Installing Dual Batteries with isolator.
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Installing Dual Batteries with isolator.
Ok I going to need a lot of power here so I bought a isolator for my 2000 legacy sedan GT. I have a optima in the front I will put another one in the truck. But I am having a problem with the alternator. THe alternator is charging ok, but when I wired the isolator in without the second battery ( a little short on money right now) the car started ok but when i went to leave I noticed that if I reved the engine at all the battery warning light came on.
I am going to be running the following system.
Mtx 81000D using 150 amps alone!!!
Kenwood 2-chan. 40 amps
alpine 4-chan 35 amps
and mabey a power inverter using 35 amps.
plus I have a 1 farad cap. for the MTX amp.
Now I have a 200 asu fuse to wire in between the aux battery and the isolator. and I have 0 guage wire to run from the aux battery to a fuse block.
So here is te real question. Do you think it's the alternator and how do I fix it. Is there a place that sells a high output alt. for the 2.5L engine.
O plus I have a brandnew 160amp high output alt. for my 1991 GMC truck If I could find a mounting bracket fo it or something.
I am going to be running the following system.
Mtx 81000D using 150 amps alone!!!
Kenwood 2-chan. 40 amps
alpine 4-chan 35 amps
and mabey a power inverter using 35 amps.
plus I have a 1 farad cap. for the MTX amp.
Now I have a 200 asu fuse to wire in between the aux battery and the isolator. and I have 0 guage wire to run from the aux battery to a fuse block.
So here is te real question. Do you think it's the alternator and how do I fix it. Is there a place that sells a high output alt. for the 2.5L engine.
O plus I have a brandnew 160amp high output alt. for my 1991 GMC truck If I could find a mounting bracket fo it or something.
there is a thread here a few months ago where high output alts were discuseed.
if i were you, you are better with a HO alt...
alex (imprezer) said to go check a canadian version of the outback which has a bigger than stock numbers...
if i were you, you are better with a HO alt...
alex (imprezer) said to go check a canadian version of the outback which has a bigger than stock numbers...
OK unless you are going to be listening to your system with the key off then a second battery hooked to a isolater is a waste of money and a waste of charging voltage. Once the car is running, the alternator is actually powering the car. NOT THE BATTERIES......
All the battery is used for is to start the car and run your accesories when the car is NOT running. Infact once you have started your car, the battery is a "Load" (Read as more work) for your alternator. Adding a second battery simply means that your alternator will now have to charge the main battery, power the car, power your system and recharge the second battery. Get the biggest alternator you can find and/or add a second biggest alternator you can find and then build your system to work within the voltage and current you have to work with. Good Luck
PDQWRX
All the battery is used for is to start the car and run your accesories when the car is NOT running. Infact once you have started your car, the battery is a "Load" (Read as more work) for your alternator. Adding a second battery simply means that your alternator will now have to charge the main battery, power the car, power your system and recharge the second battery. Get the biggest alternator you can find and/or add a second biggest alternator you can find and then build your system to work within the voltage and current you have to work with. Good Luck
PDQWRX
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I don't know. I had a 1991 GMc sierra with the same system in it. But I had the alternator rebuilt to 160 amp's and even that wasn't enough with one battery. I know you have a good point about loading the alternator but when you have two batteries the alternator load doesn't change because of the isolator( thats it's job) so you use the power in the second battery first that swhy you need to buy a deep cycle battery so that if you do use more power than it can charge you can then fully recharge it again.
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Joined: Oct 2003
Posts: 436
From: cali
Car Info: sti wrb
Originally Posted by pdqwrx
" Once the car is running, the alternator is actually powering the car. NOT THE BATTERIES......
All the battery is used for is to start the car and run your accesories when the car is NOT running. "
PDQWRX
All the battery is used for is to start the car and run your accesories when the car is NOT running. "
PDQWRX
now for your problems with the battery light going. i would assume the battery u are using is not getting the full charge at the moment cause the alt is not strong enough or the batt is getting bad or the wiring is not good enough. so many problems but just go at it systematically. first get a bettery tester that can check it at a very precise number. get a digital one they are pretty cheap now. and then call the maker of the battery to find out what the volt should be at. then measure it. measure it at running and when the engine is not running. its both different. one is with the alt running (2 sets reving and idle) and when the car is not on check to see if the batt is losing power over a period of time . so check the volt then wait 1 hour and come back to see if it the same then wait another hour and check again. it should be at around 12 v. but no less then 11.5 in the 2 -3 hours of testing. i believe the car needs at least 11v or so to start. but anyways when u rev and the batt light comes on have someone have the meter on the batt. see what it is and then at idle. just get some numbers first and then come here to post. we will go from there. do a mess of test first and write them down.
oh, here it the test i told u in the beginning. the batt is needed all the time for the engine to run. while the car is running disconnect the positive of the car. what happens? try it! its fun. it kinda brings to light what that means. hmmm higher CC, higher RA is good too. oh what type of optima are u running? that is also a thing too. red optima is for starting and yellow is for playing.
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yeah thanks for the reply. I am running a red optima. I don't have the yellow one yet but it's on the way.
One thing I did do is I have a power converter with a digital read out that reads the voltage coming in and I noticed it was reading about 11.1/11.0 volts when I put the isolator in and when I reved the car the voltage went down.
but when I did test the isolator I didn't have the yellow optima in the trunk hooked up yet. I am thinking that is the problem.
One thing I did do is I have a power converter with a digital read out that reads the voltage coming in and I noticed it was reading about 11.1/11.0 volts when I put the isolator in and when I reved the car the voltage went down.
but when I did test the isolator I didn't have the yellow optima in the trunk hooked up yet. I am thinking that is the problem.
Hello again- I thought I might share a little more info about the average cars charging system.
As I stated before all the battery should do in a properly working system is START THE CAR and supply power to the cars accessories when the car is NOT running. Car manufacturers go to great length to engineer their charging systems to be just big enough to run all the accessories that you might use and still CHARGE the battery after it started the car.
Now let’s say for the sake of argument that the car did run off the battery as asionboy101 claims. The car would only run until the battery was dead, correct? Oh wait the battery doesn’t die, Why? Because it has an alternator "Charging it" so the alternator in fact does power the car because you wouldn't get past your local 7-11 with out it.
The reason some cars have larger output alternators is that they have more 12volt stuff to operate. Generally a car with no power windows or door locks will have a smaller alternator then a "Fully Loaded" car will all kinds of stuff to draw extra power from the alternator.
Lets talk about battery isolation- Using a resistor based "Battery Isolator" is a bad idea in the car audio environment because they are very inefficient in the way they work. You end up loosing a volt or two of power into heat to make the darn thing work and that means that it will take longer for the alternator to charge the batteries. This also means less power for your stereo and stuff because you are wasting it as heat in the isolator. That type of product was designed for motor homes that will be running on the road for many hours and have generators on board to help out the electoral system. Cars don't generally have that luxury. A better way to isolate the two batteries would be to buy to very similar batteries at the same time (Two Optima yellow tops) and use a relay to isolate them. This way they will both see maximum charging potential and you won’t be wasting any charge current. But really you don’t need to isolate them at all. By not isolating them at all they would act as one big battery which is really what it sound like you’re after anyway. Just remember that when the battery is discharged then it must be charged and that is a load on your alternator. 10 amps spent charging your batteries will me 10 less amps to run your amps or lights or windshield wipers.
My suggestions still stand. Buy a bigger alternator and design a better system that will work within the power available.
Feel free to PM me and we can set up a time to talk by phone and I will be happy to help you out. I have almost 20 years of 12 volt experience and I am happy to share. By the way, after reading your last post you need to trouble shoot you car very quickly. Things are starting to go down hill.
Good Luck
Scott
P.S.
I will post an article on dual batteries written by a very smart guy named Dave Navone. It will shed some interesting light on what you’re doing.
As I stated before all the battery should do in a properly working system is START THE CAR and supply power to the cars accessories when the car is NOT running. Car manufacturers go to great length to engineer their charging systems to be just big enough to run all the accessories that you might use and still CHARGE the battery after it started the car.
Now let’s say for the sake of argument that the car did run off the battery as asionboy101 claims. The car would only run until the battery was dead, correct? Oh wait the battery doesn’t die, Why? Because it has an alternator "Charging it" so the alternator in fact does power the car because you wouldn't get past your local 7-11 with out it.
The reason some cars have larger output alternators is that they have more 12volt stuff to operate. Generally a car with no power windows or door locks will have a smaller alternator then a "Fully Loaded" car will all kinds of stuff to draw extra power from the alternator.
Lets talk about battery isolation- Using a resistor based "Battery Isolator" is a bad idea in the car audio environment because they are very inefficient in the way they work. You end up loosing a volt or two of power into heat to make the darn thing work and that means that it will take longer for the alternator to charge the batteries. This also means less power for your stereo and stuff because you are wasting it as heat in the isolator. That type of product was designed for motor homes that will be running on the road for many hours and have generators on board to help out the electoral system. Cars don't generally have that luxury. A better way to isolate the two batteries would be to buy to very similar batteries at the same time (Two Optima yellow tops) and use a relay to isolate them. This way they will both see maximum charging potential and you won’t be wasting any charge current. But really you don’t need to isolate them at all. By not isolating them at all they would act as one big battery which is really what it sound like you’re after anyway. Just remember that when the battery is discharged then it must be charged and that is a load on your alternator. 10 amps spent charging your batteries will me 10 less amps to run your amps or lights or windshield wipers.
My suggestions still stand. Buy a bigger alternator and design a better system that will work within the power available.
Feel free to PM me and we can set up a time to talk by phone and I will be happy to help you out. I have almost 20 years of 12 volt experience and I am happy to share. By the way, after reading your last post you need to trouble shoot you car very quickly. Things are starting to go down hill.
Good Luck
Scott
P.S.
I will post an article on dual batteries written by a very smart guy named Dave Navone. It will shed some interesting light on what you’re doing.
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hey thanks scott. You sure are a big help. Ya, it would be awsome to talk to a real person sometime. I will try to get a hold of you later this week. O by the way do you know of a kit that would allow me to use my basically brand new high output alt for my GMC truck.
That is a resistor based device which means wasted power. Check out the Concept MBR-100. It used solid state technology to switch between the two batteries and can sense which one needs more charge without wasting current into heat.
http://www.concept-intl.net/proddeta...4&ProductLine=
If anybody wants one let me know.
Later
Scott
http://www.concept-intl.net/proddeta...4&ProductLine=
If anybody wants one let me know.
Later
Scott
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