Low-Power Play: sensor-triggered video on D-cell packs and 5V lithium power banks, from 4.3″ to 37″ and from 720P to 1080P

A battery-driven display kit: screen, speaker, trigger button and D-cell battery pack

Using battery power for small LCD displays is a smart idea. It makes installation quick and hassle-free and opens up new areas of the store for powerful digital promotions. However, putting batteries behind screens designed only for AC mains power gives disappointing results: short battery life and sluggish performance.

To get startlingly effective performance from battery-powered promotions, AOK Displays developed the “Low-Power Play” solution. It combines modern power-management technology with interactive triggers so that displays deliver effective content where and when it is needed. Since the first edition of this guide, the range has grown: a second series with 1080P video decoding, a much wider choice of panel sizes, and support for 5V lithium power banks alongside the classic D-cell pack.

This guide explains how Low-Power Play works, which displays and batteries to choose, and how to calculate battery life for your own campaign.

1. How Low-Power Play conserves power

Most battery-driven promotions aim to balance effectiveness with battery life. Content can run continuously on batteries, but that is not the norm because the batteries would need frequent replacement. Most successful battery-driven deployments use a sensor or another form of interactivity, so the display sleeps until someone is there to watch it.

1.1 Video triggering

Playing content when no customer is present wastes battery power. Low-Power Play uses interactive triggers, such as a motion sensor, push buttons, or a touchscreen, to control when it delivers content. The most common arrangement is an ultra-low-power standby-sleep state while nobody is near, with a motion sensor waking the display and starting playback. Buttons and touchscreens can then regulate further content.

1.2 Two motion sensors: passive infrared and microwave

Two motion-sensor types are available. They behave very differently, and the choice affects both the shopper experience and the battery budget.

The key difference A PIR sensor will not trigger the video if a person is standing still in the detection range: it needs real movement. A microwave sensor still responds and triggers the video even if the human body is still in the detection range.

	Passive infrared (PIR)	Microwave
How it detects	Senses the change in infrared heat as a warm body moves across its field of view	Emits low-power microwaves and detects the reflection from a person in range
Person standing still in range	Does NOT trigger the video: movement is required	STILL triggers the video, even if the body is still
Line of sight	Needs a clear view; typical range about 3 m	Can sense through thin non-metal materials such as plastic, acrylic and glass
Standby power	Very low; fits the 0.5 mA standby budget of the display	Higher; use the real module current in battery-life calculations
Best for	Aisles and shelf edges where shoppers walk past; longest battery life	Counters, kiosks and displays where shoppers stop and look
Watch out for	Strong heat sources and direct sunlight	Movement behind thin walls or glass, and moving objects such as fans

Choose PIR when battery life is the priority and microwave when shoppers are likely to stand still near the display.

1.3 Super-short power-up interval

The time taken to change from low-power sleep to playback is critical for battery-powered solutions, because a customer approaching or touching the display is the moment to catch. Low-Power Play displays wake and start playing in under 2 seconds every time. Many displays on the market take several seconds to power on, so customers see a power-up screen and move on to a more compelling promotion.

1.4 Smart playback control

In high-footfall areas, a sensor can trigger the same video content repeatedly with little benefit, and since battery life is measured in playbacks, unwanted playbacks deplete the battery early. Low-Power Play has a customizable playback profile that limits how many times content can be triggered within a time window. For example, a delay interval can be set in the firmware so that after each activation the display stays in standby (sleeping) for a preset period, and activation is also disabled while people are leaving the detection area. Customers still get the message, and the display controls content playback and battery usage.

1.5 Power mixing

Many deployments mix AC mains and battery power. Low-Power Play detects the power source automatically. Installers and store staff never change settings or switch modes manually: the display plays continuously on AC mains and in triggered mode on battery. An optional extra circuit adds a UPS function, using the battery as backup when mains power fails.

Main board with separate battery and AC power inputs

2. Which displays can be battery powered?

Using battery power for shelf-edge displays neatly overcomes the problem of distributing mains power to the shelf edge and avoids complex, costly installations and trailing cables. AOK Displays has thousands of battery-powered displays deployed in many environments. Two series are available, and both support motion sensors (PIR or microwave), push buttons or touchscreens.

	720P series	1080P series
Video decoder	720P	1080P
Maximum screen resolution	Up to 1366 x 768 pixels	Up to 1920 x 1080 pixels
Typical sizes	4.3″, 5″, 6.2″, 7″, 10.1″, 15.6″, 18.5″	All standard 16:9 retail screens up to 31.5″ (including 10.1″, 11.6″, 13.3″, 15.6″, 21.5″, 23.8″, 27″ and 31.5″), plus stretched screens such as 8.1″, 16.4″, 23.1″, 24.4″ and 37″
Heritage	The proven first-generation Low-Power Play platform	Released in 2024, re-engineered from the AOK Displays retail POP seamless-loop solution, with extraordinary battery efficiency at 1080P
Wake-up time	Under 2 seconds	Under 2 seconds
Standby current	0.5 mA	0.5 mA

The 4.3″ mini displays and the 7″ and 10.1″ shelf-edge ranges remain the most common battery applications, but any size can be supported provided its resolution is within the limit of the video decoder.

Panel options by series: standard, square and stretched screens (schematic, sizes in inches)

Is functionality the same as on mains power?

Functionality is not affected by the power source, but some adjustments conserve power on batteries. In most cases, a motion sensor does the job, and video length should be kept short. Continuous video playback is generally not recommended unless frequent battery changes are feasible.

3. Choosing the power source

Option	Output	Capacity (typical)	Strengths	Limits
8 x D alkaline pack	12 V, cut-off 8 V	12,000 mAh	Low self-discharge, easy to swap, best size-to-performance ratio	Bulky, disposable
Parallel D packs (16D, 24D, 32D)	12 V	Multiples of 12,000 mAh	Extends life without changing the display	Larger, heavier pack
5V lithium power bank	5 V USB	For example 20,000 mAh rated, about 12,000 mAh usable at 5 V	Rechargeable, compact, widely available	Self-discharge, conversion loss; must be an always-on type
Custom rechargeable packs	Per project	Per project	Suit fixed installations	Different cost and logistics; designed per project

3.1 D-type alkaline packs

D-type alkaline cells are our standard because they give the best performance for their size. Cell capacity varies between brands, so we plan on 12,000 mAh per cell at 1.5 V. Eight cells connected in series make a 12 V pack with the capacity of one cell, 12,000 mAh, and the display stops working when the pack falls to 8 V. Connect packs in parallel to multiply capacity: three 8D packs make 36,000 mAh at 12 V, and four make 48,000 mAh.

Mini displays (4.3″) use cells in multiples of 4; shelf-edge and larger displays use multiples of 8. The number required depends on how long the pack must last, any size or weight limit, and budget.

D-type alkaline cells

3.2 5V lithium power banks

A standard 5V lithium power bank is a convenient, rechargeable alternative, and 10.1″ displays and below are designed to run from one. Four points decide whether it works well in the field:

• Rated capacity is not 5V capacity. Power banks quote capacity at the cell voltage of about 3.7 V. A 20,000 mAh bank holds about 74 Wh, which is roughly 12,000 to 12,600 mAh at 5 V once conversion losses are included. Always size from the 5V figure.
• Choose an always-on bank. Many power banks switch themselves off when the load falls below roughly 50 to 100 mA. A display in standby draws only 0.5 mA, so an ordinary bank shuts down and the display never wakes. Use an always-on (low-current) mode bank.
• Self-discharge. Lithium banks lose about 3 to 5% of their charge per month even when idle, and low-cost banks can lose more. This becomes a fixed daily drain, and it matters most in long campaigns with few plays.
• Conversion loss. Holding the 5V output on costs energy in the boost converter, most of all, at very light standby loads. Our planning figures in section 5.3 include this.

A 5V lithium power bank feeding a battery-driven display

As with D cells, we recommend keeping a 20% safety margin on capacity.

4. Battery housing

Batteries sit in a separate pack with a wired connection to the display. The pack has to be accommodated on the shelf or in the POS structure with the display, and the cells can be arranged to provide some flexibility in pack shape. Lithium power banks connect through a 5V cable and can be tucked behind or beside the display.

Battery holder for D cells

5. Power consumption and battery life

5.1 The calculation method

A display uses power in two states: working (playing video) and standby (sleeping). Daily consumption is the sum of the two, and each play includes 2 seconds of wake-up time.

• Active time per day = plays per day x (video length + 2 s)
• Working draw per day (mAh) = working current x active time / 3600
• Standby draw per day (mAh) = 0.5 mA x (86,400 s – active time) / 3600
• Battery life (days) = usable capacity / total daily draw, where usable capacity = rated capacity x 80%

Worked example: a 16.4″ stretched display (600 mA working current) on an 8D pack, 20 plays a day of a 20-second video. Active time is 20 x 22 s = 440 s. Working draw is 600 x 440 / 3600 = 73.3 mAh. Standby draw is 0.5 x 85,960 / 3600 = 11.9 mAh. Total 85.2 mAh a day. Usable capacity is 12,000 x 80% = 9,600 mAh, so the pack lasts 112 days.

5.2 Battery life on D-cell packs

The tables show life for a 20-second video, with the 20% safety margin applied. Packs of 8, 16, 24 and 32 cells are 1 to 4 parallel 8D packs.

Battery life in days, 20 plays per day

Display	Working current	8D	16D	24D	32D
4.3″ mini (720P)	200 mA	263	527	791	1,055
7″ shelf-edge (720P)	250 mA	225	451	677	903
10.1″ shelf-edge (720P)	560 mA	119	238	358	477
16.4″ stretched (1080P)	600 mA	112	225	337	450
21.5″ (1080P)	800 mA	87	174	262	349
37.2″ stretched (1080P)	1000 mA	71	143	214	286

Battery life in days, 100 plays per day

Display	Working current	8D	16D	24D	32D
4.3″ mini (720P)	200 mA	71	143	215	286
7″ shelf-edge (720P)	250 mA	58	116	175	233
10.1″ shelf-edge (720P)	560 mA	27	54	81	108
16.4″ stretched (1080P)	600 mA	25	50	76	101
21.5″ (1080P)	800 mA	19	38	57	76
37.2″ stretched (1080P)	1000 mA	15	30	46	61

Number of plays of a 20-second video (including 2 s wake-up), standby is not included

Display	8D	16D	24D	32D
4.3″ mini (720P)	7,855	15,709	23,564	31,418
7″ shelf-edge (720P)	6,284	12,567	18,851	25,135
10.1″ shelf-edge (720P)	2,805	5,610	8,416	11,221
16.4″ stretched (1080P)	2,618	5,236	7,855	10,473
21.5″ (1080P)	1,964	3,927	5,891	7,855
37.2″ stretched (1080P)	1,571	3,142	4,713	6,284

Planning values at 12 V, 0.5 mA standby and a 20% capacity margin. Working current varies with brightness, volume, and content; confirm the figure on the specification sheet of the model you order. A microwave sensor adds to the standby current, so use the module’s actual current.

5.3 Battery life on a 5V lithium power bank

The next table is for a 10.1″ display on a 20,000 mAh (rated) power bank. It uses the working currents of the current 5V models, 300 mA for 720P and 600 mA for 1080P, a 20-second video with 2 s wake-up, and includes conversion loss, self-discharge of 3% per month and the 20% safety margin.

Activations	720P: daily draw	720P: life	1080P: daily draw	1080P: life
20 plays per day	135 mAh	118 days	193 mAh	82 days
50 plays per day	222 mAh	72 days	367 mAh	43 days
100 plays per day	367 mAh	43 days	659 mAh	24 days
200 plays per day	658 mAh	24 days	1,241 mAh	12 days

Daily draw is measured at the 3.7 V cell side. Assumptions: 85% boost efficiency while working, 50% at standby load, 1 mA converter quiescent current, 3% self-discharge per month. At 5% per month the results fall by one to five days. Real results depend on the power bank model.

Two lessons stand out. First, with a power bank the fixed daily losses (self-discharge, converter current and standby conversion loss) add about 76 mAh a day, so battery life is well below the ideal calculation, especially at low play counts. Second, at 50 or more plays a day the screen itself dominates, and a 20,000 mAh bank no longer covers a long campaign.

Power-bank size for a 90-day campaign

Plays per day	10.1″ 720P (300 mA)	10.1″ 1080P (600 mA)
20	15,000 mAh rated	22,000 mAh rated
50	25,000 mAh rated	41,000 mAh rated
100	41,000 mAh rated	74,000 mAh rated
200	74,000 mAh rated	140,000 mAh rated

Rated capacity (at 3.7 V) needed for 90 days, including the 20% safety margin, conversion loss and 3% monthly self-discharge. For very high play counts, mains power or swappable packs are usually the better answer.

6. What battery do I need for this campaign?

6.1 Fixed campaign length

Display: 7″ with motion sensor, 250 mA working current. Campaign: 6 weeks (42 days). Video: 20 seconds. Activations: 100 a day.

• Active time per day 100 x 22 s = 2,200 s
• Working draw per day 250 x 2,200 / 3600 = 152.8 mAh
• Standby draw per day 0.5 x 84,200 / 3600 = 11.7 mAh
• Total per day 164.5 mAh, so 6,908 mAh over 42 days

An 8D pack gives 9,600 mAh usable, which is more than enough: it lasts 58 days (8 weeks), so the 6-week campaign needs one 8D pack.

6.2 How long will a given pack last?

Display: 21.5″ (1080P) with motion sensor, 800 mA working current. Pack: 16D (two 8D packs in parallel, 19,200 mAh usable). Video: 20 seconds. Activations: 50 a day.

• Active time per day 50 x 22 s = 1,100 s
• Working draw per day 800 x 1,100 / 3600 = 244.4 mAh
• Standby draw per day 0.5 x 85,300 / 3600 = 11.8 mAh
• Total per day 256.3 mAh

Life = 19,200 / 256.3 = 74 days (10 weeks).

6.3 Practical tips

• Keep videos short and use the playback-profile delay in busy areas, so one crowd does not use up hundreds of plays.
• Pick PIR for the longest life, and microwave only where shoppers stand still; add its standby current to the calculation.
• With power banks, use an always-on model, apply the 20% margin and expect 3 to 5% monthly self-discharge.
• For campaigns above roughly 50 plays a day on a large screen, consider parallel D packs, swappable power banks or mains power with the battery as UPS backup.

 

 

 

 

 

 

 

Today’s consumers are quite familar and informed with some in-depth technical specifications and they want to stay with their obsessions about those high profile technical parameters. This new consumption trend brings great challenges to brands of Hi-Fi headphones, earphones, speakers & soundbars. When building a retail audio POP system, which helps shoppers try and compare the sound quality of products in the field, audio brands’ product managers try to go to extreme asking for 32-bit digital output at sample rate of 384KHz.

Technically, this is reasonable if we look into the following chart which explains the audio signal flow during retail demonstration, taking headphone retail demo for example:

Say if you have USB audio DACs to get 32-bit audio at sample rate of 384KHz from the 32-bit compliant ARM processor( it requires USB audio class driver at the low level to support), or you can even use some higher end DAC which delivers a DNR of up to 127dB and THD+N of -120db, whose performance level should satisfy the most demanding audio enthusiasts, next you will need a good amplifier to drive the headphones, the most complicated part of which is tuning the amplifier to match the expected audio characteristics of the headphones.

Common sense is that digital audio signal is NOT audible, what people can hear is analogue signal, so to build an impeccable retail audio POP system for real audio enthusiasts, if the analogue part is not tuned up, 32-bit @ 384KHz digital output does Not make any sense.

We have to point out that high quality digital input is not the king, the most important part is the analogue: DACs and amplifier. Unless for headphones with retail price above 1,000USD, it is not suggested to mislead shoppers using 32-bit DAC, due to the super large size and scarcity of 32-bit 384KHz music files. Actually in most cases, 24-bit 48KHz is quite competent for retail audio demo. Why ? CDs use a sample rate of 44.1KHz, so we say 48KHz is not that bad, and 48KHz is a natural choice of audio sampling in digital television applications  such as DVD and HDTV. Most importantly, what shoppers finally need is an audio product with high performance price ratio when they make any buying decisions.

Here are some typical wrong understandings about Hi-Fi audio:

No.1: Strong bass means Hi-Fi.

No.2: High clarity means Hi-Fi.

No.3: Hi-Fi is for all kinds of music.

High-fidelity (Hi-Fi) means high quality reproduction of sound (https://en.wikipedia.org/wiki/High_fidelity) , ideally high-fidelity means minimal amounts of noise and distortion with an accurate frequency response.

You may note that high-fidelity is 50% objective and 50% subjective, for a branded headphone, hearing experience from a professional piano player and non-professional can be totally different in terms of sound “distortion”.

To satisfy the real audio enthusiasts, audio brands need professional audio design engineers who understand and love music like a music performer to perfect the design for high quality audio transmission from digital to analogue, and tune the sound both objectively and subjectively. AOK Displays is partnering with leading headphone brands and taking advantage of their acoustics lab & professional team for analogue audio tuning. We are happy to be able to offer the most impeccable audio retail demo system to please the fussy and demanding market, to see is to believe, check out the tech-data as below:

Digital:24bit /48KHz DAC,

Aanlog:SNR:105;

THD+N: 0.02%;

Frequency Response Range: 20Hz—-20KHz

(Tuned By Audio Precision AP2700)

Please click through the following for ready soundbar, headphone, speaker demonstrator,

Soundbar, Headphone, Speaker Retail Audio Demonstration

For project oriented inquiries, please contact us directly for more information.

Top 6 Commercial Tablet Android Solution Processors:White Paper, Design Norm & Performance Comparison

	Rockchip RK3288	Rockchip RK3188	Amlogic S905	Allwinner A83T	AllWinner A33	Amlogic 8726MX
Processor	Quad-Core Cortex-A17, 1.8GHz	Quad-Core Cortex-A9, 1.6GHz	Quad-Core 64Bit Cortex-A53, 2.0GHz	Octa-Core Cortex-A7, 1.6GHz	Quad-Core Cortex-A7, 1.5GHz	Dual-Core Cortex-A9, 1.6GHz
GPU	ARM Mali-T764	ARM Mali-400	ARM Mali-450MP6	PowerVR SGX544	Mali400MP2	Mali400MP2
RAM	2G	1G	2G	1G	1G	1G
Video	4Kx2K H.264/H.265 10-bit	1080P @ 60fps	UHD 4K 60fps hardware decoding, H.265 10-bit	1080P @ 60fps	1080P @ 60fps	1080P @ 30fps Hardware decoding
Connectivity	WiFi a/c	WiFi b/g/n	WiFi a/c	WiFi b/g/n	WiFi b/g/n	WiFi b/g/n
Gigabyte Lan	Supported	Not Supported	Supported	Not Supported	Not Supported	Not Supported
HDMI 2.0	Yes	No	Yes	No	No	No
Applications	Commercial & Retail Tablets	Commercial & Retail Tablets	Commercial 4K UHD Media Player	Android POS Terminal & Commercial Tablet	Android Touch Controller For Home & Industrial Automation, entry-level retail tablet	Android Touch Controller For Home & Industrial Automation, Retail tablets

Among all the ARM processors listed as above for commercial tablet advertising, we would like to put RK3288 on the top of the performance ladder, due to the obvious key factors including 4K video decoder, 5G WiFi (802.11 ac)  & Gigabyte Lan for multi-cast IP streaming. The other reason why RK3288 gains the top position is that tablet advertising professionals learned from the mistakes, failures, and drawbacks of what they got from the long learning curve of RK3188, the No.2 runner of the commercial tablet performance racing.

Rockchip RK3288 mother board diagram

And RK3288 is introduced together with Android 5.1, this version of Android carried some expectations that are not available in the widely accepted & popular Android 4.4: screen pinning (multi-screen), and there are quite more apps available based on such a newer version.

The benchmark of commercial tablet is Allwinner A20 powered tablet display and Rockchip RK3188 based retail tablet. When Allwinner is more developer-friendly, A20 is widely used for tailor-made commercial, retail & industrial applications when peripherals & device communication are needed.

Allwinner A20 Mother Board Design Norm

Rockchip RK3188 as a follower, starts retail & commercial application from a designed-for-price consumer-line mother board. Thanks to Rockchip’s partnership with Intel which sends a clear signal to industry that Rockchip gained entrenched advantage in reputation which influences the end-users and the buyer-preference based marketing finally helps Rockchip won over the market share of commercial tablet market that was previously occupied by Allwinner family.

RK3188 Classic mother board with extension interface for RJ45

RK3188 mother board with 3G module slot

Allwinner A83T, the Octa-core processor, entered the market with a super short boot up time(as short as 10s), for comparison, RK3188 is almost in the same level as A83T in performance.

Allwinner A83T mother board diagram side A

Allwinner A83T mother board diagram side B

With A83T targeting the middle & high-end market, Allwinner released A33, the down-performance model of Allwinner A20, it was designed for small sized screens like 10.1” or below sized retail tablet, business hospitality tablet used for room management (touchscreen controller for example).

Allwinner A33 mother board diagram

Amlogic family, owned by Chinese and headquartered in US, it entered the commercial tablet market earliest since 2012 when dual-core processor was new to mass market. Amlogic is operated in a westernized way to buy up-to-date advanced IP for its ARM processor, it is NOT developer friendly, but it is built with managed engineering & due consideration for long-term-win strategy. We choose it for openframe touch panel at the early stage when hardware options are very few. We built abundant communication interface for various commercial applications, see the following circuit diagram.

In early 2014, after CES, 4K became a tech-topic in the industry, RK3288 took the lead again, but due to its market-first strategy, it is mass production ready until later 2015 for commercial use. During this time, Amlogic learned the market and released 64-bit quad-core S905, it gained the top position in 4K set-top-box market thanks to its great success in tele-operator market. Amlogic’s main know-how for commercial application is the color reproduction and hardware video decoding. Our MP40 is one of the very few commercial use 4K media player that can run for months without failure. But due to the fact that Amlogic S905 does’t have built-in LCD panel interface, it lost the power for high-end commercial tablet, while RK3288 takes the lead again and occupied the market.

In a long-term, the solution design norm for mass market belongs to Rockchip, from RK3188 to RK3288.