Battery in battery operated HP-IL Thinkjet 2225B

[hesc]

Dear all,

I am revitalising my HP collection and try to bring life to my battery operated HP-IL Thinkjet 2225B. It is fed by a dead rechargeble battery. I assume that it is also a 4.8 V battery, as it is charged by the same power supply as the batteries in the small thermal HP-IL printers and the digital tape drive. What I read in another thread was that the connection near the centre of these batteries is the positive one, and indeed, I used a DC power supply to feed the digital tape drive in this way.
However, the look of the battery of the Thinkjet is different. See picture in the attachment. Does anyone of you know if the middle connection in this battery is also the positive voltage one?

Thanks again for replying.

Henk Schellen

[BitWiz]

The center contact is the Negative contact and the side contact is the Positive contact.

I just rebuilt my thingjet 2225B battery pack. It takes six sub-c cells in series. There is a fuse between the battery and the external contact. Since I didn't have an original battery pack to work from I connected a 5A quick blow fuse in series with the Positive contact.

I believe the original pack had the fuse between two of the cells.

The battery case is easy to open. I have attached a picture of my refurbished battery pack (opened).

Please feel free to contact me if you have any questions.

Mike

[Dave Frederickson]

NiMH cells also work. Get the cells that already have tabs spot welded to them.

[BitWiz]

I would not recommend NiMh cells because the charging circuitry in the printer is very primitive and designed for NiCd

[Dave Frederickson]

Ever notice how NiCd chargers work with NiMH? It's because the charging circuits are nearly the same. Some smart chargers, like the MH-C9000PRO, can even perform a "forming" charge at 0.1C.
Note: Most of the "charging circuitry" in the battery pack is for converting the 8 VAC from the wall wart to 7.2 VDC.

The issue is that it takes a long time to slow-charge high-capacity cells using the wall wart. For that reason I prefer to use a smart pack charger, like the Tenergy 01006.
https://www.tenergy.com/01006

[BitWiz]

(03-15-2024 01:24 PM)Dave Frederickson Wrote:  Ever notice how NiCd chargers work with NiMH? It's because the charging circuits are nearly the same. Some smart chargers, like the MH-C9000PRO, can even perform a "forming" charge at 0.1C.
Note: Most of the "charging circuitry" in the battery pack is for converting the 8 VAC from the wall wart to 7.2 VDC.

The issue is that it takes a long time to slow-charge high-capacity cells using the wall wart. For that reason I prefer to use a smart pack charger, like the Tenergy 01006.
https://www.tenergy.com/01006

The issue between NiCd and NiMh is more of a life time and optimum charging. Though NiMh cells don't have a shelf like NiCd's do. If they are not periodically refreshed (full discharge/recharge cycle) their life is shorter.

I prefer to use the type of battery the charger was designed for, rather than "well it will work".

The 2225B charging circuit, it not much more than a rectifier and regulator.

In the HP battery packs that I make or refurbish, I choose to use NiCd because that is what the original engineers used and is most compatible with the original HP chargers and power supplies.

[hesc]

Dave and Bitwiz,

Thank you for your reply. In the meantime, I also opened the case and came to the same conclusion.
I used a power source of 7.2V to see if the printer came alive. It did.
I only had a short part of paper to test and the printer head is moving when I gave printer statements over HPIL. An ink cartridge costs about €20, but I can only buy paper by 1000 parts for about €50. That is rather expensive, only for testing.
Do you have any experience on the chance of a working printer head after 40 years of drying out?

Kind regards,
Henk

[Don Williams]

I can tell you my experience with these printers. The ink that HP used in those cartridges is corrosive. In about 90% of the printers that I have seen the ink has ate through the conductive traces on the flex ribbon around the print elements. A really difficult problem to repair. I would disassemble and thoroughly clean that ribbon cable and print head, then check for continuity on those traces first before proceeding to spend money on supplies.

[BitWiz]

I bought one on ePay recently.

It has no case screws and it looks like a cartridge leaked in it pretty badly.

Windex cleaned up the ink perfectly. After the inck was all cleaned up, I cleaned the rest of the printer (inside and out) with 99% Isopropyl Alcohol (IPA). I purchased a new ink cartridge from Amazon (https://www.amazon.com/gp/product/B00000...UTF8&psc=1) and I am using regular single sheet paper for now and it's working perfectly.

You shouldn't need to clean the cartridge contacts with anything more than alcohol but you can use deoxy if it is really bad.

I have not experienced the flex cable being damaged but that is only my experience.

IMHO it's worth a $10 cartridge to see if it works or not.

Do not attempt to use old cartridges. These cartridges have a shelf life. They will not work properly and can rupture if too old.

Also, current cartridges for the thinkjet can print on normal paper.

I would also like to buy some fan-fold (z-fold) paper (whether inkjet or not) but like you I don't want to pay the price for something I'm not going to use every day.

I'm also trying to find one of the 922615S (or some other kind of bottom feed stand for it.

Enjoy your thinkjet, they are great little printers.

[Don Williams]

See this video for the type of damage I described in Thinkjet printers.

[url=https://www.youtube.com/watch?v=eUmBRMlxDZo][/url]

[Dave Frederickson]

(03-15-2024 09:36 PM)BitWiz Wrote:  I would also like to buy some fan-fold (z-fold) paper (whether inkjet or not) but like you I don't want to pay the price for something I'm not going to use every day.

A case of fanfold paper is available here: https://www.hpmuseum.org/forum/thread-14...#pid183460