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]
