hooking up muiltple batteries. how to?

[Dirtrider4eva 10+ year member]

so. this week, i have an oppurtunities to get 2 extra batts for a reasonable price,

so i have a 90 amp alt, some farm and fleet battery up front, and will be running 2 dekas in the rear,

now from the front battery, how many runs of 0 gauge will i need? 2?

i do plan on upgrading the alt soon.

and then how would i connect 3 amps to the batteries?

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[bubbagumper6 5,000+ posts]

If your alternator is only 90A why do you think you would need more than a single run of 1/0? 1/0 OFC is usually rated for 300A

What do you mean, how do you connect the amplifiers to the batteries? I assume the Deka's have threaded inserts, so ring terminals and 1/0 (or 4 gauge depending on amp size). It's all connected in parallel so it doesn't really matter which battery you connect to.

 

[Dirtrider4eva 10+ year member]

thats what i was refering to. which battery. but thats true, since their all in parallel the load will not matter on which batt.

i have knu collosus, ill just use a single run.

when i looked around some guy did 1 extra run per battery, i found that a little too much.

 

[LosIsATool 5,000+ posts]

1 run for every 2500 to 3000 rms depending on cable being used

 

[audioholic 5,000+ posts]

First off, the new batts will have a different internal resistance than your old F&F batt. This means if you simply parallel them all together, you will have a problem with parasitic drain (the older batt will continually drain the newer ones in an effort to stabilize voltage). Unless all the batts in the circuit are approx the same age, you will want to use an isolator or relay to separate the new batts from the old one.

Second, the wire running between the old batt and back to the new ones, will simply be recharging the rear batts, not handling much/any of the transient peak demands from the amp(s), so you dont have to use multiple runs of 1/0. One should suffice.

 

[Dirtrider4eva 10+ year member]

thanks man. i might, if it fits, swap the old F&F with a deka, and then just keep one in the back. and get a ho alt. im pretty sure 165 will be fine for my demands..

ill be running daily about 1.5k, comps, 3k.

 

[audioholic 5,000+ posts]

That sounds like a much better plan.

 

[i2ain2thunder 10+ year member]

I know scientifically speaking you will suffer from what is referred to as parasitic drain, a good point to keep in mind. I've seen systems with older/newer bigger/smaller nicer/worse batteries in parallel and the people didn't seem to have any issues ever, I guess it really depends. But yeah unless you're going past 3k rms 1 run is fine.

I stick with the same battery for all the ones used in parallel just so I never have an issue, thats the best way to do it.

 

[audioholic 5,000+ posts]

I know scientifically speaking you will suffer from what is referred to as parasitic drain, a good point to keep in mind. I've seen systems with older/newer bigger/smaller nicer/worse batteries in parallel and the people didn't seem to have any issues ever, I guess it really depends.

Ive already addressed parasitic drain here. Its real, and it will occur if not accounted for. Whether you realize its occurring or not can depend on many things. But personally I wouldn't want to spend the money on an upgrade, and not get the best results out of it possible, just because someone I once knew 'seemed' to do okay without considering it.

 

[Dirtrider4eva 10+ year member]

thanks for all your chime ins.

i will be getting them monday.

they 100 amp hours each, so 200 ah in batts, and when i get the HO soon enough, all set.

its only running a single 15.

 

[bubbagumper6 5,000+ posts]

Ive already addressed parasitic drain here. Its real, and it will occur if not accounted for. Whether you realize its occurring or not can depend on many things. But personally I wouldn't want to spend the money on an upgrade, and not get the best results out of it possible, just because someone I once knew 'seemed' to do okay without considering it.

In most cases I would agree with you....but I still say to this day isolators are optional. I'm STILL running the USED yellowtop that I bought for my first system, and it's seen multiple different aged/sized batteries in parallel with it...I agree that it's always good to try and maximize results but if the drain is so small that the difference is negligible then what? The only argument that I've ever heard is that this will shorten the life of the battery but like I said, my Optima is old as fawk and still running fine...

 

[Dirtrider4eva 10+ year member]

i mean.. for daily driving.. and my system, im not too worried about parasitic drain, when the F&F batt, its well over 3 years old, nothing special, if it does go, then be it, but from what i will be running, its nothing im worried about. ill never be DD with 3k. only burping for a comp once in a great while. but i appreciate the info.

 

[audioholic 5,000+ posts]

In most cases I would agree with you....but I still say to this day isolators are optional. I'm STILL running the USED yellowtop that I bought for my first system, and it's seen multiple different aged/sized batteries in parallel with it...I agree that it's always good to try and maximize results but if the drain is so small that the difference is negligible then what? The only argument that I've ever heard is that this will shorten the life of the battery but like I said, my Optima is old as fawk and still running fine...

It will shorten the life of all batts in the circuit. The more current passed thru a batt, the more it sulfates/oxidizes, the sooner it dies. So if one batt is constantly draining the other batts in the circuit, all batts are working harder than necessary, and lifespans are affected, and internal resistance of even the new batts is getting higher artificially quickly. And when you add batts to help with storage capacity and (ultimately) system voltage, having one batt that impedes that, it seems counter productive to me. In your situation, who knows, maybe your storage is overkill enough that even with a parasitic drain, you dont see the problem.

You can buy a 200 amp relay for 50 bucks, to me that's well worth it when each batt costs at least twice as much. Its like adding a new, larger amplifier, but not forking out the extra money to upgrade the wiring to it. Sure you might/probably are getting more wattage than your previous amplifier, but not what you could or should be, you'd have been better off just settling for a smaller amplifier, because you dont spend the few extra bucks to have the proper install that gets the full potential out of it.

 

[bubbagumper6 5,000+ posts]

It will shorten the life of all batts in the circuit. The more current passed thru a batt, the more it sulfates/oxidizes, the sooner it dies. So if one batt is constantly draining the other batts in the circuit, all batts are working harder than necessary, and lifespans are affected, and internal resistance of even the new batts is getting higher artificially quickly. And when you add batts to help with storage capacity and (ultimately) system voltage, having one batt that impedes that, it seems counter productive to me. In your situation, who knows, maybe your storage is overkill enough that even with a parasitic drain, you dont see the problem.
You can buy a 200 amp relay for 50 bucks, to me that's well worth it when each batt costs at least twice as much. Its like adding a new, larger amplifier, but not forking out the extra money to upgrade the wiring to it. Sure you might/probably are getting more wattage than your previous amplifier, but not what you could or should be, you'd have been better off just settling for a smaller amplifier, because you dont spend the few extra bucks to have the proper install that gets the full potential out of it.

I'm not saying that I disagree with the science behind your theory. I'm saying there's no proof that the difference between having the isolator and not is significant. An isolator will add additional resistance in the circuit causing a voltage drop (albeit probably small, but still worth mentioning), who's to say that's better then the parasitic drain scenario?

 

[audioholic 5,000+ posts]

I'm not saying that I disagree with the science behind your theory. I'm saying there's no proof that the difference between having the isolator and not is significant. An isolator will add additional resistance in the circuit causing a voltage drop (albeit probably small, but still worth mentioning), who's to say that's better then the parasitic drain scenario?

Notice I recommended a relay, not an isolator.

And an added resistance in the circuit, such as an isolator, is not the same thing as a parasitic drain. The resistance added by an isolator only adds to the 'work' on the circuit/batts when current is flowing, a parasitic drain will always be there.

If your setup works for you, more power to you man. Again each individual situation is different, and you might get away with it just fine. But people should understand the situation before making their choice, so they can make an educated decision.

Cheers.