Adding another 12v

I know that I have to upgrade my audio one of these days cause it sounds like screaming baby to me, but do i have to go through that hassle? it took me all day just to replace the bumper, that much how suck i am. anyway, cant wait for the good tips and pics. that for upload.

 

Definitely nice and clean so far. Great non-wood woodworking skills.

Are you going to do any sound insulation? If I were to spend money on the Prius audio, the first thing I would do is add accoustic material to the doors/roof to keep the road noise out. Basically make it a CT250h for the panels. Then the speakers could be nice and I would actually hear the whole range, not the whole range plus a bunch of harmonics from the road.

It appears you are going for more "I can make your car shake when I am in the next lane" rather than good sounding/fidelity audio, so sound dampeners may be the opposite of what you want!

 

Yeah, back to the thread..

You should ask around about this idea of two 12V batteries connected without any isolation.
I don't think you are supposed parallel two different battery types.
There is no control over which takes the most or gives up the most current.

Is the idea to be able to play your sound system longer when in Acc mode?
Mine switches off after a set time anyway. Is that programmable?

 

GOPD,
Wow ! That is a beautiful cabinet. You know you could sell these if you wanted too?
I owned a 1Gen 2000 Honda Insight and bought a custom sub cabinet for it.
A guy in Portland decided to mass produce his design. You could even farm out some of the panel cutting to shop with cnc equipment, if you get enough pre-orders !

My JBL system in my IV is good enough for me. Maybe, I'm still getting used to it. Source material is inconsistent.

I'm sure you know about using big nice person capacitors on your sub amp's power in to help smooth voltage drops when it's Thumpin.
You should ask an EE about paralleling two dissimilar 12V batteries. The theory is there can be current flow between the two different batteries.
One bigass battery, (Li-ion, physically smaller but A/hr bigger) and a bigass cap might be a better way to go.

 

Yes multiple dissimilar or even multiple similar batteries will fight current between them. Luckily lead acid batteries have crap ESR ratings. So it is like having a big resistor in series with your output. This current limits the sharing.It will still be going back and forth. In the car where they are being charged most of the time and flat, just make sure the top charge voltage is the same for both. Under discharge they won't share equally but they won't fight eachother.

A battery isolator is the way to go. That is a fancy name for a diode essentially. Some of the better ones use multiple FETs to achieve what we call an "ideal diode" without the forward voltage drop (well millivolts instead of hundreds of millivolts).