Article from Redarc
In our last blog we explained what you need to know to calculate your 12v requirements. Now we tell you exactly what you need to keep track and manage your power needs while out on the road. Last thing you want is to drain your batteries to 0, keeping the beer cold will be the last of your worries!
When it comes to getting out in the great outdoors, we all have a different approach, as it depends on time, your budget, and the style of adventure you’re looking for.
Many of us today travel with a fridge and perhaps some camp lighting, and charging camera batteries, phones, tablets, and many other electronic gadgets we travel with. This pretty well become the norm.
A vehicle’s 12v battery system is designed to start a vehicle and run items such as headlights, windscreen wipers, keep the fuel up to the engine, and to charge the occasional 12v accessory while on the move. But if you expect the starting battery to also be the 12v supply for all your camping needs, you might just find yourself not being able to start your vehicle the next day.
This is where a dual battery system comes into play. And that second battery should be designed to discharge and recharge on a regular basis. When there are so many brands, designs and types available in the market these days, you really need to look for some form of deep cycle battery.
The issue you face is just how do you connect that second battery? How will it be recharged? What sort of controls need to be in place? How will you know when it’s going flat, and when will you know that’s it’s been fully recharged? Do it wrong, and yes, it may work for a while. But chances are, that expensive second battery you purchased won’t last that long, and will more than likely let you down in the middle of your holiday.
So this is where a system that can manage your batteries comes into play. A well designed system will have a circuit that will ensure your starter battery always has enough power to restart your vehicle, but allows your second battery to operate independently. You need a system that will recharge to the correct levels, keep control of the state of charge, but also provides you with information so you can decide when, and how long, you recharge all of your portable items.
Now, for getting a system so it works to its optimum performance and with the minimal amount of intervention from you, you’ll want some form of complete Battery Management System (often called a BMS).
We use the REDARC BMS systems in our camper and in our vehicle, as it controls all our charging needs and provides us with accurate diagnostic information, so we can adjust our power consumption according to the SOC (state of charge).
The beauty of having the Battery Management System, is it allows us to be in control of our power requirements whereby we are alerted well in advance (multiple days’ notice) of battery levels. This then allows us to decide what will be the best recharging solution, eg, extra solar hours, a longer driving day, or cutting back on recharging portable items so we won’t fall short of 12v power for essential items like refrigeration and recharging communication equipment.
In the past, we have had all sorts of systems; from a manual key type switch, to many small devices, including solar regulators to control the solar, and separate 240v battery chargers. And we would rely on just a 12v gauge to help us decide whether our batteries were full, half empty, or about to be flat. Yes, they all work to some degree, but we would find ourselves spending a lot of time trying to work out the SOC of our second set of batteries, and often with mixed results.
Here’s our Top 10 Tips to maximise your Power Management system:
- Fully recharge all of your batteries using a Battery Management System on a 240v power supply well before heading off.
- Charge all of your portable devices before starting your trip so you leave with everything fully charged.
- Run your fridge for a couple days while on 240v power before heading off on holiday. Aim to also have it loaded with food and drinks while on 240v power. This will bring the fridge to an optimal operating level before taking off.
- It might not always be possible, but we learn a great deal by simulating a “day in the life” using our 12v system while we still have access to 240v power. It’s during this time when we learn the 12v demands we have well before we’re really out bush.
- When starting out, keep a small notepad to record your 12v usage and recharging information. This allows you to determine whether you’re operating a balanced system or using more 12v power than you are making.
- When travelling, check the SOC readings on the BMS periodically (around 4 times per day), with the aim to having your second battery at 100% charge when stopping at camp.
- Check your fridge’s operating temperature and turn it down slightly overnight to reduce cycling, particularly if it’s a cool evening.
- Use rechargeable lighting units so they discharge without any load on your battery bank during night hours. Simply recharge them the following day during morning daylight hours when either driving to your next destination, or perhaps when you have solar panels out.
- Charge all your portable devices during daylight hours when you can view the loads on your system, and make adjustments to keep it in a recharging phase.
- When making adjustments to your load requirements, don’t leave it too late, as you can’t always rely on the fact that every day will be like the previous one when it comes to daylight solar hours…cloudy days can appear at any time!
These days a Battery Management System can come as one complete unit. It’s not uncommon for a unit to include the following:
- A 240v supply
- Input for solar
- Input for the vehicle’s alternator
- Controls set to disconnect loads from batteries should voltages get too low
- A sophisticated readout screen displaying SOC, logs on solar, real time load draws, the state of health of your battery bank, and timeframes until flat.
So for trouble free power management when you’re out on the road, a well-designed Battery Management System removes the guess work as to whether you have enough power to stay out for a few more days. And for us, that’s the way we want to be travelling….no 12v worries!
See ya out there!
Grant & Linda
My Aussie Travel Guide