9114B battery replacement: equivalents?


Hi, all;

I am trying to organize my equipment after leaving them almost 8 months without being touched because of many reasons (only a few daily-use calculators). Now I see that the 9114B battery pack is barely able to move the disk drive´s head when it is turnned on.

In all of this ´resting´ time, I left the battery pack in charge for at least once a month for keeping the battery with the nominal charge. Now I left the battery pack in charge for more than 12 hours so it can make the drive´s head move, but the three power indicator LED´s simply go off if it tries to read any disk (DIR command), and I get [TRANSMIT ERROR] in the HP41 display. If I remove the disk and try [DIR] again, I get another message about the medium (no medium or medium error, I don't recall).

Maybe I'm wrong, but I understand that the TRANSMIT ERROR message in the HP41 display may be caused by a reset in the driver (and consequent communication loss) if the battery voltage goes low enough so the 9114B is reset when the main driver motor is turned on. Also, the medium error message instead of transmitt error when no disk is inserted on it corroborates my reasoning. Is there any other way to see this? I'd sadly accept a final word of R.I.P., but I'd like to be sure it is definitely bad. Also, should I try another power supply instead of the original batery pack? In this case, what are the recommended procedures to deal with the internal sealed battery? I thought about removing the sealed battery from the battery pack and charge it outside, but I would like to hear from you about the current values and monitoring.

Any guidance? Suggestions?

Thank you all.

Best rewgards.

Luiz (Brazil)


Hi Louis,

Had about the same with my 9114A. I opened the batterypack, there is a simple lead battery inside. You can simply replace it. The original pack is the Panasonic LCR-226P (6V, 2.4Ah).

For testing if this is the cause take a stabilisid PSU capable of delivering 3 Ampere (peak currents when staring up) and test. Alternatievly take 4 normal batteries of 1.5 volt and connect these.

By the way, did you do a pwrup command first before accesing the drive, in my case this was mandatory to get it working after being switched off.




Hi, Ronald;

thank you for your suggestions. I thought about going straight buying a new battery and replace the one in the battery pack. I`ll follow your suggestion, thank you.

About the PWRUP command: this 9114B I have with me (thanks, DM) worked perfectly fine about seven months ago. I don`t recall needing to use PWRUP to activate it. Anyway, I tested both PWRDN and PWRUP to see its reaction, but it remains the same 'no read disk' state.

I`ll go for the external package for a testing tomorrow and post results. In the meantime I`ll also try to externally check/charge the LCR-226P. Have you done this before? I know it is a sealed, high-current battery and I`ll take the necessary pecautions, and I`ll try to keep a 1/10 to 1/8 nominal current for charging. Should I use other figures?

Thanks again.

Luiz (Brazil)



I charged it with 0.3 amp (10% - 15% of capacity) and keep a watch in the time. Normaly 130 - 140% should be sufficient.
In this case 2.2 A/h capacity * 130% = 2.9 Ah needed. 2.9/0.3 --> 9 - 10 hours needed for a new accu.

In the case of the old accu I would feel it every now and then but on the other hand 0,3A * 6 volts is only 1.8 watt, so temperature should stay more or less acceptable.
Please note that it is a sealed Lead accu and unlike the ones in a automobile not vented, so keeping the temperature down is important.
Funny by the way you only had to a pwrup once, I need to do it every time (maybe a difference between the a and b model ?).



The first 9114B I got came with a AC/DC converter with 6V/2A output. This fed into the battery case, which was suspiciously light. Opening it up, I saw that the converters DC leads were wired to a fairly large capacitor (10000 uF, 10V) in parallel with the inputs to the disk drive. This obviously serves as a voltage regulator. If you open a standard battery pack, you'll see fair amount of electronics inside that must amount to the same thing. (Regulated DC 6V/2A) The battery in the standard pack actually says 6V/2.5A, but the lash up with the AC/DC converter works fine for me.

Here's a picture:

Edited: 3 Aug 2005, 11:33 p.m. after one or more responses were posted


re: "in series with the inputs to the disk drive"

For the sake of anybody who tries to copy this scheme, I think you mean "in __parallel__ with the inputs ...."


Yes, you're right. I've corrected the parent. Thanks.


Hi, all;

thanks for your valuable suggestions. I`ll go ahead trying an external power supply (as I mentioned in a recent post here) and see if the rechargeable pack is in trouble. I`ll also try to charge the LCR-226P externally. Any additional suggestions of yours? Anyone else?

Thanks for the enlightening picture, Howard. Just let me understand: your unit comes with an external, regulated power supply and a battery pack case with a single 1000µF/10Vcc capacitor inside? I mean, your 9114B with these components can only work when plugged in the AC outlet? Did I take it correctly? If so, that's interesting!

I remember reading about this possibility that was proposed by someone here about one year ago and I was not aware it was actually done somehow.

Best regards and thanks again.

Luiz (Brazil)

Edited: 4 Aug 2005, 2:37 a.m.


Yes, that's right. The external supply is an AC/DC transformer with a sticker that reads "Personal Software." (I seem to recall that they were an HP dealer back in the day. If that's so, then I suspect this modification may have been made back in the 1980s.) The transformer is labeled "6V/2000mA". Since it works fine, I haven't measured to see if that's what it's putting out.

This is actually my only working power system for the 9114 drives, though I have four (!) drives that work otherwise. (These have been picked up in combination with various other bits of hardware.) I have one dead battery pack which I want to refurbish with a new battery. But the other two drives need a hack like this one in order to work independently. The tricky bit there will be the connector on the drive side of the pack.


Good evening Luiz,

I have encountered the same issue than you with the 9114B battery pack.

If I remember well, Tony Duell uses his 9114B directly with his bench PSP.

I found the following threads might be interesting to you :

Using the 9114B without the bulky, old, ugly polluting lead battery

Retiring 9114B battery pack once for all

Hope they help you as much as they helped me.

Solutions were provided by Tony Duell and Dale Richmond.

Warm regards from France!



Hello, Etienne;

merci beaucoup, mon ami! The threads were full of important information.

Best regards.

Luiz (Brazil)


You can run a 9114 (either version) off an external 6V power supply. I often run mine off my bench power supply, I also made up a PSU (just transformer + rectifier + smoothing capacitor) for an HPCC member. The supply should be around 6V, capable of supplying at least 2A, and doesn't need to be regulated.

You connect it to the 2 pin mini-jones plug inside the battery compartment at the back of the drive. I forget the polarity, but if you open up the drive unit and look at the wiring on the back of the plug, then red is +ve and black -ve as usual.

For testing you can also connect the same sort of PSU to the wiring inside the drive (this is easier if you don't have the mini-Jones socket). Connect the -ve side to the drive mechanism metalwork, and the +ve side to one of the wires on the back of the on/off switch. If you use one of the wires, you bypass the switch, the unit is powered up all the time. If you use the other one, then you have to turn the 9114's switch on

The battery pack opens easily (2 Torx screws on top). Inside is a charger PCB and a lead acid battery block. If you can't get the right replacement for the battery, you can use 3 2.5Ah Cyclon cells in series, connected to the wires that go to the original battery. These fit perfectly into the housing.

Schematics for these drives (including the charger PCB) are, as usual, on the HPCC CD-ROM


...I'm putting my hands on a sealed, 6V, 2800mAh battery by tomorrow. I don't know the brand, but it seems it will be the replacement I have for now.

As I have it, I'll take a picture and post.

Thanks again to all of your support, guys.

Best regards.

Luiz (Brazil)


Hi, all;

The person who assured me he had a sealed 2800mAh battery had, in fact, a 1300mAh. I took it anyway and asked for another, 2500mAh or more. As I`m waiting for a new one, I decided to test the 1300mAh and I assembled it in place of the original 2400mAh battery. The fact is that the 9114B is actually working fine. I simply plugged the newly bought battery, connected the pack in the standard charger and inserted the battery pack in the 9114B battery compartment. The three LED's that indicate the battery charge did not even blink when the unit was turned on, all three LED`s on as well. With the HP41 connected to the 9114B (HPIL), one disk in place, I XEQ`ted DIR and the contents list was shown perfectly fine. As the battery is new, I accepted the mid-charge (two LED`s on, upper LED off) monitoring. Also, as the battery is about half the `ampacity` (sorry, no better word for that... anyway, what is the word for ampère capacity?), I must expect more charging cycles and a continuous check for temeperature while charging (higher charge current than the one specified as nominal). Well, at least I`ll keep it for necessary operation while some 2500mAh battery comes to take place.

Hope this is all for now. I`ll take a picture of the battery pack with the new 1300mAh battery inside of it later.

Best regards and thank you all, again.

Luiz (Brazil)


For topics that are certain to have been covered in the past (e.g. HP41 card reader repairs, floppies for the 9114, batteries, etc.)
it is best to quickly search the archives. I find the best way to do this is to use the google search facility.

Go to www.google.com and type the following string

site:http://www.hpmuseum.org 9114 battery

and google will return only the results from the web site in the site: directive. This is fast and convenient.

Try it.



Hi, all;

as promissed:

Click to enlarge

I added a small piece of transparent plastic to help isolating the battery contacts from the PCB surface. This piece o'plastic was cut from a regular calculator blister (I have found many usefull applications to those blisters...).

Data printed in the battery case is in Portuguese, but the main facts are:

fluctuation: 6.8 to 6.9 V

charging: 7.2 to 7.35 V

Starting current: .52A (max)

additional data refers to necessary care (no short circuiting, do not dispose with regualr trahs, return to the supplier instead of throwing away, etc.).

As I mentioned before, I`ll use this pack when it`s necessary till I find the correct replacement. I am aware of the fact that under regular use, it will demand at lest twice the number of charging cycles when compared to the origianl (1300mAh against 2400mAh).

Beest regards.

Luiz (Brazil)

Edited: 6 Aug 2005, 8:09 p.m.

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