Batteries in old Macs: Useless or Not?

The battery (oft called the "BIOS" battery, albeit incorrectly) is there to maintain system settings, such as the clock, when power is removed. They're not necessary to run, but without power applied, many settings would have to be reset each time the machine was plugged in and powered up.

The sort of settings that will be lost include

Startup Boot disk selection

AppleTalk on/off status - doesn't matter on systems with "Open Transport" installed.

Disk Cache size setting. (Defaults to 32K).

Cursor Blink rate.

International Map setting.

Current Date & Time

Highlight colour setting.

If none of these worry you, then it doesn't matter. Note that if you booted from a second boot drive, when the battery goes flat, it will boot from the FIRST logical boot drive.

Also, with respect to the AppleTalk setting, if you had a serial printer connected, when the battery goes flat, your printer won't work until you turn AppleTalk off (unless your printer is using the AppleTalk protocol). For serial printers, often the "cheap" solution was to configure the printer to use the "Modem" serial port, since Appletalk never defaults to the modem port.

Date & Time and international Map setting can (and does) cause problems with date-stamps applied to outgoing emails, such that the receiver of the email might see the year the email was sent as "1970".

Additionally, it can make some internet security certificates appear to be expired when in fact they are not.

Note also that file "Date Created" & "Last Modified" date & times will be erroneous.

So... it depends on what your needs are.

On a side note, a battery that goes flat in some models (LC475 / Quadra605 , PPC 6100 & PowerMac 7220 / PowerMac 4400, iMac Tray Loaders) can make the machine look like the logic board has failed even if your replace the dead battery. The trick is to remove the battery, AND ALL POWER SOURCES, and short the battery connector's terminals out overnight. Many "authorized" dealers got caught out with those.


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MacTech68 said:

The sort of settings that will be lost include
...

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The one that bugs me on my Mac Plus is the mouse pointer tracking rate. It defaults to the SLOWEST possible setting. When the battery's dead, I have to heave the mouse all across the desktop to get it changed to a sane setting each time it boots.

David Schmidt said:

The one that bugs me on my Mac Plus is the mouse pointer tracking rate. It defaults to the SLOWEST possible setting. When the battery's dead, I have to heave the mouse all across the desktop to get it changed to a sane setting each time it boots.

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I forgot about that one.

I wish Apple would come out with a firmware update to fix a similar complaint on the Mid-2005 iBooks with scrolling trackpad. Startup Manager (holding the option key on boot-up) does the same thing. The tracking speed is WAY too slow.
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froggytreafrogg said:

Hi, I'm a collector of vintage Macintosh computer: LC, LCII, LCIII, LC 580, PwrPC 7500, Classic II, PwrPC 6400, PwrBk Duo, Apple IIE, Newton 2100, SE/30, Apple IIgs, Plus 1mb, and some other stuff. Anyway, after many months of working on many Macs, I have found that these computers work wether or not the internal batteries are any good. I have in fact booted a computer with no battery at all. Everyone tells me that they are necessary for any operation of the computer whatsoever. Does anyone know if these batteries are really useful? Thanks.

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The battery in the Mac LC is required to even start the computer. Way back when, my LC had a dead battery and would not start. My friend, an Apple store manager, gave me a solution: turn on the LC, then turn it off and quickly turn it on again. That charges the capacitor, and the LC will then boot. Naturally, your settings will need to be reset.

I have a question for you: How can I get data off my Apple II 5.25" floppies to put on my Macs or PCs?

maccompaq said:

The battery in the Mac LC is required to even start the computer. Way back when, my LC had a dead battery and would not start. My friend, an Apple store manager, gave me a solution: turn on the LC, then turn it off and quickly turn it on again. That charges the capacitor, and the LC will then boot. Naturally, your settings will need to be reset.

I have a question for you: How can I get data off my Apple II 5.25" floppies to put on my Macs or PCs?

Click to expand...

Well, the battery isn't needed to start it up. What happens in that case is the battery is flat enough that it corrupts the PRAM and the computer can't start. (See my earlier post)
In your case, removing the battery would have prevented the scenario from occurring. The solution you were given does work but either way, you'd still have to reset settings every time until you fitted a new battery.
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The battery on my iMac G3 has been dead for ages. It just automatically resets the clock through the internet on startup. I hate prying the case apart so I never got around to replacing it.

MacTech68 said:

Well, the battery isn't needed to start it up. In your case, removing the battery would have prevented the scenario from occurring.

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My Mac LC ABSOLUTELY would not boot up with a dead battery unless I used the trick mentioned previously. My Performa 475 and my Performa 637Cd would boot up normally with a dead battery as would my Power Mac 7300 and several other similar models. Naturally, all settings had to be re-done.

Additional thoughts:

On earlier operating systems that don't have the "Monitors" control panel your display settings may revert to 640x480 and 16 greys. You then need to switch it manually to colour and the desired resolution.

IIRC, later operating systems can override the PRAM setting for display settings and all is fine. I think system 7.5 or the PPC 7.1.2 system overcame the problem.
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Just to add,

I have a lovely Powerbook 15" with flat batteries. When I boot it, it always forgets wifi password, date and time, and all drives will show 0KB free. Also it can't log onto Time Machine or save anything on external drives (they show 0KB free too). Other strange errors will happen too.

Solution - reset time and date, and reboot, and then everything is back to normal. Until the next time it's off for more than 5 minutes.

I find it completely bizarre that having date and time set to 1976 or whatever the default is could cause so many seemingly non-related errors.

froggytreafrogg said:

Does anyone know if these batteries are really useful? Thanks.

Click to expand...

They are useful for leaking and ruining vintage motherboards when left installed in non-climate controlled storage.

MacTech68 said:

On a side note, a battery that goes flat in some models (LC475 / Quadra605 , PPC 6100 & PowerMac 7220 / PowerMac 4400, iMac Tray Loaders) can make the machine look like the logic board has failed even if your replace the dead battery. The trick is to remove the battery, AND ALL POWER SOURCES, and short the battery connector's terminals out overnight. Many "authorized" dealers got caught out with those.

Click to expand...

Thanks For the trick, as it helped me out alot as i had a g3 imac not wanting to boot, I am doing this trick to see if it will work as i know the pram bat is dead as a door nob