So, I've gutted the empty spot behind the passenger seat and realized, "Holy Crap! I could put my battery here."

What advice could you offer before I undertake this adventure?

0 Gauge wire?
Battery box?
Circuit breaker, and what amp size?
Can you ground the Battery right to the frame or just run it from the original negative line?

Thanks!

 

Some car batteries produce gas while charging and require constant ventilation. The jack and spare tire crank for my 87 is underneath that. If I found extra room it would be for tools, spare parts, test meter etc.

 

you could, but why?

 

Weight balance.

the guy tracks his car, and it’s better to put the battery on the right to help offset weight from the driver and also to the rear to add weight close to the real axle for powering out of a corner.

 

A few options. You can run the power all the way back to the original and run a junction there. You can run the negative through the backside of the cubby bin and directly to the rear crossover frame brace. You always want a short run on your negative cables.

You will need to create a mounting plate and also a way for the battery to be secured. I would suggest using a different battery than a group 75. Use an Odyssey 925 and it is a squat tier battery or any of the Braille batteries that fit.

 

If it is a true race car it's already been stripped down to save weight, what about fabrication of a box in spare tire space. It's Close to Axle and you can't get much lower and gases aren't an issue.

 

I'm thinking of mounting the battery tray right to the fiberglass in that cubby. Do I just drill a hole for the negative to affix to the frame? How do I affix it to the frame without drilling holes and weakening its integrity? And what do I do with the original negative cable that will be left?

Thanks everyone for the help.

 

Bump...still need advice.

 

First, My advice is, if you have room to keep the battery in the front where it belongs... just leave it there. Update the cables and do maintenance but don't bother moving it.
whole bunch of stuff can go wrong if its your first time. Not worth it if you don't literally need the space for something like a turbo (add a turbo pls)

Alright say you want to do this.
You need a crash course in grounding before anything
I go through this all the time with people before I tune their cars, there is always some ground issues
https://www.haltech.com/news-events/...dos-and-donts/

The ideal star point is near or on the battery itself, e.g. connect the engine directly near the battery ground using a long cable just like the starter, and connect the ECU and harness and all electronics to that point by re-wiring the chassis harness grounds there, usually there is a large bundle somewhere from the factory. If you choose the chassis this can mimic factory wiring (Most factory battery ground to the engine and chassis right by the battery tray) but there will be a larger voltage drop between the engine and battery which will influence cranking and charging.
In other words, if you attach the battery in the trunk to the chassis and then attach the engine to the chassis, the chassis has more resistance and variation than a big wire, so over time the engine could charge poorly or crank more slowly when things get hot or whatever. Its best to have a nice large thick ground cable from the engine come back to the trunk to your star point on the chassis for example.

Next, the alternator wire must charge the battery so this wire usually runs to the fuse box and there is often some extension required or a fuse box relocation type of thing. Depends on the vehicle. The vehicles that run alternator to fuse box which is attached originally to the battery I guess. I've seen some BMW do it differently and I am not sure which design yours will have. Its been a while since I've done one of these. Just make a note of the alternator pathway, fuse box where it winds up, and how that fuse box is attached to your battery. If the cable involved must increase in length, I always upgrade the thickness of the alternator wire when running it some distance.

Grounds and power cable aside, now focus on the installation itself. You can add a battery tray to most cars by welding in a few angle irons and fab a hold-down. Make sure whatever you do it is attached to the vehicle properly and held down or the battery will fly through the air in an accident. I avoid battery box if possible by using the Sealed Lead Acid battery design, my favorite is Might Max battery (look on ebay for a battery). I tested a 48?AH Battery I think about maybe 8lbs pretty light weight, about half the size of typical car battery, its base voltage is 13.2V and it cranks over the V8 from the trunk easily I've used in friend's installs successfully since 2015's. I've also tried the smaller version out of curiosity they have a a 32AH design that works just as well and its even smaller, I carry as a jump box now. They are like $35-$45 back when I got it but they went up in price since then. Its sealed to mount almost any position and wont give off fumes when charging. It uses standard size attachments if you get the right posts for it. In my trunk I just use the walmart battery because every year they give me a new one free so why not and since its in the trunk its legal with no box I think. Its been a while since I Check the rules though in the past they just look to see if its held down and then kick you out for 10 seconds or whatever.

What else is there, hmm. Its sealed. Its wired right. Its firmly attached to the vehicle. I think thats it?

Not a corvette but shows the angle iron battery tray with slots for a hold down and decent designed connectors.



Ah, the connections and a fuse. Yes. I use 'knuconceptz' battery connector posts because they have insulation and multiple ports for wires (I run my fuel pump relays directly from the 8gauge port on the red terminal, very handy). I also have a 150AMP Inline fuse on the positive cable as it runs inside the vehicle and through the firewall. Use a proper firewall plastic insulated grommet designed for battery cables, not a rubber one, use the heavy duty plastic insert screw on style.


Here is the relay box I prefer for the trunk install in my vehicle


This box has a lid, so water proof. Its from some kind of SAAB. I prefer this one because of the 60Amp Relay and 60Amp Fuse (Yellow relay is 60) Perfect for high amp fuel pump. The red relays are typical 40amp for stuff in the trunk like water pump or methanol or whatever. kinda cool for $12 junkyard box. I don't use anything aftermarket in my vehicles, only OEM wiring/relays/boxes and only use solder and heat shrink to make connections. Never use crimps and anytime you have a power wire with a heat shrink I advise double shrink and sometimes even tape it up over that shrink. No accidents no mistakes.
Make a little diagram of where you put stuff so you can remember later.

 

I relocated mine to the spare tire location because I have a bunch of Optima 34/78 Batteries in use. If I was willing to use a smaller Battery dedicated to this car I would probably of put it in the storage compartment as most people do. My battery location is real easy to charge if needed. You can buy long side post Cables from people like Speedway Racing along with Battery Box's etc. My Cables run threw the Trans Tunnel and the Positive to the Starter and the Negative to a Disconnect in the Engine compartment and then to the original Location on the Bellhousing. I then needed to run a Smaller Positive from the Starter over to the Accessory Pole where the original wire went from the Battery.

 

Maybe I should just try to use a smaller, lighter battery until I'm experienced enough to know how to do this correctly. What are your thoughts?

 

I have a 2006 Chrysler 300. It has a trunk mounted battery from the factory. It uses an H7 group battery which has a small hose fitting coming out of the battery that connects to a vent pipe in the trunk. You might want to check one of those cars in the wrecking yard and see how it goes. Might even be able to get the battery wiring from it.

 

Here is where my Battery ended up. The hold down is a billet Aluminum one made specifically for the Optima. The rest of it was made in house. It bolts to the rear crossmember.

 

The ground runs to a disconnect before it goes to the original location on the Bellhousing. Note this car has had the AC deleted.

 

The compelling reason to move it was to create a space to put my Holley Terminator X ECM and it's components.

 

Yes, you can drill a hole to go out the backside of the cubby and go straight to the frame that crosses side to side. If you are not running the spare, you can use the mounting holes where the brackets screw in for the spare tire tub.

 

Dumb question...

So if the battery us grounded to the frame, where do you attach the original negative cable? Ive never seen people run both the posi and neg wires all the way back to the new battery location.

 

I've got my battery mounted way back where the gas tank was. I have a fuel cell.

 

Not dumb. I used to wonder why you "couldn't do that"....but you can. Ground it to the frame.

The whole ordeal is not hard. The hardest part is "engineering" a good, solid mount where ever you want it. And even that isn't too hard if you can fab a little bit.

.

 

Here's what I did...