I bought this car in 2016 to see how far I could push a hypermiler's dream car. After hitting a staggering 96MPG on a road trip (without the "Hybrid" part; no electrical assist is installed any longer, just the 3-bang'n 1.0L and it's insanely long gearing) and completely falling in love with this car, I figured it was time to have this car meet a hobby that I love: Car audio. Well, any audio really... but it's been a while since I've done a decent speakerbox on 4 wheels.
For years, I drove around with a minimal system: Basic Kenwood receiver, pair of Polk 6.5"s in the door, pair of generic tweets tossed on the dash, and an 8" Infinity sub sealed with maybe 200 watts in a small fiberglass box. It was great for what I paid, but I often dreamed of bigger. After having great success with my Dayton in-wall DSP build and awesome lows with my 4x Fi 18" Infinite baffle subs (10hz makes every door in my house chatter, lol), I made up my mind that I wanted something similar in my car.
Goal: Make this a fun daily driver that loves road trips. Keep the weight to minimal, but high efficiency output with awesome sound quality on a tight budget. Make it modular for upgrades in the future and insure the output is plentiful.
First step was to get an enclosure going. Since pulling out all the hybrid parts from the trunk, I was left with something... ugly. And LOUD! Road noise galore.! So I started with the box bottom. You can see in the pics, empty trunk. Then layers of I think 9 or 11 ply baltic birch. PL 3X all parts together and ultimately a few layers of fiberglass for further strength. I used 1x1 to give me a frame to attach baffles and such to.
Slowly, chunked the rest of the box together. It took a lot of thought: I wanted to have some trunk space still (around factory amount). Without the factory hybrid battery and DC/DC system, I could put enclosure space there instead! I also still wanted to be able to keep a spare tire, so I made a nice spot for that. Also had to make sure my lithium battery would fit properly as well (more on that below).
12awg and 16awg CCA was ran to each door in the factory channels for the midbass and tweets. Not pictured: 12awg CCA also ran to the mids (overkill, but had it on hand, so figured it wouldn't hurt).
Here are some of the electrical upgrades. The factory wire was I think 8awg copper from the trunk (DC/DC converter factory in the trunk to the battery under the hood). I went 0/1 CCA. CCA was chosen because of the low weight to conductivity ratio. It gets a bad rap in the business, but really, it works fine as long as you size properly.
I chose to keep the under-hood install as clean as possible. I did crimp-on terminals and loomed it all. Kept the look nice and clean that way!
I 3D printed a fuseholder. It looks pretty good and is plenty strong. I recycled parts from some cheap InstallGear fuse holders to complete the hardware.
The lithium was bought used in a ply box, but that isn't compressing it at all! So I used angle-iron and all-thread Mounted it next to the power supplies (this car has no alt. It has a 3-phase generator. I convert to high voltage DC, then feed the meanwells to get stable DC output). The cells seem to be CMAX cells. They are 25ah NMC lithiums with 3.7v native, 4 in series and 2 parallel, giving me 50ah 14.8v. I keep 15.5v charging thrown at it with the meanwell power supply.
I created a rear chamber with the last of my 1/2" baltic. It took about 10 hours and gave me a little over a quarter cube of airspace... lol! It had some crazy angles to make it fit. It also allows the wires to go through dedicated channels, keeping RCAs and power line separate. Oh, and you can see I had to redo one of the faceplates due to not thinking about the overhang connecting to the primary enclosure. Whoops. Also, some of the amp rack and it's wiring tray in one of these pics.
Baffle glued together using 2x 11/16" ply. Love a solid baffle! Also, because I wanted the subwoofer centered to the car, it was a tight fit. I ended up doing a little work to brace and aero support the subwoofer at this mounting location. Tight fit for sure!
Other pics are of the closed cell foam. Figured it would fill the gaps and give the box a little decoupled "spring" to it to absorb some road noise. These cars are EXTREMELY noisy, so every little bit is going to count here.
Everything in place: a completed enclosure and amprack. I had only 1 small air leak I could find when pressing on the sub and it was at the baffle. Was easy to fix. After that, the sub went down and came up extremely slowly, no air leak noises what so ever! This was pretty damn suprisingly honestly, given the box has 7 modular parts and I was just using basic weather stripping for all of it. The box itself is fiberglassed in a few spots and siliconed extensively.
Cramming in the rest of the equipment: 6x100 on display behind the seats, fuse holder mount, etc. I 3D printed a bracket to center a 6" hole for the 7" drivers in the doors. Using 11/16 + 1/2 inch ply to space the speaker out enough. Everything just fits like a glove! Thankfully not one OJ Simpson is trying to put on.
I threw together some "cans" for the midranges on my dash. This is only temporary until I get to working on my A-pillars. Only having done tuning by ear, no sweeps on a mic yet... but it sounds great! Really surprised. Current crossovers (all 24db/oct LR) are Tweets at 4K, Mids 4K-400, Midbass 400-80, Sub 80. Measured phase, then adjusted by ear with the nulling method. No EQ at all. Can hear a few obvious spots that'll need touched, but it's good enough for now. You are now all caught up to where it sits today.
I know my car is rather unique, due to the alternator-less nature of it. So as you can see, the Insight has a nice 3-phase generator (the electric engine side of the hybrid). It is sandwiched between the transmission and the engine. Normally, it generates the electricity for the hybrid system through normal driving and regenerative braking. I pulled out the battery, factory DC/DC converter, and all the misc computers and wiring to the system. An Arduino lets the car's computer system that the system is fine and dandy and not to worry about it... lol.
The way it works now is that the 3-phase goes into a rectifier to convert it to a constant DC signal. The voltage goes anywhere from 50v to 400v DC! So it feeds into a pair of Meanwell power supplies to give me a constant output. Originally, I planned to run these in parallel. This model isn't designed for it as it turns out and will shut the other down, so only whoever has the highest voltage setting wins. These are adjustable from 13.5v up to 18v. For now, I simply separated the 2 systems: one goes 14.0v to the factory 12v battery and powers all the cars OEM systems; the other goes to the audio system and lithium battery at 15.5v. The output of these are only ~600 watts (just over 40 amps) so the audio system can pull beyond that pretty easily.
I plan to, in the future, replace the 12v battery with a 25ah lithium (similar to the current 50ah in the trunk) and get 2 power supplies that want to go parallel with eachother. For now, this setup works just fine. The lithium under the most demanding draw still doesn't drop below 15v! Very impressive.