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I guess it just wasn't meant to be

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pl1984

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Oct 31, 2017
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A couple of months ago I picked up an "as-is" 17" PowerBook 1.5GHz G4. The system is in great shape and the price I paid was just too good to pass up. One of the problems with it is a dead NVRAM battery, not a big deal but I'd like to resolve that issue. So off to Ebay I go and I purchase a new (not new to me but new in unopened) NVRAM battery from one of the sellers.

The NVRAM battery arrives and it doesn't appear to be new but rather used. No problem, I really don't care as long as it works. I install it and...nothing. Throw it on a meter and it measure 120mV. OK, maybe I got a bad one. Seller sends me a "new" one (it too looks used), I measure it...80mV. Seller agrees to refund my money and I send it back.

So off I go to find a different seller and I find them. A new (as in never used) NVRAM battery. I buy it and it arrives yesterday. I inspect it and the battery is different than the three others (the original and two "new" ones). It's a little harder to get at with a meter so I decide to just install it. Hey, this is the third one and I can't have three bad batteries can I? Yeah, right...I install it and...nothing. I take it out, figure out a way to get it on the meter and...10mV.

Seriously??? I've purchased three new batteries and not a single one can muster even a single volt? The one I'm replacing measures 2.7 volts (they should measure 3.7 volts). Argh! Frustrated to say the least. Anyone know where I can buy a working replacement NVRAM battery for a 1.5GHz, 17" PowerBook?
 
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Dronecatcher said:
Are these meant to be rechargeable cells? In which case they'd need powering up a while first?
Click to expand...

I think they might be, my 17" one was definitely dead when I got it but I didn't get the usual clock battery message when I was messing around with the ram the other week and had the battery out so I guess it suddenly got some life back in it.
 
Dronecatcher said:
Are these meant to be rechargeable cells? In which case they'd need powering up a while first?
Click to expand...
I have no idea. I could have sworn when I first mentioned the depleted NVRAM battery in this forum I was informed they were not rechargeable and needed to be replaced. If they are rechargeable I'd be good with that but that would mean I'd have to disassemble the unit, again, and I'm not looking forward to doing so unless I knew for certain that would address the issue.
 
pl1984 said:
I have no idea. I could have sworn when I first mentioned the depleted NVRAM battery in this forum I was informed they were not rechargeable and needed to be replaced. If they are rechargeable I'd be good with that but that would mean I'd have to disassemble the unit, again, and I'm not looking forward to doing so unless I knew for certain that would address the issue.
Click to expand...

My understanding is that PRAM/NVRAM batteries are rechargeable. I imagine this is why a Mac which has been stored for 10+ years can be switched on, then successfully retain PRAM/NVRAM settings between power cycles.

If the battery is holding less than it's rated voltage when charged then it's due for replacement, but that's not to say a mostly depleted battery won't recharge (to a point).

If you leave the battery installed in the PowerBook with the power connected it should begin to charge the PRAM battery. Have you tried giving it time before testing the voltage?
 
Only on some Powerbook models is the PRAM battery rechargable. I believe most of the 68K and some of the earlier G4 models.
 
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pl1984 said:
The one I'm replacing measures 2.7 volts (they should measure 3.7 volts)
Click to expand...

Keep in mind when measuring batteries that you will not get a true reading until you test the battery under load. A 'dead' AA battery will show lots of voltage - until it has to push current and the voltage drops below what the device/circuit requires.
 
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Dronecatcher said:
I'd find it odd that PRAM batteries that aren't user replaceable (in the pop out/pop in sense) wouldn't be rechargeable.
Click to expand...

It's funny, of all my Macs current, I've only replaced the PRAM batteries in the Pismo and soldered in the PRAM capacitor replacement in the clamshell iBook. My Mac mini G4 is due for it, but I'm amazed at how well these have held up. I can recall changing in the batteries out on the Old World Macs every 3 years or so.

My original G5, which I've owned since early '04 has never needed a replacement. It has certainly lost it's date and time when in long term storage, but since putting it back to work last year, it hasn't lost it's settings once, and I turn the Macs off and flick the wall switch off every night.

Even my twin Sawtooth G4s held a solid 3.7V and haven't lost track of time since putting them back to work. I don't know if they are stock batteries from 1999, but I wouldn't be surprised.
 
AphoticD said:
My understanding is that PRAM/NVRAM batteries are rechargeable. I imagine this is why a Mac which has been stored for 10+ years can be switched on, then successfully retain PRAM/NVRAM settings between power cycles.

If the battery is holding less than it's rated voltage when charged then it's due for replacement, but that's not to say a mostly depleted battery won't recharge (to a point).

If you leave the battery installed in the PowerBook with the power connected it should begin to charge the PRAM battery. Have you tried giving it time before testing the voltage?
Click to expand...
I did not for two reasons:
  1. I seem to recall I was informed they were not rechargeable.
  2. When I first got the system I left it plugged in for approximately 24 hours and it didn't appear to change anything.
I've decided I'm going to give charging a try. It might explain why the original battery had 2.7 volts and the three new ones almost none.
[doublepost=1517057318][/doublepost]
barbu said:
Keep in mind when measuring batteries that you will not get a true reading until you test the battery under load. A 'dead' AA battery will show lots of voltage - until it has to push current and the voltage drops below what the device/circuit requires.
Click to expand...
All four readings were unloaded.
[doublepost=1517057435][/doublepost]One thing to note is I do not have the main battery for this unit. I've been holding off on the purchase until I get the NVRAM battery straightened out. Will this be an issue with recharging the NVRAM battery?
 
Intell said:
Only on some Powerbook models is the PRAM battery rechargable. I believe most of the 68K and some of the earlier G4 models.
Click to expand...
May be true, but the later PowerBooks definitely too! My 1.67 (Al) had an empty/dead pram battery when I got it. The big battery was also dead. I replaced the battery and after it was fully charged several times I took the PB apart again to replace the HDD with a SSD and it kept the time and date during the process (ca 1h disconnected from power)
 
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I replaced the PRAM batteries in a couple of G4 PowerBooks. One at least was a grey rectangular power pack that had to be detached from the PRAM housing. I had to Google around for a bare replacement. Other G4 PRAM batteries are of the coin variety that also are removed from the rest of the PRAM housing. There is no need to replace the whole PRAM unit.
 
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amagichnich said:
May be true, but the later PowerBooks definitely too! My 1.67 (Al) had an empty/dead pram battery when I got it. The big battery was also dead. I replaced the battery and after it was fully charged several times I took the PB apart again to replace the HDD with a SSD and it kept the time and date during the process (ca 1h disconnected from power)
Click to expand...

The later Powerbook G4s had a non-rechargable battery. In all Mac laptops, if the PRAM battery is dead, it'll use the main battery to keep the PRAM/clock alive.
 
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Intell said:
The later Powerbook G4s had a non-rechargable battery. In all Mac laptops, if the PRAM battery is dead, it'll use the main battery to keep the PRAM/clock alive.
Click to expand...

It looks like people have had different experiences with this.

All it comes down to is if you take the main battery out of a ‘book for some time (maybe an hour or more?) and it loses date and time then the PRAM battery is due for replacement, rechargeable or not.
 
Intell said:
The later Powerbook G4s had a non-rechargable battery. In all Mac laptops, if the PRAM battery is dead, it'll use the main battery to keep the PRAM/clock alive.
Click to expand...
Can't be true, sorry :D my PB proves the opposite. Wouldn't remember time and date when I got it, now it does
[doublepost=1517153781][/doublepost]Remember that?
Intell said:
iBook's don't have a PRAM battery, but all Powerbook G4's do except for the 12" ones. Starting with the Powerbook G4 550Mhz/667Mhz model, they have rechargeable lithium coin batteries. These only start to charge after the main battery is fully charged or is removed. They have a much longer usable life that the main battery. They can die, but it is very rare. Typically, when replacing one, you should always replace it with the same model battery for maximum reliability and safety.
Click to expand...
 
I haven't forgotten that iBooks and 12" Powerbooks don't have a PRAM battery. You also said that you replaced that battery in your Powerbook. That allows the logicboard board to use it to keep the PRAM/clock alive. The DLSD's had a rechargeable PRAM batter, but those in the middle of the Powerbook G4's run (not including the 12") do not.
 
Here is what I know regarding this particular PowerBook (17", 1.5GHz, A1085). First I'd like to remind everyone I do not have a main battery so if this is a factor then perhaps disregard everything to follow:
  • The system would not retain the date and time with the original (i.e. when that which came with the laptop upon my receiving it) NVRAM battery. I left the laptop plugged in for approximately 24 hours thinking it may recharge the NVRAM battery. After a power cycle I discovered the system still would not retain the date and time. Conclusion: The system doesn't recharge the NVRAM battery or the NVRAM battery can no longer hold a charge.
  • I ordered a new (as in brand new, not new to me) replacement battery. I installed it and experienced the same issue with the date and time not being retained after a power cycle. I pulled this battery and measured the voltage which read 130mV (or .13 volts, expected voltage is 3.7 volts). At no time did I leave the laptop plugged in in an attempt to charge this battery.
  • Since I had the original NVRAM battery out I measured it and it read 2.7 volts.
  • I contacted the seller of the new battery and he sent me a replacement. I measured the voltage of the replacement battery and it measured 80mv (or .08 volts). Since I measured the voltage before even attempting to install there was no attempt to charge this battery. I contacted the seller, returned both batteries, and received a refund.
  • I then purchased another new (again new as in brand new, not new to me) from a different seller. This battery was different in that it was not the dual coin configuration but a different type (single battery). This one wasn't as easy to measure and because as much I decided to just install it (after all I couldn't get three dead batteries could I?) Again the system would not retain the date and time. Frustrated I pulled the system apart once again and swapped the new battery for the original. I then decided to figure out a way to measure the voltage of this new battery and found a way to do so. It measured 10mV (.01 volts), almost completely dead. I contacted the seller, informed them of the problem, and he is going to send me a new battery this week.
  • At this time the original NVRAM battery is installed in the laptop and it's been plugged in to charge for the past 24 hours. A power cycle reveals the time and date are lost. This could merely be the original NVRAM battery will no longer hold a charge.
  • I am thinking of reinstalling the new NVRAM battery and seeing if it will charge. Having done it so often I can almost replace this battery in my sleep.
  • At no point did I every attempt to recharge any of the new batteries. I had no reason to believe they were rechargeable but I'm willing to give it a try. It might explain why I received three discharged batteries. But then again these are old batteries. Even new, old batteries could be depleted / unusable.
Since there's no clear consensus if this particular model will recharge or not I see no reason not to give it a try. If anything I'll install it, let it charge, and even if it doesn't retain the date and time I'll re-measure the voltage to see if it's increased at all.
 
Look at the numbers on the OEM coin cell PRAM battery. Look up that cell's model and it'll tell you if that cell is rechargeable or not. The commonly used PRAM battery Panasonic CGL3032 is a rechargeable one.
 
amagichnich said:
Nay, never have said that ;) I replaced the main battery and then the "dead" pram battery came back from the land of the dead
Click to expand...

You very clearly said that you replaced the batter in post number 13. When replacing the main battery, it will appear as if the PRAM battery works again. But in nearly all cases, it's just the PRAM/clock using the main battery as a power source.

amagichnich said:
May be true, but the later PowerBooks definitely too! My 1.67 (Al) had an empty/dead pram battery when I got it. The big battery was also dead. I replaced the battery and after it was fully charged several times I took the PB apart again to replace the HDD with a SSD and it kept the time and date during the process (ca 1h disconnected from power)
Click to expand...
 
OK, I have an update on this which might be helpful. I just swapped out the original NVRAM battery for the new one. The idea being that I am going to leave the laptop plugged in to see if it charges the NVRAM battery.

I decided to measure the voltage of the original NVRAM battery and I discovered it is now reading 4.17 volts. It appears that in this model PowerBook the NVRAM battery does recharge (it was at 2.7 volts the first time I took a voltage reading).

Which is both good and bad. Good in that I no longer believe I need a new NVRAM battery, bad in the fact it appears the NVRAM battery may not be the problem with losing the date / time settings. As this is the unloaded voltage it may be the volt drops when loaded and therefore results in the lost date / time. But a voltage reading of 4.17 volts leaves me with the impression that might not be the problem.

Since I've had the laptop I've always had to hold down shift-option-command to restart the laptop after immediately powering it down (I can leave it off for a day and restart it without having to do this). I was hoping the bad NVRAM battery was the cause of this but that may not be the case.

So, all that said I have the new NVRAM battery installed and the laptop plugged in to charge it. I'll give it a few days and report back. In the meantime if anyone has any theories of why the date / time may not be retained I'd love to hear them.
 
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