Have I bought the wrong pump?

[DonA4000]

Hi my Knaus has a submerged water pump (unbranded) which stopped working, after googling I found what looked to be the same replacement pump Barwig but after fitting the flow rate is dreadful, I’ve now read over the small print of the add which says 12v but low voltage 6-9v tested with volt meter and is 9.5v

I wanted to ask for your help and if you know if the low voltage 6v - 9v is the problem?

Other info from the description is 22 L max 1.4 bar

Any help would be great thanks

 

[Spriddler]

The 9.5v that you registered will be your battery voltage which suggests to me that the reason for the poor flow rate is extremely low battery voltage and more than likely a knackered battery, or at least one that needs recharging - (if it's not to late to save it).

The bit about engine cooling and 6 - 9v is a bit of Chinese gobbledegook and doesn't apply to your use of the pump.

 

[Lenny HB]

Not uncommon for the voltage to drop at the pump it's due to the small wires the manufacturers fit.
If the wires to the pump are blue & brown, blue will probably be positive. Try reversing the connections most pumps will run with polarity revered but slower.

 

[Spriddler]

Not uncommon for the voltage to drop at the pump it's due to the small wires the manufacturers fit.

I agree with that but understood that the OP was measuring the voltage where the pump lead has been connected to the loom. I can't see how the OP could've measured the voltage at the pump as the lead and connections at the pump are sealed into the pump casing.

 

[Lenny HB]

I agree with that but understood that the OP was measuring the voltage where the pump lead has been connected to the loom. I can't see how the OP could've measured the voltage at the pump as the lead and connections at the pump are sealed into the pump casing.

It will only be ½m of cable out of the pump then the loom will be a few meters.

^{_{Subscribers  do not see these advertisements}}

 

[DonA4000]

Hi thanks for your reply’s we’re out and about in the van, just parked up for the night. I have tried changing the wires around didn’t make any difference, the van wires are black and white and the pump is brown and blue. Taken the voltage reading at the spade connectors. The habitation batteries are old so will need to test them.

Do you think the pump should be powerful enough?

Just did another reading 9.9v when turn on bathroom sink, 9.0v when kitchen sink turned on which is further away from pump (if that helps?) and we’ve just did a 2 hour drive.

Thanks

 

[Spriddler]

Do you think the pump should be powerful enough?

I'm not familiar with submersed water pumps but my Shurflo pump in a locker is rate at 10.6 l/min which is adequate for taps and the shower. Yours is rated max 22 l/min so with enough voltage it should be more than adequate although yours at 1.4 bar max pressure is a bit less than my Shurflo at 2.1bar,

Just did another reading 9.9v when turn on bathroom sink, 9.0v when kitchen sink turned on which is further away from pump (if that helps?) and we’ve just did a 2 hour drive.

I wouldn't expect the voltage of a good battery to drop so low as to around 9v with just the relatively little current required by the pump but again, I'm not particularly au fait with your pump.
A two hour drive probably won't be enough to have fully charged the batteries (dependent upon how discharged they were before the drive). It would be useful to know the off-load voltage of the batteries but I guess you are now needing to have at least the lights on at present. Are you now on EHU?

 

[autorouter]

Do you think the pump should be powerful enough?

This pump has a 22 litres per minute flow rate, and a working pressure of 1.4 bar (about 20 psi). It should be a reasonable replacement for an unknown submersible pump,

If you are getting low voltage (9.5V) at the pump, the next thing to check is the voltage at the battery terminals when the pump is running. That will tell you if there is voltage drop along the wiring, or if the battery voltage itself is dropping when the pump turns on.

 

[DonA4000]

Hi thanks for your help we’re currently wild camping tonight so will check the battery off-load voltage in the morning, we do have solar but not sure how the battery were when we set off has been in storage over the winter only been out a couple of times

 

[pappajohn]

so will check the battery off-load voltage in the morning, we do have solar

Then check the voltage now it's dark
Tomorrow the panel will be charging the battery at a higher voltage and show a charge voltage rather than a true battery voltage.

^{_{Subscribers  do not see these advertisements}}

 

[Spriddler]

Hi thanks for your help we’re currently wild camping tonight so will check the battery off-load voltage in the morning, we do have solar but not sure how the battery were when we set off has been in storage over the winter only been out a couple of times

Do the hab lights dim significantly (if they are the filament type) when you turn on the pump?
I have a switch that enables me to select the battery source for the hab power. If yours has the same it may be informative to select the vehicle battery briefly to see if the pump performs better than when on the hab batteries.
------------
Ah, now you mention you have solar, yes as pappajohn mentioned the meter will register the solar voltage tomorrow unless you throw a blanket over the panels, disconnect them or remove a battery lead when you check the battery voltage as it's going to be sunny again, well at least it is in Sussex.. (Caution - I've never had solar panels so disconnecting them when it's sunny may not be advisable. Dunno).

 

[DonA4000]

Ok just been out (in the dark) in the garage to get to the batteries so everything off I get 12.6v and trying the pump (tap) only 12.4 and dropping slowly below.

 

[pappajohn]

That points to the battery failing if it drops that fast.
When you turn off the pump does the voltage rise again.

 

[DonA4000]

It went back to 12.58v but didn’t spend much time checking on it go up afterwards

Also tonight we have had light and Tv on before doing the test

 

[Spriddler]

It went back to 12.58v but didn’t spend much time checking on it go up afterwards

Also tonight we have had light and Tv on before doing the test

12.58v is as near as dammit fully charged, especially if you've had the light and T.V. on., although a good battery voltage doesn't guarantee that the batteries are in good condition and can deliver the current (amps) demanded (although they've been running a light and the telly O.K..............)
(I admire your determination going out at this time of night and in the dark ).

If it's not failing batteries it could be a faulty pump, even if new.

Tracing leccy problems is largely a process of elimination so to eliminate the (unlikely) possibility of faulty wiring or connection somewhere between the batteries and the pump I'd try the pump with it connected directly to the batteries, (e.g. a temporary bodge using a spare length of wire or even jump leads if you have any).

BTW - did your previous pump just suddenly stop working or was it failing noticeably before it packed up?

^{_{Subscribers  do not see these advertisements}}

 

[DonA4000]

Ok just been and did the test again stated at 12.6v with running the pump it dropped to 12.37v in about 10 seconds, after water pump switched off it climbed back up to 12.56v in about 20 seconds.

As I said the batteries are old and doesn’t show any light with those battery charged indicator peep hole on the battery itself.

Is there anything else I maybe missing when fitting a new pump eg, blocked valve or something?

Thanks for all the help

 

[DonA4000]

12.58v is as near as dammit fully charged, especially if you've had the light and T.V. on., although a good battery voltage doesn't guarantee that the batteries are in good condition and can deliver the current (amps) demanded (although they've been running a light and the telly O.K..............)
(I admire your determination going out at this time of night and in the dark ).

If it's not failing batteries it could be a faulty pump, even if new.

Tracing leccy problems is largely a process of elimination so to eliminate the (unlikely) possibility of faulty wiring or connection somewhere between the batteries and the pump I'd try the pump with it connected directly to the batteries, (e.g. a temporary bodge using a spare length of wire or even jump leads if you have any).

BTW - did your previous pump just suddenly stop working or was it failing noticeably before it packed up?

Hi the previous pump started to make a loud noise and then stopped working, just a pity it had no markings on the pump not even a serial number just looked the same as the photo above. The van is an 08 so maybe the original pump

 

[Spriddler]

Ok just been and did the test again stated at 12.6v with running the pump it dropped to 12.37v in about 10 seconds, after water pump switched off it climbed back up to 12.56v in about 20 seconds.

If I'm understanding your first post correctly you said that when running the pump you were getting 9.5v (was that measured at the pump or at the batteries' terminal posts?) although you're now getting 12.37v at the batteries' terminals with the pump running. If the 9.7v was measured at the pump it would suggest that the fault (e.g. a voltage drop of 2.87v) lies between the batteries and the pump or the batteries may be failing since even though there's an acceptable voltage at the batteries they cannot supply enough current.
I'm an inveterate fiddler so assuming that your starter battery is good I'd try powering the pump directly from it.

Hi the previous pump started to make a loud noise and then stopped working,

Hmm, that sounds like a mechanical failure rather than an electrical one so can't draw much of a conclusion from that vis-à-vis a possible electrical issue unless there was a partial blockage in the water piping or debris in the pump which caused it to overwork, overheat and die. Unlikely I'd guess.
Out of interest here's a failed submersible pump that I cut open. Water had leaked into the electrical motor and it gradually rusted, seized and blew the fuse.

 

[mitzimad]

try it again with the engine running should get better voltage then

 

[Lenny HB]

Batteries sound OK to me.
Check the non return valve could be partially blocked.

^{_{Subscribers  do not see these advertisements}}

 

[DonA4000]

Hi just to update the thread (sorry forgot), I bought another pump Reich twin submersible pump and it’s working great

Thanks

​