DCM MkIII (Digital Circuit Monitor)
Updated Monday 18/05/2009 1:38pm
Features at a glance
Having essential information at a glance is the first step to solving electrical problems on the move.
- Up to 4 circuits can be monitored simultaneously.
- Voltage/Current displayed instantly.
- Can measure up to 199 amps.
- Large 4 digit display.
- Low voltage alarm, with audio visual functions.
- Adjustable threshold level provides ample time to react.
- Back lighting facility.
- Low power consumption - less than 5 mA.
- Compatible fascia plate - white legend on black traffolyte.
- Straightforward installation.
Foreword:
Installation and Operating Manual (requires Adobe Acrobat)
We at Adverc believe that boat owners, (and operators on bomb disposal vehicles!) like to know what is going on, electrically speaking. They would like to be more ‘hands on’ and, of course lives can depend on their knowledge at the end of the day.
So, they want meaningful information and it helps if this is easy to acquire and simple to understand. Which is where the DCM MkIII comes into the frame. For twenty-five years the ‘by-word’ at Adverc has been ‘Keep things simple’ and giving boating people (and operators on bomb disposal vehicles) credit for adopting a common sense approach.
We take the view that, even without training in marine or automotive electrics, they can take on-board information such as:
If the voltage across the terminals of a battery in the static condition i.e. with no charging taking place or electrical load applied is 12.8 volts then it is fully charged.
If the voltage is 11.2 volts, the battery is flat to all intents and purposes. You’ve got a problem.
If it is 12.2 volts it is 50% charged and something needs to be done.
The voltage of a fully charged battery, immediately after charging, can be 13.4 volts. This is due to ‘surface charge’ i.e. charge on the surface of the battery plates, with nowhere to go in the short term. Leave the battery overnight and this will dissipate, leaving the voltage at 12.8 volts.
Note the simple cross-reference guide, providing state-of-charge (S.O.C.) against voltage and specific gravity of the battery electrolyte. These days, voltage is the simpler and more practical option, unless there are reasons to suspect a battery’s integrity or condition.
Apply an electrical load to the battery and the voltage usually drops, commensurate with the load. Remove the load and the voltage rises again. A measure of battery condition is its ability to quickly respond, like an elastic band. If this process is sluggish, then the battery may have seen better days.
With the engine and alternator performing and no electrical loads applied, the voltages at the batteries should be a minimum of 14.0 volts. 13.7 volts is a poor charging voltage. 13.2 volts is disastrous! So, too, is 15 volts plus, an over charging situation which must not be ignored.
The DCM MkIII helps in all of these respects and more, monitoring any four circuits for volts and amps. So it is possible to quantify e.g. fridge or auto-helm consumption or the contribution or output from an alternator or solar panels, etc.
With regular use and familiarity, the DCM MkIII can be used to diagnose e.g. alternator or battery problems, usually well before failure occurs and it can reduce fuel consumption.
For example, when do you need to re-charge your batteries?
At 12.6 volts you don’t, at least not yet.
At 12.2 volts you do, to preserve battery life. Most batteries don’t like going below 50% S.O.C. regularly.
Under 12.0 volts, you definitely do. However, if you forget, there is an audible low voltage alarm built into the DCM III. It is time to do something.
Using the engine and alternator charging route for well discharged batteries, one could expect 70-80amps, from an 80A alternator, initially, especially with an Adverc system fitted.
The battery voltage, can be depressed at this stage, depending on the size of the alternator and the battery capacity. However, as the batteries re-charge, the voltages will rise, and, eventually, the charging current will fall.
Once the charging current falls to approximately 10 amps, or so, this means that most of the charge has been accepted by the batteries and they are almost fully charged. In other words, unless you are cruising, there is little point in running the engine any longer, simply to put the last 5-10% back in, which could take some time. So switch off, if you are able to.
Ampere-hours (Ah) has always been a useful feature on any monitoring device. However such functions can be more expensive, are complex because, firstly, ampere-hours involves the use of Peukert’s theory (read your books for more information!) and the use of a micro processor to carry out calculations and make predictions, such as ‘time remaining’.
Unfortunately, the ‘goal posts can move’, where electronics are concerned, and where battery performance and condition can vary with time, necessitating a reset of the instrument parameters. Fine if you know what you are doing, otherwise can you totally rely on the information?
You can rely on voltages and current values.
This information can be obtained using a hand-held multi-meter, of course (we sell these too). Ideal for the real handyman, they are an extremely, useful tool to have around in any event, but, we submit the notion of two knobs, monitoring four circuits for voltage and current, using a single LCD display, a low battery alarm and a bit of common sense, are all you need on a day to day basis.
With familiarity, practice and a bit of spare time on your hands, the DCM MkIII can even become something of a plaything!
For sure you will learn a lot about batteries and their charging. Add to this our excellent customer and technical support – we are only a phone call or email away – then you have peace of mind covering your electrical system.
