Detailed Guide on Refill T802 / T802XL Cartridge and Reset Cartridge Chips

The Mechanism

Contrary to many people's beliefs, an Epson printer can't measure how much is ink left in a cartridge.  Instead, the printer uses a computer chip on the cartridge to track how many pages have been printed.  For example, if a cartridge is able to print 1,000 pages and it has printed 500 pages, then the printer's ink gauge will show that it is half-full.  This is the reason why many people who refill their cartridges and find the printer still think the cartridge is low on ink or empty.  Therefore, our goal is to put the printed page back to zero after a refill, so the printer will read a full tank.

Traditionally, we have two ways of doing this.

1. Resetter.  A resetter is a device that writes "Page=0" forcefully to the Epson's OEM chip.  Therefore, the reset time is controlled by us (active reset).  However, we must do this before the ink level drops down to 15 %.  Once the ink level is low (with a triangle warning sign), our chance of resetting decreases dramatically.  At the end, when the cartridge monitor shows depletion (red cross), the reset is not possible anymore.

2.  ARC chips.  ARC stands for Auto Reset Chips.  The chip is not made by Epson.  The chip is rolling a continuous loop of page numbers.  Once it reaches the maximum, it rolls back to zero.  Just opposite to the resetter, we cannot control the reset time.  The chip will display low ink warnings and then depletion (red cross).  Once it reaches depletion, it will roll back to full tank level.  As a result, the printer will be confused and display "the following cartridge cannot be detected" because the printer will not understand how we have a full-tank without changing the cartridge.  Therefore, once we see this error, we will simulate a cartridge-changing event, taking the cartridge out and putting it back.  Then the printer will be happy to work with a full tank of ink again.

The Problem

Epson found out about this and put a serial number and an encryption on their chip.  Now, instead of "Page=0," the new models will say "Serial=1234; Page=0.”  With encryption, the information becomes "pBP9iG/uYryZp04vqYObbFOH4h/WXK4myllFZ8zNm6U=.”  There are two things that are significant about this:

1. We can't understand (and thus can't change) the word anymore.

2. Even if we understand it, the printer remembers the serial and can only control the page going up.  Therefore, even if we can set Page=0, the printer will still remember that cartridge 1234 had the highest page reading, say 1000 pages, so it will still think the cartridge is empty.

We don't really believe Epson's claim that this method is to protect the printer from running out of ink.  A set of OEM 802XL inks costs $110, but the WF-4720 printer is $99 on sale at Office Depot.  The cartridge contains about $15 worth of ink, but the printer should be worth considerably more than $99.  Currently, there is no refill solution for T202, T220, T410, T288, T702, or T802.  If we accidentally buy any Epson on the market, we are stuck with their expensive cartridges.

Current Solution

If we search online, we will see third-party "remanufactured" Epson cartridges for these "non-refillable" models.  They are selling these a little cheaper than the OEM cartridge.  For example, a set of remanufactured 802XL costs about $85.  How did they "remanufacture" this set?

First of all, the set contains new cartridges.  Because Epson has the copyright on the shape of their cartridges (Yes, the Epson copyrighted rectangle), these third party manufacturers can't have the exact shape as Epson's.  Also, there are two lawsuits that consumers won: 1. consumers have the right to refill their cartridges.  2. printer manufacturers cannot stop consumers from refilling their cartridges.  Therefore, the result is the third party manufacturers call their new cartridges "remanufactured" to avoid copyright issues, and Epson says their chip is not to prevent refills but to "prevent the printer from drying" to avoid lawsuits.  Furthermore, Epson is known for adding code to their "update" to kill off third-party cartridges, so we should turn off the automatic update on the printer.

Secondly, the manufacturer doesn't have to decrypt the string.  Instead, they can just copy the encrypted string from a new cartridge and put it on a new chip.  The printer will decrypt it as "Serial=1234; Page=0" and will show a full tank of ink.  

A problem with this cloning method is the collision.  For instance, this would occur if a cartridge with serial 1234 was used until depletion.  The maximum page number is 1000,.  If we buy a cartridge from another seller, which happens to have the serial 1234, then even if the new cartridge has the Page=0, the printer will still use the page count 1,000, and thus show an empty tank.  To avoid this, there are serial banks that collect tens of thousands of such encrypted strings.  The manufacturers will buy them and rotate them randomly on their chips.

BCH Solution

Because of the encryption and serial numbers, we cannot loop the page number anymore.  We don't want to make a one-time use cartridge which violates Epson's copyright either.  Therefore, we made a refillable cartridge, designed differently than Epson, and we rotated the encrypted string.

As a result, the regular third-party clone will have a string, saying: "pBP9iG/uYryZp04vqYObbFOH4h/WXK4myllFZ8zNm6U="  in a cartridge, and we can use it one time.  BCH puts four rotating strings on a chip, so once the "Serial=1234; Page=0" is used up, it rotates to "Serial=1235,Page=0."  In theory, each cartridge can be used four times, unless we have a serial collision.  We try to get numbers from the largest serial bank but unfortunately, the largest also contains the most popular ones.

Thus, buying one set of BCH 802XL cartridges is like buying four sets of Epson or third-party cartridges.  Because we cannot control the serial collision, we will not accept returns because one or more of the resets is not working.


To demonstrate how a BCH chip works, we will use an Epson WF-4720, using 802 cartridges.  We will unbox and initialize the printer with the starter cartridge.  In order to test if this solution works with the most recent firmware, we will update the firmware to the newest version, but we will suggest that our customers turn off their updates.  After that, we will use a BCH 4-Cycle 802XL cartridge and print until its first reset.

Ink types:

Because our cartridge is a high-capacity, XL version, the black is supposed to print 2,600 pages, so we will try some fun experiments with ink type switching and unclogging.

The Epson OEM uses pigment ink, which is waterproof and UV proof but expensive. It is also a little weak on printing pictures and very hard to unclog.  As an alternative, dye ink is not waterproof and UV resistant, but it is cheaper and easier to unclog.  In fact, if you buy third-party cartridges, you may be converted to dye ink already, without your knowing about it.  

There are many horror stories about "don't use dye ink in a pigment ink printer."  Actually, it is safe to use dye ink in a pigment ink printer but not the other way around.  We shouldn't use a mixture of dye ink and pigment ink and therefore the conversion is most likely to introduce clogging.  However, after we deal with the clogging and have a successful conversion, we should enjoy dye ink printing without any problems.  We often tell our clients that if we want to refill a printer, we should know to unclog it first.  

Our plan:

To test this, we designed the process that gives the printer the most shock by switching completely different ink types.  We hope to clog up the printer so we can practice our unclogging skills.

Epson OEM Ink-> BCH Standard Dye ink

BCH Standard Dye ink -> BCH Pigment Ink

BCH Pigment ink -> BCH Premium Dye Ink

BCH Premium Dye ink -> Epson ink

There are other things we want to demonstrate:


To avoid air bubbles from the first use of a refillable cartridge, we can draw some ink from the bottom.  We can accomplish this by using a special priming tip or modifying a syringe.


We will use the printer's built-in function to run cleaning cycles twice and then wait two hours before we do two more cycles.  After that, if the clogging still exists, we will use a tool to flush the printhead.  We will discuss further deep cleanings in other articles.


We will show the first reset of the cartridge.

Jul 6th 2019 BCH Technologies

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