68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.
Generic PRAM batteries
Posted by: aftermac on 2010-03-10 15:55:53
Wow... If I were to count, I have less than twenty, most doing something useful. I'm still trying to find a useful place to host two m68k Macs - one is a Quadra 610 for which I need a NuBus adapter so I can have two ethernets so it can do NAT...
Nice! It's good to have projects. 🙂

I've got several I'd like to setup... Quadra 950, IIsi, Q605, MacTV, DuoDock w/ Duo 2300c, one of my Sun machines, one of my Atari's. I already have an SE/30, Beige G3, G5, MacBook Pro, Apple IIe, and a home built PC in my MAME cabinet setup.

It seems like most of my projects involve cataloging, testing, and repairing my old systems 🙂

Thank you. I like to keep old machines running, although I'm not super-sentimental about keeping them completely original. Many of mine have added oscillators, m68040s with permanently attached heat sinks, QuadDoublers, batteries, et cetera. But seventy six... Damn! That'd be around $450 just for the lithium batteries if you put two in each machine!
I definitely like to keep them running, but I lean toward keeping them original. I will switch cards, HD's, RAM, use parts from one to repair another, and the occasional processor upgrade, but nothing too drastic.

Yeah, the cost of keeping batteries in these old systems is a prohibitive factor, as well. Most of the batteries I have were pulled from my collection. If they register 3.6v, I keep them for when I need to plug them into a system.
Posted by: Osgeld on 2010-03-11 16:12:49
I dont have a problem with buying batteries online, but only from certain trusted places, random google hits and ebay are just too loaded with half battery half led weight for me to gamble my almost non-existent toy budget
Posted by: Paralel on 2010-03-11 19:56:18
I got a brand new SAFT 3.6V lithium online for a good price. My multimeter shows its perfectly good.
Posted by: Unknown_K on 2010-03-11 21:31:43
I dont have a problem with buying batteries online, but only from certain trusted places, random google hits and ebay are just too loaded with half battery half led weight for me to gamble my almost non-existent toy budget
The only thing I worry about online is giving out my credit card info. If some non descript site takes paypal then I might order from them, but I don't enter my credit card info to some fly by night website.
Posted by: Bunsen on 2010-03-12 04:07:12
Would I have to solder the wires to the existing battery socket? If I could attach the wires without soldering, that would be better.
In the case of machines that take a 1/2AA 3.6V battery, you can substitute the battery for a piece of wooden dowel the same size, with a thumbtack pushed into each end. Strip the wire ends coming from your new battery holder and twist them securely around the centre pin of each thumbtack, and mark your dowel for + and - . If you purchase a new battery holder with leads already attached, then there's no soldering at that end either.

One good thing about using rechargeable AAs is they are exactly 1.2V when fully charged, so three = 3.6V. Alkaline AAs are 1.5V, so x 3 = 4.5V. I have no idea whether this would be a problem compared to the original 3.6V battery.

In the case of older Macs with the square 4.5V battery that plugs into a motherboard jumper, cut the lead and plug off the old battery and attach the wires to your new battery holder. You can either solder the wires or twist and tape/heatshrink. Then simply plug back into the motherboard jumper.

Of course a properly soldered joint between wires/thumbtacks etc is going to be more secure. In either case, there's no need to risk soldering anything directly to the motherboard.
Posted by: johnklos on 2010-03-12 09:59:53
I use the AA and AAA lithium which are usually around 1.55 volts when new.
Posted by: Bunsen on 2010-03-12 15:24:38
Do you use two (3.1V) or three (4.65V) to replace a 3.6V PRAM battery? Or are you referring to replacing the 4.5V square PRAM batteries as pictured above?
Posted by: tyrannis on 2010-03-15 20:56:09
Here is a way to get these 3.6V 1/2 AA PRAM batteries at a better price; 10 for $26 shipped in the US ($28 worldwide). I have purchased from this lot recently and I can attest to their quality.
Posted by: Patater on 2010-03-15 21:16:33
Mike Richardson seems to only sell this package to ppcmla folks. Perhaps a PPCMLA dude could get Mike Richardson to sell this package to 68kmla folks as well?
Posted by: tyrannis on 2010-03-15 21:30:23
Membership in the PPCMLA is free and easy. Anyone can sign up. Their forum also boasts a number of mysterious and liberating features which seem to be absent here.
Posted by: johnklos on 2010-03-15 21:55:31
Do you use two (3.1V) or three (4.65V) to replace a 3.6V PRAM battery? Or are you referring to replacing the 4.5V square PRAM batteries as pictured above?
Two batteries. 3 (or 3.1) volts is plenty for the backup. For the 4.5 volt square batteries, I use three batteries like so:



For the motherboard which take the little rechargeable batteries (like Amigas), I use three batteries with a diode.
Posted by: Quadraman on 2010-03-15 22:37:10
What about the square batteries that you sometimes find in old cameras? Are they the same 4.5 volt batteries Bunsen mentioned or are they different?
Posted by: johnklos on 2010-03-16 01:48:53
That all depends. There are many kinds of square batteries for cameras. I'm sure some are 4.5 volts.
Posted by: Quadraman on 2010-03-16 17:06:24
The batteries arrived today and I put one in the PM 7500 that I am using right now. Seems OK so far. Rebooted several times already without losing the time and date.
< 2