HP110 Battery (OK, it's not a calculator)


The HP110 may not be a calculator, but maybe someone can answer a dumb question or two...

1) The keyboard on mine is a bit dicky. Sometimes keys need to be pressed twice, sometimes they bounce and I get 2 or more characters. Is the keyboard accessable in a way that I can clean it? Any suggestions as to how?

2) The battery is (probably) completely dead. The 110 dies if left unplugged for more than about the blink of an eye. The battery appears to be held in with screws and a strap (with 3 connectors??). What is the battery (nicad, Lead acid, mice and wheel, other)? Any precautions on taking it out? Repair/Replace options?

The 110 is a personal favorite of mine. I used one *many* years ago, and I had to get one again. This is the first series with the 16x80 screen.

Interestingly (for us Australians) it has the inbuild modem that was not available in Australia (at least initially).


The battery is three D size lead acid cells (6V). It's not too hard to remove, but you've got to be careful about the earthing straps which are a little fragile (one of mine was torn).

Speaking of the earthing straps, they almost look like lead, but they're soft copper. I soldered a wire to the broken one after peeling the plastic back and scraping the coating.

However I still have problems with the keyboard.

Anyone opened one of these and cleaned the keyboard? Is it possible?


I might be talking to myself, but maybe someone will want to do this too some day...

Remove the battery first.

There are 10 screws holding the bottom cover of the HP110 on.

2 are shorter than the rest and are under the feet closest to the front.

The others are under the rear feet (2) under the plastic strips between the feet (closest to the front) (2) and under the large model number sticker (4).

Once you find them, the bottom comes off. There are 2 leads that must be removed. The HP-IL connectors can stay connected, they will come away from the top half.

4 screws (same as the long ones holding the cover) are removed to free the panel between the LCD supports. Removing this reveals that the hinges that an HP person told me were the result of much HP engineering effort are actually made by a third party. It also reveals 4 recessed nuts that must be removed to get the keyboard out.

I havn't yet got myself a small enough nut driver to do this, so the next episode will have to wait.

Questions: can I upgrade the RAM by piggy backing other chips?

Will I be able to clean the keys after I get the keyboard out?


Actually there's 11 screws (10 are hidden under things though)

The keyboard is labelled as being manufactured by Cherry. This is interesting because the PCB has an HP part number.

Even more interesting (once you get the keyboard out) is that the keycaps are easily removable, so you don't need to take the whole damn thing apart :-)

Oh well...

Anyway, with the key up, a sprung plastic cam holds a sprung contact apart. When you press the key the cam moves out of the way allowing the contacts to close. So pressing the key harder achieves nothing!

Possibly after so long, some of the sprung bits have become a little weak, so I removed the keycap, pressed the plastic post down, and gently pressed the contacts together with a screwdriver to sort of bend the spring into a more springy position. Voila! key works perfectly. No bouncing or failure to make contact.

As for adding more RAM. Well, maybe I'll persue this for interest in the future. I don't think I'll do it, but it would be interesting to see if it's possible.

When the unit is opened, you can see one part of the motherboard, but there is another layer of it under a shield. I didn't look in there, but maybe the board even has pads to place more RAM?

I like the 110 almost as much as I like my HP41's :-)

But I wish David Chambers didn't mislead me as to the manufacture of parts of the HP110 those many years ago when he was demonstrating it to me.

Anyone else (in Australia) remember David Chambers? Nice guy, but a bit fond of Safari Suits for my liking. :-)



Replacement HP-110 batteries are available (apparently, I mean to order one) from http://www.batteries.com. Use this URL to go straight there:



I've just been told by batteries.com they won't ship outside the USA, so one would need an agent in the US to forward the mail on.


Where are you? The cells that make up the HP110 battery are easily available in Australia.

Probably the same wherever you are.


I'm in the UK. I've not identified a UK source yet.


Check this link out:


A bit (I jest - A LOT) expensive, but a solution.

Do you have an old battery pack? The top detaches from spade connectors at the top of the batteries. The top bit is REQUIRED (so don't lose it).

The battery is simply 3 D size 2V lead acid cells. I'm still searching for a reference to them on the net.

Amazing... Here's a reference to a UK supplier with a picture of them on their web page.


Described as "2 volt 2.5 Ah Cyclon 180g £5.30" (and you need 3 built up into a pack). So that would be at least £19.90 (as they charge a minimum of £4.00 for postage).


Laurel Drive,

Rugeley Road,


Staffordshire, WS7 9BL


Telephone (+44) (0) 1543 683122

Ain't the web wonderful :-)


Excellent. Thanks very much. For some reason my own web searches didn't reveal what your's did.

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