Backing up battery in HP48 ram card
vmo
How the memory cards are working in HP48GX ?
I have a TDS 512kB GX ram card with an internal battery (I hope the
battery in inside the card, I guess it cannot be replaced without
brutalising the card), and the card is located in slot 2. Are the
calculator batteries charging the back-up battery while the power is
switched off in the calculator. I wonder how long the back-up battery
will work without powering on the calculator. This card cannot be very
new but its battery is still working.
regards,
vmo
Nate Eldredge
Page A-8 of the HP48 User's Guide (available at
http://www.hpcalc.org/hp48/docs/misc/hp48gug.zip if you have lost your
copy) says "RAM cards run off the calculator batteries only while the
calculator is on," and instructs you to change the card battery with the
card inserted and the battery turned on.
The cards described there use a type 2016 coin cell. I looked these up
on Duracell's web site; they use a lithium-manganese chemistry, and have
a quite long life; they specify "capacity retention of over 95% after
five years at room temperature". But they are not rechargeable.
My wristwatch uses this same type of battery. The last one powered the
watch for 3-4 years, and a watch probably draws considerably more power
than a RAM chip (the watch has an LCD display, a microcontroller, a
crystal, some buttons to scan, and a backlight and a beeper that are
used occasionally).
So it's entirely plausible that your battery would last a long time.
The HP48 manual suggests that the card batteries should be replaced
yearly, but this may be paranoia on their part, or a kickback from the
battery manufacturers ;-)
vmo
Thanks Nate for your responce
The card I own has no replaceable battery, so I wonder how to change it
in future if needed (or is it needed)
/vmo
Mike Bryant
> in future if needed (or is it needed)
> /vmo
I have the same card in my HP 48-GX and yes, it has a replaceable
battery. It's a CR2016 coin battery available just about anywhere in
the US (Walmart, Radio Shack, etc...)
To replace the battery, turn the 48GX ON and then turn it around
making the port cover (the cover thingy on the top end of the
calculator) easily accessible. Remove the cover so that you can now
access the cards. The port 2 card will be the one on top of the other
(port 1) card. In other words, the TDS card will be the card you see
on top (my TDS card is a weird blue/green color - mold maybe? lol).
The very tip of the card (next to the read/write switch) has a kind of
lip that you can slip a fingernail under. Slip a fingernail under it
and gently slide it away from you, toward the top of the calculator.
The battery will be in a sort of 'C' shaped holder. Note the polarity.
The + side will face the back of the calculator. Replace it with a
fresh battery and slip it back into it's holder, then back into the
card. The calculator must be ON during the entire process or you will
lose everything in it.
I hope you can follow my instructions, and good luck!
Joe Horn
battery in it, and one with a removeable battery. The rechargeable
one looks like the 1-Meg TDS card shown here: http://www.hp-collection.org/memory.html
SMI also made a rechargeable HP-48 card, with a "ten year battery" in
it... that dumped all your data 60 days after last recharge.
To answer your question, rechargeable HP-48 RAM cards only get
recharged when the HP-48 is actually turned on.
-Joe-
John H Meyers
> The card I own has no replaceable battery,
> so I wonder how to change it in future if needed (or is it needed?)
See:
http://www.tdsway.com/support/knowledge_base/survey_pro/on_the_hp_48gx/general_tips/KB704
Excerpt:
The older cards had a replaceable battery
that could be replaced once a year
to keep a full current running through the card.
These cards are no longer available
and have been replaced by RAM cards
that have a non-replaceable battery
that must be charged in the 48GX
to keep a full current running through the storage media.
The 48GX must be turned on for the charging process to work.
If your 48 is not used regularly,
your RAM card will have insufficient power
to maintain data integrity.
This is the main cause of data loss.
It only takes approximately 30 days of inactivity
for a fully-charged RAM card to lose data.
The following procedure can be used to set an alarm
to wake the 48GX up [every 5 minutes] to keep the RAM card charged,
or just prior to use if the card has been inactive for some time.
This procedure takes at least 24 hours to charge a card for use.
[...]
Example of card with built-in battery
(will disappear about 60 days after sale on eBay):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180363918959
No read/write switch, either?
[r->] [OFF]
ekep...@gmail.com
----
Maintaining data integrity on the 48GX
The 48GX is a reliable platform for collecting and storing your survey data. However, data loss can occur under some circumstances. Following the recommendations outlined in this document will help prevent the possibility of data loss and minimize the negative impact should data loss occur.
Download the data from the RAM card daily. Download to a laptop, or external storage device. In a worst-case scenario, the most you should ever lose is one day’s work.
Keep RAM Card 0 battery charged. The older cards had a replaceable battery that could be replaced once a year to keep a full current running through the card. These cards are no longer available and have been replaced by RAM cards that have a non-replaceable battery that must be charged in the 48GX to keep a full current running through the storage media. The 48GX must be turned on for the charging process to work. If your 48 is not used regularly, your RAM card will have insufficient power to maintain data integrity. This is the main cause of data loss. It only takes approximately 30 days of inactivity for a fully-charged RAM card to lose data.
The following procedure can be used to set an alarm to wake the 48GX up to keep the RAM card charged, or just prior to use if the card has been inactive for some time. This procedure takes at least 24 hours to charge a card for use.
Install new AAA batteries in the 48.
Hit right shift, then "4". This will bring up the 'Browse Alarm...' options box.
Select 'Set Alarm..., and confirm that the time and date of the alarm is set in advance of the current time, since the default value for the time field is the currently set time on the 48.
Toggle down to the 'REPEAT' section, which will display ‘NONE’, and choose 'Edit' from the soft key menu
At the arrow prompt, enter "299". The next prompt will be for the unit of time. Select ‘ Second’ from the CHOOSE menu.
To edit the alarm, select 'Browse Alarm...' from the main menu, then ‘Edit’ the specific alarm. To delete the alarm after it has served its purpose, highlight the alarm, then select PURG from the soft key menu.
Keep RAM Card clear of electro-magnetic fields. The RAM card is susceptible to electro-magnetic fields i.e. magnetic prism bases, high power lines, etc.
Protect the RAM Card from the environment. This primarily refers to dust and moisture but can also include extreme temperatures.
Keep job point numbers and point gaps schemes in control. It is possible to overflow a RAM card under some circumstances, such as by setting your first point as point 1 and the next point to 10,000 or some other large number. Since the 48GX can only store data in sequential format, the 48 will attempt to allocate 10,000 memory storage blocks to hold 10,000 points and thus lock a card out of free memory. A card with this problem generally cannot be recovered. Large point gaps can also cause problems for file transfer as well.