Circuit design for tracking 0-12V deep cycle battery voltage with 5-min interval logging

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How can I measure a 0–12 V deep-cycle battery every 5 minutes and store each voltage reading in memory on a chip?

Use a microcontroller with an ADC to sample the battery voltage through an appropriate resistor divider, then save each reading to EEPROM every 5 minutes [#21659293][#21659305][#21659306] If the MCU has enough non-volatile memory onboard, you can store the values there; otherwise use an external EEPROM [#21659293][#21659299][#21659312] Choose an EEPROM large enough for your data and one that matches a bus your microcontroller can master, such as SPI or I2C [#21659299] You can generate the 5-minute interval from the CPU clock or use a real-time clock (RTC) [#21659306] If you want wireless transmission too, look at an integrated module or microcontroller with built-in RF and EEPROM, such as the examples mentioned in the thread [#21659305][#21659312]

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#1 21659292 29 Jul 2011 03:45

Victor Ocheri Victor Ocheri

Anonymous

Post #1
21659292 29 Jul 2011 03:45

I am an intern at a solar power company and am working an a project that tracks deep cycle batteries voltage level.

I need help with putting together a circuitry that would enable me get a hold of the voltage level of a battery at a time interval of 5 minutes, it then store this value at a memory location on a chip (am not sure which one). voltage level calibration should be in the range of 0-12 volts.
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#2 21659293 29 Jul 2011 06:33

Olin Lathrop Olin Lathrop

Anonymous

Post #2
21659293 29 Jul 2011 06:33

I don't understand the problem. What's keeping you from simply measuring the battery voltage with a microcontroller and storing the value in EEPROM? What exactly are you stuck on?
#3 21659294 29 Jul 2011 07:59

Victor Ocheri Victor Ocheri

Anonymous

Post #3
21659294 29 Jul 2011 07:59

The issue is am new at this.
I want a guild in building the circuitry to do the measurement as well as how i can do the storage on an EEPROM.
If you could work up a schematic, i would be grateful. a specification of chipset names for the MC and the EEPROM would be ok too.

The essence of the storage is to enable me get a hold of voltage level values and send them to modify a remote database file.
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#4 21659295 29 Jul 2011 10:17

Cody Miller Cody Miller

Anonymous

Post #4
21659295 29 Jul 2011 10:17

How do you plan to communicate between the microcontroller and the remote database file?
#5 21659296 29 Jul 2011 10:32

Victor Ocheri Victor Ocheri

Anonymous

Post #5
21659296 29 Jul 2011 10:32

ooh i get the part on 'simply measuring the battery voltage with a microcontroller' but am in a fix as to how i can do the storage.
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#6 21659297 29 Jul 2011 10:36

Victor Ocheri Victor Ocheri

Anonymous

Post #6
21659297 29 Jul 2011 10:36

based on suggestions i got from an IRC session, i am trying to see if i could use RF Link Transmitter.
this was the one suggested to me http://www.sparkfun.com/products/8945

what do you think?
#7 21659298 29 Jul 2011 11:00

Cody Miller Cody Miller

Anonymous

Post #7
21659298 29 Jul 2011 11:00

If you plan to communicate via RF you need to answer a few questions:

* How much data do you need to transmit and how often? This will be based up on your spec of how often you need to measure the voltage.
* How far away do you need to transmit the data?

Other questions come to mind:

* What is the power requirements of your measurement and communication circuit?
* Is this a battery powered circuit?
* Can you use the power from the battery that you are measuring to power the device?
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#8 21659299 29 Jul 2011 11:11

Alec Alec

Anonymous

Post #8
21659299 29 Jul 2011 11:11

Victor,

If your microcontroller doesn't have non-volatile memory on chip or otherwise insufficient amount on chip you will need, as Olin mentioned, an external memory IC such as a EEPROM to store the values.

You will need to choose a memory device large enough for your data that uses a communication bus your microcontoller can act as the master for (SPI, I2C, etc.).

You would have to read the datasheets for the microcontroller and memory chip to determine how to set up the communication protocol between them (whatever it may be).
#9 21659300 29 Jul 2011 11:17

Victor Ocheri Victor Ocheri

Anonymous

Post #9
21659300 29 Jul 2011 11:17

i can't say the amount of data, except that it wouldn't be something more than can be held in a memory location on my storage chip.

I intend to measure and transmit at a 5 minutes interval.

For i would use a range of a little over 50 meters, since the batteries i would be using are in battery boxes on solar streetlight poles at my companies premises.
the circuit would be powered by battery.
#10 21659301 29 Jul 2011 11:23

Victor Ocheri Victor Ocheri

Anonymous

Post #10
21659301 29 Jul 2011 11:23

With regards the consideration on using the batteries i am monitoring to power my circuit, i can't yet.

I would be dealing with deep cycle batteries(over 100Ah) and am not sure how a small circuit could cop with supply from such.

Until i find a way of making supply from the batteries harmless to my circuit, i might have to stick with batteries that have low amperage.
#11 21659302 29 Jul 2011 11:38

Victor Ocheri Victor Ocheri

Anonymous

Post #11
21659302 29 Jul 2011 11:38

Thanks Alec, you've just taken me over one hurdle.

But am not really clear on how to make the microcntroller act as the master in communication process.
#12 21659303 29 Jul 2011 11:38

Alec Alec

Anonymous

Post #12
21659303 29 Jul 2011 11:38

If you plan on having several in the same area to make it easy by having the ADC, microcontroller, and RF transceiver all in one, take a look at the following module.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=602-1096-ND
#13 21659304 29 Jul 2011 11:46

Alec Alec

Anonymous

Post #13
21659304 29 Jul 2011 11:46

Better yet, here is one with 32k of Flash memory on it.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=602-1181-ND
#14 21659305 29 Jul 2011 16:31

David Deleonardo David Deleonardo

Anonymous

Post #14
21659305 29 Jul 2011 16:31

Victor:

Take a look at the www.synapse-wireless.com. I don't know how cost sensitive your solution has to be, but these guys make a really nice solution for what you are doing. Better yet, you MAY be able to use the micro inside their module to ALSO sample your battery voltage (through an appropriate resistor divider) and then send it onto the PC based system host. ALL of the wireless protocall management has already been done with their "SNAP" system: it is amazingly slick. Worst case here is that you would take a small PIC microcontroller and use it to sample voltage and communicate with the Synapse module. Still, you should try to get the Synapse part to do the entire job. That way, you will be up and running in no time! (Their system would require you to write simple little PYTHON scrips inside their development enviroment which is very easy to get up the curve on.)

Best Regards,
#15 21659306 29 Jul 2011 19:49

Dennis Bauer Dennis Bauer

Anonymous

Post #15
21659306 29 Jul 2011 19:49

Just use a micro controller with an A/D converter, use can calculate a 5 minute interval from the CPU's Clock cycle or use a RTC.
#16 21659307 30 Jul 2011 11:46

Alec Alec

Anonymous

Post #16
21659307 30 Jul 2011 11:46

Hi Victor,

I wasn't sure if you also read the comments on the same question you posted on Digi-Key's TechXchange below.

http://www.digikey.com/techxchange/message/3404#3404

Did you get all the basic explanations you needed so that you at least know what topics you need to do some research in to get yourself started?
#17 21659308 31 Jul 2011 05:52

Victor Ocheri Victor Ocheri

Anonymous

Post #17
21659308 31 Jul 2011 05:52

Thanks David.
#18 21659309 31 Jul 2011 06:06

Victor Ocheri Victor Ocheri

Anonymous

Post #18
21659309 31 Jul 2011 06:06

Thanks Dennis.
I was thinking they should be a way of simulating the timer in the microcontroller by adding a timing functionality to my codes for the conroller?
#19 21659310 31 Jul 2011 06:16

Victor Ocheri Victor Ocheri

Anonymous

Post #19
21659310 31 Jul 2011 06:16

My deduction at this point is that i would be needing a microcontroller with an ADC and that has peripheral connections for a RTC (Real time clock), an EEPROM and that i would need to set up a communication bus between the the MC and the EEPROM based on specifications on their datasheets, keeping in mind that the MC would be the master.
Am i correct?
#20 21659311 31 Jul 2011 06:22

Victor Ocheri Victor Ocheri

Anonymous

Post #20
21659311 31 Jul 2011 06:22

I would check the SNAP system.
#21 21659312 31 Jul 2011 12:08

Cody Miller Cody Miller

Anonymous

Post #21
21659312 31 Jul 2011 12:08

I think that you should be able to find a microcontroller with an ADC and enough memory for your application. You might even get one with a built in RF transceiver. Take a look at this "microcontroller":http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010384

* 10-bit Analog-to-Digital (A/D) converter
* ASK/FSK RF transmitter
* 128 bytes of EEPROM

This is the first device I came across. There are other devices with different options.
#22 21659313 31 Jul 2011 14:17

Victor Ocheri Victor Ocheri

Anonymous

Post #22
21659313 31 Jul 2011 14:17

I would certainly check it out.
Thanks Cody.
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Topic summary

✨ The discussion focuses on designing a circuit to measure and log the voltage of 0-12V deep cycle batteries at 5-minute intervals, with data storage and remote transmission capabilities. The solution involves using a microcontroller (MCU) with an integrated analog-to-digital converter (ADC) to sample battery voltage, employing a resistor voltage divider for calibration within the 0-12V range. Data storage can be handled by either the MCU's internal EEPROM or an external EEPROM chip communicating via SPI or I2C, with the MCU acting as the bus master. For timing, either the MCU's internal clock or an external real-time clock (RTC) module can generate the 5-minute measurement intervals. Wireless data transmission to a remote database is considered, with options including RF link transmitters and integrated RF transceiver modules. Powering the measurement circuit from the monitored deep cycle batteries is uncertain due to high capacity and potential risks; thus, separate low-amperage batteries are suggested. Recommended components include microcontrollers with built-in ADC and EEPROM, or modules combining ADC, MCU, RF transceiver, and flash memory for simplified integration. Examples and references include SparkFun RF Link Transmitter, Digikey RF modules with 32k flash memory, Microchip microcontrollers with 10-bit ADC and ASK/FSK RF transmitters, and Synapse Wireless SNAP system for streamlined wireless communication and data handling.
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FAQ

TL;DR: Log a 0–12 V battery every 5 minutes (288 records/day). “Use a RTC” and sample with a microcontroller ADC, then store to non‑volatile memory or transmit by RF. [Elektroda, Dennis Bauer, post #21659306]

Why it matters: Field techs need simple, reliable 5‑minute battery‑health logs they can store locally or send wirelessly.

Quick Facts

Measurement target: deep‑cycle battery, 0–12 V range, 5‑minute interval logging. [Elektroda, Victor Ocheri, post #21659292]
Controller: pick a microcontroller with ADC; add EEPROM if on‑chip NVM is insufficient (SPI/I²C master). [Elektroda, Alec, post #21659299]
Wireless: ~50 m site range; RF link or integrated transceiver modules are suitable. [Elektroda, Victor Ocheri, post #21659300]
Storage option: integrated MCU+RF with 32 kB Flash simplifies multi‑node installs. [Elektroda, Alec, post #21659304]
Example device: 10‑bit ADC, ASK/FSK TX, and 128‑byte EEPROM in one chip. [Elektroda, Cody Miller, post #21659312]

What’s the simplest way to log 12 V battery voltage every 5 minutes?

Use a microcontroller with an ADC to read a resistor‑divided 0–12 V input, then timestamp each sample using a CPU timer or RTC and store it in non‑volatile memory. A 5‑minute cadence is straightforward with a hardware timer or RTC alarm. [Elektroda, Dennis Bauer, post #21659306]

Do I need an external EEPROM, or can I use the MCU’s built‑in memory?

If the MCU’s non‑volatile memory is small, add an external EEPROM or Flash. Choose a part that speaks a bus your MCU can master, like I²C or SPI. Check both datasheets to set addresses, timing, and page‑write sizes before coding your driver. [Elektroda, Alec, post #21659299]

How do I scale 0–12 V safely into an ADC?

Use a resistor divider to keep the ADC input within its maximum (often 3.3 V or 5 V). Add an input filter and consider clamping diodes. Sample at your 5‑minute interval, then store or transmit the result. “Measure with an ADC” was the recommended starting point. [Elektroda, Olin Lathrop, post #21659293]

How can I transmit readings about 50 meters on site?

A low‑power RF link or a module with integrated radio works. Define payload size and interval (every 5 minutes) to pick data rate and duty cycle. For ~50 m, simple OOK/FSK links or integrated transceivers are common choices for pole‑mounted nodes. [Elektroda, Victor Ocheri, post #21659300]

Is there an all‑in‑one chip with ADC, RF, and some EEPROM?

Yes. For example, a Microchip device combines a 10‑bit ADC, an ASK/FSK RF transmitter, and 128 bytes of EEPROM. This reduces BOM count and eases firmware integration for periodic telemetry. “This is the first device I came across,” noted an expert. [Elektroda, Cody Miller, post #21659312]

What if I want a module that handles networking for me?

Use a pre‑certified wireless module running a mesh/stack and script it to sample via a resistor divider. Synapse SNAP modules were suggested for rapid deployment, with simple Python scripts and PC‑host integration. That offloads RF protocol work from your MCU. [Elektroda, David Deleonardo, post #21659305]

How do I power the logger from the same deep‑cycle battery I’m measuring?

Regulate the battery down to the MCU’s supply and protect against transients. Capacity (e.g., 100 Ah) doesn’t harm small circuits; voltage and surges do. Add a regulator, input protection, and fusing. Avoid direct connection without conditioning to prevent damage. [Elektroda, Victor Ocheri, post #21659301]

Do I really need an RTC for 5‑minute timing?

Not strictly. You can derive 5 minutes from the MCU clock using a timer, or use an RTC for drift‑resistant scheduling and time‑stamping. An RTC simplifies sleep‑wake cycles and keeps accurate intervals during long deployments. [Elektroda, Dennis Bauer, post #21659306]

How much storage do I need for a day of logs?

At 5 minutes per sample, you store 288 records/day. Even small EEPROMs handle many days if each record is compact (e.g., 2–4 bytes plus time). Consider wear‑leveling if you retain logs locally for long periods. [Elektroda, Dennis Bauer, post #21659306]

What’s a practical RF part to start with for basic links?

An off‑the‑shelf RF Link Transmitter like the SparkFun unit can work for short, low‑data telemetry. Pair it with a compatible receiver and design for your 5‑minute duty cycle. Validate range on your site with antennas mounted at pole height. [Elektroda, Victor Ocheri, post #21659297]

How do I wire the MCU as the I²C/SPI master to an EEPROM?

Pick one bus, set the MCU as master, and the EEPROM as slave. Match voltage levels, pull‑ups for I²C, and clock rates per datasheets. Implement byte or page writes with required delays, and verify with a logic analyzer during bring‑up. [Elektroda, Alec, post #21659299]

Is there a module that bundles MCU, ADC, and RF for multi‑node deployments?

Yes, integrated modules include an MCU with ADC and a radio, plus onboard Flash for code and logs. A cited example provides 32 kB of Flash, easing local storage and OTA updates in clustered streetlight installs. [Elektroda, Alec, post #21659304]

What’s an edge case that can break my logger?

Unregulated power from the measured battery can over‑voltage the MCU during charge peaks, corrupting logs or killing the radio. Always include regulation and surge protection before field trials. Treat capacity as a source of large fault energy. [Elektroda, Victor Ocheri, post #21659301]

How do I get data into a remote database from the pole?

Log locally, then forward via RF to a gateway PC or base station that inserts records into your database. Modules like SNAP can send directly to a host app, reducing custom protocol work between logger and server. [Elektroda, David Deleonardo, post #21659305]

Three steps: how do I build a 5‑minute voltage logger fast?

Divide 0–12 V to ADC range; add input filter.
Use MCU timer or RTC to trigger 5‑minute samples.
Store each sample to EEPROM or transmit by RF. [Elektroda, Dennis Bauer, post #21659306]

What did experts suggest for first‑time builders?

Start simple: MCU with ADC, log to EEPROM, and add RF only after storage works. Read the MCU and memory datasheets to configure the bus with the MCU as master. “What exactly are you stuck on?” helps focus effort. [Elektroda, Olin Lathrop, post #21659293]

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