Batteries

Pack up the caravan, hit the road and find that seaside view you’ve dreamed of. Sounds good until it gets dark and we realise we have no electricity. That’s where batteries and solar come into it. Virtually all caravans have them and rely on them, (well batteries at least).. Even those that connect to 240v in a caravan park can still be reliant on them so what’s the gossip on types of batteries to use and how much juice do i need. ?

Without getting too technical let’s take a look at our setup of batteries in the caravan.

We started off for the first 2 1/2 years with AGM batteries. These are most common in Caravans. AGM batteries are deep cycle batteries that come in a range of amperage values. They are not the same as the starter battery you have in your car.

Our initial setup was :

3 x 12 volt AGM Deep cycle batteries. Each battery is 120ah (amp hour).
 
battery

 The key to a battery is the ah reading. Ah is short for Amp hours. So for simplicity reasons, a 100ah battery means you can use 1 amp of electricity from that battery for 100 hours before the battery is totally flat. Connecting batteries in series doubles the voltage but keeps the amp hours the same.

Connecting batteries in parallel maintains the voltage and increases the amp hours. Refer to google if you want to know more but in general for caravans you’ll be connecting in parallel.

 

​Connecting batteries

batteryWireDiagram

Having 3 x 120ah batteries connected in parallel gives us a total of 360ah of current we could use. however, a deep cycle battery does NOT like to go less than %50 charge or else the life expectancy of the battery drops dramatically. There’s a chemical reason for that which I won’t go into but feel free to read the battery university website if your curious. Therefore our 360ah battery system is effectively 180ah “useable” amps.  Which means in one day if we used 180amps of electricity, our batteries would be %50 flat. That’s as low as we would want them to ever be, which equals 7.5amps per hour usage.

Everyones consumption is different so it’s hard for me to say to you that on average you’ll use x amount of amps per hour. You may be running three fridges 6 inverters and 20 laptops. That’s definately going to use more than someone who just turns the lights and tv on at night. So what i’m saying is it changes for everyone. However to get a guide on what you might need try this handy solar calculator

Solar and battery calculator

Our usage

Even though it will vary for everyone, over the last three years we average 72amps usage a day. We run a 218 litre compressor fridge , inverters, phone chargers, laptop chargers, Tv and lights all on regular occasions during the day. Not to mention our smart home network is always running, so that’s an additional , Router, 16 Wifi switches, 2 x Raspberry pi’s (miniature computers for automation control) and a few other gadgets 🙂

The Lithium Movement

In early 2019 we upgraded to Lithium batteries. Although still fairly expensive they have come down in price alot. There are the following advantages of Lithium batteries over AGM batteries that help ease the pain of handing over cash to purchase Lithiums.

  • Lithium batteries almost double the available amps when compared to AGM
  • They can be run down to %20 safely unlike AGM’s which as mentioned is %50
  • Lithiums maintain their voltage until almost flat.
  • They charge quicker
  • They last several years longer than a AGM
  • They are Super light weight
  • and several more advantages but you get the point i hope.

For us as fulltime on the road who could be in the bush for weeks, Lithiums are definitely the way to go. Along with our 600w of Solar panels on the roof we don’t run out of electricity. I still watch the charge meter with a eagle eye but that’s just me 🙂 we can go 4 days with no solar before i break into a major meltdown and have to charge them by some other means. Been close …. but never got to that stage yet 🙂

Enjoy a happy and fully lit up life 🙂

 

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Leave a Comment

    • LazLaz
    • February 25, 2018
    Reply

    Here’s a comment

    • Rebecca Muller
    • March 23, 2018
    Reply

    We have two AGM house batteries (120 i think) in our MH. How many hours would you be able to run a TV ? Thanks so much for your help.
    KInd regards
    Rebecca

      • LazLaz
      • March 24, 2018
      Reply

      Hi Rebecca thanks for the question. That question depends on how much electricity your TV uses. They all vary so would pay to have a look at the back of your TV and find out what the amp’s (normally reads like 3A or 3Amps) or wattage (W) of the TV is. As an example… a Tv might draw 3amps that means if you had the TV running for 10 hours you would use 30amp hours from your batteries. 3A x10 hours = 30amp hours. your 120ah batteries should only ever be taken down to %50 discharged which = 60ah. Therefore….. based on this example you would get 20 hours usage from the batteries providing nothing else was draining the batteries and you weren’t automatically charging the batteries as well. Hope that helps and wasn’t too confusing.

      PS if you can only find out the wattage of the TV and not amps ( look at the label on back of the TV) then take the wattage figure and divide that by 12volts. EG : 35W / 12 = 2.9amps …. 2.9 amps x 10 hours usage = 29amp hours 🙂

    • LazLaz
    • April 28, 2019
    Reply

    another test comment 🙂

    • George
    • July 16, 2019
    Reply

    What is required to have a setup that shows amperage in each battery (there are 3 AGM 120 ah). Necessary? It’s something that could be advantageous.

      • SueSue
      • July 16, 2019
      Reply

      Hi George, 3 x 120ah batteries is what we have due to free camping often (in fact we now have that in lithiums rather than AGM’s due to our power needs). However depending on your electrical requirements just 2 of those batteries could be sufficient. Some batteries you buy now have built in bluetooth management systems which can show you the amperage of each battery via your phone. otherwise you have options of using a BMS system (battery management system) like the redarc bms1230 to show you all your power and amp consumptions, (along with probably heaps of other products on the market)

      cheers

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