To invert or not to invert....that is the question (1 Viewer)

sidaorb

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Alas MHers, I know not well.

As explained in the intro page, this is our first dabble in the MH world.

Compass Calypso coming shortly and although obviously it has hook up for on site visits, we intend to do a bit of wild camping.

It is currently fitted with a single 85 a/h leisure battery, so will be upgrading, was thinking twin 110 if they fit, or at least twin 85s.

Now I need to draw on your collective knowledge, we know it doesn't have an inverter fitted, my initially thought was first job, but the more I think about it I'm wondering do I need one?

Thinking what normally runs 240v and if they can be run on 12v.

Firstly, and most importantly, my CPAP machine, I've already bought and used a 12v travel unit for my machine and used it successfully festival camping. Both our laptops have car chargers, my camera charger is 12v, phone chargers as per the car, we need to buy a TV so getting a 12v one is an option.

So what needs 240v?

Kettle......gas hob, sorted

SWMBOs hair dryer......hmmm

Anyone want to bounce a few more 240v devices at me that I'm gonna need?

If it is only the hair dryer, then I'm buying her a new towel!
 

Zigisla

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Towel(y)(y)
Straigtners - Gas ones
Battery charger for Drill if you use one - Maybe or charge before you go
Hoover Charger - Dustpan and Brush

We use an inverter and hammer our batteries as we use it for everything above and more, but only cos we have it. We had 2 x 95 Ah AGMs and replaced them in quick succession and we now have 1 x 100Ah Lithium. If I had the choice again, I would think longer before fitting one.;);)
 
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Other than occasional hair dryer usage, everything else we need is usable on 12v only, when we first viewed our van I noticed it had an inverter, along with it's little 75ah battery and 100w solar.

On collection I saw tht the Dealer (Becks) had removed the inverter, saying they could lead to aggrevation that wouldn't be covered on the warranty they offered.

Haven't felt the need to refit another.
 
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Sep 17, 2017
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I've been in Spain for the past month and being doing a lot of Aires without EHU. We have lots of gadgets. I thought I was going to need to get another battery as my single 100Ah was going to be hammered. I also recently fitted a Victron battery monitor. It turns out that I've never used more than 15Ah in a day, and most of the time it's half that.

Now it has been sunny and I have got a large solar panel... but most modern electronics use a lot less juice that I assumed. The only things I've got my low power 200w inverter for is my laptop and my drone. Every few days we manage to get to a 240v EHU and I charge wifey's electric bike battery.

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sidaorb

sidaorb

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We had 2 x 95 Ah AGMs and replaced them in quick succession and we now have 1 x 100Ah Lithium. If I had the choice again, I would think longer before fitting one.;);)

Ok woosh parrot moment, explain please.
 
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hilldweller

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Our main use is to charge ebikes using the supplied 240v chargers. This is huge can of worms anyway because a pair of flat ebike batteries are close to the capacity of the hab battery.
 
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Zigisla

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Ok woosh parrot moment, explain please.
When I had the Inverter fitted we had 2 x 95 Ah AGM batteries. Because of the need to seriously look after these; and we don't, they were caput in 18 months. :( The second set, were seriously on their way out even after a bit more care of them in the same period of time - probably had maybe another year. :cautious: Recently I had 1 x 100 Ah Lithium battery fitted as it suits our way of MH use. I don't have a battery monitor as this would take over my life and to be honest my battery troubles may very well be down to the fact that I don't care what I use; I just use what I have and if the inverter and 12v panel switch off due to low voltage, my Wife's hair is as dry as it's going to get for a while. :rolleyes: However, that said, if I had a new MH, I would probably do without the Inverter and adapt the way we use it - If I'm allowed.:whistle::whistle:
 
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Jan 19, 2014
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We use our very small, efficient pure sine wave inverter to charge electric toothbrushes and charge the vacuum cleaner.
We also have a 230v Samsung TV so that uses it too.
Because the inverter is small it only uses 0.2amps itself.

I put a 1000w one in for Ann's straightening irons too, that is less efficient for small things, probably uses an amp on standby :(
 
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Sundowners

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I think an inverter is more useful along with solar power -- we have nearly 500 w and it is a waste not to use it, we watch our battery situation and during the summer we never have to use gas kettle, plus we have other appliances to make the most of the power available when we have it-------- in Portugal the summers are long and sunny:whistle::whistle:

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GPW

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Remember when you double your Hab battery capacity the electricity needs to get in there somehow, so make sure your charger, wiring and alternator can cope with the sudden load of having to charge 220Ah instead of 85Ah!

I would suggest you keep inverter power to 300 or 500 Watts only and go for a Victron Multi to do the entire switchover, charging and inverting in one go, and try to fit it between your main EHU isolator switch and the RCD in your electrical distribution.

Get a competent electrician to do the wiring if you are not sure about what to do, lots of scope for electrocution, fire and dead batteries if done wrong ;)

Once you go into a real 800W or higher you really need to redesign the entire electrical system to do it properly. Note that £50 eBay 2kW inverters are not real and will not work as you expect, you need to be buying top european brands for these items, save the money on the batteries instead as cheap wet cell lead acid are better than people think.

Also fit a proper isolator switch, theres nothing a battery likes more than to be totally disconnected.

Also read:
https://www.motorhomefun.co.uk/forum/threads/inverter-question.193346/
 
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eddie

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Inverters are the new generators I think, for dividing opinion :D2

Not everyone needs on, but, done correctly they can be great

Not everyone needs one, and not everyone needs to spend the money on one

We "wanted" one and we were happy to spend the money on one.

I have a large camper, with three large domestic TV's all capable of running independently (showing different things) or all three showing the same simultaneously. One in the lounge one in the rear bed room and the third mounted externally under the awning (in a locker) The HDMI distribution system is 220 VAC as are the TV's and the 1Tb Humax digibox/hard drive.

Before the naysayers and the Luddites shoot me down, I have a lot of automation at home, and I am happy with it in my camper, my money my choice.

We have a hand held Dyson, rechargeable and the Dyson mini ball vacuum, both 220 VAC

We have two Dysons and we have a long haired German Shepherd Dog, so we also have a 220 VAC dog groomers "dog dryer" A large volume low temperature hair dryer

My wife loves doing jigsaws and as we approach end of life, eyesight in poor light is a problem at 58 ;) so a 220VAC table top "Daylight lamp" is very welcome

Hairdryer for my wife is a must, so a copy of the house 220 VAC hairdryer lives in the van at all times

220 VAC Stick blender, coffee machine, Halogen grill, eBike chargers, 4G WiFi Router, Sound bars, in face pretty much anything we want we can have without worrying about voltage

It is an inverter charger, so take this weekend for example, when I unplug the camper from the mains before we leave the inverter will automatically switch over and everything will work.

We are driving to a site about an hour away, where there is hook up, when the inverter/charger will automatically switch back to mains.

While we are away, should the campsite mains supply not be sufficient for our needs, the inverter/charger will automatically compensate for the shortfall to avoid the site bollard tripping, all automatically

If we go away to a site with no hook up, again realistically, our batteries and solar array (450w) would cope Spring through to Summer. Winter we wouldn't consider a site without hardstandings and electric hook up, but a night or two off grid doesn't present us with a problem.

I keep saying that not everyone wants or needs this kind of set up, everyone is different and everyone uses their motorhomes "differently"

But, if the truths known, I don't really "need" a camper, I "chose" to and I "chose" to do it the way that I do.(y)

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thebriars

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We use our very small, efficient pure sine wave inverter to charge electric toothbrushes and charge the vacuum cleaner.

We use electric sonic toothbrushes that charge from a USB socket, as does my electric razor. Only £25 and just as good as the named brand.
 
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Ivory55

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They are all brave on here but yes the hairdryer can be a line in the sand. Why not buy a 2nd hand generator and see how much you use it or need it. If you find that you’re needing a lot of 240v you can then work out what size inverter and batteries you need and sell the generator for probably what you paid for it. It could be cheaper then guessing what size inverter etc to get.

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bigtwin

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Remember when you double your Hab battery capacity the electricity needs to get in there somehow, so make sure your charger, wiring and alternator can cope with the sudden load of having to charge 220Ah instead of 85Ah!

They will cope perfectly well but, depending on the kit, will simply take a little longer to get to full charge.

Ian
 
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funflair

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Why not buy a 2nd hand generator and see how much you use it or need it. If you find that you’re needing a lot of 240v you can then work out what size inverter and batteries you need and sell the generator for probably what you paid for it. It could be cheaper then guessing what size inverter etc to get.

I am not sure that is a fair test, I run an inverter for all sort of things like charging Dyson, camera batteries toothbrush as well as Microwave coffee machine and of course the hairdryer, I wouldn't run a generator though;)

Martin
 
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Ivory55

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I am not sure that is a fair test, I run an inverter for all sort of things like charging Dyson, camera batteries toothbrush as well as Microwave coffee machine and of course the hairdryer, I wouldn't run a generator though;)

Martin
Was just trying to save them rushing out and buying but not knowing exactly how and what power they need .
 
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GPW

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They will cope perfectly well but, depending on the kit, will simply take a little longer to get to full charge.

Ian

Yes that's the theory, but in practice you may see 2 problems:
1. More charging current for longer = more alternator wear, more EHU charger heat and more cable heat.
2. If your fridge is also on 12V while driving the extra charging load means your hab batteries may never see The 14.4 V absorption charge they need and therefore never get to full charge, shortening their life.

I.e. if your batteries + fridge are taking 20A a resistance of just 0.1Ohm drops you 2V so 14.4V at the alternator becomes 12.4V at the battery.

I'd be more wary if the batteries are a long way from the alternator, if they are under the passenger seat you're probably good. It's all down to how good the original installation is and whether the converter/maker cut corners with the copper wire thicknesses.

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Ivory55

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To give them a rough idea on power that they would need, we use a 2kw genny for the hairdryer and you can definitely hear the engine change note when the hairdryer is switched on.
 
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busbuddy

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in my last van i fitted 2 big 250ah batteries and a 2000w inverter plus 2 100w solar panels because a daughter with shoulder length hair demanded the suitable equipment if she went away off grid and i thought my solution was the minimum needed to cope
after a couple of years with this setup, and at a 10 day off grid race meeting in september, i made a decision to test the limits of my system (beer inspired obviously) using toaster(german van)/kettle/hairdryer/mini oven/etc
at the next meeting i went with only one battery, the next only one panel, still couldnt kill it
race season was march to october in uk, sweden and germany
fast forward a decade and current van has 2 110ah batteries because it came with them, i fitted a 160w panel and 1000w inverter which is the bare minimum for hairdryer of OH (short hair) and everything possible in the van is 12v....hairdryer and straighteners only 240v, lights are all led

i have only had this van for a couple of years but my system copes, at the 10 day september meet we usually have at least 5 phones a day charging, couple of laptops, flagpole leds, usual interior day to day stuff and it works fine

i could fit a massive lithium all singing setup but my power usage dont need it, its all trial and error how big a system you need and i imagine quite frustrating and costly if you keep exceeding it


one thing i will say is the wiring for the 2 batteries (factory fitted) was pathetic, when i fitted the inverter i took both front seats/carpet out, replaced the battery wiring and fitted good fuses at the battery positives
 
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bigtwin

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Yes that's the theory, but in practice you may see 2 problems:
1. More charging current for longer = more alternator wear, more EHU charger heat and more cable heat.

The alternator is spinnng irrespective of whether or not it’s delivering current.
The charger/cables are designed to dissipate heat at their rated load so there are no challenges there.

2. If your fridge is also on 12V while driving the extra charging load means your hab batteries may never see The 14.4 V absorption charge they need and therefore never get to full charge, shortening their life.

I.e. if your batteries + fridge are taking 20A a resistance of just 0.1Ohm drops you 2V so 14.4V at the alternator becomes 12.4V at the battery.

Are you speculating that the additional battery is located some (considerable if it’s dropping 0.1ohm) distance away from the charger? Otherwise the voltage drop would apply equally to the original battery.

In any case, to get a 0.1 ohm resistance on a 16mm or 25mm CSA would need a 100m cable run!

I’d be more wary if the batteries are a long way from the alternator, if they are under the passenger seat you're probably good. It's all down to how good the original installation is and whether the converter/maker cut corners with the copper wire thicknesses.

Agreed, but any of the weaknesses you allude to would exist irrespective of the fitment of an additional battery.

As I said earlier, the existing setup would cope but would simply take longer to achieve full charge.

Ian
 
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suavecarve

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Remember when you double your Hab battery capacity the electricity needs to get in there somehow, so make sure your charger, wiring and alternator can cope with the sudden load of having to charge 220Ah instead of 85Ah!

I would suggest you keep inverter power to 300 or 500 Watts only and go for a Victron Multi to do the entire switchover, charging and inverting in one go, and try to fit it between your main EHU isolator switch and the RCD in your electrical distribution.

Get a competent electrician to do the wiring if you are not sure about what to do, lots of scope for electrocution, fire and dead batteries if done wrong ;)

Once you go into a real 800W or higher you really need to redesign the entire electrical system to do it properly. Note that £50 eBay 2kW inverters are not real and will not work as you expect, you need to be buying top european brands for these items, save the money on the batteries instead as cheap wet cell lead acid are better than people think.

Also fit a proper isolator switch, theres nothing a battery likes more than to be totally disconnected.

Also read:
https://www.motorhomefun.co.uk/forum/threads/inverter-question.193346/

According to this I have done everything wrong for the past 10 years.
I am in no position to disagree with the poster though as i dont know but the FiL is/was a sparky.
I ll get back to this in a mo.

We changed vans and obviously the set up was slightly different but esentially the same. Solar at 120 watts, 2x100 amp batteries. Used mainly in france in the summer, never on hook up.
First van 240 volt tv 12 volt lights etc. batteries with tv on lasted maybe 2 and half films. Tv was served by inverter.
2nd van same solar and battery setup. 12 volt tv. everything the same only new. Yet to go below 85% but we watch less tv.
Dont need the 2nd battery. (I would still have one though)
To combat 2 electronic cigarettes (just in case i have a panic if one goes down) 2 phones and numerous other 12 volt chargeable items we bought a solar battery pack charger which we can take to the beach with us. Brilliant little back up, so we have bought another one.

So back to the inverter. And i say this as an amateur overseen by a pro. It was dead simple to attach directly to the batteries and screw it in on to some woodwork. 10 minute job just get the wires round the right way. It was a 50 quid one from Maplin and allegedly 2000 watts but something scientific makes it only 1000. (Something to do with sine wave) Am i showing my level of electrical competence yet ? But the reason i tell you this is your wifes NEED to dry her hair. Try finding a decent hairdryer under 1000 watts. Try finding one under 500 watts. There is one for 400 watts which looks as if it has come off the set of Life On Mars that was scoffed at by the wife. She needs to cut her hair and use a towel. It is your job to tell her this and not your job to quote me and bottle out of it.
The inverter is now only used to provide an extra charging point for said mobile phones etc.
 
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