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Charging leisure battery etc


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Hello all

I’m a brand new campervan owner trying to understand about charging so I can do it better and keep my batteries in good condition and I have a few questions.


1) I have two x 120ah batteries and an inverter so I can use 240v appliances. I’m finding that despite using appliances sparingly I’m losing charge quicker than I thought with the two batteries. For example the other evening I used the lights for about 2 hours, the microwave for about 2 minutes and the tv for 20 mins. In the morning I used the microwave for 2 x 3 mins and the lights for about 40 mins but I was barely able to use anything after that. The compression fridge was on all of the time.


2) I’m currently charging at home using the hook up cable I bought for when I’m on campsites with EHU, but I’m finding that after several hours I’m only getting to 12.7v. Is this right? Surely I’d get higher than that or will this take longer? I was charging for 7 hours yesterday.


3) should the inverter be switched on or off if I’m just charging and not using anything? Should the inverter be switched off overnight while I’m using the van if I think the fridge will stay cold enough?


4) Is this type of EHU camping cable the best/most appropriate type of charger or is there something else? It’s a 16 AMP to 16 AMP Extension Lead (1.5mm)


Thanks for any advice and tips. I’m a beginner so be kind!

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There are others on here with more technical knowledge than me, and I'm sure they'll be along shortly, but a few queries:


1 Age and make/model of van?


2. Age and type of batteries?


3. Size and type/make/model of inverter?


4. Do you have a solar panel, if so, size ie watts


And here's a link to read about inverters in motorhomes




My initial thoughts are that inverters can crucify batteries in no time because of the very high current draw, and running a microwave from an inverter is very hard on batteries.


Having had a compressor fridge in a previous van, my experience has been that they draw a lot of power from your batteries over a 24 hour period especially with no solar power.


Inverters should always be turned off if they're not being used as there is a current draw, albeit a small one


Compressor fridges run off 12v so don't need an inverter to function


So maybe your leisure batteries are past it?


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I thought I'd read in an article that invertors should be turned off when not in use but I'm sure an expert will give you their opinion later. I dint have an invertor but know that I have the TV on and lights for 6 - 7 hours without any problems when away during the winter months so you should get longer than you currently are so maybe try turning it off and see what difference it makes.

Oh, and welcome.

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Your compressor fridge is likely to be drawing quite a lot from your batteries and that might be the fundamental issue.


If the battery voltage is only 12.7 while charging you are not charging effectively and your onboard mains battery charger may be faulty. Your leisure batteries might also be towards the end of their service life. How old are they?


Your 1.5 sqmm EHU cord is under-specified and you might do better with a 2.5 sqmm cable size.


Really your system need checking by someone who knows what they are doing, either a motorhome dealer's workshop, a mobile caravan habitation engineer or an autoelectrician.

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You're doing everything possible to kill the batteries very fast :-D After all, it's still a MH running on batteries not your home wired to the grid.


You best get a head start and read most of the website already linked above. That should give you a good baseline to figure out how you can optimize your electricity use and why things don't work the way you think they should.

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Arthur49 Thanks for your input.


The van is a 3 year old citroen relay which has been converted from scratch to a campervan.


The batteries are brand new SuperBatt VDC120 leisure batteries


I think the Inverter is an EDECOA 2000w Power Inverter 2000W DC 12V to 240V


I have 2 x 120w solar panels - probably doing very little at the moment here in the uk.


I need the inverter on to run lights and 240v sockets but what I want to know should it be on or off when I'm simply charging.


Re microwave, I know its a big draw (even tho only 500w) but I used it very little, I was literally heating some milk for 2 mins a few times


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Whilst 2.5mm sq would be better for an EHU cable (particularly at longer runs) a 1.5mm sq one should be adequate for most things, and definitely for the load imposed by mainly battery charging.


12.7V is pretty normal (within the variation of measurement methods) for a standard lead-acid battery bank that has been stood for a while after charging., and is off-load.


13.5 volts is somewhat low, however, for best recharging of such batteries. You are unlikely to get the best out of them with such a regime. In addition, though you've described how long you've left them on charge, you haven't detailed the charger, or its rated charging current, so it's difficult to assess how much you've "re-energised" them in that time.


Whilst it is possible to do some calculations on the consumption of the Microwave, that from the lights and TV will be very dependent on how many (lights, and are they LED), and the type and consumption of the TV (240V or 12V).


Nonetheless, the main suspect for consumption will be the compressor fridge - you don't however, detail the model, so that's again a bit of an unknown. There is quite a bit of detail on here about such fridges, and experience of their conumption.


As for the inverter - the general recommendation is to turn them off when not in use. I've found data that indicates yours has a "no load" current draw of 0.8A, though I wouldn't be surprised if it were actually more. That is not an insignificant amount for no value in a full day.

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You appear to be running everything(or at least most things) as 240v from a invertor, if so this is very inefficient, even 240v LED lights will use much more than 12v versions, let alone the nuke and fridge, then there is the constant low level draw from the invertor even if it is not running anything, not sure on the one you have but many draw power even if their own switch is off, and they need a separate switch to disconnect from battery.

If you had asked prior to conversion my advice would have been don't do it like that, if the sockets are all powered by the invertor and all the EHU is doing is charging the batteries, my advice would be rip it all out and start again.

p.s. if the nuke is 500w output it will be using close on 1000w.

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As said 12v led lights are good and efficient, your tv, you're running an inverter and they use power to supply 240v for the tv and the tv then reduces it to around 12v or not a lot more, a 12 volt tv uses very little, a gas saucepan will heat milk without the inverter and the microwaves gobbling power

switch the inverter off as they use power while on.

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When a motorhome is on EHU, it would normally be expected that any 230V appliance would receive its power from the EHU. However, if a 230V appliance is to be used when the motorhome is not on EHU, there will be a need to provide a 230V power-source via an inverter or a generator. Although it would be understandable to use an inverter to power a 230V microwave oven, it would be unusual to use it to power lighting.


As has been asked more than once above, it could be helpful to know the make and model of the battery-charger. ‘Old tech’ chargers had an output- voltage not exceeding 13.8V - more modern chargers can provide a higher charging voltage above 14V.

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By the sound of it you need to rethink everything and move away as much as possible from stuff relying on 240v unless your going to spend all your time hooked up.


lights as suggested need to be 12v.


Throw away the microwave or only use it on hookup via 240v socket that only works when your on mains hookup.


not sure what you can do about the Fridge but I would never have a fridge that didnt run on Gas and EHu


Fit some 12v sockets and run as much stuff as possible off them rather than relying on the inverter so stuff like laptop chargers etc. Get a 12v adaptor rather than using an inverter. Same for the TV. You need a 12v TV.


Sounds like you have wired the van more to rely on the inverter and 240v when an inverter really should be used as a last resort when there simply isnt a 12v option.

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Lisa (Winedineroam) will not have installed the camper-van’s electrical system herself.


It might be that the batteries, though apparently new, might be the culprits (It’s happened before and the victims have reported it on this forum) but with no electrical expertise she would be best to ask the converter for advice if that’s practicable. If modifications to the camper’s electrical system are required, Lisa won’t be making those changes.

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To make it easy to follow my post I am relating power used to the capacity of the two leisure batteries. ( regarding them as a single 'big' battery).


Its usual practice to power the compressor of the Vitrifrigo direct from the 12v leisure supply. Typical use of the fridge, assuming no other charging from solar, engine or mains, will use around 25% the power in the leisure batteries per day, that’s 3 to 4 days before the batteries are flat.


Provided you are not parked in the shade, the 240 watt panels, will at this time of the year, will put back in around 10% to 15% of battery capacity, on average, per day. ( this is based on my actual readings in south UK).

There should me no problems powering the fridge in summer with 240 watts of solar panels


The inverter, even when not powering anything, but switched on, will take a small amount of power, that will add up over a day. The specification for your inverter is not too clear but could be 10% of battery capacity per day.


Thus without any other form of charging, engine or mains, there is no way the solar can keep up with the fridge beyond a few days.


I doubt the inverter is used for anything other than the microwave, and that the LED lights, TV and fridge are powered from the 12v battery. This means the TV, lights and fridge should work with the inverter switched off. ( most inverters have a means to do this, perhaps with a remote panel).

If this is not the case get back to whoever completed the electrical installation and request that things are done correctly.


SuperBatt VDC120 leisure batteries are low cost generic branded leisure batteries and perhaps not the best for your use with an inverter. Any powerful inverter, with limited battery capacity, will reduce battery life but provided you accept that you will need new batteries more often, then the convenience of using a microwave or hair dryer via an inverter is the trade off.


What is necessary for good service life from batteries is correct charging. This requires quality solar controllers, mains charger and engine charging system, competently installed with correct fusing and cable sizes.


Some idea of the type of solar regulator, mains and engine charging would be useful.


Installing an inverter in a motorhome that will fully protect against electrical shock requires an understanding of the regulations and how protective systems operate. If your inverter is connected to a metal bodied appliance, like a microwave, and is also connected to multiple sockets in the vehicle, then a RCD, residual current detector, with a correctly configured inverter, is needed. Perhaps your converter has installed things correctly but all to often the inverter system does not meet the regulations for electrical safety.


Don’t take the 'doom and gloom' too seriously regarding 12v compressor fridges, inverters, and battery types. It sounds that you have a reasonable system with an excellent fridge. With suitable management and understanding of your system I am sure the problem can be resolved.





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Dear Mike

Thank you for the most informative and clear reply to my questions and for being kind to a beginner. You've already helped me understand so much more than I did previously, and most of my confusion is, I'm sure, down to my (lack of) understanding about how these things work. But everyone started somewhere right, and I'm learning fast thanks to people like yourself.


Sounds like I don't need the inverter for anything other than my luxury items (microwave and hairdryer) and I use both sparingly.


Point taken re batteries. Regarding charging I have been using a 16amp EHU Cable(1.5mm) with an adapter and plugging into a regular socket at home. I'd be v happy to find out there's a better/more efficient way of doing it.


And this might sound obvious but am I right that my battery charger switch needs to be on before anything will charge it, eg solar, alternator if I'm driving?


Thank you again for your time and patience




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Winedineroam - 2019-11-06 6:15 PM


...Regarding charging I have been using a 16amp EHU Cable(1.5mm) with an adapter and plugging into a regular socket at home. I'd be v happy to find out there's a better/more efficient way of doing it.


And this might sound obvious but am I right that my battery charger switch needs to be on before anything will charge it, eg solar, alternator if I'm driving?...





Advice on using electricity on a campsite is provided on this link




You’ll note that, in the “Your supply cable” section, a maximum cable length of 25 metres is suggested using 2.5mm-core cable. But Continental European motorcaravanners use much longer 1.5mm cables without any problems. There are reasons for using 2.5mm-core cable, but (as Robinhood said above) your 1.5mm-core cable will be perfectly adequate for charging your motorhome’s batteriies in the way you’ve described. Your method is exactly how many motorcaravanners (including me) charge up their motorhome’s batteries when it’s parked at home.


The power-supply for a battery-charger comes from a 230V hook-up (ie. your from home’s 230V mains circuit at the moment), and the charger will definitely need to be turned on (chargers commonly - though not always - carry an On/Off switch) before the charger can charge the batteries.


As no 230V power-supply will be present when the motorhome is being driven, the battery-charger cannot operate and, even if the charger’s On/Off switch were in the Off position, this would not prevent the motorhome’s alternator or the solar panels from charging the batteries.

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