NiCd battery replacement in vintage computers

Paul Koning paulkoning at
Sat Feb 6 15:29:44 CST 2016

> On Feb 6, 2016, at 4:21 PM, Mark J. Blair <nf6x at> wrote:
> Today I discovered that I hadn't replaced the NiCd battery in time in my Amiga 3000. Pictures:
> ...
> While I begin to figure out how I'd like to perform this repair, I'm curious about what others have decided to do in similar circumstances. Many options come to mind:
> * Solder in the same kind of NiCd pack to keep things original.

I haven't yet done this, but I have a device (Fluke 881AB voltmeter) with dead NiCd batteries, and when I get around to replacing them that's what I was thinking of.  NiCd batteries are still available.

> * Solder in a supercap instead.

That has vastly less capacity, and a very different discharge curve (exponential vs. nearly flat).  Depending on the circuit using it, that might work slightly (at 10% capacity, maybe) or not really at all.

> * Reconfigure the circuit to use a non-rechargeable lithium coin cell in a holder instead. I don't think I've seen one of those leak before.

It hasn't happened to me, but have heard of one case of a leaking Li primary cell.  Not a coin cell, but a C-sized one: I remember a report of one leaking in an automatic parachute opener (AAD), wrecking the parachute.  In fairness, that was one left in quite a number of years beyond its expiration date.  (Before someone asks the obvious: the problem was found during a required inspection on the ground.)


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