CPS 2 Battery replacement question

[adsa]

Hi Folks

Looking for a little advice. I won a Marvell V Streetfighters full kit on ebay for £95!!! The B board had never come apart as all of the seals were in place. The battery measures 3.6v, so still good at the moment. Do the lithiums drop off of the cliff as far as voltage is concerned, or is the drift from 3.6v downwards gradual? Really should I replace the battery as it has been in for a long time????

Thank you

 

[xodaraP]

Lithium batteries work until they don't, some people say you can see voltage drop but typically if you do the encryption keys are already lost.

Fortunately that's now repairable if you want to run on original code and are happy to run a battery (like me) - but if it's currently happily running on a battery and you're comfortable replacing it, it's going to be almost 30 years old.

I replace them on my boards when I buy them regardless of whether the previous owner says they've replaced it.

tl;dr it's old. Replace it.

 

[Mitsurugi-w]

The biggest drift I've ever seen was .2 volts. So if you want to keep using batteries I suggest changing it and putting a,label on your pcb. Then just change it every 5 years to be safe.

Don't use battery holders!!!!

 

[adsa]

Fabulous guys. Thanks for the feedback. I shall now replace the battery

 

[freddiefiasco]

The biggest drift I've ever seen was .2 volts. So if you want to keep using batteries I suggest changing it and putting a,label on your pcb. Then just change it every 5 years to be safe.

Don't use battery holders!!!!

Just curious why battery holders should not be used. I replaced the soldered battery on a CPS2 board with a holder like this. But now I'm worried.

 

[Mitsurugi-w]

There is another thread here somewhere where it is explained but basically when you add a battery holder you double the number of contact points that can fail from two to four. The way I explain it is this; How many times has your TV remote stopped working until you open the battery door and spin the batteries? Now imagine the same thing happening to your decryption keys.

 

[freddiefiasco]

There is another thread here somewhere where it is explained but basically when you add a battery holder you double the number of contact points that can fail from two to four. The way I explain it is this; How many times has your TV remote stopped working until you open the battery door and spin the batteries? Now imagine the same thing happening to your decryption keys.

Yep found it.
Good analogy. I will have to consider changing it back. Thanks!

 

[xodaraP]

It's easy enough to remove the battery with the axial leads anyway.

I can understand convenience and the concern of causing damage through desoldering and soldering in a replacement. But realistically you're replacing them once every 2-5 years, it's not worth the extra risk of the battery holder

 

[ChuChu Flamingo]

The biggest drift I've ever seen was .2 volts. So if you want to keep using batteries I suggest changing it and putting a,label on your pcb. Then just change it every 5 years to be safe.

Don't use battery holders!!!!

Just curious why battery holders should not be used. I replaced the soldered battery on a CPS2 board with a holder like this. But now I'm worried.

It doesn't help most battery holders are chinamanese quality.The technical reason from my research is something called Galvanic Corrosion. This phenomenon happens when two different metals are in contact with one another electrochemically. Basically, one metal corrodes preferentially to the other in the absence of an electrolyte.


https://en.wikipedia.org/wiki/Galvanic_corrosion

Once it corrodes enough the resistance gets too high which means the battery backed up ram holding the decryption tables isn't being powered, thus the boards suicides. A user named Mainman iirc lost like 100+ boards to this.

 

[Mitsurugi-w]

Damn. That happened to Mainman? I was not aware of that. Must have happened since we left the Neo forums.

 

[ChuChu Flamingo]

Well at least now you can return the original encryption keys back, although for that many it would be a bitch.

 

[Asayuki]

There is another thread here somewhere where it is explained but basically when you add a battery holder you double the number of contact points that can fail from two to four. The way I explain it is this; How many times has your TV remote stopped working until you open the battery door and spin the batteries? Now imagine the same thing happening to your decryption keys.

Hard to explain it better than this