Re: Fresh Water Level Indicator Not Working

by -mojo- Fri May 09, 2014 12:18 am

Steve Cheetham wrote:does anyone know of an alternative on the market that perhaps works on the same principle as a fuel gauge???

People have been trying to solve this problem reliably for decades. Anything working on the principle of a conventional fuel gauge sender simply won't work - a tank of water is too corrosive an environment for it to survive for more than a few months.

Hence the change to non-moving parts and corrosion-resistant sensors. In theory this should be very reliable, but it seems that shortcuts may have been made with the electronics...

by Peter Brown Fri May 09, 2014 6:39 am

When the indicators do work they are still only a very rough indication of what is in the tank and that is when the van is level, only a few degrees off in any direction can make a big change in the indication.

I like my level indicator to work because it should but I place little reliance on it. I have a 10l water container and I know that on a typical day we will use 15l or if we don't cook 10l so I know what I have put in and how much I've used.

Peter

by artheytrate Sat May 10, 2014 4:35 pm

We have just been to Benidorm for 6 weeks in our new Broadway and we've also had problems with the readings on our waste tank telling us that there was still the same amount of water in tank although we had emptied it. then it would read empty at another time, and then the alarm started sounding that the tank was full although we had emptied it.

John.

by Peter Brown Sat May 10, 2014 4:41 pm

I think the waste tank sensor is a float and the only indications are empty and full and if full an alarm sounds till cancelled on the control panel.

I had the same symptoms as you and the sensor was replaced to cure it.

Peter

by artheytrate Sat May 10, 2014 5:31 pm

Thank you.
Peter.

John.

by Clarina Wed May 14, 2014 8:03 pm

I have just joined this forum and found this thread, we are also having a problem with the fresh water gauge. We previously filled via the supplied hose pipe but kept changing from 75% to empty when tap run, also internal pump would not stop running when taps turned off. Thought may have got air in system.

Today we drained down completely and filled again using external pump from 40L Aquaroll so we would know how much water had been put in. Refilled the Aquaroll 4 times although not emptied completely each time sure enough water to fill tank (105L ?)

Gauge has not gone above 25% and when we run taps shows 0% and bleeps!! Did manage to sort out internal pump so now does stop (made sure the joints pushed together and clips for wires on top pushed firmly on) however the gauge still fluctuates between 0 and 25%.

Is there any easy fix for this??

Many thanks

Gill

by Peter Brown Thu May 15, 2014 4:05 am

Gill

Short answer - No!

I was surprised at the large size of the tank but the spec is 102 litres.

I've had all of the symptoms you describe (and more) and had all sorts of fancy theories with consequential replacement of cables and connectors under warranty but in February all 5 sensors in the tank were replaced (which involved the Service Centre dropping the tank to get access to them all) and all has been well since then.

I had the same system on two previous vans and had no problem with them so know the system can work reliably. We'll see how the system holds up on a forthcoming 4 week trip.

Peter

by Clarina Thu May 15, 2014 7:08 am

Many thanks for your reply, will see how it goes over weekend, have spoken to dealer to get them to look at it when we get back.
Was pleased with myself at sorting out pump though!
Enjoy your trip.
Gill

by inspiredron Wed Jul 02, 2014 9:28 pm

Mark at the service centre has told me to check if the studs have been covered with tape and if so to remove it and seal them individually. Apparently tape can affect the readings. I have not checked mine yet but I was getting sporadic 0% indications while in Spain. They usually came when the tank was at about 50% and would clear if the Sargent was switched off and then on again. Stud corrosion may be a contributory factor but my electrical experience tells me that the resistance should not vary if the water did not move. Seems very odd - maybe the Sargent circuitry is over-sensitive to resistance variations? That would tie in with Mark's comment about tape over the studs.

by Peter Brown Thu Jul 03, 2014 8:44 am

There are five studs set into the side of the freshwater tank and for this description I will number them 0 (bottom) to 4 (top). Each stud is connected back to the Sargent PSU via a wire loom that goes via a connector block under the van floor.

When stud 0 is connected to 1 the level indication is 25%. 0 to 1 & 2 - 50%, 0 to 1 & 2 & 3 - 75% and 0 to 1 & 2 & 3 & 4 - 100%. The Sargent unit only look for connectivity, it doesn't measure resistance. Water inside the tank connects the studs as the level rises and disconnects as it falls.

The standard practice in the factory is to cover all of the stud connections with pieces of tape to protect them from road dirt/salt. If (when) water gets behind the tape it connects the studs and you can get indications of level when the tank is empty. The service centre remove the tape and protect each individual stud connection with a blob of sealant.

The under floor connector is wrapped in tape and if water gets into that you can get the same symptoms and additionally the pins corrode.

The corroding pins increase resistance until eventually the PSU cannot detect connectivity between studs and you get a 0% reading with water in the tank. The same happens when the studs in the tank corrode.

When the studs in the tank have corroded there gets a point where the hardness/chemical content of the water combined with the resistance of the stud will enable level indication depending on where you fill the tank with water so for instance last year I filled the tank at Stoke and had no level indications. Over a few days I replaced the contents with Whitby water then the level indications started to work. The reinstatement of readings when Ron switches off/on is enabled by the initial voltage peak breaking down a point of resistance for a while.

Because the symptoms are so nebulous it can be very difficult for either Sargent, the Service centre or your dealer to pin down exactly what the cause of a level indication problem is. After the replacement of control panel, internal wiring loom and external connector blocks over 2 years things eventually settled down for me when all 5 studs were replaced in February.

The indications have been fine since with water from many different locations in Europe but I do expect that the studs will become a problem again in the future. This is really surprising as both previous vans had the same system that worked faultlessly over a period of six years!

Peter

by inspiredron Thu Jul 03, 2014 10:14 am

Thanks for that detailed explanation, Peter. It is just what I expected and is consistent with what Mark has said. However, damp being retained in the tape would, as you say, give false positive readings. What most folk seem to get is false negatives, ie 0% when the tank is more than 25% full. My point about the Sargent being too fussy about resistance was that it is looking for conductivity - it will measure conductivity by putting a voltage across the studs. The chip will see if there is any current but there will be a turnover threshold to trigger the transistor "switch" within the chip. If that threshold is set "too high" then the chip may think it is an open circuit when a smaller than threshold current is flowing- ie it thinks ther is no water.
My Hymer had a sensor that did the same job with four (or maybe 5) rods that dipped into the tank from the top. The principle was the same except that an analogue meter was used as an indicator but the length of the rods exposed to the water reduced the chance of false readings. And the waste tank had exactly the same indicator. I had no false readings in 10 years.
I still believe that the Sargent circuitry may have a bearing on these problems!

by Dutto Thu Jul 03, 2014 11:14 am

mikethebike wrote:Reading this thread ,i am glad i have an old Symphony.I can select any water level i want on the panel.
i know it is iffy ,but i never have run out of water.

regards

Mike

Ditto!!

Also, why would anyone NOT know when they are about to run out of water? scratch head

I think much more important (but NOT measured on most vans) is when the Grey Water tank is overflowing; a really anti-social situation! tap_fingers

Another useless level gauge is the one on the toilet cassette! look here

Surely, anyone stupid enough to overfill a toilet cassette wouldn't have enough brain cells to read a level indicator!! gimmefive

Best regards,
drinksallround

Ian

by DeeGee7 Sat Jul 05, 2014 11:47 am

Peter Brown wrote:
DeeGee7 wrote:I don't know if this may be of some use to anyone but having experienced the same problems with the water level indication I have now fitted an extra earth wire from the bottom stud on the fresh water tank directly to the vehicle chassis. So far this has fixed the problem for us.
That certainly fits in with my theory as to why there is a problem. I had not thought of the possibility that the reference wire is at earth potential in the PSU but if it is, your solution to reduce the resistance in that part of the circuit is a real brainwave. Please let us know if it goes wrong again and if mine starts to play up again I will investigate whether your fix would work for me.

Thanks

Peter

Peter, as a follow up to my previous post, my water level indication has been perfect since fitting the extra earth wire. I wish I had tried this earlier, it would have saved a couple of years frustration.

Dave G

by micknhilary Sat Jul 05, 2014 2:00 pm

As the owner of a much older 'van may I recommend the 'Toucan' system of fresh water measurement.
I leave home with the tank pretty full and then, each morning I fill my 10 litre watering can twice and pop it into the tank. Experience has shown that using this system I am most unlikely to run out of water and I get a little exercise at the same time.

Mick. hugegrins

by inspiredron Sat Jul 05, 2014 3:18 pm

micknhilary wrote:As the owner of a much older 'van may I recommend the 'Toucan' system of fresh water measurement.
I leave home with the tank pretty full and then, each morning I fill my 10 litre watering can twice and pop it into the tank. Experience has shown that using this system I am most unlikely to run out of water and I get a little exercise at the same time.

Mick.

Take those hugegrins

off your face !!! lol4

As the owner of a much older van you don't have these fancy electronics that shout at you when they think you are out of water but the tank is nearly full! censored!

But when they work (which is most of the time) they are great.

by artheytrate Sat Jul 05, 2014 3:21 pm

micknhilary wrote:As the owner of a much older 'van may I recommend the 'Toucan' system of fresh water measurement.
I leave home with the tank pretty full and then, each morning I fill my 10 litre watering can twice and pop it into the tank. Experience has shown that using this system I am most unlikely to run out of water and I get a little exercise at the same time.

Mick.

With you saying Toucan I thought you were filling it with Guinness.

John.

by bazil Fri Jan 09, 2015 7:02 pm

Anybody found a reliable way of cleaning out waste tanks?

by Jaytee Fri Jan 09, 2015 7:40 pm

Bazil wrote:Anybody found a reliable way of cleaning out waste tanks?

Don't know if this an approved method but after reading various posts from Dutto et al on the benefits if bio washing detergent I chuck some liquid bio down the drain with a half full ish grey tank before a drive and then as soon as I get to a site or home I empty it. Seems to keep it fresh and clean.

by The Duke Tue Jan 27, 2015 5:55 pm

Hi,

So glad I found this thread, as I likewise have a problem with an incorrect water level indicator. Judging by the responses there's not a quick an easy fix either. Why bother putting inadequate equipment that fails into expensive motorhomes/campers. Good job we are not building Lunar space modules otherwise we would be in trouble. Does the problem bother me .....no not really, now I know its a problem. Its just another piece of useless electronic junk that doesn't work. Bring back the manual 'dip stick's'................and there's plenty of them about.

The Duke

by tcc Wed Feb 11, 2015 5:50 pm

I had the same problem on a Peugeot Broadway that I have just bought and it's less than a year old.
The gauge had erratic readings and not consistent with what was in the tank. It was returned under warranty and the guy's in the workshop fitted an extra earth from the lower stud to the chassis and although it's fairly recent it seems to be working fine.
I'll monitor the gauge and let you know if there are any other problems.

Tony

by Jaytee Wed Feb 11, 2015 5:52 pm

Yes, that's on my list of little jobs to do as well content

by groundhog Wed Feb 11, 2015 7:10 pm

Same problem, dodgy water levels and pump packed up in fresh water tank. Marquis fitted a hatch in the tank for me so now the pump can be replaced in lightening quick time and the probes on the gauge cleaned.

Simple idea wonder why A/S didn't do it in the first place?

by Jaytee Thu Feb 12, 2015 7:47 am

That is very very interesting. Where did they fit the hatch and is it a kit or home brew type of thing?

by JDS Thu Feb 12, 2015 12:48 pm

I had a problem with my pump on my 2012 Broadway, I got under the van opened the hatch shook the pump refilled and air lock problems gone. I noticed the screws on the flange were corroded obviously not stainless steel. When I went to Willersey for a hab service I mentioned to Mark I wanted the screws replaced under warranty, he said they don't fit a hatch. So it must have been fitted by Marquis. (He did replace the screws) I don't when or why as I bought the van new.
Mark said the Kit could be bought at CAK tanks. I would highly recommend it as t is so easy to get into the tank.

by Jaytee Thu Feb 12, 2015 1:36 pm

Where was the hatch fitted? I have contacted CAK tanks for costs.