?

 

[knukonceptz 10+ year member]

Green = corrosion, that raises resistance which causes a voltage loss. Up north where it is cold, salt from the roads helps accelerate a problem like this. You being in FL is probably not as common. But if you ever see some white or green stuff on your battery terminals, that is what I am refering to.

After you charge them see what they read at after they have sat for 30 minutes. Make sure they can hold a charge.

 

[filtor1 10+ year member]

Ah-ha. Green. I see now. I popped the panels hiding the 0ga and have inspected the wire from the front battery to the rear. It all looks fine. The terminals are nice and shiney as are the ground connections. Thankyou for explaining that!

I cannot believe it is still raining. I will try and get this done after class tonight. SO I can have them sit before checking them tomorrow morning. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[HowLowd 10+ year member]

An isolator uses power to operate, so you will actually have less voltage after you install one. The only real advantage you have is that with the car off, the rear battery is isolated and you can boom away and still start your car. The current way you have the sytem wired is IMHO the better way to go. Why your volgate is low could be either weak batteries, an Alternator on its way out or a wire problem (like a key off drain ******* your batteries while they sit idle) Before you go spending, try to sort out things so you can put the funds you have toward the problem

alright, now that brings a question up for me. And this was from personal experience so bear with me. Upon initially going to a multi battery system

As its been explained to me you essentially have to match the two batteries or purchase at the same time hopefully with the batts matching voltage, or the lower will discharge the higher over time. Hence why I went to the isolated setup, and mentioned his vampire discharge. I ran into multiple times that the car wouldnt start even after just being cut off, but while running my zapco old skool at full tilt with the car running.

From there I added two batts in the rear and with the isolator never had another problem, to include dimming lights, low voltage, or voltage dips like i did previously. What BRI said makes sense on if the voltage drops and to me thats the point of batch matching them. Make sense?

 

[knukonceptz 10+ year member]

When you add any battery, you want to charge both first so that they are at the same voltage to start. These things should be checked before installation. If your one battery is constantly drawing power from the other, then it is actually a bad battery. It no longer has the ability to hold a charge and should be replaced. If that battery were alone in the car it would eventually leave you stranded.

 

[filtor1 10+ year member]

OK, i have an update. After sanding and cleaning my grounding points, my voltage has stabilized. I get 12.7 from both in the morning w/o starting the car and 14.1 there after. It was apparently that the grounds were weak. I will be using the trickle chargers soon to top them both back off. kinukoncepts, you have been awesome. I can't thank you enough for all of your advice and attention to my problem. Thanks again! //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[knukonceptz 10+ year member]

Great to hear you got it resolved. Its good you had the right tools though to help the diagnosis. A lot of people have problems, with out the right tools though we are all just guessing.

 

[filtor1 10+ year member]

I actually just bought the multimeter the week before last b/c it was on crazy sale at Sears, $9.99. It it a basic multimeter, but it was the only way I could get you enough information to make a diagnosis. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif It was worth every penny IMHO. I now need a good panel puller, all in good time.

 

[knukonceptz 10+ year member]

LOL thats funny, I was gonna mention a $10 DMM is nothing compared to the money we spend on amps/subs, everyone should own one.