i wanted to do a 1 5channel amp, powering 4 normal speakers and 1 10 in sub.... nothing crazy.....

thing is, i have the rotary extreme mini battery kit:

http://www.rotaryextreme.com/minibattery.html

here are the battery specs:

# 16 Ah @ 10hr rate
# 280 CCA
# 680 Cranking Amps for 5 Seconds
# 28 Minute Reserve Capacity
# Cycle life @ 77°F 400 at 100% DOD

anyway just wondering if you think it would support this system ok, while still being able to start the car and power the rest of the electrical system.

its not a huge deal to me.... bottom line is that if i have to spend more money on a capacitor, or another battery and start adding weight, its just not worth it to me.... i'll just stick with a head unit powering the normal 4 speakers.....

harrison

 

To tell you the truth battery is not what run your electrical is your alternator. People add batteries to the ca for more time without running the engine. But to answer your question I think is too small to run with the engine off.

 

well yea, i wouldn't run it with the motor off... just while it was on... i just didn't know if it would work... so if i only use it while the car is on it should be ok?

harrison

 

That battery ran four mids, four tweeters, and 2 12's, as well as the 1100watt 5 channel amp. A 7 inch in dash dvd player with that battery and the stock alternator. The headlights dimmed a good amount, so I added a 1 farad capacitor. No light dimming at all.

Josh

 

^Did you have issues starting your car the next day?

 

cool thanks...

 

A better (ie optima) battery will help you run you stereo hard. It adds stability to the system much more than any cap. It can compensate for a week alternator to a point. In addition, the RX-7 alternator is VERY capable at idle and more so at cruise RPMS.

 

yea, well i don't have ac, or a ps pump to run either though, so its not going to get a whole lot of load......

 

A 1 farad cap would end all your worries, plus it will help lighten the load on you altanator.

 

A 1 farad cap will not end all your worries. It supplies energy on a short time basis. It requires time to charge it up once you have pulled energy form it. So if you continue to drive the same load before the cap put out energy and now you are trying to recharge the cap you have increased your load on the alternator for the short term.

A battery, such as an Optima, acts as a long term solution. If the alternator can't put out the load then the battery has the capacity to really hold your voltage supply high. There is not a LARGE time constant associated with it.

 

but the amp will still drain the battery no matter what you do.

Fit a larger altenator, or possibly a 2nd one if you want to be flash. This way, you get a CONSTANT supply of power, and not a limited amount.

Plus power-caps actually put more load on your altenator/battery as well - nothing in this world is 100% efficient! (in this case, it's the "leakage" current)


I'm sure my old moped had a bigger battery than that

 

Another small battery to look at are the SVR's. Good price, and they're probably just as good as the Optima's. I got their small one, which cost $100 (plus $20 shipping since no one stocks them) and it fit in the bin behind the driver seat (with the bottom cut out, that is).

Blake

 

This was the second post in the thread... and he is the only right one!!! Unless you are running your stereo with your car off... the battery doesn't really matter that much.

If the alternator is good and you are not exceeding the load limit on it, the battery doesn't have to jump in to help.

A capacitor WILL solve most your problems.... since you never draw constant current from it, it can sustain your system. There is no worry about the time constant either, because the amount of time to charge is MUCH less than the time it takes for the next big bass note to hit.

 

ok cool... like i said, i'm not running A/C or Power Steering either, so there is really no other drain on my alternator, besides the car lights, spark etc....

i think it'll be fine, again, i'm looking to just get a moderate system for driving with... nothing super loud or anything like that.

harrison

 

I am just curious. Who here is into car audio? (And I mean big time ...)

 

I would be...I don't have the money or a garage to work on my car stuff, so I'm not into it as much as I'd like to be.

 

I used to have 7 batteries in my Truck. Then again, 8 Memphis 1000d's running four 18 inch strokers called for it. However, I sucked the batteries dry the instant I hit my note at the competitions. I did have a bigger alternator, and to be honest, all it did was handle the recharge of the system. The guy who built the system, told me that capacitors were good for the job, but that the batteries he used (SVR) had given him better results during his competitions than capacitors. I guess, its another of those questions like the AST or No AST. To each his own. Buy what you want. If you are looking for performance of the stereo, I would think the battery would be a better idea. A cap works, but I think they are used a bit more for the showing ability they possess. If it were me, another small battery would be in there. Hence the reason I run two small Optimas. Just my $.02.

 

Your battery and battery condition matter while drawing heavy continous loads otherwise I agree the alternator does the work. The RX-7 alternator is also an extremely good unit. A battery can supply power while a cap can only store it. The bigger the cap the more it can store, but the longer it takes to resupply it with charge. I have seen caps make things worse especially if the battery is suspect. There is a reason cars start off batteries and not caps.

 

I run the stock system off that same rotaryextreme v-mount battery setup, and I get max 20 min. out of it before my timer cries that the battery voltage is getting low... so ... it's fine as long as you don't plan on listening to your radio while teh car is off... if you park and you want to listen, leave it running...

-DC