07-09 Mazdaspeed 3 trunk mount batteries

OK, I've looked, no decent how to or kits for us that I could find. Looking for an easy and safe kit for the trunk. Anyone got ideas?

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Why did HTP lose interest in making battery relocation boxes? The made one for the 6 and then just stopped?

 

Not enough interest. Of the few that were, a bunch of people bitched about the price. It was well worth the price though IMO.

 

I saw their kit, looked pretty nice! Had wondered if it could be modified for ms3...

 

The ms6 one couldn't. The reason being is that the ms6 has an enclosed trunk, so no need for an enclosure or battery box. Since we have an open hatch, the concern was having to build a box for it. I dont remember what precaution they took for venting possible fumes though.

 

Did I hear group development/buy?

 

The HTP kit for the MS6 is very nice, but bear in mind that the cables weigh close to 7 lbs. If you are moving from a 35-lbs battery to a 15-lbs battery, you will only save about 13 lbs, less if you need an enclosed battery box. So from a weight-saving perspective it is not that great. If you need to free some space in the engine bay it is totally worth it of course.

 

I have a trunk mount battery in my second gen. It was custom fabbed by a friend for $80. Where my battery was in the bay he put a plate that holds my ECU, fan controller, and BCS.

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I ended up grabbing regular moroso battery box and a zero gage amp kit. Its vented out below the jack storage. Notched out my rear carpet and done. Mounted the ecu to the inside opposite side of the stock batt box. I cut the box and lid to allow my intake to fit then put a piece of sheetmetal with L brackets mounted to the batt box to cover up the opening. The box hides all the wireing and hoses out of sight.

 

I'm just trying to free up space. Biggest concerns is safety. It's gotta be secure in a wreck because my kids will be on the other side. If I can't be 100% sure of their safety, I'll probably just stay how I have it now. Jbr 3.5" intake and CS battery box are a tight fit, but it's better than having existing wiring damaged like it did a year ago.

 

Well in a wreck anything is possible. In a sealed trunk like the 6 it can be ok but in a hatch its kinda sketchy. The fumes can be really dangerous if the vent tube or box seal fails. Sure you can get a sealed battery but in a crash the battery hold down can twist or get mangled and short the terminals out then the battery goes into melt down mode back there. The only super safe way would be to mount the battery upside down in a battery box outside under the hatch.

 

You could have a fender or bumper mount like Chrysler did in some cars. It would make changing the battery a PITA, but it would free up space.

 

My mom has that in her Concorde. What a pain in the dick. A 51R may just be needed.

 

That's how Flyin' Miata does it on their v8 builds.

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I have the same setup and one thing I did was abandon the devil clamp that jbr provided (that was already scratching the shit out of the battery box per protocol) and just used two tie wraps to hang the intake from the bracket. I also added some armor to the wire harness since the CS instructions had me remove the plastic junction piece and all kinds of crap. I have been let to believe the newer box doesn't ask for that.

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Got pics? I just simply bent that bracket.

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I'll take some for you no problem. It will be a week or so as we're on vacation in South Dakota with Sharon's mz3.

 

Got my car back from Dr. Bob. Wow, firm clutch is firm. Will take pictures of DIY intake hanger within the next two days.

 

OK I probably passed two days, but not by much. You can see that I have my JBR Tru-3.5 hung from the hole in the bracket above the normal location by several zip-ties strung together. This might not be perfect - I'm sure since it's not a rigid mounting that while the intake can't bounce downward, that it can still bounce upward some. Also I'm sure it wiggles at the filter end. However, if it does move much up there it hasn't caused any noticeable problems (even with inspecting the area) in 25k miles or so. It's definitely a bit close to something I think may be the HID ballast, so I've kept an eye on it a bit.

Here is a slightly cleaner solution, which I actually bought but never deployed: https://www.mcmaster.com/#7295K43 . This would go on the stud the stock hanger uses, and you could put a nut down. However, because this is plastic the joint won't clamp correctly so you would have to either double nut it, or use a nylock nut, preferably both. Actually if you want to try this I have the 10 pack of ties so I could send you a couple in the mail. Since my other solution has been working fine I never bothered to tidy it up with this.

You can also see some of the armoring I did to the wire harness with an old suede work glove cut open, wrapped around the the junction area, and then tie-wrapped in place.

Let me know if you want moar pictars. I forgot to take one of the scratches on my battery box where the JBR hangar was scratching the shit out of it per protocol but knowing what their silly T-bolt mess looks like I'm sure you can imagine

 

Yeah mine is zip ties as well, with the battery box trimmed up some too. I'll snap pics too.