Please can anyone help with some electrical info?

Mike Lawrence

Mike Lawrence

Joined
Feb 20, 2012
Posts
32
Likes collected
52
Location
Southbourne, Bournemouth.
Funster No
19,884
MH
Swift Bolero 712SB
Exp
15 years
Having re-filled the water tank after the winter in our Lunar Premier H622 there is no water flowing. I've tried all the usual stuff, checked the fuses, replaced the pump etc etc. Here's the odd bit...

At the pump connector (top of the tank) to the loom there is 13v whenever I turn on a tap (they are microswitch taps and the pump is a Reich Twin submersible) but the pump doesn't run. I unplugged the pump and plugged in a 12v bulb - it didn't light up. With a meter attached the voltage disappears immediately with a load connected -weird!

I connected the pump to an old motorcycle battery and it works fine and there is water to the taps, shower and loo but the pump runs continuously as there is no control, obviously.

I have pulled the plug out of the main charging/distribution system and located the pin that connects to the loom for the water pump. When the pump switch is turned on at the control panel the pin is live and with a test-wire running to the pump it works. So it's not the charging system unit that's at fault.

The problem then appears to be buried in the loom somewhere. What I am trying to locate is the junction at which all four tap microswitches meet and talk to the pump feed. Can I find it? NO! It's buried somewhere and I have no idea where. I've unscrewed every panel I can find but to no avail. Each tap has two wires that disappear into the interior panelling.

Has anyone else had this issue and found the offending relay/junction?

Can anyone help me please?

Thanks ever so much, Mike
 
You appear to have a poor connection somewhere. I assume you have tried all taps?
One way to work around it, and is quite a good upgrade anyway, is to add a 12v relay at the pump connection. You will need to supply a 'good' 12v feed for the relay.
What this will do is use the poor supply from the micro switches to work the relay, which in turn will give the pump a good 12v everytime. It will also take the load off of the micro switches and should prolong their life.
Before you proceed with wiring best check that there is sufficient power to work the relay.

Geoff
 
Are the other 12v items working?
I've just spent half a day sorting exactly the same issue (good on test then disappearing voltage under load of the pump) on my son's m/h.
There were two issues. Firstly there was corrosion/bad connection at the 12v master switch. The 12v lights worked but connection failed under the start-up surge when the pump was switched on.
Second was a fuse that tested o.k. on the meter but went open circuit under the pump load.
Quite a few similar electrical posts on here which may be due to the up to a year's non-use of the m/h.
 
GeoffnDee said:
Is there an earth connection that is poor/ corroded causing a power drop under load?
Click to expand...
Thanks for your help! My first thought was an earth issue. I've just finished re-wiring a 1971 beach buggy which was fraught with earthing problems. Finding the earth mounts on a buggy is very easy. Think it's time to crawl under the Lunar.

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Spriddler said:
Are the other 12v items working?
I've just spent half a day sorting exactly the same issue (good on test then disappearing voltage under load of the pump) on my son's m/h.
There were two issues. Firstly there was corrosion/bad connection at the 12v master switch. The 12v lights worked but connection failed under the start-up surge when the pump was switched on.
Second was a fuse that tested o.k. on the meter but went open circuit under the pump load.
Quite a few similar electrical posts on here which may be due to the up to a year's non-use of the m/h.
Click to expand...
Hi, thanks for your help. Yep, the lights work perfectly. I've tested all the fuse connections and the main switches. It could well be lack of use and also the fact that we live less than 50 metres from the sea.
 
donkey said:
You appear to have a poor connection somewhere. I assume you have tried all taps?
One way to work around it, and is quite a good upgrade anyway, is to add a 12v relay at the pump connection. You will need to supply a 'good' 12v feed for the relay.
What this will do is use the poor supply from the micro switches to work the relay, which in turn will give the pump a good 12v everytime. It will also take the load off of the micro switches and should prolong their life.
Before you proceed with wiring best check that there is sufficient power to work the relay.

Geoff
Click to expand...
Thanks Geoff! The relay idea is a good one definitely. I have a couple floating around in my garage. My only concern is that the current isn't enough to activate the relay... especially as it won't even light a small bulb. I'll try that this afternoon. (y)
 
Had a similar issue lights worked but pump would not.
It turned out to be the quick release battery terminal on the leisure battery had split.
Voltage showing low current items would work soon as tap opened lost power.
Poor connection at battery in my case
 
Phill D said:
Had a similar issue lights worked but pump would not.
It turned out to be the quick release battery terminal on the leisure battery had split.
Voltage showing low current items would work soon as tap opened lost power.
Poor connection at battery in my case
Click to expand...
Thanks Phil, I had one split on my previous m/h. The current ones are absolutely solid. Took the battery out yesterday to Halfords and they ran tests and pronounced it all good. I double checked the clamps when I put it all back together.
 
Mike Lawrence said:
Thanks Geoff! The relay idea is a good one definitely. I have a couple floating around in my garage. My only concern is that the current isn't enough to activate the relay... especially as it won't even light a small bulb. I'll try that this afternoon. (y)
Click to expand...
Hi Mike

I know it is not the absolute cure as you may need to find the poor connection at some time. However, the relay will only draw milliamps to operate and would be a good mod anyway. So many pumps have wiring that is not up to the job and the relay will ensure you have a good 12v to the pump regardless.

Geoff
 
it could be a bad connection or a partial break in a wire causing that
 
donkey said:
Hi Mike

I know it is not the absolute cure as you may need to find the poor connection at some time. However, the relay will only draw milliamps to operate and would be a good mod anyway. So many pumps have wiring that is not up to the job and the relay will ensure you have a good 12v to the pump regardless.

Geoff
Click to expand...
Hi Geoff,
Found a spare relay and checked it worked with a spare battery. Hooked it up to the pump but nothing happened sadly. Ran a temporary earth directly from the battery to the pump as well. Just spent 15 minutes crawling around the underside checking for cable breaks or scuffs but everything is fine. I've come in for a cuppa and a cogitate now. :confused:

Giving serious thought to removing the submersible, cutting the main water feed from the tank and inserting a pressure-fed Shurflo pump. That way the taps opening will work the pump and bypass any hidden dodgy wiring.
 
Last edited:
If you need help with anything, you can always pm me. I am in Christchurch

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TheBig1 said:
I would opt for the update to a shurflo pressurised system personally. micro-switches fail all too often
Click to expand...
The only issue with the Shurflo is that it will have to be installed in the storage space under the French bed. Not in itself a problem but filling the kettle to make a cup of tea at six in the morning is liable to cause strenuous abuse from the bed area. :LOL:
 
I feel for you Mike. Been there a few times. Maddening innit?
I'm no newcomer to vehicle electrics either as like you I also built a kit car.
FWV 999 V.JPG


Scamp3.JPG


donkey said:
So many pumps have wiring that is not up to the job and the relay will ensure you have a good 12v to the pump regardless.
Click to expand...
How true. I was getting just over 11v showing for my hab battery at my control panel yet at the terminal posts the battery gave a reading of 12.5v. I spent best part of two days checking and tracing the wiring and it turned out be as you suggested; an undersized cable to the panel from the hab battery . That possibility had never ocurred to me until I tested again after running a more substantial temporary feed.
Professional manufacturers , eh?
 
Spriddler said:
I feel for you Mike. Been there a few times. Maddening innit?
I'm no newcomer to vehicle electrics either as like you I also built a kit car.
View attachment 498189

View attachment 498190


How true. I was getting just over 11v showing for my hab battery at my control panel yet at the terminal posts the battery gave a reading of 12.5v. I spent best part of two days checking and tracing the wiring and it turned out be as you suggested; an undersized cable to the panel from the hab battery . That possibility had never ocurred to me until I tested again after running a more substantial temporary feed.
Professional manufacturers , eh?
Click to expand...
Is that the mini-based Scamp?
 
Mike Lawrence said:
The only issue with the Shurflo is that it will have to be installed in the storage space under the French bed. Not in itself a problem but filling the kettle to make a cup of tea at six in the morning is liable to cause strenuous abuse from the bed area. :LOL:
Click to expand...
mounted on soft rubber blocks, the shurflo is much quieter

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Hi Mike

The change to a Shurflo will indeed get you over the issue.
I have just replaced my original with a Shurflo and thought it would be a good time to do some silencing mods. They can be quite noisy.
Things I did, which resulted in a near silent pump were:
Mounted to a heavy board.
Don't overtighten the mounting screws.
Use the barbed connections supplied with at least 300mm of flexible hose. I used clear reinforced plastic hose and some suitable hose clips.

Geoff
 
donkey said:
Hi Mike

The change to a Shurflo will indeed get you over the issue.
I have just replaced my original with a Shurflo and thought it would be a good time to do some silencing mods. They can be quite noisy.
Things I did, which resulted in a near silent pump were:
Mounted to a heavy board.
Don't overtighten the mounting screws.
Use the barbed connections supplied with at least 300mm of flexible hose. I used clear reinforced plastic hose and some suitable hose clips.

Geoff
Click to expand...
Thanks Geoff, excellent advice. All the pipe in my m/h is uniQuick 12 x 1.5 semi-rigid pipe. I need to find a supplier that will have adaptors from push-fit to 13mm threaded as per the Shurflo connectors.
 
1/2 inch BSP thread not 13mm metric
 
Mike Lawrence said:
My only concern is that the current isn't enough to activate the relay... especially as it won't even light a small bulb.
Click to expand...
Easy solution to that.... Replace the in tank pump with a pressure switch pump... Shurflo etc.
Easy enough to find a supply source and just plumbs into the existing water pipe
 
Off to Weymouth tomorrow for work and I know there's a load of chandleries there so I'll see if I can grab one. The current pump is a 19LPM Reich so I need to find a close match. Probably this...

Shurflo Aqua King 2 12V 15 LPM​

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