2nd battery and alternator questions...

[bikerpunker]

Hi,
I'm considering putting a second battery in the boot of my stato to power my amps. I will be wiring a relay in so that when the car is running its charging and running from both batteries but when switched off and to accessories the stereo will only run from the 2nd battery.
First question is if i change the alternator regulator to one with a higher voltage output will it charge both batteries quicker than the current regulator?and will it affect or shorten the life of the battery?
second will there be much or any voltage loss due to the battery being so far from the alternator?

Any help would be greatly appreciated

[Brycestro]

Hi there dude how's it going?

Quick question: what's the overall power of your amplifiers? First and foremost, a dual battery setup should be a last resort option. Before even considering one, you should upgrade your existing battery and existing grounding cables. Not only will it save you a hell of a lot stuffing around, but probably some money too.

I'd recommend to you an Optima Yellow Top (D34 i believe is the model no.) or Optima Blue Top battery (D34M). If you know where your looking these can be had for around $315.00 for the red top and $335.00 for the blue top after postage. The former is deep cycle, 750 CCA and has a reserve of 120 minutes. The later is exactly the same as the Yellow Top , but on the battery has two more physical smaller accessories posts which also come in handy if you later on want to chuck in other electronics and connect em up using simple ring terminals. So what's it mean? Deep cycle battery - means you can fully discharge and recharge it over and over again without causing the damage you'd cause to a regular battery. 750 CCA - (stands for Cold Cranking Amps). Pretty much the higher CCA you can get the better. Take a look at the battery you have in there now and i bet you'll find it's at most 500-550CCA and probably lower than this. Once again, reserve capacity, the longer time you can find the better.

You can find batteries with higher than 750CCA, but i suggest the Optima because you'll be hard strapped finding any other brand or type apart from possibly an Odyssey that puts out that much power while still maintaining a compact design that will fit in stock under the hood (i.e. no other modifications necessary). Both Optima and Odyssey do make more powerful batteries, but as said, these won't fit straight in without you having to either make some significant modifications under the hood or relocating it to the boot. Check out www.optimabatteries.com.au for more info on the optimas.

Upgrading grounding: the simplest and cheapest power upgrade you could ever do. Simply run another run of 4 gauge or 0 gauge cable from the negative battery terminal to the chassis ground where everything else already grounds (your looking at around $15-$20 for half a metre of 4 gauge and a few ring terminals). This will in many cases be enough to stop the tell tale headlights dimming with bass hits etc.

Other simple advice would be to make sure you have strong connections both at the battery and that your amps have strong ground connections. Also make sure they're physically clean connections (i.e. clean away any dirt and grime/sand away paint before attempting to ground the amplifiers so that there's a solid connection).

If you do these things, there's a very small chance you'll have problems with not having enough power. There's a general concensus among car audio fanatics that capacitors look pretty but are useless, so don't let the store guy con you into buying one. All in all, the best thing you can do for your charging system is to upgrade everything that's there and make sure it's all good before you even consider going to a dual battery setup. Alternator upgrades are another option, but once again, your looking at a significant amount of money for a very small increase in power and having difficulty fitting higher amperage aftermarket models that weren't made to suit said vehicles specifically. Alternators can also be re-wound for higher amperage, but doing this has other disadvantages over buying an alternator originally made to put out more power.

At the end of the day, tend to your battery and grounding system first. It should solve your issues for you unless your planning on using very large amounts of power (and i mean quite large indeed). Hope this helps, cheers, Bryce.

[garfa]

yup upgrade these connections aswell.
neg terminal to chassis (already said).
alternator pos to batt pos terminal.
engine block earth strap to chassis.

[semi]

a second battery is the only way to go if you want to crank your stereo for long periods with the car turned off- no amount of connection upgrades and higher current battery will do as good a job. You really want a battery with a high amount of charge, and a deep cycle is far better, so a yellow top (as brycestro said) is great.

You cant get a higher voltage alternator (well, you can, but it will break your car) but you can get a higher current one, possibly from a wrecked police vehicle or an aftermarket one from a company such as bosch

[Brycestro]

just to add to what semi said, try and think of your battery as a dam. And think of the water in that dam as power. Your alternator is the pipe pushing water into that dam and your stereo is taking water out of that dam. Once the dam is full your alternator will stop pushing water into it, so the alternator is pretty much working to "top up" and try and keep your dam full. If you've only got a low capacity dam though (a battery that doesn't have a large reserve) it doesn't matter how capable your pump is putting water into that dam, if it can't hold that water then it's pointless. So unless you have a battery with a larger capacity, a larger alternator isn't always the best idea.

Anyways, as far as a second battery goes i suppose it depends on the application. Realistically an Optima Yellow or Blue top would be sufficient to give you music at a good volume for a fair amount of time even with the ignition off. If you hold hillbilly parties in the middle of nowhere every weekend and want to use it for hours on end as a stereo then perhaps a second battery shoudl be considered. With that, consider everything involved in a dual battery setup though. Connections, Building boxes etc, wiring, all that jazz. And remember that law requires batteries to be vented to the outside of the vehicle, whether they're a sealed design or not. So you'd have to have it in an enclosure in the boot and then vented to outside the vehicle somehow.

My turn for a brief question - i'm shite under the hood with stuff, garfa, where do i go looking for engine block earth strap? Cheers, Bryce.

[aperfectcircle]

Here,

http://kinetikpower.com/default.asp

[semi]

earth strap?? wtf is that?

[garfa]

well actually he is concerned about the batttery getting good connections in order to reduce any resistance between the batteries and their connections, so yes it does matter that he upgrades all the ones i stated.
an earth strap is a like a ribbon cable for computers but the wires are bare and are braided together. just a shit all round connection

[Brycestro]

Here,

http://kinetikpower.com/default.asp

I was under the impression these hadn't hit Australia yet?

[bikerpunker]

thanks to all who had a say.
I will be running 1 alpine monoblock 1000wrms @2ohms
and 1 alpine multi channel 500wrms.@4ohms
Correct me if im wrong but by replacing my current battery with a fancier 300+ dollars one is going to cost me just as much as whipping up a box and putting another one in the boot.
I realise what you are saying about upgrading but to me putting a second battery in doesnt seem like that much hassle as i will have the car in many pieces when installing all the audio gear.
The alternator regulator question was just an idea as ive had to replace one on my previous vr ute..and learnt all about it then.

Thanks for the advice on the batteries though..i was completely clueless about that.
Ill be sure to do those upgardes on earths and such.
But as to whether i pursue the 2nd battery idea ill have to sit on it and talk to my uncle who's a wizz on all that stuff.

thanks

[semi]

I was thiunking that you wnated a 2nd batt. for when the car is off. If his is the case, get a 2nd batt. If you want the 2nd battery to make the system power better while driving, and dont care about having music when the car is off, i wouldnt bother with the 2nd batt. and upgrade connections as garfa has said, and then a higher current alt if needed.

Does anyone know what units are usually used to measure charge in a battery? is it Ah? (amp hours)?

[Brycestro]

thanks to all who had a say.
I will be running 1 alpine monoblock 1000wrms @2ohms
and 1 alpine multi channel 500wrms.@4ohms
Correct me if im wrong but by replacing my current battery with a fancier 300+ dollars one is going to cost me just as much as whipping up a box and putting another one in the boot.
I realise what you are saying about upgrading but to me putting a second battery in doesnt seem like that much hassle as i will have the car in many pieces when installing all the audio gear.
The alternator regulator question was just an idea as ive had to replace one on my previous vr ute..and learnt all about it then.

Thanks for the advice on the batteries though..i was completely clueless about that.
Ill be sure to do those upgardes on earths and such.
But as to whether i pursue the 2nd battery idea ill have to sit on it and talk to my uncle who's a wizz on all that stuff.

thanks

Yeah dude, the only reason i've chucked in the suggestion of getting one higher capacity battery over two perhaps not so higher capacity ones is the fiddling around. You have to remember it'll take up room in the boot, which can either look messy or you have to build something nice to cover it up which will cost both time and and money. You'd then have to pay for additional connections and other pieces required for a dual battery setup. The words 'smart solenoid' ring a bell here. The cost of the physical wire running from primary battery to secondary battery etc. The cost of the second battery in itself. It all builds up.. Time and possibly money of finding a way to vent the battery to the outside of the vehicle. If it was up to me i'd be upgrading everything existing before considering a second battery, but at the end of the day it's not up to me and the decision is in your hands. Regardless of what you do, let us know how you go with it all. Cheers, Bryce.

[aperfectcircle]

I was under the impression these hadn't hit Australia yet?

No they havn't.
I thought that I would throw these in the mix.

To start some trouble

[bikerpunker]

thanks again bryce..
So in your opinion a single high quality battery will run the amps i said i was going to use?
i dont have access to the optima batteries but i can get other brands nice and cheap..
Could you give me some specs of the optima battery so i can compare with one of a differant brand?

thanks

[Brycestro]

thanks again bryce..
So in your opinion a single high quality battery will run the amps i said i was going to use?
i dont have access to the optima batteries but i can get other brands nice and cheap..
Could you give me some specs of the optima battery so i can compare with one of a differant brand?

thanks

Yeah mate, i think you'll find that for what you've got in mind a single good battery such as the Optima Yellow or Blue Top will give you everything you want from it. Especially if you don't plan on running your stereo for extended periods of time loudly with the ignition off. Just make sure you chuck in that extra ground wire from battery chassis earth and if you could be bothered the other two garfa mentioned :P. Also make sure all your ground connections are clean - no grease and grime impeding them, make sure wherever amp is grounded has paint sanded off first so you have a strong metal connection.

As for the Optima's i've put the two links to specs below. Be careful as there is a number of different batteries that come under the "Yellow Top" and "Blue Top" headings, i've just chucked the links for the two most suitable for use in the stock battery location as the others are bigger and won't fit in without some other modification.

The Yellow Top - http://www.optimabatteries.com.au/PDFs/D34_082104.pdf
The Blue Top - http://www.optimabatteries.com.au/PDFs/D34M_082104.pdf

Especially make sure if you opt for the Blue Top that you get the "D34M" and not the "34M" as the 34M isn't deep cycle. There's only two other batteries i can think of with similar performance in the same sort of compact size. One is Odyssey batteries and the other - i can't remember right now :P. But yeah, the Optimas do have a fairly good name in the car audio world. I'll let you do the choosing though. P.S. - let me know what else your looking at getting and how much your looking at paying for it and i might be able to put you in contact with someone that can do a competitive price on an Optima for you. Cheers, Bryce.

[aperfectcircle]

So what are the dimensions of the battery that fits in there at the moment, with out modification.

[Brycestro]

I've got a VS with an Optima Blue Top. I doubt you'll have any problems fitting one in. If your worried just measure up before buying. Also note that the Optima's are sealed batteries (but do vent from the top). So if you have a battery in at the moment that says to leave room for it to vent from the side you won't have to worry about that side room between battery and chassis with the Optima. Cheers, Bryce.

[semi]

just a point, a deep cycle battery, like the D34M is a battery that you can charge and discharge heaps without ruining the battery. Batts that arent deep cycle really dont like being fully discharged (ie going flat) and it stuffs them up