Upgrading Vintage Boombox With Rechargeable Battery

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If you love jamming out with your vintage boombox but hate forking over $15 or more for a set of batteries, here is a solution for you.  Vintage boomboxes are great for a lot of reasons, but they’re missing one creature comfort we’ve grown accustomed to- rechargeable batteries.  Most boomboxes from the 70’s, 80’s & 90’s require a large number of D cell or C cell batteries- sometimes up to 8 of them.  The cost for 8 D batteries today is around $15 or more- yikes!  Luckily there is a solution, and it’s possible to modify your old boombox with a rechargeable battery pack.

For this guide we will be upgrading this Panasonic RX-4930

Before you get started- Do you feel comfortable opening up your boombox and soldering in new wires?  Hopefully you said yes, if not, you can learn or ask a friend for help.  This does take a little bit of knowledge and a decent comfort level working with electronics.  And since this is a DIY project, there’s a chance something could go wrong and you could ruin something, so make sure you’re comfortable knowing there’s a risk.  Don’t do this on your pristine Lasonic 975. 


Do not have anything plugged in while you do this.  Never work inside the boombox if you have any AC power going to it.


First things to check:

Start by determining what DC voltage your boombox operates on?  Look at the back of the boombox for a label that indicates the DC voltage- they are typically somewhere between 9V and 12V.  My experience is that a 12v battery pack is compatible with anything between 9V-12V, but I make no guarantees.  There is always a chance that using a higher voltage than stated on the back can permanently damage your system.  Also see if the Wattage of the boombox is listed.  If your boombox is really big and states a high wattage, say over 50 watts, you will need to make sure that the battery you use can provide enough power.  We’ll get back to this.



This boombox takes 6 D batteries and shows a voltage of 9V

Next see if your boombox will allow the battery pack to fit in the existing battery compartment.  Hopefully it does since these batteries are relatively small, slightly larger than a deck of cards, but if it doesn’t fit you’ve got a decision to make- are you comfortable modifying your boombox case?

Parts Needed: 

Boombox– One that you’re comfortable modifying. 

Rechargeable Battery Pack– For mid-size and smaller size boomboxes- under 50 watts, I recommend a battery pack sold by Talentcell on Amazon- Amazon Link 

This battery pack is a lithium ion battery comprised of three 18650 cells, a BMS, and a charging circuit.  It also comes with a charger and pigtail DC plug. The voltage when fully charged is approx. 12.6V.  The stated capacity is 3 amp hours.  This is technically lower than the total capacity of 8 D cell batteries, which have more than double the capacity.  But the benefit of the lithium ion battery pack is that it’s rechargeable and only costs a few dollars more than a set of D cell batteries.  And if treated correctly, they can be charged and discharged over 100 times.  Based on the voltage- 12V and a max discharge current of 3 Amps, this battery will provide up to 36 Watts of power.  

Needing More Power? Scroll to end of article for larger battery link.


You might be wondering how long this battery pack will last- well that depends on a few factors.  The main factor is how loud you’re playing music.  Often the “wattage” listed on the back of boomboxes is inflated and not a good indicator of how much power the boombox will require.  Even at a decent volume many boomboxes will only be drawing a few hundred milliamps.  At 250mAH current draw (3 Watts), this battery pack would be good for around 12 hours of run time.  And when discharged it’s easy to recharge the battery by plugging in the charger. 

The Process:

Prepare your battery wire:

If you’re using the battery pack recommended above you will start by modifying the pig tale power wire that comes with the battery.  The DC “Y” adapter has two male ends and one female.  You will cut and strip the wires on one of the male plugs.  Stripping the wire should leave you with two exposed wires- a positive and negative. 


Solder in your new wire:

The easiest way I’ve found to integrate the new battery into the system without much modification is to solder your wires onto the points where the existing battery wires leave the battery compartment, pictured below.  

This is where the old batteries output their power to the power supply area in the boombox.
Showing new wires for new battery being soldered to existing junction.

Adding your new wires here will allow you to continue using the boombox with an AC cord if you want to.  Basically we are splicing in the power from the new rechargeable battery at the same place where the old D Cell batteries tied in.  The systems will/should be built with a diode or other mechanism to block the AC current from feeding back to the battery in the event you plugged the boombox it into the wall. 

In this case the battery power wires in the boombox are not red and black, they are white and blue.  To determine the polarity you can trace the wires to their termination and see if that area is labeled.  In this case the wires terminate at the power supply area and there are little marks showing which wire is positive. 

If yours doesn’t show you the polarity you can install batteries and use a multimeter to determine the polarity.


If you solder your wires to the existing battery wires as shown above you will end up making the existing battery springs “live” with power (12v) when you plug in and turn on your new battery.  To prevent accidentally shorting the old spring connections cover one of the terminals.

Fitting the Battery-

The goal is to get the new battery to fit in the battery compartment and still be able to get the battery cover on- that way the boombox looks perfectly original. There are some boomboxes that have a battery compartment which will allow the new rechargeable battery pack to fit inside with plenty of room, but there are some that you will have to modify. The modification is up to you.  If the springs are in the way and you are comfortable permanently removing them, pull them out.  If the battery compartment is way too shallow or way too small nothing you do will work unfortunately.  But if it’s just a little shallow or just a little too small you can cut out some of the plastic.  I remove the back case, mark where I need to cut, and then use my oscillating multitool with a flat blade to carefully cut some of the plastic out of the boombox battery area.  It is important to do this in such a way that when you put the battery cover back on it’s all hidden.  

Added Benefits- Powering Additional Devices

Another great benefit of adding a rechargeable battery is that you can also power additional things- like a Bluetooth receiver.  One version of the battery includes a 5V USB output in addition to the 12V output- Amazon Link.  If you are also adding a Bluetooth receiver or something else to your boombox you can often power it from the 5V port.  One thing to be aware of, if you are powering the boombox and an audio source (Bluetooth receiver) off the same recharegeable battery, you can suffer from ground loop noise.  In these situations it is strongly recommended that you use a Ground Loop Isolator (Amazon Link) with the audio source.  

Power it up:

With the new battery pack placed in the boombox battery compartment, plug in the male DC plug from the new wire that you have soldered in.  Turn the battery on and verify that your boombox is working properly.  Because this battery has a led indicator showing the battery level, it is important to turn the battery pack off each time you are done using the boombox.  If you forget to, the small leds will eventually drain the battery.  

Need More Power?

For boomboxes that demand more power you’ll need a bigger battery like this one that can safely discharge at 6 Amps- providing up to 75 Watts.