Dead PRAM battery = not recognizing main battery?

[sambapati87]

Will a dead PRAM battery in a Duo 2300c cause a battery in the bay to not be recognized at all? ('X' over battery icon)

I've cleaned the contacts, etc. already. The batteries are easy to replace, luckily, if this is the issue.

 

[beachycove]

Corrupt power manager settings can cause all sorts of troubles – including the failure to recognize batteries in some models, but as I understand it, this is owing to software in the power management system rather than juice in the backup cells per se.

My advice, having worked on these a fair bit over the past year, is to reset the power manager as per Apple's instructions; if it doesn't then immediately recognize the main battery after the reset, it's most likely a defunct main battery.

For real use rather than an idle tinkering once every 6 months, however, you would likely want a working backup battery, even if the main battery were good. I have a 280c with a dead backup battery, a 270c with a working backup battery, and a 2300c with a working backup battery. I have two working main batteries between them. Even with the best of the batteries installed, there is a world of difference between the three: the 280c exhibits random problems that I put down to the dead backup battery. Failure to recognize the main battery is not among them; glod and random shutdowns are more the thing, but the problems are so persistent that they make the machine unusable. I put the 270c and the 2300c to good use for some writing projects over the past year, and they were both rock solid, and very portable in a briefcase. I couldn't have used the 280c because of its erratic power-related behaviours.

 

[equill]

In addition to beachycove's succinct summation I would point out that, as has already been recorded in previous threads in these Forums, most of the older PBs do not begin to recharge an exhausted backup battery before the system battery has reached near-complete terminal voltage (ie, not complete charge, which depends on the battery's condition). This can leave you in a cleft stick, in that if the system battery is NBG, and therefore will not reach full terminal voltage, it may take somewhere from a long time to never to get the backup battery up to scratch. That is, having a fully chargeable system battery is the need, even though the PB may work quite happily from its AC adapter alone.

For intermittent use, and given that you don't care about clock or PRAM settings, uncharged backup and missing or defunct system battery may work perfectly well. For optimal use, you need a working system battery. QED. The backup battery will also not give you part of its designed service: graceful shutdown and maintenance of memory contents for 24hr when the AC adapter (or the system battery) is removed or fails.

de