Of all the popular upgrades that we do to our 4WD vehicles, the management of the 12 Volt power system is arguably the toughest to get right. The standard power system of a vehicle consists of a battery, a charging system and a network of electronic devices that manage this power to ensure that the vehicle starts, that the now depleted battery is charged back up to full capacity as quickly as possible and that all of the standard electronic devices of the vehicle are properly and sufficiently powered. This is no small feat, but this system works.
As overlanding enthusiasts, we have additional requirements for power that the standard vehicle is not sufficiently geared for. This is especially true when we venture away from places that offer 220V plug-in power. We want to run an electric fridge/freezer to keep our food and beverages cold, we need lighting after dark, we have cameras, phones, laptops, drones, etc. that have batteries that need charging, and some of us just cannot get by without our DSTV fix…
In these situations it is necessary to upgrade the availability of power in the vehicle and then ensure that this power is readily available, sufficiently replenished, and, most importantly, does not affect the functionality of the vehicle’s original power system. The simplest way to achieve this is to install an additional battery to provide the power needed for these additional appliances. This additional battery will thus have a different function to the vehicle’s main battery.
Cranking & auxiliary batteries
The primary function of the main battery is to provide power to turn the engine starter motor and start your vehicle engine. We refer to this battery as the cranking battery. The cranking battery is also responsible for functions that include the ignition and lighting and they are also sometimes referred to as “SLI” batteries. Cranking batteries are typically Flooded or Wet Cell Lead-Acid batteries. They are great for large current delivery for a short time when cranking an engine. Typically this action would consume between 3 and 5% of the battery capacity. It is important to note that once the engine has started and the alternator starts to deliver charge to the battery, it is the alternator that supplies power to the vehicle electronic system. The cranking battery will accept a large charging current to get back to full in a short period of time, ideally 10 to 15 minutes under perfect conditions. These batteries are relatively inexpensive and are suitable for quite adverse operating conditions. They do not do well with prolonged deep discharge cycles such as running lighting and refrigeration overnight. It is essential that your alternator and charge system is working correctly to ensure long service life. The secondary function of the cranking battery is to provide extra power to the vehicle electronic system when the requirements exceed the supply from the alternator.
For the auxiliary battery application one needs to look at a deep-cycle battery. A deep-cycle battery does not like a large sudden discharge from starting your car or running a winch. They do well running fridges and lights that have a prolonged nominal draw on the battery. One can therefore regularly deeply discharge this battery with prolonged low current draw such as powering that fridge and those LED camping lights. Deep-cycle batteries can handle being discharged typically to 50% of their capacity, and in some instances, depending on the construction of the battery, even as low as 75%. There are various types of Deep Cycle batteries falling into two main categories – FLA (Flooded Lead Acid) and VRLA (Valve Regulated Lead Acid. Also found under VRLA are AGM (Absorbed Glass Matt) and Gel batteries.
The difference between a Cranking FLA and a Deep Cycle FLA battery is in the internal construction. The Deep Cycle battery has thicker lead plates to resist corrosion during the extended charge and discharge cycles. Unlike FLA batteries in which the lead plates are submerged in a liquid electrolyte (diluted liquid sulfuric acid), an AGM battery has the electrolyte contained in a fiberglass matt, while in a Gel battery, the electrolyte is in Gel form. The advantage of AGM and Gel batteries is that the immobilised electrolyte allows for these batteries to be utilised in more portable and hazardous situations. This is due in part to the fact that, under normal usage, these batteries do not give off hydrogen gas and do not need to be topped up; they require much lower maintenance than conventional FLA type batteries. AGM batteries seem to be the flavour of the month, depending on who you speak to.
These different battery types require different charging techniques to extract the maximum and most efficient service life out of them. I have come to the conclusion that no matter how good your auxiliary power setup is in your 4WD overlander, you are going to have to put your auxiliary battery through a maintenance charge over a quiet weekend from time to time. That R99 charger that you bought from the Auto shop is not going to do you any favours and you will need to invest a fair amount of money in a proper intelligent charger to ensure that you do not have to replace your auxiliary battery with tedious regularity.
For me, refrigeration and lighting in and around the vehicle are the prime power requirements when camping. It is not ideal and in fact not very wise to attempt to run these items off the main cranking battery of the vehicle. A flat cranking battery in the middle of the Kgalagadi is not my idea of fun. An auxiliary battery would thus be an essential requirement for our Bush Truck. For an auxiliary battery to be of any use, it requires a proper battery management system to ensure that power is available when needed and, more importantly, that your camping appliances do not interfere with or drain your cranking battery.
Fundamentally, more power should be put back into the battery during charging than what is consumed during normal refrigeration and lighting use when camping. If you consume more of this power than you are able to restore through charging, you will at some stage run out of power. Without your lights you will be groping around in the dark and your fridge will turn into an expensive cooler box. This will certainly ruin anybody’s overland experience. Upon investigating the requirements for a proper dual battery management system, I came across a number of important but relatively unknown points.
Battery management systems are plentiful and range from the very affordable to the downright expensive. Some are quite simple in their execution while others would leave even the best engineers a tad puzzled. What perplexed me the most in my research regarding a proper, efficient battery management system is the fact that there is an enormous amount of opinion and claims out there. Over the last 24 issues of the SA4x4 magazine, there have been no less than 15 articles covering many facets of power management, including battery management, solar implementation, battery maintenance, refrigeration and more. More perplexing still is the fact that I constantly come across people who have spent good money with experts for expensive gear and don’t know the ins and outs of their systems and run out of battery power when in the bundu.
With our Bush Truck build I had a short list of absolute requirements for the power management system that we were looking to put together.
- First and foremost, I needed to understand how the system operates to ensure that I could manage it properly.
- I often camp at camp sites with 220V power so I wanted a system that could safely use this power to run some components as well as charge both the main as well as the auxiliary battery.
- When I am away from 220V power, I want to be able to use our Ironman4x4 120W solar mat to charge the batteries.
- My sundowner of choice is Gin and Dry Lemon. It has to have ice, a slice of lemon and a couple of mint leaves. It is a small thing but when it cannot happen it becomes a big thing. My wife is a lover of the Nectar of Bacchus and absolutely has to have her Chardonnay chilled and demands a couple of bobbing ice cubes in her glass. Happy Wife, Happy Life! I would thus need the ability to make/store ice as well as be able to refrigerate food without freezing it. Our Ironman4x4 65Lt Icecube dual compartment fridge freezer would fit the bill nicely so I would need sufficient power to run this baby without issue.
- I am a novice photographer using DSLR and drone equipment and my Macbook Pro goes where I go. Clean, pure sine wave 220V power was an absolute requirement to ensure prolonged battery life for these items even when away from a 220V supply.
- All canopy lighting must be LED. All headlamps and camping lanterns, also LED, must run off rechargeable batteries so a rechargeable battery charging bank would need to be installed as well.
- There would be no other high current draw items used during periods where there is no 220V available.
Charging sources & strategies
The main component of a dual-battery setup is of course the battery. It is important to establish your main requirement and then decide on the correct battery for this. The auxiliary battery has three potential sources of charge while you are away from home. The first is of course the vehicle charging system. This is essentially the engine-driven alternator and it’s charging circuitry. Back in the day, the alternator would deliver a charge to the battery and power the vehicle electronics. The rate of charge or power delivery by the alternator is dependent on engine speed and the regulator. At engine idle speeds, the rate of charge would be low, and at highway speeds it would be high. Pottering around the bush at low engine speeds doesn’t always provide a high rate of charge which can be a problem if your battery management system is not very efficient. In recent times modern vehicles have become more efficient in especially the way they use power and fuel.
To make things more complicated, many modern vehicles have intelligent alternators. These have come about in the interest of saving fuel and thus lowering emissions. Essentially, these alternators read the capacity of the cranking battery as well as any other power requirements that the alternator needs to satisfy in the standard vehicle electronics network. The intelligent alternator has no interest in your dual-battery management system or your auxiliary battery. When the cranking battery has been replenished and there is a low level of power required from the vehicle electronics, the intelligent alternator starts to decrease its level of charge, thus decreasing the drag on the engine and lowering fuel consumption. Depending on your auxiliary battery management system type, this drop in output voltage will cause the management system to disconnect the auxiliary battery from the cranking battery and no charge is sent to your auxiliary battery. This problem is becoming more prevalent and will need to be addressed.
The second source of charge for your auxiliary battery is via a solar panel. Gone are the days where you needed to transport a large 1 metre by 2 metre rigid panel on your roof rack. Nowadays there are foldable compact solar panel arrays no larger than a laptop bag. The advancement in solar cell technology has allowed for smaller panels that are more efficient. We have just such a product at Ironman 4×4 and it’s a little gem. Folded up it is 30cm by 40cm and features an integrated carry handle. Expanded, it features 6 x 20Watt panels and becomes 40cm by 1.8m. It has its own digital solar controller and is ready to clamp onto just about any 12V DC battery (except for Lithium). During the day, you can attach your portable solar mat and its controller to your batteries and, provided the sun is shining, you can replenish battery power.
There are a couple of different types of solar cells used in solar charging mats but they all work on the same principle of converting sunlight energy into electrical energy. I am not going to delve into this massive subject in this article due to the enormous complexity of the subject matter. What is important to note is that all solar panel products that we use to recharge our vehicle battery systems are dependent on bright sunlight for the best results. Solar panel technology is advancing all the time with products appearing n the market claiming vast improvements over the rest, and it can be a bit of a minefield to determine what works and what does not. As a member of the Ironman 4×4 team I am of course obliged to use my own product and I can honestly say that after using our Solar Mat a couple of times, I have found that it works well for my needs and I can recommend it with confidence.
The third source of charge for your batteries is of course a 220V battery charger running off an external 220V power source, typically at home or at a camping site that offers this. Camp site 220V feed is pretty straightforward. Plug an extension cord into the camp site 220V socket and run it to your vehicle where you can plug your charger and other appliances into it. You can now run your fridge and lighting from the 220V and charge your auxiliary and even your main cranking battery from the camp site power. As I mentioned previously, do yourself an immense favour and purchase a proper, good quality 220V DC smart charger. There are several on the market and I personally recommend CTEK, Victron Energy and the new one from National Luna. These smart chargers will ensure long service life from your batteries as well as efficient charging when needed.
So what did we do with our Black Ops truck?
I wanted to put together a system that was complex enough to ensure efficient and sufficient power to cater for the requirements mentioned previously but also simple in its application. I was not keen on clamping battery chargers to batteries or solar panels to batteries when needed. I wanted it all to be plug-and-play, so to speak. All of the connections needed to be mounted in one place for ease of access and use whether I was at home, at a campsite with 220V power or at one without. I also wanted to ensure that as many safety measures are in place as required. Accepting 220V from a campsite is not always as simple as it sounds. I have personally lost a fridge to a power spike in the Kruger National Park, and on investigation I measured heavy over and under fluctuations in the 220V supply. I would thus need to ensure that my system could deal with this safely.
Due to the fact that I needed clean and stable 220V power sockets in the canopy to cater for the charging needs of my photography equipment, I would need to have a decent Inverter in the system. I also wanted to have a simple change-over switch installed that would allow me to switch between incoming 220V power from an external source and the 220V from the inverter. Both these sources needed to be able to supply the power sockets individually. Having investigated all of the products available for this install, it became apparent that there was no one product to cater for all my needs.
Initial component list:
Auxiliary battery – FLA Deep Cycle battery from Deltec – 110Ah.
- Load bin battery tray by Frontrunner
- Ironman DB250SD split charge system by CTEK.
- Ironman DBMXS10 220V intelligent charger by CTEK
- Trailboss 1000W modified sinewave inverter (this would not work long term so needed a better option)
- Household DB board and enclosure from AC-DC Express electrical.
- A 50Amp cross-over switch to switch power source between 220V external source and 220V from the inverter.
This setup had a couple of drawbacks which I felt would need to be addressed before any serious touring was to take place. There was no way of monitoring any data from the system regarding health or efficiency other than the Voltages of the main and the auxiliary battery. The inverter was not suitable and a better option would need to be sourced. The CTEK DB250SD unit could only deliver a maximum of a 20Amp charge which would not restore a 105Ah battery in a hurry. I had just completed this install when I saw a picture of an extensive power management install on the Land Cruiser Camper of Johann “Tyres” Viljoen from 1st Outdoor and 4×4 in Cape Town. I immediately knew that I was barking up the wrong tree with my system and decided to rip it all out and start afresh.
The system that Johann uses is by Victron Energy, arguably the world’s leading supplier of power management systems for a multitude of marine and automotive applications. I have been aware of this product for a while as it is employed by our sister company, Deltec Power Solutions, in several of their solar projects. It is also the brand of choice for many of the world’s leading RV camper manufacturing companies. A quick visit to their website confirmed that this had to be my choice of product for this vehicle build. This website visit also confirmed that I would need some expert help in selecting and putting together a system that would suit my needs.
Victron Energy is a Dutch company and has local representation in the form of Gerrit Tromp. We got hold of Gerrit and he promptly visited our offices for one of our world famous average cups of coffee. After a short discussion Gerrit drew up a list of all of the components that we would require. What struck me was the fact that Gerrit immediately understood my needs and he was very clued up on the pitfalls and changes that should be made to ensure sufficient and efficient power management of our Bush Truck. All of the components other that relays and switches were Victron Energy product and this soothed my OCD tremendously.
The new list of components:
Deep Cycle Battery: Victron Energy 12V Deep Cycle AGM 110AH battery BAT412101084
- Intelligent Battery Combiner: Victron Energy Cyrix-ct 12/24V 120Amp module
- Solar Charge Controller: Victron Energy SmartSolar MPPT 100/20 module
- Inverter: Victron Energy Phoenix VE Direct Pure Sinewave Inverter 12/800
- Intelligent Battery Charger: Victron Energy Blue Smart 12V/10A Intelligent Charger
- System Monitor: Victron Energy BMV-712 Smart Battery Monitor
- Plastic casing housing a household DB board, 50Amp cross-over switch, 220V wall sockets as well as all connections and the System Monitor Display unit.
This system would allow me all of the functionality that I was after. I can move seamlessly between camp site 220V and inverter 220V at the flick of a switch. When external 220V is plugged into the system, the smart charger would immediately fire up and charge the auxiliary battery. My fridge would also sense the 220V and run off the external 220V feed. The Ironman 4×4 IceCube fridges are auto sensing and will switch to 220V when available or fall back to 12V when there is no 220V. I can thus leave it plugged into both power sources in the truck. The external 220V feed runs through a proper DB board with rated circuit breakers and earth leakage for safety of my equipment and my truck. My Inverter fed 220V would be pure sinewave so very safe for my camera and drone batteries as well as my Macbook laptop. Solar power is a mere plug-in away, and, to top it all off, I can access any information about how healthy my system is either inside the truck or remotely via an App on my iPhone.
On to the Install
This is quite a bit of gear to be installed and I wanted it to be easily accessed and out of harm’s way. Typically auxiliary batteries are installed under the bonnet of the vehicle provided there is sufficient space. On the Ford Ranger you do not have this luxury and the battery would have to be mounted elsewhere. Inside the vehicle cabin was never an option due to the size of the battery. A section of the load bin would have to be sacrificed to accommodate the battery. The cranking battery in the Ford is on the left-hand or passenger side of the engine bay. It thus made sense to install all of the electronics on the passenger side of the vehicle to ease the routing of cables. The battery would reside in a dedicated metal battery box from Frontrunner. It is a simple design and is mounted to the floor of the load bin at the left rear behind the left-hand wheel arch. I have a Frontrunner bakkie slider drawer which sits between the load bin wheel arches so there is sufficient space next to it in the load bin corner. Riv Nuts were installed through the load bin floor and the battery box bolted into place.
With my RSI canopy, I have a full kitchen unit installed on the right hand side. This is in the form of a box which bolts against the right hand door aperture. I decided to replicate this box on the left hand side of the canopy to accommodate my power management system with some leftover space in this box for other bits and pieces. When you peer into the canopy from the back, you now have the two inner surfaces of the window boxes facing each other parallel. This has the added bonus of allowing me to add the high-level sliding shelf halfway up the inner height of the canopy to accommodate light luggage. This shelf has its sliders attached to the parallel inner surfaces of the window boxes and prevents said luggage from lying on top of the water tank, fridge and touring case fixed to the lower bakkie slider. Very neat and even more OCD stroking.
I proceeded to cover the inner surface of the window box with some automotive acoustic carpet for neatness. The plastic box to house the DB board and other connections is mounted on the far right-hand side of the inner panel of the window box when you look into it from the side of the vehicle. To the left of this box I have a carpeted MDF plank which is mounted 15mm proud of the inner upright surface of the window box. The modules of the power management system are installed onto this board and all wiring is routed behind the board and out of sight. All wires are sleeved and grommeted where applicable and the entire system is correctly fused.
The Cyrix battery combiner is mounted up front close to the cranking battery in the engine bay. I found a good mounting point against a bracket close to the cranking battery and the main vehicle fuse box. If Ford found it okay to put their electrical gear in this location I was happy to follow suit. There is a 50Amp maxi fuse right at the cranking battery on the red positive wire that runs to the rear of the vehicle. The Cyrix battery combiner sits on this line and thus connects or interrupts this feed to the rear. The black negative wire runs to the rear uninterrupted. These main power feed wires are routed on top of the vehicle chassis right up to the rear of the truck. At this point, they are routed upwards, close to the left-hand tail light wiring, and then through the load bin wall close to the mounted battery box.
This feed is first routed up into our main DB junction box and attached to heavy duty connection posts. Power connections are routed from these posts where required. The BMV-712 Smart Battery Monitor has a large connection shunt unit from which most connections are made. This allows another great feature: when the auxiliary battery is receiving charge from either the 220V intelligent charger or from the solar panels and has reached capacity, the system can then look at the cranking battery, and, if required, the Cyrix battery combiner will connect it and allow it to receive charge as well.
220V power coming in from home or a camp site 220V feed goes directly to the 50Amp cross-over switch. This is the same switch typically used in households that have a generator with a manual switch-over when Eskom supply fails. This switch has 3 positions: “Gen”, “Off” and “Mains”. When there is 220V incoming, the switch is switched to “Mains” and power is then fed from this switch to the DB board through a proper earth leakage. Also connected to this switch but bypassing the actual switching is the intelligent battery charger. As soon as you plug in 220V from outside, your batteries start to charge so there is no chance of forgetting. The circuit breakers in the DB board supply power to a couple of wall sockets mounted in the face of the plastic DB board box. This is where 220V camera and drone battery chargers and other low-current-draw appliances like laptops can be plugged in. The DB board also feeds another 220V wall socket mounted inside the load bin area of the canopy to primarily power the fridge with 220V.
When you are camping away from 220V power and you need to charge those batteries, it is time to employ the Inverter. The 220V output from the Inverter is routed to the other side of the cross-over switch. When the switch is moved to the “Gen” position (Generator or in this case, Inverter), the 220V feed from the Inverter follows the same route as the external 220V through the DB board. In this instance, of course, the intelligent charger does not receive 220V from the Inverter so you will not charge your batteries with their own power. The only shortfall with the system here is that the 220V socket in the rear of the canopy area where the fridge is plugged in will also get 220V from the Inverter and ideally I do not want to run the fridge from the 220V Inverter. I therefore always have to ensure that the circuit breaker for this plug is off when I’m running the Inverter. When the sun is shining, I can plug my solar panel into a socket mounted in an enclosure above the rear power socket in the rear of the canopy. I could have mounted this socket inside the window box in the DB board enclosure and I may move it at a later stage.
The canopy has a couple of LED strip lights installed throughout for lighting at night while camping. There are also four work lights on each corner of the canopy pointing in four directions away from the vehicle so there is plenty of light when required. I am however always in the habit of wearing my trusty headlamp when camping, which saves power. These lights all run directly off the auxiliary battery as they are very low draw. The fridge can draw 12V from the battery as well when there is no external 220V feed, and, of course, the Inverter also draws from the battery. Interestingly, the lights and the 12V supply for the fridge are fed from the auxiliary battery via the Solar Controller. By connecting them this way, I am able to monitor real time current draw information.
This is done via one of the best features of this system. All of the Victron Energy components feature Bluetooth connectivity and are all linked to the VictronConnect App on my iPhone. The VictronConnect App allows you to access each of the components individually. With the Inverter, I can see how much load there is on the inverter from my battery chargers, laptops or any other 220V devices plugged into the 220V sockets being fed by the Inverter. It also shows me AC output level, as well as battery Voltage. With the Solar Controller, I can see how many Watts are being fed by the solar panels, the input Voltage and Amperage as well as the Voltage and current going into and out of the battery. I can see real time how much power the lights and the fridge are drawing. The information from the intelligent charger covers Voltage and Amps as well as an indication of which stage of the charging cycle is being employed.
By far the most information is to be had from the BMV-712 Smart Battery Monitor. A large graphic displays the battery state of charge. Below that one can find a huge amount of info pertaining to not only real-time Voltage and Amp information both for input and output but also estimated battery life under prevailing conditions. The system allows you to customise parameters to ensure that you do not discharge your battery too deeply and therefore one can better manage what you are doing with your available battery power. It is really a fantastic system and I fear I have only really scratched the surface in this article.
I am confident that this is the best option for my needs and I am really stoked with the outcome. I am very glad that I came across Gerrit and I can certainly recommend him to anybody who is serious about getting a proper system together. I have given the system a couple of light duty runs and it performs exceptionally well. I look forward to an upcoming trip to Botswana in September though. We’ll be camping and touring for 8 days and as they say in the classics, “The Proof is in the Pudding.”
By Mic van Zyl