I am going to be doing some basic work on a girls truck tomorrow and she works for a tow truck company and has acquired a battery for me.

It's just a standard top post - nothing kinetik or anything extreme - but just enough to let me use my saz1500d v1 to it's full potential (well almost maybe)

A few of my concerns:

1. What is this little black thing? I've heard that it regulates the charging, so I'm wondering if I need 2 of them.

2. Does it matter how much different the resting voltage is on the second battery? I just bought a brand new battery from autozone and it's 650cca and rests around 12.8 on a good day. Will the second battery ruin the health of the new one if the second one rests at around 12.5 max? I figure 2 600cca batteries will be fine, even if they both rest at 12 flat, right? What would a safe range of resting voltage be for the second battery?

3. Will there be any issues with the stock electrical system, or for that matter, the "big 3"? (alternator to battery, mainly - will the main line catch fire if it's trying to charge 2 batteries instead of one?)

4. Is the big 3 necessary for 2 batteries? Or will I just be limited to whatever one 4awg line from alternator to battery can handle, and charging will be a little slower?

All in all, I think having 2 batteries alone would solve any issues, and unless I'm bumping at full tilt and draining the batteries every time I drive, I think it should be ok?

Here is the little charging thing I am talking about.

 

Let my preface my response with this, in my day a "banging" system was a new Kenwood cassette deck in the dash, and Pioneer 6x9's cut into the rear parcel shelf.

But this thread, and some of the sub-threads linked in various posts might answer your questions.

https://www.chevyhhr.net/forums/audio-video-17/second-battery-39371/

I'll now go back to listening to Foghat on the 8-Track now.

 

They had subs in the early-late 80's ya know :p

 

You're assuming I was in a condition that would have allowed me to remember the late 80's, Reagan's second term is a bit fuzzy and let's leave it at that.

 

To the OP.
Granted I'm new here but I never read why you want to add a second battery.

Without upgrading the alternator it is actually going to have to work harder to charge up 2 batteries instead of one. If you have a big audio system I would recommend a bigger alternator. That gives you constant power, remember, a battery's only job is to start the car. I have 2 batteries in my show truck with a 200A alt.

And on a HHR you can only do the big 2. One big power wire from the alt to the battery, and a bigger wire from battery to chassis. Since there is no frame, you can't do the ground from body to frame.

 

I had a reel to reel in my Olds 98, so only 3 people could sit in the front seat.

 

Casey , If I am not mistaken . The charging system is computer controlled , only giving a signal to the alt to charge when needed .
But if you must do the dual battery set up , Eric B on here and the other site actually has a dual bat set up ... I think ....
Get with him and I am sure he will assist you .. Follow the link below ..
https://www.chevyhhr.net/forums/members/eric-b-8660/
Greg

 

That thing monitors the voltage or amperage that is passing through it ,that's what I was told ...
Also we upgraded the alt to the fuse block stud wire . Then ran wire from the stud to the battery . Also we upgraded the ground wire at the battery . We added a ground wire from the alt mount to the frame where the engine mount is .
When adding a second battery , you will need the isolator kit ..
try this link .. I know its stinger , but it is all there in a kit ..
http://www.darvex.com/store/pc/Sting...mp-137p962.htm

 

Would this work the same way?

http://www.ebay.com/itm/Scosche-12V-Car-Relay-Battery-Isolator-100-Amp-Battery-Connector-PMBC100-/151045851522?_trksid=p2054897.l4275
From what I read on these, they isolate the 2 batteries from eachother and provide charging to each?

 

That's the one .. same thing