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I have a jabsco par-max 2.9 25 psi automatic fresh water pump, supplying all my hot and cold water requirements. In the last few days it will not shut down after running a tap. Have checked for leaks and airlocks and found none. Today it ran on for 5 minutes and whilst looking for clues noticed a "low volts" red light on my victron inverter. Started the engine and the pump stopped! Waited awhile and ran some electrical things until low voltage light came on and yes pump pressure switch did not cut flow. Ran engine, pump stopped. Measured batteries and got 11.8 v.

This has never happened before and comes following a sludge problem with my fresh water tank after re-coating it. Can anyone shed any light on why the pressure switch has started to not work at a lowish voltage whilst all my other "low volts" indicators, fridge, dim lights etc are all ok ? Is there an adjustment on the pressure switch ? Should I remove the pump and flush it out ? I have cleaned the crap out of the mesh filter between the tank and the pump. Have also raised a topic about cold water sterilisation.

Thanks

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It sounds to me like the pump can't achieve cut out pressure with your flat batteries. 

I suggest you require new batteries and either some decent battery monitoring or, if you already have some, the knowledge of how to use it. 

If you regularly take the voltage down to 11.8V the batteries will be shot. 

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I don't understand why a low voltage would prevent a pump with a pressure switch from achieving it's cut-out pressure? Surely the pump will just run slower and it will just take longer? Perhaps it's the low voltage combined with a blockage of sludge that you mentioned. If there is sludge stuck somewhere between the tank and the pump causing a partial blockage then it won't be able to draw enough water and will run on, in the same way as when your tank runs dry, only that eventually it does manage to draw the water and reaches the cut-out pressure

Edited by blackrose
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21 minutes ago, blackrose said:

I don't understand why a low voltage would prevent a pump with a pressure switch from achieving it's cut-out pressure? Surely the pump will just run slower and it will just take longer? Perhaps it's the low voltage combined with a blockage of sludge that you mentioned. If there is sludge stuck somewhere between the tank and the pump causing a partial blockage then it won't be able to draw enough water and will run on, in the same way as when your tank runs dry, only that eventually it does manage to draw the water and reaches the cut-out pressure

Whilst the pump sounds as though it is working, it will not be pumping sufficiently to produce the required pressure.

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11 minutes ago, Ex Brummie said:

Whilst the pump sounds as though it is working, it will not be pumping sufficiently to produce the required pressure.

But my point was that unless a tap is open then even a slow pump pushing water into a closed pressurised system will eventually reach the required pressure. 

7 minutes ago, Bright Angel said:

I am going to disconnect the pump and blow back through the pipe from the tank. I will also blow through the pump and see what, if anything, comes out.

Happy days !!

 

If you have a strainer before the pump check that isn't blocked too. 

Edited by blackrose
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8 hours ago, Bright Angel said:

Thanks WotEver. Batteries 2 years old and monitored. Have solar so rarely fall below 12 v.

 

1. is that 12V when it is dark and last thing at night /first thing in the morning? If not the solar input is giving an artificially high reading.

2. By what means are you monitoring them? If its an amp hour counter you have probably been mislead and encouraged to destroy your batteries.

3. 12v rested is far too discharged for the optimum battery life. 12.2 to 12.3 is a better "recharge NOW" voltage

 

Edited t add Very good point Rusty, far too many pumps are wired with undersized cables.

Edited by Tony Brooks
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I have exactly the same on Belfast. The domestic batteries are knackered, but I'm not replacing them until the charging is sorted. With the engine running or batteries freshly charged the pump is fine. But as it gets flat the pump runs slower and can't reach the cut out pressure so it just keeps running. I just turn the pump off, and the water in the accumulator is enough for a few quick handwashes or to fill the kettle. When no more water comes out of the tap I just turn the pump on and off to recharge the accumulator and water is once more available. Works for me as a stopgap.

 

Edited by David Mack
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Thanks David. I have come to the conclusion that due to either wear or gunge in the pump body it is now adversely affected by low voltage, which makes it run on. My batteries are only 2 years old and by no means have had continuous usage over that time. We have moored up for a few weeks to come home but when I return to drain down etc I intend to take the pump off and clean it out. Thanks for the reply.

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7 hours ago, Phil Ambrose said:

You have already cleaned out your strainer so no point doing it again, I would need the advice regarding your battery voltage, it seems to me that you have consistently under charged and so have goosed your batteries, 

Phil

+1. Batteries are almost certainly goosed  

‘Rarely fall below 12V’ tells me straight away that they’ve been abused. ‘Never fall below 12.2V’ might have reassured me. 

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Thanks for comments about batteries.

I have been "plugged in" at a marina since fitting the new batteries then used either my 230/240v  Electrolux power pack or my 12v engine mounted alternator to top whilst cruising. I also have 28Watts of victron solar connected to the battery bank via a victron controller. I use the 501 meter that is linked to my Victron Multi inverter charger, to monitor percentage charge and try not to let this drop below 50%. What amongst all this attention might I have done to Knacker my batteries. If they are, then what proof will I need to claim under the 3 year guarantee that they came with ? Any advice or similar experiences appreciated.

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10 minutes ago, Bright Angel said:

What amongst all this attention might I have done to Knacker my batteries.

Perhaps you haven’t, it’s only my opinion. :)

Let’s look at the facts...

On 18/09/2017 at 22:26, Bright Angel said:

... noticed a "low volts" red light on my victron inverter. Started the engine and the pump stopped! Waited awhile and ran some electrical things until low voltage light came on and yes pump pressure switch did not cut flow. Ran engine, pump stopped. Measured batteries and got 11.8 v.

All of the above shows that, far from not letting your Batteries go down to 50%, you had them down somewhere close to 20%. Do this just once on some batteries and they’ll never recover. Some batteries can cope with going down to 20% a handful of times. Only semi-traction or better can regularly go down to 20% but even then it seriously shortens their life. 

17 minutes ago, Bright Angel said:

I use the 501 meter that is linked to my Victron Multi inverter charger, to monitor percentage charge...

This is probably your biggest mistake, Ah Counters are notorious for telling lies about a battery’s SoC. See this article for why:

http://thunderboat.boards.net/thread/867/battery-state-charge-meters-tell

Lastly, forget about any warranty claims, they only cover manufacturing faults, not battery abuse/misuse. 

But hey, I could be wrong. 

  • Greenie 1
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You should ignore the % charge reading on your BMV 501.

Instead use the voltage and current scales to determine when to start and stop charging. 

Start charging when the voltage is 1.2 volts or more with no load on the batteries.

Stop charging when the ammeter is 2% or less  (ideally 0.5%- 1%) of your battery banks capacity,

Edited by cuthound
To unmangle the effects of autocorrect.
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2 minutes ago, cuthound said:

Start charging when the voltage is 1.2 volts or more with no load on the batteries.

That could be a little low ;)

5 minutes ago, cuthound said:

Stop charging when the ammeter is 2% or less  (ideally 0.5%- 1%) of your battery banks capacity,

At 14.4V or higher. If the charger has dropped into float then switch it off and on to get it back into Absorption. 

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1 hour ago, WotEver said:

That could be a little low ;)

At 14.4V or higher. If the charger has dropped into float then switch it off and on to get it back into Absorption. 

Whoops, meant to say 12.2 volts.

Yes, the tail current must be read with the charger in absorption mode.

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1 hour ago, cuthound said:

Whoops, meant to say 12.2 volts.

Yes, the tail current must be read with the charger in absorption mode.

I know what you mean but you correction read on face value could mean 12.2 volts not 14.4 or higher, I know you were referring to an earlier misprint but if not reading the whole thread you could get  the wrong idea.

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  • 3 months later...

I would suggest that the lack of a reply suggests that the OP found it was a battery/low volts problem and feels a bit sheepish.

The symptoms described are typical of faulty, well discharged batteries, especially if the size of pump wiring is marginal. Take the number of people who said as much as them being correct.

Do not let any solar charging voltage confuse you during daylight hours. Voltages just as you turn in at night and as you get up are far more useful as long as its dark.

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Hi Ezshay.

sorry for delayed reply but not on boat since October so tend not to look at forum too often.

Glad to report that I,m not feeling "sheepish",  and did find that having cleaned out the pump filter and finally got rid of a few airlocks following long time with system drained down, the problem dissapeared. My water system does not have an accumulator so slight run on has always been present.

Thanks for the advice on battery voltage Tony, I will monitor it more carefully. Good to learn that a pump "problem" is not always the pump.

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