50g Backup Battery

[matalog]

I'm pretty sure that I changed the reserve battery in a 50g 3 months ago. Then I took out any AA batteries, and yesterday went to use it, and it asked to try to recover the old data, which it failed to do.

Does that mean that the 3 months completely drained the backup battery and I need to replace it again?

[Dave Frederickson]

Three months ago you replaced the backup battery and removed the main batteries. Then yesterday you replaced the main batteries and it failed to recover the old data.

According to the User's Guide the backup battery maintains the volatile memory while the main batteries are being changed and is intended to be used sparingly, not as the primary power source for the volatile memory while the calculator is in storage. So, yes, you need to change the coin cell again.

My recommendation if you are not going to use the calculator for an extended period of time is to backup your data then remove all the batteries.

Dave

[Vtile]

Yes the above. The backup battery circuit is extremely simple what I can remember... IIRC it was parallel with main batteries, not separate island powering memory chips (if any) only.

I suggest to use good quality modern "ready to use" NiMH cells, in your device if it is not a daily user. Those should be less prone to leakage than alkaline cells (which always leak when they are fully empty and chemicals start to eat the seals and body).

[franz.b]

I don't understand. I have several 50g units but every time one of them runs out of batteries the risk of total memory loss during battery change is very high, about 1 time out of 2. If the batteries are low enough to not allow the calculator to be turned on then it is almost certain that the memory will be lost, even if the battery is discharged for only a few days. I wonder what purpose this backup battery has if it cannot withstand even a short interruption of power. I think it might be safer to change the batteries while powering the calculator with a USB cable.
I use LSD rechargeable batteries such as Eneloop and other brands.

Thanks

[rprosperi]

(11-05-2024 11:30 PM)franz.b Wrote:  I don't understand. I have several 50g units but every time one of them runs out of batteries the risk of total memory loss during battery change is very high, about 1 time out of 2. If the batteries are low enough to not allow the calculator to be turned on then it is almost certain that the memory will be lost, even if the battery is discharged for only a few days. I wonder what purpose this backup battery has if it cannot withstand even a short interruption of power. I think it might be safer to change the batteries while powering the calculator with a USB cable.
I use LSD rechargeable batteries such as Eneloop and other brands.

Thanks

Most likely, your backup battery is simply low or dead. I have changed batteries in 50g's for years without ever losing memory, most recently just 2 days ago. Of course this can depend on how long the main cells have been dead and the unit's RAM has been maintained by the backup battery, if it has been months, perhaps this can happen, but it sounds like you use them enough that this is not the case.

[franz.b]

(11-06-2024 01:32 PM)rprosperi Wrote:  

(11-05-2024 11:30 PM)franz.b Wrote:  I don't understand. I have several 50g units but every time one of them runs out of batteries the risk of total memory loss during battery change is very high, about 1 time out of 2. If the batteries are low enough to not allow the calculator to be turned on then it is almost certain that the memory will be lost, even if the battery is discharged for only a few days. I wonder what purpose this backup battery has if it cannot withstand even a short interruption of power. I think it might be safer to change the batteries while powering the calculator with a USB cable.
I use LSD rechargeable batteries such as Eneloop and other brands.

Thanks

Most likely, your backup battery is simply low or dead. I have changed batteries in 50g's for years without ever losing memory, most recently just 2 days ago. Of course this can depend on how long the main cells have been dead and the unit's RAM has been maintained by the backup battery, if it has been months, perhaps this can happen, but it sounds like you use them enough that this is not the case.

My calculators are the ones in the signature, is it possible that it happens (randomly) on all of them? only the 39g+ seems to suffer less (but it doesn't have the buffer battery), the Casio does the same (but it doesn't have the buffer battery). the buffer batteries were checked months ago, they were good but I replaced them as a precaution without avoiding the problem

thanks for the feedback

[HP67]

You could save a backup on the SD card and not worry about loss of memory during a battery change.

[franz.b]

(11-06-2024 08:39 PM)HP67 Wrote:  You could save a backup on the SD card and not worry about loss of memory during a battery change.

It's become a habit of mine B)

[FLISZT]

Hello,

(…) You could connect your HP 50G to a PC (USB cable) just before changing the batteries.

[BruceH]

(11-06-2024 08:39 PM)HP67 Wrote:  You could save a backup on the SD card and not worry about loss of memory during a battery change.

And if you don't have a suitable (i.e. small) SD card then you can always save a backup to internal flash (port 2) as that will survive a loss of power.

[franz.b]

(11-08-2024 09:08 PM)FLISZT Wrote:  Hello,

(…) You could connect your HP 50G to a PC (USB cable) just before changing the batteries.

(11-14-2024 01:20 AM)BruceH Wrote:  And if you don't have a suitable (i.e. small) SD card then you can always save a backup to internal flash (port 2) as that will survive a loss of power.

Thank you all, they are all excellent solutions that I already use.
I was just wondering why use a polluting and expensive battery if I then have to use workarounds because it doesn't do its job well. I was hoping there was something to check in the software or some hardware failure.

[FLISZT]

Hello all,

(11-14-2024 08:31 AM)franz.b Wrote:  

(11-08-2024 09:08 PM)FLISZT Wrote:  Hello,

(…) You could connect your HP 50G to a PC (USB cable) just before changing the batteries.

(11-14-2024 01:20 AM)BruceH Wrote:  And if you don't have a suitable (i.e. small) SD card then you can always save a backup to internal flash (port 2) as that will survive a loss of power.

Thank you all, they are all excellent solutions that I already use.
I was just wondering why use a polluting and expensive battery if I then have to use workarounds because it doesn't do its job well. I was hoping there was something to check in the software or some hardware failure.

Indeed, my advice was rather obvious.
I could have added “Et voilà !” for a touch of humor...or not, you never know.

On a more serious note, I too have noticed that CR-2032 battery life seems rather short, even though I've never bought high-quality CR-2032 (pack of 8 from Ikea). After storing one of my HP 50G for about 1 (more?) month (without AAA batteries), I had more than one “Memory Lost” when I wanted to use it again.

Perhaps two CR-2032s would have been better but was there enough space? Or did the designers think that it was fine as it was, and that the possibility of using a USB cable and/or an SD Card provided for the weakness of the battery? We may never know.

[franz.b]

(11-18-2024 07:44 PM)FLISZT Wrote:  Hello all,

(11-14-2024 08:31 AM)franz.b Wrote:  Thank you all, they are all excellent solutions that I already use.
I was just wondering why use a polluting and expensive battery if I then have to use workarounds because it doesn't do its job well. I was hoping there was something to check in the software or some hardware failure.

Indeed, my advice was rather obvious.
I could have added “Et voilà !” for a touch of humor...or not, you never know.

On a more serious note, I too have noticed that CR-2032 battery life seems rather short, even though I've never bought high-quality CR-2032 (pack of 8 from Ikea). After storing one of my HP 50G for about 1 (more?) month (without AAA batteries), I had more than one “Memory Lost” when I wanted to use it again.

Perhaps two CR-2032s would have been better but was there enough space? Or did the designers think that it was fine as it was, and that the possibility of using a USB cable and/or an SD Card provided for the weakness of the battery? We may never know.

My guess is that when the calculator was designed the batteries were mercury and lasted a long time, in addition to being able to supply high currents when needed. Now that mercury is banned there are 2 topologies, alkaline or lithium. I consider the alkaline ones to be terrible, in my car remote control they last a month or so, the lithium ones a few months, the mercury ones lasted years... maybe the explanation lies here.

thanks

[rprosperi]

(11-18-2024 07:44 PM)FLISZT Wrote:  Hello all,

(11-14-2024 08:31 AM)franz.b Wrote:  Thank you all, they are all excellent solutions that I already use.
I was just wondering why use a polluting and expensive battery if I then have to use workarounds because it doesn't do its job well. I was hoping there was something to check in the software or some hardware failure.

Indeed, my advice was rather obvious.
I could have added “Et voilà !” for a touch of humor...or not, you never know.

On a more serious note, I too have noticed that CR-2032 battery life seems rather short, even though I've never bought high-quality CR-2032 (pack of 8 from Ikea). After storing one of my HP 50G for about 1 (more?) month (without AAA batteries), I had more than one “Memory Lost” when I wanted to use it again.

Perhaps two CR-2032s would have been better but was there enough space? Or did the designers think that it was fine as it was, and that the possibility of using a USB cable and/or an SD Card provided for the weakness of the battery? We may never know.

The purpose/role of the backup battery is to preserve the memory contents when the main batteries die long enough to let you install new main batteries. It is not intended to power the device and maintain memory for extended periods with no AAA batteries installed, so it's not surprising you had multiple memory lost episodes.

Also, given the important role these play, I would think you should use top-quality batteries from a proven vendor, but maybe that's just me...

[franz.b]

(11-19-2024 12:46 AM)rprosperi Wrote:  

(11-18-2024 07:44 PM)FLISZT Wrote:  Hello all,


Indeed, my advice was rather obvious.
I could have added “Et voilà !” for a touch of humor...or not, you never know.

On a more serious note, I too have noticed that CR-2032 battery life seems rather short, even though I've never bought high-quality CR-2032 (pack of 8 from Ikea). After storing one of my HP 50G for about 1 (more?) month (without AAA batteries), I had more than one “Memory Lost” when I wanted to use it again.

Perhaps two CR-2032s would have been better but was there enough space? Or did the designers think that it was fine as it was, and that the possibility of using a USB cable and/or an SD Card provided for the weakness of the battery? We may never know.

The purpose/role of the backup battery is to preserve the memory contents when the main batteries die long enough to let you install new main batteries. It is not intended to power the device and maintain memory for extended periods with no AAA batteries installed, so it's not surprising you had multiple memory lost episodes.

Also, given the important role these play, I would think you should use top-quality batteries from a proven vendor, but maybe that's just me...

Yes, I agree, but I have never used poor quality batteries or expected them to power the calculator for long periods. Memory loss for me occurs in the few seconds it takes to change AAA batteries.

[FLISZT]

Hello,

First of all, I have to say that I'm not complaining. The HP 50G is an excellent machine.
To avoid any memory loss, several solutions (already mentioned) are available: port 2, port 3 (SD-Card) and USB cable.

As for the CR-2032 batteries from IKEA, I strongly suppose they're not as good as Energizer batteries, for example. (According to the IKEA website, these batteries no longer seem to be available.)
However, the CR-2032 that saves time and date in my old PC (Win98 updated to Win98 2nd Ed.) lasts several years. It's not the same type of device as a calculator, but...

In an HP 50G, I don't know how the memory backup is divided between the AAA batteries and the CR-2032 battery. Does the CR-2032 ensure memory backup even when AAA batteries are present? This could explain why they are more than “tired” when it's time to change the AAA batteries.
What's more, it seems to me that the time and day are not saved when the calculator is stocked with only a CR-2032 battery.

Finally, the manufacturing differences mentioned by franz.b between the old CR-2032 and the current ones seem very interesting to me.

Just putting my 2 cents in.

[Eric Rechlin]

(11-18-2024 08:05 PM)franz.b Wrote:  My guess is that when the calculator was designed the batteries were mercury and lasted a long time, in addition to being able to supply high currents when needed. Now that mercury is banned there are 2 topologies, alkaline or lithium. I consider the alkaline ones to be terrible, in my car remote control they last a month or so, the lithium ones a few months, the mercury ones lasted years... maybe the explanation lies here.

I'm pretty sure this is completely false. As far as I can tell, CR2032 batteries have never had mercury. The platform the 50g is on was designed in 2002-2003, and CR2032 batteries definitely didn't have mercury then, and even alkaline batteries hadn't had mercury for quite a few years by that point.

There are lots of other formulas for batteries. Some, like the silver oxide batteries (SR44) that we like to use in the original Voyagers and original Pioneers, do still have mercury, but HP switched to lithium coin cell batteries instead of LR44 alkaline/SR44 silver oxide button cell batteries for new calculators in the 90s.

(11-20-2024 06:12 PM)FLISZT Wrote:  In an HP 50G, I don't know how the memory backup is divided between the AAA batteries and the CR-2032 battery. Does the CR-2032 ensure memory backup even when AAA batteries are present? This could explain why they are more than “tired” when it's time to change the AAA batteries.

I believe the CR2032 is only used when the AAA batteries are unable to provide sufficient power to keep the memory intact, but I'm not 100% certain. I've had the CR2032 last for quite a few years as long as good AAA batteries are kept in the calculator. If you are seeing very short lifespan of the CR2032 when good AAAs are installed, then either the CR2032 is defective or the calculator is defective. But if the AAA batteries are removed for several months, then it makes sense that the CR2032 battery could be drained. I don't think it was intended for long-term memory storage.