At least one main battery that is capable of reaching full terminal voltage is a desirable goal, for reasons that have been well-and-truly rehearsed in these forums. The battery may not then hold enough total charge for you to take the PB 5x0 off the AC adapter, but it ensures that the rechargeable backup battery also becomes charged, and the main battery also acts as a quasi-capacitor for input DC supply smoothing.

And yes, conceitedjerk, there is but one PCMCIA cage connector, and that only in the left battery bay.

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