Modern Batteries

For some of the earliest MiniDisc portables, they used proprietary batteries. They are almost all guaranteed to be dead by now; no longer holding a charge, or chargers not detecting it at all.

Here we want to show you a (growing) list of modern replacements, and the units they belong to.

Sony MZ-1

The MZ-1 uses a NiMH BP-MZ1, these will no longer work.

There are a few modern equivalents. Both are 3D-printed shunts; they are basically just structural holders for 18650 cells.

First, is a two-piece shunt. For this you will need two 18650 cells, and some kind of conductive material (nickel metal strips, or copper tape) to get the power into the device.

Second is a one-piece shunt. Same general idea here; you will need to have some kind of conductive metal on one side of this.

Sony MZ-E20

The MZ-E20 is normally powered by AA cells, an AC adaptor or an optional Ni-MH battery pack BP-DM20 (Japanese original page) BP-DM20 (Google Translate version). This pack can be charged inside the unit with the AC adaptor. With standard rechargeable AA batteries inside the charge mode does not engage although it can be easily made to work.

Sony's original battery pack for this unit is the BP-DM20 which was made up of two AA cells and had a rating of 2.4V at 1.200mAh. Due to the pack going into a standard AA battery bay, the pack didn't implement the serial connection of the cells but rather only fixed them into a single package leaving the connection to the device hardware.

The pack's frame is basically just a simple piece of plastic and a sheet of metal wrapping the cells around this central piece. The cells were also glued fixed into this construction.

The key part of turning the cells into a chargeable package is a piece of the frame's plastic pushing a small switch inside the bay (on the in-device short end of the bay, located between the contact springs). Once this switch is engaged, pushing the player's stop button will activate the charger (twice to stop first and then charge or once to charge on an already stopped unit).

Replacing the aged and bad cells in an older pack with fresh 1.2V/1.200mAh ones is pretty straightforward. Gluing them into the holder is not requrired as the pack is held together pretty well with the metal wrapper.

It is advisable to only use cells with the above specs in order to operate within the originally designed parameters of the player's charging support. Also, inserting standard AA alkaline cells this way and engaging the charger is an absolute no-no!

Sony's actual AC adaptor to be used with the player would be the AC-E45HG. Similar adaptors such as the AC-E455F came with other 90s Sony hardware such as Discman devices. The two adaptors vary slightly in their specs (AC-E45HG: 4.5V/700mA, AC-E455F: 4.5V/500mA) but the lower rated one still seems to work fine and its charging current is still within the range of common Ni-MH wall chargers.

For people without an old battery pack frame at hand, not all is lost. One can prepare a short piece of plastic (for example from cutting a CD jewel case inner tray or an expired credit card), supporting it with the AA cell separator in the bay and simply fix it into place with a piece of tape. One should remember, though, that the safety mechanism against accidental charging attempts of incompatible batteries is now permanently overridden, requiring additional care from the user to be taken.

Gumstick batteries

For the units that use the so-called gumstick batteries, this solution is easier.

There are several vendors that make these, and they do work.

Common brands are HQRP and Vapex.

(We use affiliate links to earn a small commission on purchases made using these links.)

With these there are no special handling or prep for getting them to work. Unfortunately the way NiMH batteries work is something you need to keep in mind when using them. They have what's called a memory effect.

But the long and short of it is, you need to complete a few charge/discharge cycles when you first get them to get their full capacity.

That's it. Your Minidisc portable that takes gumsticks? It works now!

LIP series

Unfortunately, there aren't many modern replacements for these. You can take a chance with the 'remanufactured' or no-name replacements, but they are likely to be NOS (new-old stock; just sitting in a warehouse somewhere for a while).

If you have access to a 3D printer or 3D printing service, here are instructions for building a DIY LIP-4WM replacement (the battery used in the Sony MZ-RH1/MZ-M200).

There have been some attempts to do what is called 're-celling' some of the LIP units. This is *generally* a destructive process, even in the best DIY'ers hands. This involved separating the case halves from each other, desoldering the battery, and soldering in a new cell.

However, here is a less destructive tutorial on how to rebuild a LIP-12.

The LIP-12 series use plain 18650 cells, and the LIP-8 uses a 14650 or a more-common 14500 cell.

It can also be dangerous if you aren't careful, because these are lithium-ion batteries. If mishandled they will catch fire or explode.

NetMD units

Starting in late-2000/early-2001, NetMD units were released. A few of the first models continued to use gumstick or proprietary LiIon batteries.

But later, as technology improved, they started using standard AA alkaline batteries.

For many models, you can use modern rechargeable batteries (Eneloops and the like) to power these devices.

Gumstick

If you are using a new gumstick battery, sometimes it can be beneficial to add a bit of roughness to the positive end for better conductivity. This is not a standard thing for all batteries used in all units.

This might be helpful for a unit with corroded or physically damaged positive terminals (negative terminals are always inside the unit), or to test with.

Basically you take a nail file or emery board (preferably metal) and file a teensy bit of the top of the positive terminal. Just enough for you to see or feel a bit of texture to the top.

Standard AA

Some models will not like modern lithium batteries, like Energizer Lithium. The MZ-R37 is one that is a bit finicky. It will use standard alkaline AAs or Eneloop rechargeable batteries, but not lithium non-rechargeables.