LPG gauge

I filled my nuevo LPG tank for the first time ,it was down to one led so presumed it was almost empty ,on filling it took under.13 litres ,does that seem about right or is my gauge out more than normal .

Recently, obliging forecourt attendant filled up LPG tank and noticed gauge indicating only about three quarters full, oh well, something else not working properly. Several days later gauge displayed full tank, all LEDs now illuminated, oh well.

I’m not surprised as the gauge is not very accurate when compared to your diesel tank gauge and generally I’ve found the lpg gauge to be pessimistic.
I usually fill ours when down to 2 green led’s and the amount to top up does seem to vary a fair bit.
When filling up if the forecourt is sloping it will affect the amount that you can get in due to the auto cutoff device in the tank.

Quite frankly, I've come to the conclusion that all gauges in my motorhome - LPG, fresh water, waste water, internal and external temperatures - are only approximate. I came to that conclusion reluctantly, given that similar gauges on cars are more accurate. But that conclusion - based on my experience and extensive and repeated posts on the Forum - is the only one which will stop me tearing my (remaining) hair out.

I now know that I must apply common sense to the readings. And not lose any more sleep about them. Gauges on motorhomes are merely indicative!

Cymro

Cymro wrote:Quite frankly, I've come to the conclusion that all gauges in my motorhome - LPG, fresh water, waste water, internal and external temperatures - are only approximate. I came to that conclusion reluctantly, given that similar gauges on cars are more accurate. But that conclusion - based on my experience and extensive and repeated posts on the Forum - is the only one which will stop me tearing my (remaining) hair out.

I now know that I must apply common sense to the readings. And not lose any more sleep about them. Gauges on motorhomes are merely indicative!

Cymaro

Quite frankly I totally agree , but in my opinion they should be fit for purpose .

Molly3 wrote:I filled my nuevo LPG tank for the first time ,it was down to one led so presumed it was almost empty ,on filling it took under.13 litres ,does that seem about right or is my gauge out more than normal .

Is that .13 litres (sic) or thirteen litres? Does your gauge now read full?

Mine has started working differently, I parked it showing two thirds full  and it magically filled itself. Now even when almost empty it reads full whilst driving, the only way to get a reading is to park and wait. It used to work whilst driving it fluctuated a bit but it worked. Is there a damping adjustment on the sender?

In order to get the maximum amount of gas into the tank when filling your vehicle must be level in all planes. I have mentioned this previously, how most gas filling points in Europe have a dedicated flat surface, with yellow boundary markers, within which you must park your vehicle before filling. This is in order to maximise the amount of gas you can get into your tank. 
I do not think there is any damping in the sender (certainly not in mine) as the gauge appears to instantly respond to all changes in vehicle attitude - i.e. uphill or down hill, and it even responds (to a lesser extent)  to a severe road camber.
Liam

Pete Taylor wrote:

Molly3 wrote:I filled my nuevo LPG tank for the first time ,it was down to one led so presumed it was almost empty ,on filling it took under.13 litres ,does that seem about right or is my gauge out more than normal .

Is that .13 litres (sic) or thirteen litres? Does your gauge now read full?

Not sure what you mean (sic) my gauge  read full  after filling ,gauge was on one red light before filling .i would say the garage forecourt was level . That says to me I have 7 litres left when the red led is on ? .I have only had the van a few weeks so still finding my way round .I saw your post about re setting the display current yes it needed a resetting..that made me wonder what else could be reset apart from the step ?.Bazz

Molly, I agree with the conclusion that you have (approx.) 7L left when the red light has just come on, and just exceeds 7L when the red light goes out during the first of part of filling.
Notwithstanding the statements about "inaccurate gauges" and the need for a level surface, which I do not dispute, I had always interpreted the gauge on a previous motorhome as follows.  The tank has a capacity of 25L.  The LPG garage pump will only fill to 80% of that, ie. 20L
When filling from absolute empty the red light is on up to 5L, the red light goes out and the first Green/yellow light comes on and stays up to 10L when the second green light illuminates, and then in succession at each 5L of filling. I only ever reached four green lights, equalling approximately 20L
The logic of this says that if you had two green lights to start, the tank contained more than 10L but less than 15L. Your reading of .13L is thirteen litres approx.  
The same logic says that when the red light illuminates during use of gas, you still have 5L left.
All of the above is approximate, but during my ownership of that MH, it worked for me.
Keith

I'm afraid that the level measuring systems used on most MOHO's will never give any more accuracy than me grabbing a gas bottle and estimating the amount left by the apparent weight of the cylinder. I worked for many years for a well known liquid gas producer and the measurement of cryogenic liquid level is always a pain. It is possible but at a cost. In some cases it could exceed the cost of the MOHO. Weighing the tank was always favorite with radar and capacitance close runners but temperature and boiling surfaces always gave problems.
I love my MOHO's gas tank and wouldn't go back to cylinders especially when travelling abroad, But with regard to the level gauge, it's a guide and at half way I start looking to refill it.

ChrisP28 wrote:I love my MOHO's gas tank and wouldn't go back to cylinders especially when travelling abroad, But with regard to the level gauge, it's a guide and at half way I start looking to refill it.

Your comments are most helpful Chris, and coming from an expert they are even more useful. Thanks.

Your final point above is well worth repeating. The convenience of the tank is a huge advantage, specially abroad, and the gauge is at worst a useful indicator. I also regard half empty as the most sensible time for a top up, and I always regard the vehicle fuel gauge in the same way.

Very rarely do any of our vehicles have less than half a tank of fuel. You never know when you might need it in a hurry, or when (say) the French tanker drivers will go on strike again.       (In the last crisis a couple of years ago we had no problem at all, but we saw lots of vans stranded in lay byes with empty tanks!!)

Just filled mine from empty and put in 19 litres on a level for court
Geof

Our Warwick Duo has the usual 25 litre (gross) 20 litre (net) Gas-It underslung tank. Over 4 years use, we have found that when the red light first comes on, the tank will take between 11 and 12 litres to fill it. What makes a big difference is the level of the van, both side-to-side and front-to-back. The most accurate reading of the contents has been made when travelling along a straight and level section of road.

We now fill when the red light comes on, having gained sufficient experience of use, to know how long the remainder will last us before running out.

Spospe wrote: .... we have found that when the red light first comes on....

We now fill when the red light comes on ......

This may sound stupid, but bear with me as I'm colour-blind.

Do you have a separate light  - in addition to the row of 8 LEDs which I have - which comes on and is coloured red, or are you referring to the row of 8 LEDs, which go out progressively as the tank empties? I've no idea what colour they are - or whether any of them are differently coloured from others.

Is one (or more) of them red, and if so, which, please? (Not that it matters a bit - because like everyone else, I fill when it gets down to about 3 or 4 lights left illuminated, whatever be their colour!. But it would be nice to know what I'm seeing!)
Cymro

Hi Cymro

I think this is the gauge you and I have fitted. If it's not this actual model it's essentially the same.

It has nine LEDs, the first of which is red, and the other 8 are green. You will probably never have noticed the red one as the tank would have been full or partly filled on delivery of the van - but it is there.  CLICK HERE

   

As Gromit says, the leftmost LED is red when illuminated and in 'normal' use it is not lit at all. A full tank has 8 lit green LEDs and one unlit red LED. When the level drops enough to extinguish all 8 of the green LEDs, the red LED lights up. You can see the red LED in Gromit's picture above (the one under the "L" of Lo.

The last time we filled our tank the display had one green led lit before filling,  it took 12 litres to fill.

Well! Well!

Thanks, Gromit and Spospe - I didn't know that.. Still can't see the red, but good to know how it works. Most grateful.

LEDs using colour-change pose me real problems.

cymro

You will see the red one if it comes on Cymro - it's about three times as bright as the green ones!

There's a lot of confusion about the accuracy (or otherwise) of these gauges.

For a start, the red light doesn't indicate an empty tank. (What would be the point since you know it's empty when everything stops working - and it's too late then!!) I don't know the precise quantities, but it works like a reserve tank on the car and tells you when there's (I would guess) about three or four litres left in the tank. Maybe up to five litres as a worthwhile reserve, so let's work on that figure.

In a tank holding 20 litres of LPG that means the eight green lights will indicate the progressive consumption of the additional 15 litres, so that's something close to two litres per light.

It also means that four lights showing does not indicate a half full tank. It means you have used about 7 or 8 litres, and have about 12 or 13 litres remaining in the tank - including of course, the five litres which are not accounted for by the green lights.

It's all a bit iffy and imprecise as has been said earlier, but I'm convinced this is how it works. It's common sense really - there's no point in having an "empty" indicator. What we have instead is a "getting very low" indicator so we can top up as soon as possible.

Hope this makes sense.


Addendum. Sorry. Forgot to say I agree with what Keith said earlier about 5 litres "in reserve". 

Entirely, thanks! 

Takes me back to my first Beetle, with its reserve tank to which you had to switch over by means of a lever. Always was a comfort to know that there were 5 or so spare litres there .... until, in 1971, we bought a new Beetle. Very proud. After a fortnight or so of ownership, we were driving and the needle was at zero. "Don't worry" said I to my wife "As usual, I'll switch over to the reserve tank when it starts to stutter." Alas, new Beetle had no reserve tank. Marooned in the town centre square in Barry, very embarrassed!
Cymro


PS: Dave, yours is such a good explanation that I suggest it be made a sticky. This topic keeps recurring. so to have a reference answer would be good.
C

Thanks Cymro - you say the nicest things!!  

Let's see if anyone contradicts first. I'm basing the argument entirely upon simple observation of my own experience, plus a bit of logic.

For instance, I had four/five lights showing last week when I topped up for our next trip (to Pembrey  ) and it needed almost exactly 7 litres. This was confirmation of what I had been pondering ever since the start of another series of complaints about inaccurate meters.

With all due respect to anyone who complained, I think the meters are generally fairly accurate - assuming the tanks were installed with the correct rotational alignment (which quite a few were not!!).

It's more a case of not understanding how they work. The gauges on Gaslow tanks are a prime example, and offer a simple illustration. They are almost universally despised as being useless, but a quick study of a cutaway diagram reveals how they work - and why they cannot possibly give a linear indication of LPG consumption. The gauge will obviously show "full" until the level of LPG drops to about half and the float begins to sink a little.

If only people would take the trouble to do a bit of research before throwing their Teddy out of the pram . . . they would enjoy their motorhomes so much more without the self inflicted aggro! 

The Gaslow images are showing a vertical tank, in a horizontal underslung tank installation as fitted to an Autosleeper the float valve is fitted on the side and measures from top to bottom although not very accurate.

Thanks for replys most helpful

I filled up with gas as the gauge had only one of the five lights lit.The pump put less than 3 litres in and still only one light lit.Do I need a new gauge or is the fault at the tank?

Alan