Design Remote Control – Which Battery to Choose

Basically the most common seens batteries used in RF remote control are two types, alkaline battery and lithium battery, and there are two types of alkaline battery, one larger battery that is 12V 23A and the other smaller battery which is 12V 27A. if you’re using lithium battery, commonly we use one CR2032 coin battery 3V or two CR2016 as a pile providing 6V voltage.

alkaline-lithium-battery

From transporting and shipping perspective, alkaline battery is always recommended, since air cargo handlers always has more strict code against lithium battery shipping, increasing the shipping cost and risk – although there is no problem in most circumstances.

From design perspective, they all have advantages and disadvantages, thus suitable for different design and remote control products, as follows.

For most ASK or OOK transmitter, which uses 2SC3356 or similar RF transistor to transmit the signal, we always recommend the 12V alkaline since the voltage just suits what’s required for the transmitting circuit to achieve maximum performance.

While if you are designing FSK transmitter, which is likely to use transmitter chip, such as PT4450, TDK5210, Si4320 etc, then you may consider 3V lithium more, since most chip’s voltage range is around 3V, just fit for lithium battery.

However, if you need to use 12V alkaline battery to work with transmitter chip, there is always a way, what you need is to add a 3.0V or 3.3V diode to convert high voltage into what is required for transmitter chips, using this way, you may also need to cut off power when there is no button pressed, since the voltage-converting circuit will likely to consume most power during standby, greatly reduce battery life.

Aside from voltage, another considering perspective is size limit, as you know many slim or compact transmitters only have little room left for circuit board, and lithium battery has excellent advantage in size, almost all transmitters casing using alkaline battery can be converted to lithium battery, while not the opposite.

So if you have a compact casing, and also wants to employ the low cost OOK technology, you may consider using 2 x CR2016 batteries as a pile to provide 6V voltage required for the RF transistor, since usually 3V is not enough for these transistors and will have a very low usable range, but our engineers have found a way to use 3V battery with RF resistors with better performance than most in market.

Another consideration is if it is feasible for customer to get the replacement battery type, in most market around the world, lithium battery as a standard type is more easily to get than 12V alkaline, since the former is used in wide range of electronics, while the latter is designed for remote control only.

Here comes the conclusion, there are many factors when choosing which battery to use, including size limit, circuit requirement, transport and shipping, customer feasibility to get replacement etc. and always you can ask your customer for advice.

Updates – As of August 2013, DHL has suspended transporting goods contains lithium batteries to 157 countries in the world, although the countries listed are mainly smaller countries in the world, the following impact should be considered. The list is shortened in 2015, but all countries in list are not allowed to ship battery in any form, no matter alkaline or lithium, we will have to remove batteries for customers in listed region.