Low Voltage Disconnect for Glacial Movement Research GPS in Greenland

Pictured below is a special low voltage disconnect (LVD) device which we have been supplying for a few years for use by academic researchers in glaciology.

low voltage disconnect for glacial movement monitoring with GPS in Greenland

Solar charged batteries are being used to power GPS dataloggers on glaciers in Greenland. These GPS devices accurately record the movement of glaciers, and this (velocity) data can be used in a wide range of polar and climate change research.

The specific set up for which these LVD devices were designed has a 48 Watt PV solar panel charging a 60-100Ah 12V battery via a Sunguard solar charge controller.

In high polar regions, in the summer, the sun is in the sky 24 hours day, but in the winter is is below the horizon 24 hours per day. Therefore, during the winter months the battery cannot be charged. For the battery to still be usable in the spring it must retain some charge, so the GPS has to be disconnected before it overly discharges the battery.

The GPS modules have their own built in low voltage disconnect circuitry, but a step-up voltage regulator is fitted between the 12V battery and the GPS modules (which need 15+V to operate), so the GPS sees a steady consistent good voltage right up until the 12V battery is virtually dead.Glacier in Greenland - monitoring glacial moevement

In our standard low voltage disconnects, the output is turned off when the battery voltage falls and remains below a user set low voltage for 10 seconds. The output turns back on when the battery voltage reaches and remains above a user set cancellation voltage for 10 seconds.

For a solar powered system and often very limited daylight hours, this can see the output being turned on and off multiple times per day. This is not a problem for an LVD used with lighting for example, but the GPS modules used for this project create a new datalog file each time the power to the module is connected, and there is a 512 file limit. If over the course of the many months that the GPS module remains on the glacier unattended, the power to it is cut and restored more than 512 times, data will be lost which is not acceptable.

In order to prevent this problem, our low voltage disconnect engages as usual after 10 seconds of low voltage being measured ensuring that power to the GPS is rapidly cut if the voltage is low, but then the voltage has to remain consistently over the cancellation voltage for one hour before the power to the GPS module is restored. Doing this ensures that the GPS is only powered up when the battery is known to hold enough charge to make it worthwhile taking up one of the 512 available file spaces.

If you need any kind of special low voltage disconnect or voltage monitoring device, email neil@reuk.co.uk with details of your requirements.

Multi Level Low Voltage Disconnect with Display

Pictured below is a special multi level low voltage disconnect controller which we recently made. As with our other low voltage disconnect products, this device is designed to automatically disconnect loads from a battery when the battery voltage drops below a user set threshold. The loads are then reconnected when the battery voltage has risen above a second higher threshold.

Three level low voltage disconnect (LVD) controller with relays and display

What makes this low voltage disconnect special is that it can be programmed with three independent pairs of voltage thresholds, and control three sets of loads. If you have a selection of devices powered from your 12V battery, some will be more important than others, and some will use more power than others. Having multiple LVD voltage thresholds allows you to choose which devices should have their power cut first as the battery charge level goes down. Cutting the power to high consumption low importance devices leaves more charge available to keep the more critical devices going for as long as possible.

If the battery was powering a large amount of lights for example, one light could be connected to the lowest voltage threshold output to stay on as an emergency light, while the rest of the lights could be turned off at a higher threshold. On a boat, the fridge and navigation system would be connected to the lowest threshold output, while the television and most lighting could be connected to a higher threshold.

display for three level low voltage disconnectThe standard display shows the voltage measured on the battery, as well as the status of the three outputs corresponding to the Bot (Bottom), Mid (Middle), and Top ranges. In the image above, at a battery voltage of 12.32V, the Top range is off while the other two remain on.

all outputs off low voltage disconnect

At a lower voltage (10.55V shown above), all three outputs are off.

all outputs on low voltage disconnect

…and then with the battery voltage fully restored (13.53V while being charged), all three outputs are on.

By pressing the View Thresholds button, the user set voltage ranges are shown on the display.

Showing the voltage ranges for the multi threshold low voltage diisconnectAbove for example the bottom range has the low voltage disconnect at 11.0V and the cancellation voltage (at which the output will be turned on again) at 12.2V.

programming the multi threshold low voltage disconnectProgramming the six voltage thresholds is done using the two on board buttons. These thresholds are stored in non-volatile (long term) memory and are therefore not lost when/if it is disconnected from the battery.

When the battery voltage is measured to have moved above or below a threshold which will result in an output status changing, the back light of the display flashes on and off. The voltage has to remain constantly on the new side of the threshold for 10 seconds before the output status will actually change so that any spikes and dips in measured voltage do not result in devices being turned on or off unnecessarily.

If you need any kind of low voltage disconnect, battery monitor, and/or datalogging device, email neil@reuk.co.uk with details of your requirements.

Battery mAh Capactity Tester

low voltage disconnect with stopwatch for battery testingPictured above is a device we made recently to help estimate the capacity of 12V and 24V batteries. It is based loosely around our 12V Low Voltage Disconnect with Display, but with some major changes and functionality additions.

The customer for this device has a Farnell Electronic load which is capable of discharging batteries at up to 1.5kW (e.g. 12V @ 125A). He wanted to be able to use this to discharge batteries under test, to time accurately the discharge duration, and to automatically turn off the electronic load when the battery voltage falls below a user set level (for example 9.5V for a 12V battery).

This electronic load can be controlled externally by terminals on the back of the unit (Load Enable/Disable). If 5 VDC is connected across those terminals, the electronic load is enabled (turned on), otherwise it is disabled (turned off).

We therefore designed a device which the user can set with their choice of low voltage threshold. Then, when they press the Start Button, a regulated 5V is put across the terminals on the back of the electronic load which starts discharging the battery under test. At the same time, a stopwatch (created in software on the Arduino Pro Mini around which this controller is built) starts to display the number of days, hours, minutes, and seconds that have elapsed since the battery discharge began.

When the battery voltage is measured to have fallen below the low voltage threshold, the stopwatch stops, and the 5V signal to the electronic load is disconnected preventing the battery being discharged any further and potentially being permanently damaged.

The time on the stopwatch is saved in memory on our device and is displayed on the LCD until the user presses the reset button. It is saved in this way just in case after a multi-hour/day test has been completed, someone accidentally disconnects the battery from the timing device before noting the displayed timing results.

If you need any kind of voltage measuring device, low voltage disconnect, and/or timer, please email neil@reuk.co.uk with details of your exact requirements.

12V Low Voltage Disconnect with Warning Buzzer

Pictured below is a 12V low voltage disconnect circuit with a low battery warning buzzer.

Low voltage disconnect with warning buzzer sirenWe sell a wide range of low voltage disconnect circuits in the REUK Shop as well as producing many bespoke LVDs on request. This particular circuit is based around our standard user programmable mini 12V low voltage disconnect, but enhanced to have a buzzer which sounds for one minute when the low voltage disconnect is triggered by 10 continuous seconds of low voltage measured on the battery. This warns the user that they need to take measures to recharge the battery.

There is also a switch on the circuit board so that the buzzer function can be turned off when not desired/required.

If you need any kind of low voltage disconnect, please email neil@reuk.co.uk with details of your requirements.

24V Low Voltage Disconnect with SD Card Datalogger

Pictured below is a low voltage disconnect device we recently made for use with a 24V battery system. In addition to the user-programmable low voltage disconnect functionality and LCD display of our standard Programmable 12V LVD with Display, this modified 24V device also includes a full datalogger, storing measured battery voltages at regular intervals to a micro-SD card for later analysis.

24V Low Voltage Disconnect with SD Card DataloggerThis particular unit is destined to be used by a company specialising in the maintenance of the UK’s transport infrastructure; with the low voltage disconnect used to protect batteries from being overly depleted, and the datalogger used to track the rise and fall of battery voltage over time.

If you need any kind of low voltage disconnect and/or datalogging solution, please email neil@reuk.co.uk with details of your requirements.

Low Voltage Disconnect used as Charge Controller

Pictured below is our 12V Programmable Low Voltage Disconnect with Display as sold in the REUK Shop. The product is designed to prevent batteries from being overly discharged and damaged by automatically turning the load devices on or off depending on the measured battery voltage.

reuk programmable low voltage disconnect used as a battery charge controllerWe recently made a few modifications to this design of this LVD for a customer to enable this device to be used as a charge controller; turning it into a high voltage disconnect.

There is a battery bank and a generator which is used to charge it. We replaced the standard 12V output on the low voltage disconnect board with a relay so that it could switch the generator on and off automatically. We then changed the code on the Arduino microcontroller so that the relay would open (turning off the generator) if the battery bank voltage exceeded a user set value, and would then close the relay again (turning on the generator) when the battery voltage fell below a second user set value. By doing this the batteries are well cared for – never being overcharged, and never becoming overly depleted.

If you require a low voltage disconnect or a modification made to one of our LVD products such as this charge controller, please email neil@reuk.co.uk with details of your requirements.

Programmable Low Voltage Automatic Battery Charger

Our Mini Programmable 12V Low Voltage Disconnect (LVD) is designed to disconnect loads from batteries when the battery voltage falls below  a user set value, and then reconnect the loads when the battery voltage gets back above a second (higher) user set value.

low voltage connect from REUK low voltage disconnectWith a few modifications to the code on the microcontroller of this device it can also be reconfigured as a low voltage connect – a device which will (typically) be used to connect a charger to the battery when its voltage gets low, and then disconnect it when the battery voltage gets higher after charging.

Today we made such a low voltage connect for a customer with a semi off grid garden office, a PV solar charged battery bank, and a selection of lights, 5V chargers, and other low voltage DC loads to be powered. He has a mains powered 5A bench power supply which he wanted to automatically connect to the battery bank via a solid state relay (SSR) when the battery bank voltage fell due to a period of poor solar generation (English weather) or from using a lot of battery power.

With our low voltage connect controlling the SSR, the battery bank will never be able to get overly-depleted and battery power will always be available to power the garden office.

If you need any kind of low voltage disconnect, low voltage connect, or high voltage disconnect etc, please email neil@reuk.co.uk with details of your requirements.

Poultry Lighting Controller with LVD and Display

We have been selling a selection of poultry lighting controllers for many years now – devices designed to stimulate egg production in the winter months using artificial light at dusk and/or before dawn to trick the birds.

Pictured below is a bespoke lighting controller we recently made for a more advanced poultry lighting controller including a double voltage regulator so that more LED bulbs can be used in a large poultry house, an automatic low voltage disconnect, and an LCD display to show system status and for use in setting up the system.

Poultry lighting controller with low voltage disconnect and display

This device will automatically detect dusk and turn on the lights in the poultry house for a user-programmable number of hours (including zero). The lights then turn off (if they had been on) and remain off for 9 hours to give the birds a 9 hour sleep and a 15 hour day for maximum egg production. The lights then turn on in the early morning and remain on until dawn when natural light is bright enough to take over.

display for poultry lighting controller with lvd

Dawn and dusk are detected using a light dependent resistor, and the user can calibrate the exact light level which they consider to be at the threshold between day and dusk, and between night and dawn.

To protect the battery from being run too low of charge and being damaged, the user can programme into the device three trigger voltages: a voltage below which the on board red LED will turn on as an early warning, a voltage below which the output (to the lights if on) will be turned off, and a voltage above which the low voltage disconnect will be cancelled restoring the outputs automatically when the battery is recharged.

manual override active on poultry lighting controller

There is also a manual override option which enables the lights to be turned on manually at any time (low voltage disconnect permitting) when the poultry house needs to be cleaned or the eggs to be collected etc.

At all times the backlit LCD display shows the status of the system including the currently measured battery voltage, whether the LVD is engaged, whether the outputs are on or off, the current position in the cycle DAY, DUSK, SLEEP, PREDAWN, DAWN (or MANUAL when the override is active), and the currently measured light level relative to the user set threshold.

If you need any kind of poultry lighting solution, please email neil@reuk.co.uk with details of your exact requirements and we should be able to put something suitable together for you.

Low Voltage Disconnect with Dual Regulated Outputs

Pictured below is a low voltage disconnect circuit with two individually switchable 12V regulated outputs ideally suited for use with voltage sensitive LED spotlights and similar in battery powered systems.

Low voltage disconnect with two regulated outputsThis device is effectively a dual output version of the 12V Regulator with Low Voltage Disconnect which we sell in the REUK Shop. Each output has its own low dropout 12 Volt regulator (LM2940) and can supply up to 1 Amp.

This particular dual unit is most suited to LED lighting scenarios in which there are two strings of bulbs which you need to be able to switch on or off individually – i.e. String 1 on, String 2 on, or both String 1&2 on.

Should the battery voltage fall below 11.9 Volts then the low voltage disconnect will cut the power supply to the outputs until the battery voltage has gone back above 12.5 Volts.

We sell a huge range of low voltage disconnects, 12V regulators, and mixtures of the two, so please contact neil@reuk.co.uk with details of your exact requirements if you cannot find what you need in the REUK Shop.

New REUK Low Voltage Disconnect with Display

Pictured below is the new REUK Programmable 12V Low Voltage Disconnect with LCD Display. This device allows batteries and battery banks to be protected from being too deeply discharged, and also enables battery  monitoring.

reuk low voltage disconnect with displayFor full details, instructions for use, and to purchase, click here: REUK 12V LVD with LCD). It has been added to the existing low voltage disconnect circuits in the REUK Shop.