2nd battery/isolator questions

[filtor1 10+ year member]

I have a Diamond Audio D61500.1 powering 2 TDX 12"s and an Alpine MRV-540 powering 1 set of Rainbow Contours(components) and 1 set of Alpine Type-R(components). HU is an Eclipse CD8455. I have done the Big-3 in 0gauge. I have 0gauge from the stock battery(fused at battery under hood) all the way back to the Yellow Top in the trunk. 0gauge grounds for both batteries. 0gauge to the distribution block then 2-4gauge(1 per amp) to the amps. Each amp having a 4gauge ground to chassis. This is all in an 01' Nissan Maxima.

Issue time, I have noticed a steady drop in voltage at idle w/o the stereo on. When the system was first installed, everything was 14.4-14.5 at idle. It now won't go any higher then 11.5.

I am currently a student and have limited funds. I am assuming I need to replace the batteries. They are about 11-12months old. Should I bother with an isolator? If so which one would you suggest for my set-up? I would love to get a 200amp alternator but can't afford it and also the stock alternator is still under warranty. Maybe next year I will be able to fund that project.

As of today, bass response falls off dramatically with higher volumes. I obviously can't have that. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I hope I have provided enough information to aid you in helping me. Thanks for your consideration.

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[HowLowd 10+ year member]

wired mbr 70 or the concept 110 amp model. charges both without allowing the vampire discharge your getting now //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

works great and I used mine on two yellows in the rear and a red upfront no problem for about three and a half years.

 

[HowLowd 10+ year member]

and why dont you get back on the dang max boards where you belong //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[filtor1 10+ year member]

and why dont you get back on the dang max boards where you belong //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif


Open in another window. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[filtor1 10+ year member]

wired mbr 70 or the concept 110 amp model. charges both without allowing the vampire discharge your getting now //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
works great and I used mine on two yellows in the rear and a red upfront no problem for about three and a half years.

Do you have a HO alt? Do you have links handy for the suggested items? I have been looking at the Stinger SR200. That with an inline voltage display for the glove box. SVMB to be exact.

When you say you have used "mine", which one would that be exactly?

 

[knukonceptz 10+ year member]

I assume you have a voltmeter (hence the number in your post...) any way, whats the voltage with car off after say 5 minutes. In that time the batteries should rest to there normal hold voltage. Check first thing in the morning? are they much lower like a key off drain exists? Do you own a battery charger? I would start with a trickle charge over night to your front battery (disconnect the rear one) then repeat and do the same for the rear. See what happens with that.

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

 

[HowLowd 10+ year member]

I had the wired mbr70 in my other car. For years. There was slight voltage drop 14.4 at the front 13.8 at the amps. The mbr keeps it isolated while you drive not only while the car is off. charges one then the other, whichevers voltage drops it charges.

In the max, i havent upgraded yet. just starting out, but its obvious itll be needed on this car later. With drill sergeant school im about to have to drop alot of coin on some other stuff so maybe soon but HO alt as of now is a no go.

I posted links to both in the carputer link from last week or so in audio video //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif let me know if you dont see it

 

[slim j 10+ year member]

Not to threadjack, but about the 2nd battery/isolator quuestion:

If you have one wire going from your alt to your normal battery. Then you have another wire going from your alt to your battery in the trunk, is that okay? I wouldn't see the need for an isolator then. I think this would only work if you had an HO alternator though.

 

[knukonceptz 10+ year member]

I understand the isolator works all the time, it serves no benefit in car audio with the car running other then to steal power and capacity. The electrical system will operate better with two battieries wired together then two seperate systems.

Slim - an Isolator has 3 terminals - One to Battery A, one to Battery B and one from the Alternator. The factory wire from Alternator to the factory Battery (Batt A) is no longer in place. All power from the alternator is routed through the isolator.

Back to the issue of using the isolator - You are correct, the isloator will charge to lower of the two batteries and you will have a loss because the isolator is electric. It is more logical to wire two batteries together to get a larger reserve capacity in a car then to isloate two batteries.

We can all agree the factory battery is known to operate the car just fine, adding a large system puts a strain on that battery. It does however continue to operate for 90% of us out there. Add a second battery to the main system and you have more capacity for the car and stereo. By Isolating the front from rear, you still just have one battery for your stereo and less voltage from the islator operating

 

[filtor1 10+ year member]

I assume you have a voltmeter (hence the number in your post...) any way, whats the voltage with car off after say 5 minutes. In that time the batteries should rest to there normal hold voltage. Check first thing in the morning? are they much lower like a key off drain exists? Do you own a battery charger? I would start with a trickle charge over night to your front battery (disconnect the rear one) then repeat and do the same for the rear. See what happens with that.
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

The rear distribution block has a voltage and amperage display for each amp. This only measures from the battery in the trunk to the amps though. I do have a volt-meter as well. I will check the static charge in the morning as you suggest. I haven't done that yet. I also own a trickle charger as well. Can the batteries be "re-charged" using this method? Is there any way to check the output of the stock alternator with a basic volt-meter to determine if it is weakening? I have the stock ESM that has the values at idle and maximum output(@5500RPM). Do I need to remove the added alt+ to battery + of the big-3 to do this? Thanks for the suggestions so far. I didn't even think of this. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[filtor1 10+ year member]

I understand the isolator works all the time, it serves no benefit in car audio with the car running other then to steal power and capacity. The electrical system will operate better with two battieries wired together then two seperate systems.
Slim - an Isolator has 3 terminals - One to Battery A, one to Battery B and one from the Alternator. The factory wire from Alternator to the factory Battery (Batt A) is no longer in place. All power from the alternator is routed through the isolator.

Back to the issue of using the isolator - You are correct, the isloator will charge to lower of the two batteries and you will have a loss because the isolator is electric. It is more logical to wire two batteries together to get a larger reserve capacity in a car then to isloate two batteries.

We can all agree the factory battery is known to operate the car just fine, adding a large system puts a strain on that battery. It does however continue to operate for 90% of us out there. Add a second battery to the main system and you have more capacity for the car and stereo. By Isolating the front from rear, you still just have one battery for your stereo and less voltage from the islator operating

So my root issue would be a lack of initial current supplied by the alternator considering the added accessory in the trunk. The isolator would be somewhat of a band-aid to a much larger issue. I will def test the voltage in the morning. I will report back then.

When I originally searched on this issue, the threads were incomplete. The original poster usually dissappeared w/o answering some important questions that would influence the advice. I hope that this can be a good thread for others in the future, full of specifics and information. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[knukonceptz 10+ year member]

Ok, two things - if the voltage in the rear is at 11.5 and dropping and we do not know what the under hood voltage is and your head lights are normal brightness you may have simply blown a fuse to the rear battery. If the fuse is good, power knows not direction, the fuse block is connected the the rear battery, the rear battery is connected to the front battery (unless your fuse crapped out) Therefore the front battery should read the same as the D-Block (or atleast within a few tenths)

Second, your battery under the hood has a fused wire (about 18" from the battery) that then connects directly to the rear battery right? What is the point of the fuse holder at the front battery if you have a battery in the trunk with out a fuse before it? You see in a normal install with no battery in the trunk, that inline fuse holder protects the cabin from catching fire in an accident (live 1/0 can make some good sparks) SO what happens when you have one fuse BETWEEN two batteries? the fuse is the only portion of the circuit where there is no power...For two battery systems to be wired properly two fuse holders should be used (one at each end to keep power out of the cabin. Again this in case you get in an accident. Either use two fuses or none at all in the two battery case.

Without knowing what happens up front we cant go much further.

Regarding a trickle charge, set your charger to its lowest setting, normally 0.1A. Set this over night, check voltage in the morning. If you can, let the car sit for another 10 minutes and see how far the voltage drops.

 

[filtor1 10+ year member]

I have some results. These readings were taken before turning on the ignition, cold if you will. Also disconnected the power wire from the front battery to the rear battery. #1. 12.2-12.3 across the front battery. #2. 11.3-11.4 across the rear battery. I then hooked the rear battery back to the front battery. #3. 12.0-12.1 across the front battery. #4. 11.5 across the rear battery.

I then started the car with the radio on but not playing. #5. 14,4 across the front battery. #6. 13.9 across the rear battery. I also put the positive lead from the volt-meter to the stock alternator positive wire and grounded it to the neg terminal on the front battery which yeilded #7. 14.4-14.5.

There is a fuse about 1ft(wire length) from the battery under the hood. I will add another before the battery in the rear as soon as it gets here. I now understand why I would want to keep the power "out" of the cabin. I had not thought of that. The main power fuse from the front battery is fine. The final distribution block fuses are fine as well.

I will wait and see if you think the trickle charging is necessary or suggested.

 

[knukonceptz 10+ year member]

Just to confirm, these reading were both done with the same meter and not using the dist block correct?

Seems like the rear battery is a bit low when cold, I would definitly charge that one and if you charge one, you should charge both. You will have a .5A loss from front to back as a result of the fuse it will cause that loss.

I would also double check the grounds at the rear, make sure they are good and clean. The numbers seem about right with no additional accessories on. The alternator is working. What happens to voltage (Front and rear) with the stereo at normal playing level (ie loud......lol)

 

[filtor1 10+ year member]

Yes, the reading were all taken with my handheld volt-meter. The distribution block had the same reading in the rear though.

I will bust out the charger now and check the grounds. Would the grounds cause the steady decrease in output I experienced yesterday?

Should I measure the voltage with the car off and then on again to check the overall voltage drop as in the first test? Just want to know if this would help.

Chris