Watt We’ve Learnt About Leisure Batteries
A real-life, simplistic guide on how we’re powering our campervan. Today, we’re delving into the leisure battery we opted for and why, the pros and cons of the different types of battery, how our solution has helped us understand volts, watts and amps, and hopefully some relatable explanations for you to understand your own setup better.
Ever since owning a campervan, we haven’t really been able to get our heads around the electrical setup no matter how many times we’ve revisited the subject. The problem has been that both vans we’ve had, have already had the electric done for us, and especially in the van we’ve got now, all the wires are hidden!
Ahead of our next trip into Europe (the countries still in the EU!), we decided to bite the bullet and invest in a decent leisure battery and try to get to grips with what we’ve got. We’ll go more into the battery we chose later, but first, let me set the scene…
Problems:
The fridge was killing the battery even on 12v
The battery seemed to be draining much quicker than expected (charging my laptop less than two times)
We had no way of seeing how much capacity/charge the battery had left
We had two inverters; one 150W and one 1500W and we didn’t know why, or whether one would kill the battery faster than the other, etc.
We couldn’t tell if the battery was charging by the solar panels, when driving, or when plugged into an electric hookup port (EHU), and if it was, then how fast!
Basically, we were just winging it and hoping we could at least put the lights on at night.
The only thing is, now that it’s coming into winter and we’re going to be doing a route that goes something like Belgium > Germany > France > Luxembourg > Switzerland > Germany > Netherlands, we thought we’d better get a battery that can power our diesel heater on those frosty nights!
To try and combat the issue around seeing how much capacity the battery had, we bought a cheap little “Battery Capacity Voltage Meter” from Amazon to see if we could just see how much percent the battery had left, but this would either tell us it was on 100% when nothing was plugged in, or it’d shoot down to 15% then 0% as soon as we turned anything on. We probably bought the complete wrong product for what we wanted, but either way, we can categorically say this little waste of space device did not help us!
As we weren’t sure how old the current batteries were, and the fact they weren’t lasting very long, we decided that a full replacement would be the best way forward. We started researching the different types of batteries, the varying capacities and abilities to link up with each other, delving into the fancier ones with Bluetooth capabilities, and also checking out the physical dimensions of each because they had to fit under our swivel passenger seat. Ideally, we’d have more freedom with the physical size part, but as stated earlier, all the wires are well-hidden behind units and literal walls! So, with time of the essence, we opted to look for something that’d just fit under our seat. Given our current inability to understand how much capacity we had left in the battery, we decided a bluetooth-enabled one with a corresponding app was essential.
We also did some reading on amp hours, wattage, voltage and all the rest of it. Even though I might sound like an industry expert by now (joke), I most certainly am not. I urge anyone with any knowledge to correct me in the comments below if I’ve got any of this information wrong. I am honestly just winging it day by day and learning as I go, so I’m always open to people with more knowledge than me, sharing their hints and tips on this subject!
What I did find, though, is that for what we need, we should be looking to get a setup with a total of at least 200Ah. < See, doesn’t that look like I know what I mean??
Jokes aside, I learnt that an amp hour (Ah), is a measurement of how many amps (electrical current) a battery can provide for exactly one hour. So if your battery is 200Ah, in one hour, it is capable of delivering 200 amps of power before it is completely empty. Putting it like that sounds like 200Ah is tiny (without knowing anything about amps), but there’s no chance you’re going to be using 200 amps in one hour. For example, when we have all of our lights on inside the van, the current is ~1.3amps and when I then plug my laptop in, it goes up to ~6amps. This is way less than 200, and therefore I’ll get way more than one hour out of the Leisure Battery before it runs out. I’ll get to how you work this out later on in this post.
The next thing to think about is Volts. You know the digital dial you have that says something like 12.8 or 13.2, etc. Well, that’s the voltage in your circuit - and what a volt is, is the pressure pushing the electricity through the wire. Leisure Batteries are typically 12v and that’s why you need an inverter to convert the 12v current to 240v which gives you enough electricity to power devices such as laptops, TVs, etc. (Inverters also do other clever things like convert from DC to AC, but that’s for another day).
And finally, you have Watts. This is how much electricity is consumed by an end-device and it is calculated by multiplying voltage by amperage. You’ll often see on a device what the wattage is, like this air fryer, for example. It will consume 1000 watts while running, and needs 220 volts (pressure of electricity) to power it - so you’ll need an inverter first of all...
Screenshot taken from Amazon product description
This is where the formula comes into play… The whole point in this explanation is to just find out how many hours you can power devices for, right? So, the thing you need to know is how many amps are going to be consumed, and that will allow you to compare it against the Ah capacity of your battery.
The magic formula: Amps = Wattage / Voltage. It’s that simple! Especially when items have the information right there for you… In the case of this air fryer, we can now calculate 1000W / 220V = 4.54A, and therefore in a battery with 200Ah, you can work out 200 / 4.54 which means you can run this air fryer for a total of 44 hours (if your battery was fully charged when you first started roasting your potatoes. They will be criiiiispy!)
Now that’s out the way, we can talk about the battery we ended up buying. We went for the Seat Base Lithium Leisure Battery - Fogstar Drift 12v 230Ah. Straight away, the name tells you it’s a standard 12v battery but with 230Ah - that’s massive - especially for just one single battery. The beautiful thing with this is, it is designed to fit perfectly under a single swivel seat which is exactly what we were looking for. It also connects via Bluetooth to the Fogstar Drift app, which has been paramount to our understanding of how this whole electrical system works, thus being able to write about it here and share our findings.
Out with the old, in with the new. Here’s me and my dad changing the battery, acting like we know what we’re doing. The finished product looks smart as a carrot sitting snugly in the swivel seat base!
The app not only shows how much percentage it has left, but it shows the live hours and minutes of endurance/charge time (depending on the input vs output at that time), the Wattage being used/gained, the voltage of the current flowing through the battery (reflected in the digital screen on the van’s control panel), and the amperage in use at the minute. With this, you can verify the formula and see it working in real-time.
The Fogstar Drift App in Action
If you’re a bit of a nerd like me, this is truly fascinating. I tested our Diesel Heater to see how much electricity it takes, because this is something we’ve never known either. We knew it’d take more electricity when powering up, than when it’s just running at a regular pace, but we didn’t know exactly how much or how long we could leave it on for without killing our battery. Well, as it was powering up, the current was 4.5A and it was using 59.4W of electricity. This lasted just under 5 minutes then it settled down and was flickering between using no energy at all, and increasing to a maximum of 0.6A, using ~8W - so it uses practically no electricity when in use, and that makes sense as to why they call it a “night heater” - because you really can leave it on all night (providing you have enough diesel in the heater’s tank). Powering down took a couple of minutes and it peaked around 113.5W and 8.8A.
Another take-away from my research into leisure batteries, is the various types you can get; Lithium, AGM, Lead Acid, etc. Within these categories, are more variations - Lithium can be Lithium Ion (Li-Ion) or Lithium Iron (LiFePO4) and these two are quite different. Our Fogstar battery is a LiFePO4, and Fogstar themselves have written an in-depth article about the differences.
In a nutshell, Li-Ion batteries are physically much smaller and lightweight due to their ability to store large amounts of energy in smaller spaces and they charge faster but also discharge faster. LiFePO4 batteries, however, have a much longer lifespan due to their slower charging/discharging rate, allowing them many more power cycles than Li-Ion. Although LiFePo4 batteries are more expensive upfront, the fact they have a longer lifespan can make them more cost-effective in the long term. As well as that, they’re much safer to use in lower temperatures, too. Typically, the temperature range for safely charging with a Li-Ion battery is between 0°C and +45°C whereas, a LiFePO4 can function well between -20°C and +60°C. The battery we went for, comes with a built-in heater, ensuring it can charge safely in extreme low temperatures - I hope we never have to utilise this feature!! Perhaps my favourite perk of all, is that LiFePO4 batteries are more environmentally friendly due to the fact they don’t have the heavy metals that can be harmful to dispose of.
We didn’t bother looking too much into the other types of battery like AGM and Lead Acid, because they’re overall much cheaper but much more sensitive to overcharging and their physical positioning, etc. and they don’t have anywhere near the lifespan of the Lithium batteries. Given that we want to live in our van for a long time, and we use electronics daily, we wanted to be sure to have a stable battery solution with longevity.
When it comes to charging leisure batteries, there’s three ways (that I know of) to do it: Solar, Driving and Electric Hookup. With each of these, you need a compatible charger between what’s doing the charging and the battery. In our van, we have three Victron Connect devices that were installed before we bought the van. We didn’t realise at the time, but it seems the Victron Blue Smart IP22 Charger isn’t compatible with LiFePO4 batteries; only Li-Ion, which means we can’t charge our leisure battery from Electric Hook Up points. This doesn’t really matter to us, because we do a lot of driving anyway which charges the battery relatively quickly, and when we’re lucky enough to get a sunny day, the solar panels do a good job, too. Fogstar do sell LiFePO4 chargers which will resolve this issue, should we feel the need further down the line. As mentioned, we have solar and driving charging capabilities; for these we use the Victron SmartSolar MPPT 100/30 and the Victron Orion Smart 12/12-30, which are both compatible with the battery.
When driving, we are gaining between 200W and 300W of energy at any given time, and we’ve found the battery gains around 10% for each hour we drive. We haven’t had too many sunny days, but on the occasional one, we’ve noticed we could work with our StarLink (drawing an average of 20W - 30W) and a laptop plugged in, and still be roughly equalising with the energy we’re getting from the sun. Therefore, we’re looking at around 90W of charge at any given time when the sun is out. We’ll keep an eye on this statistic and update accordingly if it turns out to be inaccurate following more sunny days.
The final piece to the puzzle has been the fridge. Well, we’re still finding that missing piece, but it seems like the 12V connection is trying too hard and keeps burning out (literally) at the connection to the control panel, and it’s taking around 100W of energy at any given time, which I think it pretty high on a 12V connection and for it to be constantly running… We’re in the process of trialling it through the 1500W inverter now, for a couple of hours twice a day, so around four hours a day just to keep the food cool. It’s winter anyway, so we could always just leave it out!
All in all, we’re much more confident with our electrical setup now, and we’ve learnt a lot along the way. It’s been a journey! Hope this made sense to you all - thanks for reading.