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If you own a caravan, motorhome or a campervan, then you most likely have a battery fitted (commonly known as your house battery). You may also know that these batteries aren’t cheap. The most common battery for campers and travellers are AGM batteries, GEL batteries and in recent times Lithium batteries are becoming popular too.
When we invest in a battery, we generally look at 3 things:
1. Voltage (most batteries are going to be rated at 12v).
2. AH rating (Amp Hour) and of course
Most people often like to buy the biggest AH battery that fits into our budgets, but normally take into consideration other important factors, such as the power requirements of intended accessories you will be running, your expectation of time you wish to be self sufficient and how you will keep a charge up to the batteries (solar, generator, wind turbine etc.)
Once we have forked out a fortune on our new battery and have installed it into our system, is there a proper way of knowing if our battery is performing as it should? Normally, we would get out a Multimeter or voltmeter right? Of course we do! Other times, we check the little battery gauge that is factory fitted in our caravan which tell us the volts or indicates % of charge with LED's or similar.
But what do these numbers actually tell us and how useful is this information? Measuring the VOLTAGE of your battery is important, it starts as a basis for its true health. An AGM battery is considered FULLY CHARGED when its voltage is 12.8v. For a flooded lead acid battery its 12.6v.
A battery may indicate a voltage of 12.8v in the minutes immediately after it has been taken off a charger – but its TRUE HEALTH is based on how long it can hold this voltage.
To understand how a battery is drained we need to understand that an appliance draws amp's from the battery- most people realise this is what happens. As amp's are drained by your appliances (lights, TV, pump, fridge etc), the voltage drops. The healthier the battery is, the longer it will take for the battery's volts to drop to a low level.
As mentioned, most will look at AH ratings of a battery when first purchasing one – this is rating used to indicate the rate of current (amps) vs hours. For example - if you have an LED light that draws exactly 1 amp when switched on and then connect it to a battery that has an AH rating of 100ah – you could expect that the battery will run that light for 100 hours before it becomes flat. As batteries age, they don’t perform as well as they once did when they were new. They discharge quicker, they take longer to recharge and struggle to cope with being frequently discharged and 'cycled' like they are designed to. This information is vital to us as travellers on the road as the performance of your battery can determine whether you have an amazing adventure, or are left in the middle of nowhere with a dead battery. Nothing worse than being caught short.
A multimeter cannot provide you accurate enough information, as it's main function is to give you a volt reading at any point in time and that is all it is capable of doing. So we have a problem here, is there a REAL way of knowing if your battery is performing properly?
YES! These devices are know as Coulomb Counters or Current Counters and may go by other names too. The way that these devices work is they connect in-line between your battery and ALL of the appliances you use. Effectively, all current and volts (in and out) of your battery are monitored and calculated. By using an algorithm that measures battery volts and current draw (amps) and then calculating these two important factors based on time, these devices can determine whether your battery is running optimally or whether it's health has deteriorated and by how much.
Having a device that can count the amps in and out of your battery and report its health in real time gives you a much better picture of what is actually going on with your power system. It can help you determine any issues, help you gauge whether you may need additional batteries and can also help determine if your chargers and solar panel are working properly, therefore providing clear and concise information about your battery and power system.