QuestionI have a 1994 s-10 blazer and i have a jl audio 13.5 w7 speaker with a 1000 watt jl audio amp, i need help finding a better, or a extra battery, type, size? i don't know anything on batteries and i need to upgrade my alternator and that is something else i know nothing about! Please Help Me!!!!!!!
AnswerYou likely do, Kenneth!
Stay with me, and breath deep often for you are about to see that what 'really' makes a stout basis for a high powered mobile system, is the 12v power supply.
Which is more important, battery or alternator?
You need to understand that the stereo (and all other 12 volt accessories) should run ENTIRELY off of the alternator when the vehicles' engine is running.
Alternately, the ONLY time the battery array should run the electrical system is when the engine is turned off.
Why do my headlights really dim?
The reason that headlights momentarily 'dim' to the beat and duration of the bass, is that the load on the alternator is too high (the load demand is over the alternators' rating) and continued use can and will damage things. Fires and embers can be the result in extreme cases. The load on the alternator is always equal to what you have running (A/C or heater, headlights, wipers, De-icers, ect) PLUS the stereo and amps and any other accessories like DVD screens, ect.
How much battery power do I need?
I prefer to have at least two batteries. One for the vehicle and one that is for the addons (or even more, wired in parallel).
These have a high current (150 amp rms) isolator wired between them so that they are only connected together when the key is on. So, if you do not accidentally leave the key on, this allows you to use the secondary one(s) while parked, and you will have the fresh one left to start the vehicle when you leave. This 'key-off isolation' also keeps them from de-charging into each other when the key is off. They can and will eventually kill one another without the isolation.
Type of battery? (Parked/Engine off)
Which type of battery you choose for the system and amplifiers will be based on your pocketbook, but for this session, it suffices to say that some batteries are more suited to deliver more high current than others. Additionally, they are rated as to how long they will deliver their current [in minutes].
We are not talking about a long duration, low current situation like a trolling motor, so I will not go into the gels cells, but I will mention that this makes small 12v Gels a good candidate for backup car alarm batteries :)
Regular car batteries do NOT produce 'instant current' like high current amplifiers will demand. This would make one think that they might be better off if they bought a high dollar Ni-Cad. If you can afford one, do so. These are sealed and can be mounted in any posistion even upside down.
But for the common man, I find that using a large stiffening capacitor with normal Group 72 Sized, deep cycle lead acid battery (rated at 110 minutes+) performs just as well. The cap makes the slower responding lead acid battery able to deliver dramatically larger instant current surges than it does without the cap. Lead Acids must be mounted upright and need to have ventilation and [even with the added cost of the cap] are much more gentle on the pocketbook when trying to obtain good reults, impo.
The ultimate route for long-term, maximum engine-off performance is to get a professional grade 12volt power supply which requires an AC cord. This is what you may see in many Audio Demo vehicles.
Alternator? (Driving/Engine running)
Since the audio system often runs while the engine is running [and we know that all of the current demands are on the alternator], this is important.
They are not cheap.
You need to add the Current demands of your amplifier(s) to the maximum load the vehicle can put on the alterator by itself.
This basically means, adding up ALL of fuse ratings for the vehicle AND The amps.
Now you have an idea how much alternator you need [at a minumum].
For instance, if it all adds up to 110 amps, I would get a 140 amp one [or you will likely kill it from surges that might go over 110]. It would be a shame to waste the extra money.
I hope this sheds some light on 12v power supplys.
Jerry Mael
