Frequently asked questions about the CD-i's Timekeeper battery: What options do you have and how do you replace it? (guide+tutorial+tips+pictures inside)

In this article we will dive deeper in the use of the timekeeper battery inside a CD-i player. Every CD-i player has a Timekeeper NV-RAM chip. It holds the save files, it holds a real-time clock, it is in fact the NV-RAM chip that your CD-i player can not do without. What is it? What does it do, why does it fail? How do you replace it? What are the differences in every CD-i player (as they have different mother boards). Is it safe to just order a timekeeper chip from the internet? What do you have to look out for? And if you decide you want to replace the timekeeper battery: How to do that? Are there different ways to solve a dead timekeeper problem?

Every CD-i player has NV-RAM memory that is located in the timekeeper chip. This chip stores the settings of the CD-i player as well as the savegames of your CD-i titles. It also holds the time and date: It is non-volatile static RAM and real-time clock; it is a monolithic chip that provide a highly integrated battery-backed memory and real-time clock solution. It is located on the main board of your CD-i player. Most of the time it is actually labelled 'timekeeper' as you can see above (This one is from a CD-i 210).

Hidden inside the chip there is a lithium battery (generally a CR2032) that can have a lifetime of 30 years, if stored in a cool and cold environment and not used very heavily.

The lifetime of a Timekeeper battery is determined by two factors:

The first effect is known as Capacity Consumption and the second as Storage Life (which is primarily a function of temperature). The two effects have very little influence on each other, being independent but operating simultaneously. The data retention lifetime of the device is determined by whichever occurs first.

What does this tell you? Storage life has influence on the lifetime of the Timekeeper (temperature, moisture), it can cause reliability issues (corrosion). When you buy one online, it can be from an old stock (if inactivated it can exceed 25 years) but the risk of draining is getting higher. In theory the Timekeeper batteries can live for 30 years, in practice there are high risks.

This means in your CD-i player, if you have treated it nicely, not used it often and stored it in a cool and dry environment, the original Timekeeper will still be OK even today. But if used often and stored in a hotter space with higher humidity, the Timekeeper battery will have failed by now.

Retrostuff about the lifetime of the Timekeeper: "All of them operate within the accuracy of ± 1,53 minutes per month at 25 °C. The battery life also depends on the temperature of the environment and the state of the oscillator (started: several years, stopped: several decades)."

There are a couple of brand-less chinese chips, but the conditions they were produced and stored in are doubtful. Retrostuff advice: "Please go for an original one: Don't bother with all those hacks around online and go for an original clock chip by ST or compatible Dallas RTC. Depending on the age and condition the chip may last for 5-15 years, so have it socketed, just in chase. A desoldering gun helps greatly."

If you replace a Timekeeper battery be sure to install a socket where you can click in the Timekeeper chip. Otherwise you have to desolder everytime the Timekeeper again

Moreover, the timekeeper chips are generally not produced anymore. If you install a socket for the chip, it's basically a returning problem, until the moment these chips are not available anymore. The 3v CR2032 batteries are far more generally available and more easy to get (and cheaper)

The 8kb versions are originally by STMicroelectronics with the code MK48T08B-15. Retrostuff shares with us his advice for an alternative: "The Dallas / Maxim DS1643 NV Timekeeping RAM chips". "If you install a socket in a CD-i 450, you'll find that the chip will bump into the metal cage, you will have to bend it a bit to make it fit" - according to Retrostuff.

In the table below you will find which players have a 8kb Timekeeper chip:

For the more high-end CD-i players Philips offered a 32kb NV-RAM Timekeeper chip. Retrostuff gives the advice to use a Dallas/Maxim DS1216C SmartWatch RAM socket together with a Mitsubishi M5M5256DP-70LL-I chip. Also for the 32kb chip counts you have to be careful when you do this in the CD-i 450.

In the table below you will find which players have a 32kb Timekeeper chip:

Last year we discussed the possibility to upgrade your 8kb CD-i player with a 32kb Timekeeper chip. Would it be possible? Retrostuff took the challenge and explored the possibility: He was succesful to upgrade the CD-i 470 (8kb) with a 32kb chip. If the boards are similar (The 490 has the same board and 32kb inside) it should be possible, but this is all very experimental. Read this article for more information.

Yes, you can, but in general these Timekeeper chips are not produced anymore so you are relying on an relatively old stock. It is unknown to verify how old it is and how they have stored it, so there is no good way to predict the lifetime of the battery inside. But please note the possibility to install a parallel battery next to the chip, so you can leave the Timekeeper chip as it is. They are all feeded by a general CR2032 cell, which are commonly available everywhere.

I would advice to install a parallel battery, instead of a new chip. The ones being sold are often from an old stock and the battery could very well be half dead before you can use it. Installing a battery socket solves it once and for all, the old one will not leak

The Timekeeper chip inside your CD-i player is storing your saved games, as well as keeping the time and date. It stores game scores, player shell settings, favourite picture selections, etc. One other important usage of the NV-RAM is to store the CSD (Configuration Status Descriptor). When a CD-i player is turned on, the operating system kernel is initialized and one of the startup routines includes the creation of the CSD. The CSD contains information about a certain CD-i system, such as the amount of NV-RAM available, which kind of pointing device is connected, the version of CD-RTOS used, but also wether a floppy disk drive is available, if a printer is connected, etc. If the CSD cannot be written anymore because the Timekeeper battery is dead, all kinds of different problems can occur, depending on the last CSD settings that were written:

Yes, that is possible, by connecting a null-modem cable to your CD-i player and to your PC. You will need the CD-i Link software to copy the contents. The CD-i Link program (cdilink) communicates with a CD-i player over a serial connection. The communication uses the "stub" protocol; a specification is provided with the cdistub distribution. 

The primary purpose of cdilink is to upload the system ROMs from a CD-i player to a PC for use with the CD-i emulator, but you can also upload or download other files and display information about the CD-i player. This allows you to inspect and modify the contents of the player NVRAM (e.g., highscore files) and to inspect the contents of CD-i discs. 

To use cdilink with your CD-i player you need a so-called CD-i nullmodem cable. Such a cable used to come with the CD-Interlink disc but you can easily make one yourself or perhaps borrow one from a fellow CD-i fan. Specifications of the cable are provided with the distribution. 

The CD-i Interlink software you can find here:cdiemu.org (Download section)

For this option you will need to remove the solder connections of the Timekeepr chip and solder a new one on the exact same place. If you use a chip that is mounted on a socket, you solder the socket on the PCB and every next time you can click in a new chip. The downside of this solution is that the Timekeeper chips are not made anymore, so this is kind of a timebomb for your player. You will need to replace the chip once every 10 years, but if you have bad luck, the chips you buy online are old and not well stored (too hot and at high humidity for example).

This is the 'dremel' solution as you have to decap the chip to reach the current lithium battery inside. Once you have done this, solder a battery socket on top, connected to the + and - of the current chip and place a new CR2032 battery cell. The big plus is that these batteries are commonly available, cheap and always from new stock (as they are frequently used in all kinds of applications). Old CR2032 are very stable and won't leak after they're empty, the chance that something will happen inside your player is very low.

Inside a CDi player is a special IC where games can store data. This data is stored even when the CDi player is switched off. The data is normally the high-score list of the game. After a number of years the high-scores are not stored anymore. The Timekeeper IC does not function anymore. A simple solution is to replace the IC in the CDi player. But what is wrong with the Timekeeper IC? The IC is a RAM memory with it's own battery. This battery keeps the data inside the RAM available. Sadly after a number of years the battery will be empty.

On the picture you can see the inside of the CDi player. This is a Philips CDi-210 player. The red arrow points to the Timekeeper IC (M48T08 150). Click on the picture for a bigger version.

Opening the Timekeeper IC is not as easy to do as it's sounds. The battery is sealed inside the upper-part of the IC.

With a small saw I removed the front (upper) part of the IC. After that I took a sharp knife and slowly removed the sealing compound out of the IC. Be careful with this, because you do not want to damage the connections from the battery to the RAM memory. Also do not damage the lower-part of the IC where the RAM memory is.

On the picture you can see a small part of the battery. Remove the sealing compound until the two connections from the battery to the RAM memory are available.

Check with a Voltage-meter where the positive and the negative connections are on the battery. Solder a wire to each of the connections from the battery to the RAM memory. I used a red wire for the positive and a black wire for the negative, but you can use other colors. Keep the wires long enough so that you can place the "new" battery on a easily accessible place.

After you have soldered the wires, you need to disconnect 1 side of the old battery. The red arrow is pointing to the point where I cut through the connection with a sharp knife.

Now it's time to clean the inside of the CDi player. Make sure that all the dirt from opening the IC is removed from the CDi player.

For extra strength you can add some (hot-) glue to soldered wires.

For the new battery I used a old battery holder from a PC. The battery is a CR-2032 (3 Volt) type. The battery holder is placed upon a piece of experimental pcb. This pcb is mounted on a small metal tab that was not used.

The wires from the Timekeeper IC are connected to the battery holder. The battery can be replaced easily, but that not necessary for another 10 years.

Testing if it works. Start the CDi player and play a game. Save your high-score. Switch the CDi player off for a while and switch it on again. If the high-score is still available you have successfully repaired your Timekeeper IC.

[Thanks, Commodore-info.com, Retrostuff, CD-i fan, ICDIA, Omegalfa. All CD-i members offered valuable inputs that made it possible to compile this article]