Combined Chargers Vs Separate Chargers

Thursday, 7 April 2022  |  Craig

In this article we'll be looking at combined DC-DC, Solar and Mains charging systems versus separate components.

Both have advantages and disadvantages that need to be considered before determining which solution is best for your set-up and needs.

Triple Charger Systems

Triple Charger Systems

Triple Chargers are single units with DC-DC, Mains & Solar charging all built-in, enabling you to charge from the alternator, shore/hook-up power or solar panels. These units have become very popular where space is tight and you want to keep wiring to a minimum as you will only need one set of cables from the battery to the unit for all three types of charging. The downside to this, however, is that if one component fails you may need to replace the whole unit. Another downside is that they are inflexible in terms of sizing each charging source to your requirements. The manufacturer has to design the triple charger to suit a 'typical' system, but two systems are rarely the same so you might, for example,  find that the outputs of the DC-DC charger and mains charger are about right for your battery size, but that you need much more solar capacity than the controller allows for. You may find you need to accept a compromise in one area if your system isn't the 'typical' one the manufacturer has deigned the charger for.

The key things to take into consideration when looking at Triple Chargers for your build are:

  • Charging capacity - Do the Mains & DC-DC chargers provide the right output in Amps for your battery's overall capacity (around 10-20% for lead-acid technology; higher for lithium) and can the unit handle the size of your solar array? If you pick a unit with a charger output that is too high then it might damage your battery over time, and a charger with too low an output might take a long time to charge (see our mains charging guide for more info). If you pick a unit with a solar charger capacity that's too small, you might not be able to harvest all of the energy that your solar panels can produce.
  • Open Circuit Voltage - Check that the solar controller in the Triple Charger can handle the VOC (Open-Circuit Voltage) of your intended solar array. If the solar array VOC is higher than the solar controller can handle, it can be damaged. If you are ever unsure of your panel's VOC, we advise contacting the retailer who sold you the panel to get confirmation. All of the panels available on our website have their VOC stated for easy reference.

DC-DC Chargers + Solar Controllers

DC-DC Chargers + Solar Controllers

DC-DC + Solar Controller chargers are similar to the Triple Chargers but do not have mains charging capability. Again, these combined units enable you to save on space and cable required for your project but suffer similar limitations as per Triple Chargers. Making sure that the solar charging capacity (as well as VOC tolerance) and charging output match your intended setup are the key things to watch out for with these units.

Separate Systems

Separate Systems

Of course, all three charging systems can be purchased separately which can allow you to pick and choose each unit so that it best meets the needs of your setup. You can mix and match components by selecting a solar controller that has sufficient capacity for your intended array and mains/DC-DC chargers that have an output that's optimised for your battery type and capacity. With separate components you also have the opportunity to select models with features you want (i.e. Bluetooth communication, trickle charger features, etc), which might not necessarily be available on a Triple Charger. These systems, however, take up a lot more space which can be difficult to fit in smaller areas, and you will need significantly more cabling and fusing for the installation. It can also prove tricky to fault find should an issue develop, as you need to take into account all three systems when you look into the cause.

Key things to take into consideration with a separate system: 

  • Space & heat - As all these units produce heat it can be tricky to find an area for them that has a good airflow to help keep them cool. Gaps around the units should also be planned as having them too close can restrict cooling, potentially leading to loss of performance. 
  • Cable connections - Having multiple units feeding power to one battery can lead to a lot of connections having to be made. Items like busbars and power posts can help, however, they can cause some slight drop in performance due to an increased number of connections and therefore an increased resistance in the circuits.

Inverter Chargers

Inverter Chargers

Combined Inverter/chargers are increasingly popular as a space-saving solution where your system needs a mains charger and an inverter, and can even help reduce costs in some cases. Most Inverter/chargers can detect whether you're on mains shore power or off-grid, and will automatically and seamlessly switch between supplying mains power from the shore supply or from your battery (via the inverter), without interrupting the 240V device being powered. Although this reduces the number of cables required, because the same set is used for the charger and the inverter to the battery, you will need to ensure you use large enough gauge cable to cope with the power requirements of the inverter when off-grid.

As with Triple Chargers, these units are designed for a 'typical' system, so you might find you need to compromise on either the charger or the inverter output. For example, you might ideally need a 20A battery charger and a 1200W inverter, but you might only be able to get a 20A charger with a 500W inverter, or a 1200W inverter with a 50A battery charger.

Key things to watch with Inverter/chargers

  • Charging capacity - Again, it is key to make sure that your mains charger is providing approximately the right output for your battery type and overall capacity. Typically with Inverter/chargers, as the inverter output increases, so does the battery charger output. If you're having to compromise too much on battery charger output just to get the inverter output you need, we'd recommend looking at separate components.
  • Automatic AC changeover - Victron inverter chargers will automatically switch between shore power and inverter AC but other brands might not have this useful feature, so it's worth finding out before deciding which to buy.

 

So, if you're trying to decide between a combined unit or separate components we hope this article has helped, but if you have any questions please don't hesitate to get in touch. 

Disclaimer

The information contained in this article is provided in good faith and we do our best to ensure that it is accurate and up to date, however, we cannot be held responsible for any damage or loss arising from the use or mis-use of this information or from any errors or omissions. The installer is ultimately responsible for the safety of the system so if you are in any doubt, please consult a qualified electrician.

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