Idea: Battery Powered Hatch Speakers?

I bypassed my hatch speakers in order to keep a 4 ohm load for my rear passenger speakers (hatch and rear passenger are wired in series).

An idea I thought of is to run a set of speaker wire to the rear hatch speakers to the cargo area. Do they sell a bluetooth battery power amp (basically a portable bluetooth speaker without a built-in speaker?) that I could connect up to rear hatch speakers?

I like this idea because I can power those unused hatch speakers with a battery that is not tied to my car's electrical system (who cares if it dies). This would allow me to keep the car completely off without fear of draining the battery and would put these speakers to use

Now I realize I could call it a day and just use a bluetooth speaker and continue to not use the hatch speakers, but I find putting them to use as they are still sitting idle in my car could be a cool idea. I definitely see the value with this for tailgating, camping, etc... when I just want to chill and listen to music with my hatch open and 4runner turned off.

I'm kind of looking at this as my own version of "Party Mode".

I appreciate any ideas on this. I'm still researching components to see what is needed and if this is even worth doing.

 

I would simply get a bluetooth speaker instead of making things complicated. Even Toyota gives you a JBL in the dash from the factory.

 

I’ve noticed an uptick in complexity with many of the threads lately.

 

It’s a neat idea for sure and I would want something integrated into the we well plastic. There's just much easier ways to do things.

 

I wanted to play around with Chat GPT with your idea and this is what it came up with. Might give you some good ideas or point you in the right direction.

Try at your own risk!
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Q: I have speakers in my car that are disconnected from the factory radio/headunit. I want to use them independently to play music from my phone via bluetooth. I don't want to use the vehicle's battery power source. How can I make this happen?


To use your car speakers independently (without the factory head unit and without tapping into your vehicle’s battery), you’ll need a completely self-contained audio system powered by its own battery. Here's how to do it step-by-step:

What You Need:

1. Bluetooth Audio Receiver / Amplifier Combo

• Must include a built-in amplifier that can power your car speakers.
• Should support Bluetooth input from your phone.
• Example: Bluetooth 2-channel car amplifier (12V powered)

2. 12V Battery Power Source (Portable)

• A rechargeable 12V lithium battery pack or a portable jump starter with a 12V DC output.
• Must provide enough current to run your amplifier (~5-15 amps depending on the amp).

3. Wiring and Connectors

• Speaker wire to connect the amp to your car speakers.
• Power wires to connect the battery to the amp (usually red for +12V, black for ground).
• Optional: Inline fuse for safety.

Setup Steps:

✅ Step 1: Choose a Compact Bluetooth Amp

• Example: Fosi Audio BT20A or similar that supports 12V-24V input and has speaker terminals.
• Confirm it outputs enough wattage per channel to match your car speakers (typically 20–50W RMS per channel).

✅ Step 2: Connect the Car Speakers to the Amp

• Disconnect your car speakers from the factory harness.
• Run speaker wire from each speaker directly to the amp’s speaker output terminals.

✅ Step 3: Connect the Amp to the 12V Battery Pack

• Red wire from amp → battery positive terminal.
• Black wire from amp → battery negative terminal.
• Include an inline fuse (10–20A) close to the battery for safety.

✅ Step 4: Pair Your Phone via Bluetooth

• Power on the amp and pair it to your phone.
• Play music to test the system.

Portable Battery Ideas:

1. LiFePO4 12V Battery Pack (with charger)
   • Long life, recharge via wall outlet.
   • Common sizes: 12V 6Ah, 12V 10Ah.
2. Jump Starter Power Bank (with 12V DC output)
   • Dual-use as emergency starter + power for audio.

Important Notes:

• Don't exceed the speaker or amp ratings to avoid damage.
• Make sure the amp matches the impedance (ohms) of your car speakers.
• Use ventilation if the amp heats up in an enclosed space.

Optional Upgrades:

• Add a volume knob or remote.
• Use a fuse block or battery protection circuit.
• Mount the amp/battery in a small DIY enclosure or case.

 

I had a similar idea for making a “party mode”

then I bought bluetooths

just call it a day

 

I have a Bose Revolve now but would get a Turtlebox when the Bose dies out.

https://turtleboxaudio.com/products/turtlebox-speaker-original

 

While not directly related to your installation question, I recently purchased a Fosi Audio BT20A Pro to power some in-wall speakers and a powered sub in my home. I had never heard of them before but they came up in a search that matched my criteria. Seems like a nice unit and, having bluetooth built-in, makes it nice to wirelessly send music from my phone to the speakers.

 

I might want to try this to so I looked into it a bit. From what I understand, you are pretty much making your hatch speakers into an independent 'boombox'. Only difference is your speakers are attached to the hatch and not installed into a box. Here are a couple vids I found that may help. The application is different but I believe wiring would be similar if not the same. You just need to imagine that the ammo cans they use are your rear hatch.


https://www.youtube.com/watch?v=WAz7Uhe3Bxg


https://www.youtube.com/watch?v=sZOCMiz2R3U

 

This is perfect and exactly what I’m trying to do. I am going to build this based off of the ammo boombox video. If I don’t like the results of using the hatch speakers, I will probably scrap, but keep the rest of the components for own portable Bluetooth speaker. I just like the idea of having a portable power bank to power the hatch speakers since they can still be used. Also an excuse to tinker and learning something. Thank you!

 

You cant hear the hatch speakers when youre driving. Theyre effectively worthless when driving

You cant move youre battery powered wireless hatch mounted speakers because they're mounted in the hatch.

Seems like it makes the most sense as suggested to buy a blue tooth speaker. You will never beat the form factor. Anything you make will be larger and probably less reliable.

If it were me and I was dead set I would skip to the DIY portable speaker part and skip the hatch. Theres no room in the hatch so you'd need your battery pack and amp elsewhere. It just seems very difficult for a mediocre result.

 

I know there was some hesitation with this mod, but I moved forward with it. I am building a Bluetooth speaker (ammo can) that will allow me to connect to my hatch speakers.

I ran speaker wire to each hatch speaker. I replaced the oem speakers with some Kicker 6.5” speakers (used brackets from taco tunes).

if anyone is interested in parts, please let me know. I followed the YouTube video that Emmantik posted, but made a variation in my speaker design to include a quick disconnect to connect to the hatch speakers. I have the best of both worlds: a custom Bluetooth speaker that allows me to connect to my hatch speakers. So far, I’m pretty happy with how it is turning out.


I’m still wiring everything up now, but will post the finished product. For now, here are some teasers:

 

Great progress so far! Keep us updated on the end result!

 

It’s awesome and your ammo can link pushed me to do it, thank you! All of the parts he listed are what I bought. I just had to add Resonix sound deadening and Taco Tunes 6.5 adapters. I’ve had the hatch open playing music all afternoon - I know this is going to be my go-to when camping, tailgating, park, etc… . The coolest Bluetooth I’ve ever had and re-invents the lame hatch speakers . I bought the Ryobi battery adapter because those are the tools I have. It’s nice to not worry about the car battery and so far it’s lasting surprisingly long on a 4amp battery.

I feel like this is the cherry on top of the stereo upgrade I did.

 

All done. Happy with the result. Bluetooth Speaker works great standalone or I can use the hatch speakers with the disconnect harnesses. The only other thing I plan on doing is mounting everything inside with some Velcro tape and adding low voltage disconnect.

thank you Emmantik for the inspiration!

going on a big camping trip in a couple weeks and I know this setup is going to steal the show

 

Nice setup you made.

 

Bad ass. You thinking about making your own battery pack out of 18650 cells or something? makes me wanna make one of these. Can you tell us how long the battery lasts at a normal volume? how big is that battery?

 

It’s a 4amp… I feel like I’ve been bumping it at a decent volume all weekend and I haven’t switched it out yet. The nice thing is it’s so quick to switch out if you have another battery on hand - I’ll probably stick with this setup. I was originally planning to do my own battery, but this made it too easy. It’s much better than the UE Megaboom I have in my garage and I do like connecting it to the hatch - mainly for the novelty/cool factor.

only thing I don’t like is I can’t rename the Bluetooth on the unit itself, but I did on my phone - a minor complaint, but wanted to point it out. This speaker has pretty good output and I really like the enclosure.

 

This is great! Awesome job on the install!

 

Instead of inside the ammo box, do you think it's possible to have all wiring and parts hidden somewhere behind the hatch panel trim? With ability to only remove the battery only when it needs to be charged?

Also, how hard was it to run the wires from the hatch to the cargo area?

 

Nice work!

 

This would be very difficult. You would need to hide the components in various places behind the rear plastics. You would probably need to give up your jack for a good spot to have a removable battery. Would be easier to hide everything where its not removable and theb set it up so it charges when the car is on or have a plug to charge thr battery. But now you have speakers stuck in your car and maybe you fo activities away from the car and the boom box makes so much more sense.

 

Yes, that would work if you don’t mind the components being somewhat visible. The amp has a volume, bass, and treble control that you may want to adjust, but this could theoretically be hidden if you are happy with the settings. Battery adapter would need to be accessible. I considered this for a bit, but decided I’d rather have a speaker adapter I could connect to.

Once the hatch cover is off and the driver side speaker mount out (5 bolts?). it wasn’t too bad.

1) zip tie speaker wires where you want them on the hatch area

2)used fiber cloth tape to wrap speaker wire pair that will be fished through the hatch. I did this mainly to keep them together to avoid having it fall in the window track. I zip tied to the existing harness to keep things as tight as I could (from entry point to exit point).

I used a wire hanger for this.

3) fished speaker wire through tube grommet. Used a wire hanger with electrical tape (protected pointy end and wrapped wires). Using some dish soap helped lubricate it

4) remove 3 headliner clips to gain access and run wire in headliner to side panel. I already had my large side panel out for a subwoofer upgrade I was doing so I had space, but I imagine you could push it to the side with removing the one bolt.

be careful with the grease with the weather stripping that you have to take off. Could make a mess with the headliner and be hard to clean. I imagine the dish soap and damp towel could get it.

I’ll admit, I’ve done a lot of electrical upgrades in vehicles over the years and I took my sweet time with the 4Runner, didn’t cut any corners, and used the right connectors (I soldered and heat shrinked everything).