Inverter for 2007 Hobby Main Motorhome

[Lenny HB]

I wouldn't suggest that you need the 640ah of Lithium

Stop making me cry Martin, I'm having enough problems convincing 'er indoors I only need 460 ah of Lithium in the new van.

 

[funflair]

Stop making me cry Martin, I'm having enough problems convincing 'er indoors I only need 460 ah of Lithium in the new van.

To be honest Lenny 460ah will be fine, we had 480ah but this last one came up at about the same age and cycles as ours and with them being discontinued and we had space I thought it made sense.

In the winter we have at least 5 or 6 days using everything even if the sun never shines, a bit of spring sun on the solar makes a big difference, cutting out the electric kettle and using gas would also make a big difference but it convenient to leave the hob cover on.

 

[Mixyblob]

You might find This a worthwhile read, re 12v smoothie makers.

 

[jille67]

You really need to look seriously at your electrical system and be prepared to spend some money on it.
a 600 watt smoothie will still take around 55 amps out of the batteries, you could just get away with 2 batteries but 3 would be kinder to the batteries.
Some of the best inverters are made by Victron but they are not cheap, a 1200va (1000 watt) is getting on for £400.

I'm afraid you have fallen into the trap of a lot of new owners, you spend thousands on a Motorhome and think it is just going to work and do everything you want it to, unfortunately, it doesn't work like that.

Fallen into trap - no, I don’t think so, bought it very cheap knowing it needs lots doing to it, cosmetically more than anything, the van it self runs like a dream.
new owner yes - that was why I was looking for advice, not sarcasm

 

[funflair]

Fallen into trap - no, I don’t think so, bought it very cheap knowing it needs lots doing to it, cosmetically more than anything, the van it self runs like a dream.
new owner yes - that was why I was looking for advice, not sarcasm

Just keep asking and learning it's a steep curve, you will get get answers and help even from Lenny actually especially from Lenny and he usually gets it right

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[headlight]

jille67 unless you significantly increase your lead acid battery bank and solar or switch to lithium and more solar you won't be able to run your smoothie maker off an inverter I'm afraid.

 

[autorouter]

I totally do not understand about the batteries and inverter, I need a dummies guide.

In an electric circuit there are two things going on at the same time. There is electric charge flowing round the circuit, and there is energy carried by that charge to where it is needed. It's a bit like a central heating system, where water flows round the pipes, and is heated by the boiler, and loses heat in the radiators.

The flow rate of the electric charge is measured in amps. The energy carried by each amp is the voltage. In a 12 volt system, each amp carries 12 watts. In a 240 volt system, each amp carries 240 watts. So each amp of current at 240 volts carries 20 times more energy than an amp of current at 12 volts.

If you want to know how much power the circuit is supplying, then for example if it's a 12 volt system, each amp is carrying 12 watts, so a 5 amp current is carrying 5 x 12 = 60 watts. In comparison, if it's a 240V system, each amp is carrying 240 watts, so a 5 amp current is carrying 5 x 240 = 1200 watts.

This all condenses into the rule that Watts = Volts x Amps.

An inverter has about the same power (watts) on the input side as the output side, but it changes the volts and amps.

For example, a 600W device requires 600/240 = 2.5A from the 240V side of an inverter. On the 12V side it also supplies 600W, and because it's at 12V it needs 600/12 = 50A from the battery. So the inverter changes the 600W power feed from 50A at 12V to 2.5A at 240V.

Of course it's not quite that simple in reality, the inverter is never 100% efficient in conversion, so if you want 600W out you'll need to put in a few percent more than that to allow for conversion losses. Typically about 5% to 10%, and usually the more expensive ones are more efficient.

OK, that's the inverter, now for the batteries. Typically a leisure battery is designed to supply a small current (amps) over a long time. The maximum amps you can take from a battery depends on its type (flooded, sealed, AGM, Gel etc). But there is a rule of thumb that the maximum current is about a fifth of the battery capacity in amp-hours (Ah). Known as the C/5 Rate. So a 100Ah battery should be limited to about 100/5 = 20A.

That's fine for all the usual habitation loads - lights, pump, TV, phone chargers etc, but is a big problem when you want to connect an inverter, which can require 50A, 100A or more.

Obviously there are solutions to this problem, but it needs a bit of thought.

One possibility is to connect several batteries in parallel. If one 100Ah battery is happy providing 20A, then five 100Ah batteries in parallel will be OK for 5 x 20 = 100A, which will power a 100 x 12 = 1200W inverter. But that's a lot of battery, in weight and space.

Another possibility is to note that the inverter only runs in short bursts, for a microwave, coffee machine, hair dryer etc. Some batteries are more tolerant of short overloads. Unfortunately gels, while excellent for everything else, are not good for overloads. Flooded sealed batteries like EFBs are better, and you could even consider 'dual purpose' starter/leisure batteries. They are generally regarded as inferior for dedicated leisure battery use, but have their uses with an inverter. People run a 1000W inverter quite successfully from a couple of 110Ah dual purpose batteries.

The best but most expensive option is a lithium battery. This is smaller and lighter than the equivalent lead-acid battery, and most can supply very high amps compared to a lead-acid setup. For example, some 100Ah lithium batteries can supply 100A. 200Ah of lithium batteries to run an inverter is a very popular choice.

 

[Lenny HB]

new owner yes - that was why I was looking for advice, not sarcasm

That was uncalled for I'll leave you sort yourself out if that's your attitude

 

[funflair]

I started this before Autorouter posted so in the words of Bamber Gascoigne "i've started so I will finish"

When you are thinking about batteries there are really two specs that you need to look at, one is the capacity so that is usually shown as ah or amp hours, sometimes it might be wh or watt hours, sometimes it's easier to just keep it all in watts as you don't get confused calculating from 12v battery to making 240v from an inverter, watts don't change as they are the unit of power, but you need 20 times as many amps from the battery as your 240v equipment needs. Your 100ah battery has only 50% that you can use without damage so that is 50ah or 600wh.

The other important spec of a battery though is the maximum discharge rate, for lead acid this might typically be C5 or 20% of it's capacity so your 100ah can really only give you 20 amps safely and reliably, this will give you around 240watts from an inverter hence why we are all saying that you need more battery power jille67 .

Some people have mentioned Lithium and these batteries have a couple of specific advantages for users who wish to power an inverter, firstly they can be discharged deeper than lead acid so you have more useable capacity for the same nominal rating, the second and importantly for you is that Lithium batteries can tolerate a much higher discharge rate so a typical 100ah Lithium might support C1 or 100% discharge rate, 100 amps into your inverter will give you over 1000watts.

Don't forget though it all has to go back in if you want to do it again the next day and the next day and etc etc.

 

[funflair]

That was uncalled for I'll leave you sort yourself out if that's your attitude

Do you realise how frustrating that's going to be Lenny reading the rubbish I post and then trying not to put me right

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[Hoovie]

Further to the comment on power ratings, you can't always believe the label. I have a Bosch Tassimo Coffee Maker. It is labelled and rated at 1300W. My inverter is 1350W but it won't run it properly and the inverter goes into Overload condition.
And the reason is it actually pulls nearly 2000W! I know someone with the same machine and theirs is the same - hits nearly 2000W (In fact from memory, their loading when using the machine was exactly the same as mine).

If someone has an AC device they really need, or just want (why not!), to run when off-grid, it might be a good idea to get a cheap AC monitor, such as a kill-a-watt and see: 1) what the wattage peaks at; and 2) how much power is used on each use.
The info in 1) will tell you what size Inverter is needed at a minimum
The info in 2) will tell you how much load on the battery and if you have a big enough battery bank or not.

 

[bubble63]

Fallen into trap - no, I don’t think so, bought it very cheap knowing it needs lots doing to it, cosmetically more than anything, the van it self runs like a dream.
new owner yes - that was why I was looking for advice, not sarcasm

I think you might well have fallen into a trap, a ‘very cheap Motorhome‘ ….. good luck with that

Lenny HB is a mine of information and is always willing to help, you would benefit from listening to him
I have had campers for years, installed many electrical items and have a degree in electronics but I still listen to what the likes of Lenny et al say

 

[funflair]

I think you might well have fallen into a trap, a ‘very cheap Motorhome‘ ….. good luck with that

Lenny HB is a mine of information and is always willing to help, you would benefit from listening to him
I have had campers for years, installed many electrical items and have a degree in electronics but I still listen to what the likes of Lenny et al say

I don't really think there are traps one way or the other, you buy the van you like for all sorts of personal reasons and then inevitably spend a small fortune on getting it working just the way you want, trust me even spending a lot of money on a new van it still needs customising to your exact requirements

 

[bubble63]

I don't really think there are traps one way or the other, you buy the van you like for all sorts of personal reasons and then inevitably spend a small fortune on getting it working just the way you want, trust me even spending a lot of money on a new van it still needs customising to your exact requirements

Not really what I was referring to
Buying a cheap Motorhome is guaranteed to have some surprises in store for the person who bought it, things have a tendency to be very cheap for a reason, hence the good luck comment
The OP says “bought it very cheap knowing it needs lots doing to it, cosmetically more than anything”
Listen to Lenny was my point

 

[Hoovie]

I don't really think there are traps one way or the other, you buy the van you like for all sorts of personal reasons and then inevitably spend a small fortune on getting it working just the way you want, trust me even spending a lot of money on a new van it still needs customising to your exact requirements

It is probably pretty rare that someone buys a motorhome - old or new - and does not end up spending a fair amount to have it working like they would like.
I've done an upgrade costing multiple thousands of pounds for someone who hadn't even taken delivery of their brand new A-class.

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[funflair]

It is probably pretty rare that someone buys a motorhome - old or new - and does not end up spending a fair amount to have it working like they would like.
I've done an upgrade costing multiple thousands of pounds for someone who hadn't even taken delivery of their brand new A-class.

I was worried when we ordered a new van that I wouldn't have anything to tinker with how wrong was I

 

[Just smiffy]

Buying van/motorhome is a money pit, regardless of the age of it and how cheep/expensive it was…

 

[Bessy765]

The main thing is to enjoy what you have, all shapes sizes and values are welcome on here. Only as you use it will you really find what suits. I have been motor homing for over 50 years with units such as a 32 coach I bought from a circus, an old and I mean old converted ambulance right up to £80,000 brand new. All have had some problems and having been fortunate to have been able to change the last five buying new each time. The newer and more complex they get the more temperamental they are just like some of our posters. When you have been using it for say 6 months take every thing out and only put back what you need. And there is no such thing. As a stupid question.

 

[VXman]

Have you looked at getting a 12volt TV?

Laptops etc use a small amount of power and a cheap small inverter would suffice - or you could ger a DC to DC converter to power from 12 volt again. Any 12V use is far more efficient that transforming up to 240v (and then down again in the case of a laptop)

Kettle seems pointless is you have gas and even with a powerful expensive inverter you would need to get a low wattage/travel one which are very slow.

A smoothie maker seems to be the issue. Seems a lot of money to spend on making a smoothie. Again - worth looking into whether 12 volt ones exist.

If the smoothie maker is the main requirement and it 600W then a 1500W inverter would be plenty but I suggest you need another leisure battery. By the way - just to inform on a previous comment you made - your 'normal' battery is what is called your starter battery/cab battery/engine battery. It is nothing to do with this side of the system. adding an extra leisure battery and connecting it in parallel would double the amount of power you have and that can be supported/recharged by your solar panel.

Another question - do you really need one? Yes if you are going to off grid a lot but if you are doing campsites it may be cheaper/easier just to plug in. We travel a lot (2/3 months in Europe - mostly off grid) and to be honest we use the inverter very rarely. Laptop (we use it instead of a TV) and the wife's hair dryer (low power setting). Gas is cheaper and easier. (By they way - if doing a lot of off grid I suggest getting refillable gas)

So if you do definitely want one, simply I would suggest another battery connected in parallel to the present one. (needs to be same spec/power)

A good sine wave inverter minimum 1500 watts. (Victron. Renogy)

This company are a good reputable supplier and will offer good advice ( and fitting if needed)

Inverters

Find and shop for 12V / 24V Power & Distribution 1 - Inverters products online at everyday low prices at RoadPro

www.roadpro.co.uk

Here's a few reading suggestions that I very quickly googled but there are many more!

Top 5 Best RV Inverter Options: Detailed Comparison and Reviews

Find the best RV inverter to keep your appliances running smoothly on the road. Find the best power inverters for RVs for your next trip.

mowgli-adventures.com

A Guide to Inverters - The Camping and Caravanning Club

Researching how electricity can power household kit while you're not connected to the mains grid? We look at the pros and cons of inverters in this guide.

www.campingandcaravanningclub.co.uk

The Best 12V Power Inverters for DIY Campervans and RVs

It can be tough to find the best power inverter for your DIY campervan. Read our epic guide to inverters for everything you need to know for your build.

gnomadhome.com

 

[funflair]

Kettle seems pointless is you have gas and even with a powerful expensive inverter you would need to get a low wattage/travel one which are very slow.

You don't need to go low wattage as 2200watts is fine on a decent inverter and battery bank, but as you suggest it's not the cheapest way to heat water

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