Camper Trailers Tech Tips

Enerdrive Elite battery monitor




elite battery monitor

a little theory

Checking your camper trailers deep cycle battery for state of charge while it is charging using a voltmeter will not show its true state of charge as all you are reading is the surface charge. You need to allow the battery to 'rest' for at least a couple of hours, preferably eight, for the surface charge to dissipate. It is like filling a glass with Coke & looking as if it is full, when in fact the top is froth. You need to let the fizz settle to see how much is really in the glass. The state of charge does not measure the storage capacity, performance level or health of a battery.

Also discharging a battery, when running a fridge or recharging the laptop will pull the voltage below the true state of charge. The best time to check your battery with a voltmeter is first thing in the morning if the fridge has been turned off overnight & before you hook up the solar panel. If you use a Cpap at night or the fridge has been left on, you will need to let the battery sit for a couple of hours or more before checking the voltage.

A good rule of thumb to follow for best battery life is not to discharge your deep cycle battery below 50% capacity. As you can see on the graph below, discharging only 10% of the battery capacity can give you 5000 cycles, compared to discharging it down to 10% left, which may give you 400 cycles. 

A monitor that measures the ins & outs of a full battery is the most accurate way to gain the true state of charge & is called coulomb counting. I recently installed an Everdrive Elite battery monitor on our camper trailer's AGM batteries.

battery voltage at rest  depth of discharge v's life of battery

how the elite works

The Everdrive Elite battery monitor shows the battery voltage, percentage of charge, amperage & amp hours consumed at any given time using the monitors internal software through a shunt on the negative battery terminal while charging or discharging. It does this by using algorithms & takes into account Peukert's equation during the charge & discharge cycles.

The Elite monitor is designed for batteries with capacities from 20 to 999 amp hours & is coupled to a shut with a 500 amp  maximum current load covering any camper trailer battery system requirements. The information the monitor provides leads to the more efficient use of the battery, resulting in a longer battery life.

our 12volt system

The two 120 amp hour AGM or absorbed glass mat batteries in our camper trailer are wired in parallel, that is positive to positive & negative to negative, making them in essence one big 12 volt 240 amp hour battery. In this configuration the two batteries are charged as one. The charger positive goes to the positive on one battery & the charger negative goes to the negative on the other battery. Discharge is the same, with a positive off one battery & the negative off the other going to the fuse block.

A Redarc BCDC1225 looks after the charging of the camper trailer batteries when driving from the Jeep's alternator & through the BCDC's in build MTTP solar regulator via a Kyocera 130watt folding panel kit when camped.

what you get

*  Everdrive Elite battery monitor
*  500 amp shunt
*  shunt quick connect PCB module
*  monitor quick connect PCB module
*  five metre Powermaster category 5E UTP patchcord
*  fused positive lead with 10mm diameter terminal with one 10mm diameter ring crimp terminal
*  one 10mm diameter ring crimp terminal & two crimped spade terminals
*  screwdriver
*  installation instructions

packaged contents


Enerdrive have recently introduced a new 'quick connect kit' for the monitor which includes PCB modules on both the shunt & monitor, allowing for a hassle free connection via a five metre patch cord. There is just one more connection to make with the supplied fused wire between the shunt & the positive battery terminal. 

The Elite battery monitor is an easy DIY project. The monitor itself is 65mm in diameter & requires a 52mm to 54mm hole cut into the mounting surface. The shunt has two 6mm diameter holes for mounting near the negative battery terminal.  

All negative battery cables that were originally on the battery are now run to the side marked 'system' on the 500 amp shunt. In my case this includes the 240 volt 25 amp multistage charger, the input from the Redarc BCDC1225, plus the negative running to the fuse block as in our campers wiring diagram below.

A short negative cable runs from the side of the shunt marked 'battery' to the negative battery terminal.

You can use the Everdrive Elite to monitor the voltage of a second battery too, like a vehicle's auxiliary battery plus the starter battery using the wiring diagram included. 

our camper trailer wiring

setting up

At first glance of the instructions the setup looks complicated, but in reality it is very simple. Take the time to read the instructions a few times & understand how the monitor works, the parameters it covers & the display screen functions.

Once the monitor is installed you can connect power to the monitor by adding the fuse to the wire between the shunt & the positive side of the battery. The display will start blinking in the main battery voltage readout display. Push one of the three buttons & the monitor will stop blinking. 

First step is to set a number of parameters of your own battery system into the monitor over the factory preset settings. To do this press the 'setup' key for 3 seconds. Use the '<' & '>' keys to browse through the different functions, then by pressing the 'setup' key again the selected function can be viewed. The '<' & '>' keys can now be used to change the value. Pressing  the 'setup' key again will return you to the setup menu.

From any menu position, the normal operating mode can be accessed again by pressing the 'setup' key for 3 seconds. This will also save any function value changes to the memory. When no keys are pressed for 90 seconds the monitor will return to normal operation mode without saving any function value changes you have made.

display & control overview

 1.  Charge battery indicator
 2.  Alarm activated indicator
 3.  Numeric value indicator field
 4.  Readout units
 5.  Main battery or auxiliary battery indicator
 6.  State-of-charge bar
 7.  Synchronize indicator
 8.  Select state-of-charge readout or next value >
 9.  Select current A or Amphour Ah readout or enter/leave setup menu
10. Select voltage readout main or auxiliary or previous value <

F functions

F01 Battery capacity. Change the default 200 amp hour battery capacity for your own. In my case it is 240 amp hours.

F02 Charger's float voltage. Change the default float voltage to the lowest that your 240 volt multi stage battery charger, DC to DC charger or solar regulator puts out. The default setting is 13.2 volts.

F03 Charger's float current. The default setting is 2.0%.

F04 Low voltage alarm & state-of-charge percentage scale. When the state of charge percentage has fallen below the set value, the alarm will be activated, the charge battery indicator starts flashing & the state of charge bar is empty. The default setting is 50%. 

F05 Low battery alarm on. When the battery voltage has fallen below this value, the alarm will be activated. The default setting is 10.5 volts. I will not be using the alarm function.

F06 Low battery alarm off. When the state of charge percentage has risen above this value & the alarm was activated, the alarm will deactivate again. When FULL is selected the alarm relay is deactivated when the auto-sync parameters are met. The default setting is 80%. I will not be using the alarm function.

F07 Peukert's exponent. The default setting is 1.25. The Smart Gauge website says that the Peukert exponent varies widely between different battery manufacturers but an average figure for a true deep cycle battery is 1.3, for hybrid batteries about 1.15 & for AGMs about 1.10. More reading at 

F08 Shunt Amp Rating. The default setting is 500 amps.

F09 Backlight mode. You can change the number of seconds the backlight stays lit. The default is 30 seconds. It can be set to always be on or off. AU activates the backlight when a key is pressed or automatically when the charge or discharge current exceeds one amp. The backlight draws one milliamp.

F10 Alarm contact polarity. The default setting is No.

F11 Auto-sync sensitivity. This function has a range from 1 to10 & can be used when F02 & F03 are set correctly but auto sync still fails. If auto sync takes too long or does not occur, lower this value. If battery monitor syncs too early, increase the value. The default setting is 5.

F12 Firmware version. Displays the firmware version of the monitor.


Also displayed when you first start the monitor up for the first time is the word SYNCHRONIZE which means you need to fully charge the battery so the monitor can familiarise itself with your system settings.

The battery charge is complete when the F02 & F03 settings are reached for a period of four minutes or more which means it has reached float mode. A flashing FULL message will be displayed. The FULL message will disappear when any key is pressed or when the battery starts discharging.    

During normal operation the monitor will automatically indicate when a sync is required by displaying the word SYNCHRONIZE. The more often the battery is charged, the more precise the Elite battery monitor will indicate all parameters.

You can also manually sync the monitor with the battery if you know it is full by pressing down both 'V<' & '%>' keys simultaneously for three seconds.

monitor display

Main battery voltage will be displayed in the top of the screen by pressing the 'V' key. If you are monitoring another battery like the starter of a vehicle, the voltage of that battery will be shown by pressing the 'V<' key again. 

Battery percentage remaining will be displayed in the top of the screen by pressing the '%' key.

Amps flowing in or out of the battery can be shown in the top of the screen by pressing the 'A/Ah' key. Charging amps are shown followed by 'A' while discharged is shown with a minus prefix followed by 'A'. The result is shown in real time, for example charging from a solar panel may show '6A' while a fridge drawing on the battery may be shown as '-3A'.

If for example the solar panel is charging & the fridge is discharging the battery at the same time, using the above figures the monitor would show '3A'. Another example, if the solar panel was charging the battery at '1A' & the fridge drawing '-3A', then the monitor would show '-2A'.

Amp hours are shown in the top of the screen by pressing the 'A/Ah' key again. When you are discharging from a full battery the 'Ah' will be prefixed by a minus, for example '-20Ah', however when the battery starts to charge the 'Ah' reading will count back to zero. For example if the monitor shows '-20Ah' & the solar panel produces a steady input of 6amps over an hour then it may show a figure of '-14Ah'.

State Of Charge is always shown as a bar graph across the bottom of the screen & is a handy no brainer glance to see what is happening at any time without pressing buttons.

state of charge scale

State of charge percentage scale. The state of charge bar graph is shown across the bottom of the screen at all times. This can be set to your own preference to show the graphs lowest percentage level anywhere you wish. The default setting is 50%, that is the graph will show empty when the battery gets to 12.2volts.

As mentioned above for best battery life it is a good idea not to discharge your deep cycle battery below 50% capacity, so setting the state of charge bar graph to 50% lets you keep on eye on exactly where your ideal bottom mark is. .

monitor install & ready to go

using the monitor

After a couple of trips I am able to comment on how the Enerdrive Elite battery monitor performs. It certainly proved its worth when out camping knowing what the voltage is across the batteries, the capacity percentage of the battery system, the graph giving a quick visual from full capacity to 50% capacity (set as my preference), the amp hour shortcomings of full capacity & the amps coming in, out or the sum of, all in the one compact monitor.


 < voltage across the batteries while charging from the solar panel via the Redarc BCDC1225.
    percentage showing the capacity of the battery system >
              graph showing the capacity between full & 50%. >  

 < amps across the battery system while charging from the Kyocera 130watt folding panel kit. You can see how much difference the MPPT regulator makes boosting the possible 7.5amp maximum output to 9.1amps first thing in the morning.

     amp hours showing the shortfall of a full battery system. >

After the Redarc BCDC1225 sat in float for some time on solar I found the monitor did not show full capacity. The two 120 amp hour AGM batteries are now four & a half years old so perhaps they have lost a little of their full capacity, although they have been well maintained & regularly fully charged, they are in great condition. I therefore lower the F11 auto-sync sensitivity factory setting of 5 down to 3 which is now allowing the monitor to show full on solar & via the alternator through the Redarc charger. The last thing you should do it a manual synchronization.

The monitor consumes 0.1 amps, so over a twenty-four hour period it will consume 2.4 amp hours, over a week 16.8 amp hours & over a month 72 amp hours. If you are not using your camper trailer for a period of time it would be a good idea to either take the fuse out of the monitor or place the battery system on a multistage charger to maintain float charge.


by Rob



february 2014