Village Marine Watermaker "Little Wonder" Drawing High Current

[OSBNZ]

Looking for help diagnosing why my watermaker is drawing high current since recommissioning this summer.
I undertook a normal flush with preservative shutdown at the end of last season. The only thing done differently this year is that I had the DC motor serviced - brushes / commutator skimmed, but this was reportedly in good condition anyway.
On start up I found that the pump seemed to race a bit under no load but when pressure was wound up to normal operation level of 800psi the motor was pulling high current and would cut out. The membrane seemed to be delivering what it had historically done ~6.2gph @ 800psi (I am in Mediterranean so slightly high salinity)
To maintain current at closer to nameplate 21.5A I am having to run at 600psi and only having an output of 4gph.
I have since run cleaning cycles of Alkali for Bio and Acid for scale with only a slight improvement in output.
The only other change we have made over the winter is replacement of our LiFeO4 batteries to a complete Victron system as our original Lithium conversion was not good resulting in fried batteries. So we are getting slightly higher voltage delivered to the Watermaker, typically about 13.4V.
For those not familiar with this watermaker it is driven by a 12v DC permanent magnet 1/4HP motor 21.5A

[Avionics_Joe]

There are only two possibilities, to much load (bad bearings?), or a bad motor (some shorted windings).
My motor went bad about 8 months ago. Village Marine wanted way too much for a new motor so I got one from Granger for 1/3 the price. Since you are in the Med Granger is not an option but you should be able to find a similar motor that will work.

[OSBNZ]

Thanks AJ. Motor is running freely and also the pump when turned by hand with belt removed. I quizzed the guy who did my brushes and he was adamant that all was good with the motor on his tests. When the system is running “no load” with output restrictor valve at zero pressure, the motor is drawing 11A which doesn’t seem unreasonable.
It seems to me that this type of motor runs faster with higher voltage being provided by the new batteries. So the system is trying to deliver too much volume to the membrane which in effect is a constant load. I understand that higher voltage would normally result in lower current from a motor but if the case is that it also runs the motor faster then the opposite could apply.

[Statistical]

Originally Posted by OSBNZ

Thanks AJ. Motor is running freely and also the pump when turned by hand with belt removed. I quizzed the guy who did my brushes and he was adamant that all was good with the motor on his tests. When the system is running “no load” with output restrictor valve at zero pressure, the motor is drawing 11A which doesn’t seem unreasonable.
It seems to me that this type of motor runs faster with higher voltage being provided by the new batteries. So the system is trying to deliver too much volume to the membrane which in effect is a constant load. I understand that higher voltage would normally result in lower current from a motor but if the case is that it also runs the motor faster then the opposite could apply.

Higher voltage does not make a specific motor run at lower current in fact the opposite is true. A motor designed for higher voltage can deliver the same power at lower current but that isn't the case here.

However the voltage difference between LFP and AGM is pretty minimal I don't think that is your issue. Even if the pump was overdriving the filter then you should be able to get similar output with lower pressure but that isn't the case.

I would lean towards resistance on the filter has increased.