electronic float switch, 2 WaterWitches later, need something more reliable, Ideas???

[halcyon]

Had a quick read through, has anyone considered the old pressure switch. Pipe in bilge up to industrial pressure switch in cabin, pipe feed from upturned 'tin' to stop clogging, switch in cain in dry. Water fills up inverted 'can' creating pressure closing switch, basically no moving parts, no electronics and 'dry' location.

Brian

 

[vas]

Had a quick read through, has anyone considered the old pressure switch. Pipe in bilge up to industrial pressure switch in cabin, pipe feed from upturned 'tin' to stop clogging, switch in cain in dry. Water fills up inverted 'can' creating pressure closing switch, basically no moving parts, no electronics and 'dry' location.

Brian

confused me a bit here, don't really need the tin and stuff do you?
I mean you can have a 1m or more long hose, secure it on bulkheads or wherever is suitable and bring it all the way up to a safe dry spot and do the thing. Checked it with a longish pipe and a glass of water, I could see clearly the change in Vout from the sensor by simply dipping the tip of the pipe in the full glass of water.

Main problem I can see with the washing machine sensor is, anyone tried it on a 24V boat electrics?
I'm not going to bother if it's 12V only as I'll need a dropper + a relay, becomes a kludge, might as well go for the original plan and have full control on depth point of triggering.

cheers

V.

 

[vas]

Water Witch FAQ
Too much s---te on it??

nope, perfectly clean and dry - tbh used one didn't have anything on it, just a bit of dried muck, wiped clean with a cloth.

Not to mention that the new one didn't work out of the box before even dipping it in the tank - off the sealed packaging, wired up, tried out of the tank, always on (waited for a minute or so) nada still going...

will probably be ordering the bits later on today

cheers

V.

 

[Refueler]

I like the washing machine switch ... but my problem is even a standard float switch has too much water before it activates. I have a bilge keel boat with round turn of bilge with cabin sole barely 10cms or so above the hull. The standard float switch literally hits underside of cabin sole when it activates. The WW was a good solution - till it did same as 'vas' .....

I have it in a box and I cannot find any leak / damage / corrosion or reason for its failure ... its just does not switch OFF.

I need a solution that will activate a pump at just over minimum level required by pump .... which is too low for any switch I have seen so far ...

 

[davidej]

Instead of a pressure sensor, what about a contactless level sensor which you can glue or sikka on the outside of a plastic tank. I have on as a low level sensor on the còolant bottles of my car.

You can get them on fleabay for a fiver but you would need a relay as well.

 

[halcyon]

confused me a bit here, don't really need the tin and stuff do you?
I mean you can have a 1m or more long hose, secure it on bulkheads or wherever is suitable and bring it all the way up to a safe dry spot and do the thing. Checked it with a longish pipe and a glass of water, I could see clearly the change in Vout from the sensor by simply dipping the tip of the pipe in the full glass of water.

Main problem I can see with the washing machine sensor is, anyone tried it on a 24V boat electrics?
I'm not going to bother if it's 12V only as I'll need a dropper + a relay, becomes a kludge, might as well go for the original plan and have full control on depth point of triggering.

cheers

V.

They normally use a 1/4 inch pipe, so can get blocked with rubbish in bilge, inverted plastic container stops it blocking, tin was just a descriptive way of putting it.

They are not voltage dependent, they are simply mechanical contacts closed by air pressure, so 12 or 24 volt not a problem, have a look at this on Farnell, lots around use in industrial control, sorry not electronic.

Brian

 

[Refueler]

This was proposed to an RC Boater some years ago (Radio Shack !!) to provide automatic pump actuation ...

 

[Refueler]

Instead of a pressure sensor, what about a contactless level sensor which you can glue or sikka on the outside of a plastic tank. I have on as a low level sensor on the còolant bottles of my car.

You can get them on fleabay for a fiver but you would need a relay as well.

Many ships I was on where we had Halon and other gases in pressure tanks - it was impossible to have internal gauging other than pressure.
The method used to gauge content was Temperature. A hand held gauge was slid up the tank and when temperature spiked - you noted the level ... you then repeated in opposite direction to check. The average of the two was the level.

Your external level sensor is likely a fixed version of that to indicate that single level.

 

[Refueler]

This looks interesting ....

RAIN DETECTION WATER ACTIVATED SWITCH RELAY SENSOR RELAY KIT 10A 12V | eBay

 

[halcyon]

This was proposed to an RC Boater some years ago (Radio Shack !!) to provide automatic pump actuation ...

View attachment 87673

It also puts a positive DC supply into your bilge water, are looking to generate electrolytic corrosion ?

Can be done, but you need to use a AC sensing current.

Brian

 

[Refueler]

It also puts a positive DC supply into your bilge water, are looking to generate electrolytic corrosion ?

Can be done, but you need to use a AC sensing current.

Brian

And what do you think the WaterWitch does ?

Any contact switch MUST have a current flow albeit tiny and only as long as water is there .....

 

[Zing]

I’ve tried them all. Im

And what do you think the WaterWitch does ?

Any contact switch MUST have a current flow albeit tiny and only as long as water is there .....

A lot of sealed sensors are capacitive. There is no current flow.

 

[Paulg25]

Any contact switch MUST have a current flow albeit tiny and only as long as water is there .....

Contact switch with moving parts.

 

[kashurst]

I like the washing machine switch ... but my problem is even a standard float switch has too much water before it activates. I have a bilge keel boat with round turn of bilge with cabin sole barely 10cms or so above the hull. The standard float switch literally hits underside of cabin sole when it activates. The WW was a good solution - till it did same as 'vas' .....

I have it in a box and I cannot find any leak / damage / corrosion or reason for its failure ... its just does not switch OFF.

I need a solution that will activate a pump at just over minimum level required by pump .... which is too low for any switch I have seen so far ...

two of these on a bracket set with one @ 3cm higher ( I think Mapism has something similar) the switches move @ 1cm to activate
EHAO 2 Pieces ZP4510 Liquid Water Level Sensor Vertical: Amazon.co.uk: Electronics
into a double pole relay (I can draw you a diagram if needed no problem)
consider changing the bilge pump from a centrifugal type pump to a rubber impeller style pump. Try the float switches first and see how it all behaves

then you can set the float level really low as the pump will still suck and it won't run back if you put a non return valve after it

the transistor type sensors will work but not very reliably or very long. They may well operate when you transmit on the VHF or start the engine. The ebay device will rot very quickly.

 

[Keith-i]

Vas, have you considered any effect the sloshing around of the tank contents might have accidentally setting off the pump in rough conditions?

 

[davidej]

My system was built around one of these

XKC-Y25-V/Y25PNP Non-Contact Liquid Water Level Sensor Induction Switch Detector | eBay

despite being described as induction, I think it works by the change in capacitance that the liquid causes

 

[vas]

sorry for the delay guys, some replies/ideas and a couple of photos of the waterwitch follow.

They normally use a 1/4 inch pipe, so can get blocked with rubbish in bilge, inverted plastic container stops it blocking, tin was just a descriptive way of putting it.

They are not voltage dependent, they are simply mechanical contacts closed by air pressure, so 12 or 24 volt not a problem, have a look at this on Farnell, lots around use in industrial control, sorry not electronic.

Brian

OK, nice idea, just make sure you wont block the smallish pipe, thanks!

two of these on a bracket set with one @ 3cm higher ( I think Mapism has something similar) the switches move @ 1cm to activate
EHAO 2 Pieces ZP4510 Liquid Water Level Sensor Vertical: Amazon.co.uk: Electronics
into a double pole relay (I can draw you a diagram if needed no problem)
consider changing the bilge pump from a centrifugal type pump to a rubber impeller style pump. Try the float switches first and see how it all behaves

then you can set the float level really low as the pump will still suck and it won't run back if you put a non return valve after it

the transistor type sensors will work but not very reliably or very long. They may well operate when you transmit on the VHF or start the engine. The ebay device will rot very quickly.

yes, your approach is the only one that can manually without delay circuits solve the problem I have in the 16lt grey tank:
It's not a matter of starting the pump when tank is full(ish) but to keep the pump running enough to empty the thing!

Vas, have you considered any effect the sloshing around of the tank contents might have accidentally setting off the pump in rough conditions?

yes, haven't had such a problem in 4 seasons, tank is 600X400X300mm (approx) sensor is smack in the middle, so water moves gently around the mid.

My system was built around one of these

XKC-Y25-V/Y25PNP Non-Contact Liquid Water Level Sensor Induction Switch Detector | eBay

despite being described as induction, I think it works by the change in capacitance that the liquid causes

David you're very brave! tried to read the literature and it was well impossible !

just ordered a lot of stuff from Farnell for a few projects, few bits will address this issue as follows:

0-4kPa pressure sensor with 0.6V/kPa output
comparator turning on when thing reaches the right pressure
delay circuit keeps thing running for 10-15sec once trigger is lost (water level lowers)
most likely transistor drives the 24V@2A pump (or skip that and use some solidstate relays I have leftover
(obviously a few resistors/diodes/pots mixed in the above to enable sorting trigger point)

If that lot fails - pretty sure it wont - fallback to kashurst approach.
TBH, if I wasn't stranded with CV19, I wouldn't bother with the pressure approach.

Now, due to the extra free time I have, last night I had a go at taking apart the old failed waterwitch. With a heatgun I carefully started removing the epoxy that was used to fill the whole cavity.
Early on, it was clear that there's an normal relay 20A@30V there that triggers output.
there's a few capacitors and a dozen or so resistors plus an IC of some sort.
Ripped off the lid of the relay to check, looks fine, moves fine.
I find exceptionally odd that they have the thing wired so that it fails close circuit. I mean it needs current to pull and thus open the circuit going to the pump!
So for 2yrs this thing was in constant "stress" keeping the contacts open, how's that designwise?

It momentarily "engaged" as in opened when I first wired it, so there seems to be some current there doing what it has to and the coil is not burnt, but I guess something in this whole set of bits gone wrong making the thing fail.
My only concern is whether equalising the Trojans (@32V iirc!) may have managed to fck up the waterwitch. Still no reason for the sealed one NOT to work out of the box though.

Unless I got something horribly wrong, I'm afraid I cannot recommend WaterWitch to anyone...

cheers

V.

 

[Refueler]

I may open up and have a look !!

 

[Zing]

sorry for the delay guys, some replies/ideas and a couple of photos of the waterwitch follow.


OK, nice idea, just make sure you wont block the smallish pipe, thanks!


yes, your approach is the only one that can manually without delay circuits solve the problem I have in the 16lt grey tank:
It's not a matter of starting the pump when tank is full(ish) but to keep the pump running enough to empty the thing!


yes, haven't had such a problem in 4 seasons, tank is 600X400X300mm (approx) sensor is smack in the middle, so water moves gently around the mid.


David you're very brave! tried to read the literature and it was well impossible !

just ordered a lot of stuff from Farnell for a few projects, few bits will address this issue as follows:

0-4kPa pressure sensor with 0.6V/kPa output
comparator turning on when thing reaches the right pressure
delay circuit keeps thing running for 10-15sec once trigger is lost (water level lowers)
most likely transistor drives the 24V@2A pump (or skip that and use some solidstate relays I have leftover
(obviously a few resistors/diodes/pots mixed in the above to enable sorting trigger point)

If that lot fails - pretty sure it wont - fallback to kashurst approach.
TBH, if I wasn't stranded with CV19, I wouldn't bother with the pressure approach.

Now, due to the extra free time I have, last night I had a go at taking apart the old failed waterwitch. With a heatgun I carefully started removing the epoxy that was used to fill the whole cavity.
Early on, it was clear that there's an normal relay 20A@30V there that triggers output.
there's a few capacitors and a dozen or so resistors plus an IC of some sort.
Ripped off the lid of the relay to check, looks fine, moves fine.
I find exceptionally odd that they have the thing wired so that it fails close circuit. I mean it needs current to pull and thus open the circuit going to the pump!
So for 2yrs this thing was in constant "stress" keeping the contacts open, how's that designwise?

It momentarily "engaged" as in opened when I first wired it, so there seems to be some current there doing what it has to and the coil is not burnt, but I guess something in this whole set of bits gone wrong making the thing fail.
My only concern is whether equalising the Trojans (@32V iirc!) may have managed to fck up the waterwitch. Still no reason for the sealed one NOT to work out of the box though.





Unless I got something horribly wrong, I'm afraid I cannot recommend WaterWitch to anyone...

cheers

V.

At least it was potted. I have been through a couple of bilge pump switches from Johnson. They both failed and they have a good warranty, which is partly why I bought them, but they are junk. I will keep the warranty replacements in the spares bin, but I won’t use them.

Coincidentally, I was planning to have a go with a home made one too using the Farnel Multicomp switch. It looks to be a quality switch. Then to power a small relay with it or maybe via a transistor to the pump. They can’t switch directly, too low a current limit.

 

[vas]

well, a month later, today I powered the breaker as I was checking something, surely greywater pump fired up and was about to turn off the breaker when the thing stopped on its own.
Now I may have been too fast in assuming it's not going to work, but it seems that it eventually did work after all. Remember that's a brand new out of the box waterwitch.
Anyway, as I've got other projects going on and my back is not at it's best these days, I'll fit that for now and sort out the pressure sensor version of it when I have time (pretty sure that's going to be next winter (or lockdown whichever comes first...)
Thinking of "helping" the sender live a bit longer by adding it to the boat BMS and only power it when someone's onboard. Emptying the greywater tank is highly unlikely to be needed when the boat is unoccupied unless I get a waterleak, hence thinking about getting the freshwater pump on the same relay for good measure.

we shall see and I'll report back when I get the pressure version going.

cheers

V.