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Prepaid Meter FAQ

How does prepaid differ from pay-as-you-go?

Prepaid Meter Pay-as-you-go
Application Most are used for collection by utilities Most are used as school dorms, classrooms and other large shopping centers
Form factor The meter itself has a slot for the smart card The meter and smart card unit are separate devices, the meter is locked inside the power panel and the smart card is placed in a place accessible to the tenant.
Card insertion The smart card is inserted into the meter The smart card is inserted into the smart card unit.
Tariffing Similar to a parkting meter, the entire amount on the smart card is transferred to the meter. Similar to a phone card, pro rated, pay for the amount that you use.
Billing by kWh by cash value

How does one add credit to the smart card?

By using a handheld value adding device, the ICR815W, whether for kWh or cash, just enter the desired value.

What are the qualities that make pay-as-you-go better than prepaid?

  1. For applications such as classrooms, school dorms and labs, when the tariff rate can vary greatly from being a regular fee to being a perquisite.
  2. With pay-as-you-go, the same card may be used in many different places as it only charges as much one uses, but with prepaid, the entire value is deducted from the card, making it impossible to be used on demand, making it a non-portable.
  3. For the same classroom, stall or other spaces, at different times of the day different people will be using the place, with pay-as-you-go, it is user pays. But with prepaid it is impossible to share the cost in this way.
  4. With pay-as-you-go, as the meter is kept separate from the card reader, the meter is in a secure location that cannot be tampered with and makes the system less susceptible to being defrauding. The user can still see the remaining value at any time. When the prepaid meter is placed in the same room as the user, then it is easy for the wiring of the meter to be tampered with. When the prepaid meter is placed outside of the room where it can be easily be watched over, the meter value cannot be seen. Either way, it can be inconvenient to either the landlord or tenant.
  5. The pay-as-you-go has the option of being linked to a central computer through its communication port, or even be used as part of a demand response solution, there is no such option for the prepaid meter.
  6. The card slot is the part that is the most subject to wear and tear, with the pay-as-you-go, the card reader can be replaced without affecting the meter portion, but with the prepaid, the entire unit must be replaced.
  7. The remaining value is carried on the pay-as-you-go smart card, thus it is easy to refund the value by simply turning in the card. It would be extremely inconvenient to do the same with the prepaid system as the entire value is stored in the meter itself.

What are the advantages of prepaid?

  1. Low cost
  2. Easy to install and wire up, simply replace the original meter.

What are the different value adding methods?

  • Method 1: Selling the cards at the POS
    The cards are collected and the value added all in one swoop, so each card would have a predetermined amount. The cards are then handed to a sales clerk that will sell them at a point of sale. The value adding process is managed from one secure location. The cards with pre-added value with one or more denominations are then handed over to the sales clerk at the point of sale. At the POS, the clerk has a device that can check the value remaining on the cards, but with no ability to add value. When the value on the card has been used up, the customer can return it in lieu of a deposit on the card.
  • Method 2: Adding value at the POS
    With this method, the clerk at the POS will add the desired amount to the card. The value adding device records the transaction within itself, which can be audited later by uploading the data to a computer. Often the auditing process is aided by cross checking with the paper receipt. There is also the option of having the value adding machine linked with a computer. To insure greater security, the device should be enabled only using the key card in the presence of management. In other words, the value adding device would still be useless even if it were stolen without the key card to first activate it.
  • Method 3: Vending Machine
    With this method, a vending machine is placed at a convenient location. The process is as follows: the tenant inserts the card, puts in the desired exact amount of cash to add (no change is provided), the value is added to the card, the user removes the card. The vending machine keeps a record of all the transactions which can be downloaded later for auditing.

With the pay-as-you-go meter system, how does one insure that cards meant for a different unit cannot be used?

It is only logical that each landlord/manager would want to have their own set of smart cards that cannot be used with another landlord/manager, and vise versa. Thus there must be a way to insure that cards within the same family be compatible within itself but not with other families.

To achieve this end, when the smart card unit is first installed, it must go through a special process of imprinting that would tie that unit to only one family of cards. To do so, the key card is used to initialize and imprint its special signature to the smart card device so that it will only recognize cards from the same family as the key card. This process cannot be cancelled by using other key cards. This method of operation insures that different families of cards will not be mixed up.

With the pay-as-you-go meter, what will happen if the smart card unit is unplugged after the power has been enabled?

After a few minutes, the meter will automatically cut off the power.

With the prepaid metering system, how does one insure that cards meant for a different unit cannot be used?

The method used is similar to the pay-as-you-go system. Furthermore, there is an even more stringent protection mechanism provided which is to make sure that each card can only work with one card reader and none other. Of course, this would limit the cards interchangeability. Interchangeability and constraint are opposite sides of the same coin and one cannot have both at the same time.


With the pay-as-you-go system, it is possible to limit the meter to use only one card, but not limit the card itself to be usable in another family?


There has indeed been such a request. For example, in addition to being able to use classroom A card in classroom A, similar cards (fine arts, chemistry...) may also be used; but the classroom A card may not be used in classroom B. This product is able to overcome this limitation.

Can the pay-as-you-go system also connect to a computer?

Yes, it can, but one must specify during ordering one of the following models: DEM510-2, DEM540-2, DEM600-2. These models are equipped with dual communication ports. When connected to a computer, one can check the remaining balance, meter reading, perform remote disconnections or restoration.

Can the pay-as-you-go system be centrally managed?

Yes, but during ordering one must specify one of the following models: DEM510-2, DEM540-2, or DEM600-2. Only these models are equipped with dual communication ports, of which the second port can be used to network multiple meters together and then connected to an IS45D digital switch. After the meters are set up, each button on the IS45D corresponds to a meter. So when the meter is forced to shut off, the meter will not enable the power even when the smart card is inserted.
Which is to say that there are situations where centralized control is desired.

What is mechanism for the tariff deduction?

A unit of credit is deducted for every 0.1 kWh consumed.

What is mechanism for the tariff deduction?

A unit of credit is deducted for every 0.1 kWh consumed.

How can central air conditioning be made to use smart card metering?

There are many ways of doing so, each with different costs and benefits.

  1. The most inexpensive method is to use the time based method of metering, which can be used in conjunction with small fans, please refer to ICR520 for more information.
  2. A second way is to use the ICR815 with the LCU which meters based on the operating time of the cold water valve.
  3. Another way is to measure the flow of cold water, which uses the ICR815 in conjunction with the ICR815.
  4. At the high-end, one may use the DFSR BTU meter together with the ICR815.

Our objective in metering is not actually to charge for energy use but rather to curb overuse, how can we achieve this?

By using the ICR520 with the load box and metering based on the a/c operating time. The power is provided when the card is inserted and cut off when the card is removed. Or another way is by transferring a fixed amount of time from the card to the ICR520. Either way, when the time credit is used up, then no further use is possible, unless the card is credited once more. This way the objective of curbing overuse is achieved.

Another way is to use the IS70 with its temperature based control and delay off capability. This method is not dependent on metering. The IS70 keeps a running total of the operating time which one may check once or twice a year.