12v habitation electrics shut-off when on EHU and battery fully charged. Sargent PX-300 charger.

[markmallory]

Hello all,

 

I have a problem with my habitation electrics charging system. Autocruise Accent Van Conversion, 2011. The Sargent electrical installation is as standard when new without any adaptions/additions (no solar panel). When I plug into EHU and when the leisure battery is fully charged then the 12 volt habitation electrics shut off. Whilst the battery is below full charge everything works fine. I tested the Charger unit (Sargent PX-300) with a multi-meter and found the output to be 14.4v, this output is meant to drop to 13.6v as the battery becomes charged (there is also an LED indicator on the charger which changes from red at 14.4v to green at 13.6v - mine stays on red indicating 14.4v). If I switch to the vehicle battery on the Control Unit above the door then the charger performs as it should, dropping from 14.4v to 13.6v, and the 12v habitation system stays on. I telephoned Sargent, they advised that the 12v system is designed to switch off to protect it if the supply goes above 15v and suggested my charger may be faulty. I tried another charger but the fault is still the same with a continuous 14.4v output (as tested with a multi-meter at the output pins on the charger). I telephoned Sargent again and was advised that the chargers are pretty solid and actually cannot over-charge and it may be a fault with my battery (the original battery, now 6 years old) giving false information back to the charger. I replaced with a new battery of the same type and still have exactly the same fault.

 

Can anyone out there help me or advise an electrical expert I can contact in the Leicester / Warwickshire area?

 

Thanks,

 

Mark

[Charles]

Sounds like the leisure battery isn't connected to the van 12v system but is connected to the charger and the charger is powering the 12v system when it's on (maybe a diode is in circuit somewhere?)

I would trace the 12v cables away from the battery and see where they end.

[markmallory]

Thanks for the suggestion Charles but that is not it. The 12v system works fine when not on mains hook-up. Also when on hook-up if I turn the charger off then again the 12v system works fine.

[arthur49]

Mark

 

Hopefully Allan from aandncaravanservices will be along shortly.

[aandncaravan]

Arthur, thank you for the 'Heads up' on this.

 

If the PX 300 chargers are adhering to the voltages specified at 14.4v and the battery is good then the next possible cause of your issues could be within the voltage sensing circuit of the Sargent Power Controller/distribution unit, is it an EC4xx?

 

A difference between a 14.4v charge and a 15v shutdown seems quite a narrow tolerance, so if the sensing circuit is out by 0.5v, it might shutdown incorrectly.

 

Can you not ask Sargent to check that the voltage sensing circuit in the ECxxx Power Controller is operating at a true 15v? Sargent are usually very good.

 

If they can't/won't we would be happy to take a look.

 

 

 

 

 

 

 

[markmallory]

Hello Allan,

Yes, it is an EC400 Power Supply Unit.

Thanks for the suggestion. I guess I need to talk to Sargent again.

The 12v habitation electrics only shut down when the leisure battery reaches full charge. When the battery has been used off hook up and is partly down then the 12v habititation stays on, it only shuts down when the battery reaches full charge. Also when I select the vehicle battery on the Control Panel it all works okay and as it should.

The other symptom is that the charger does not step down to 13.6v in it's third stage as it should do when charging the leisure battery. Which it does do, correctly, when it is charging the vehicle battery.

Thanks for your advice.

Mark

[aandncaravan]

The PX 300 chargers are strong, good units.

Did both chargers perform in exactly the same way in never dropping down to 13.6 Float voltage when charging the new habitation battery or only work like that on the old battery?

 

 

[markmallory]

Both chargers exactly the same with both batteries.

Thanks,

Mark.

[Alanb]

Mark,

 

You have an EC400 system but from Sargents documentation I learn that it is comprised of several units having model numbers ECxxx. The documents suggest, as does Allan of Aandacaravanservices, that the Power Supply Unit will itself have a model number other than EC400.

 

You have tested the battery and charger by substitution. That only leaves the Power Supply Unit. Allan will probably know, but I am wondering if when the system is assembled, does the PSU take over some control of the charger? My reason for this query is that there is a system connector shown on illustrations of the charger.

 

If there is a connection to the system connector, and given a possible fault in the PSU leisure battery monitoring, your problems could be explained.

 

Alan

[markmallory]

Thanks Alan,

thanks for looking at this and coming up with this possibility. It does sound logical, however, the System Connector is not in use. I also have an illustration of the charger showing the System Connector and it actually labels the System Connector on that illustration: "System Connector (do not use)".

The only connections into the charger are a plug to the Mains Input Connector and another plug to the Output Connector.

Is it possible that the PSU does have some control of the charger via the input or the output connections?

Looking at Sargents website, and only from the look of my PSU, it is either a EC444, EC465 or EC460, unless they did other variations not shown on their website.

Regards,

Mark.

[aandncaravan]

AlanB, we have a Sargent EC 465 in for rebuild and I had a very quick look late last night for some clues as to the above problem, but don't have any new ideas.

 

The Power Distribution unit houses both the mains 230v distribution as well as the 12v distribution so therefore provides 230v to the separate PX300. But as far as I could see it has no other 12v control over the charger.

 

Both chargers failing to drop down to 13.6v Float mode and a seemingly high voltage peak suggests there is a link?.

Maybe something is placing a big load on the charger preventing it reaching Float mode, until the load suddenly drops and the Charger reaches a peak close to 15v before stabilising at 13.6v??

 

A second battery has been tried so not likely to be that.

 

 

I will have another detailed look when we rebuild the EC465, but it won't be this week as we have some big jobs on.

 

 

 

 

 

[Alanb]

aandncaravan - 2017-05-14 4:03 PM

 

Both chargers failing to drop down to 13.6v Float mode and a seemingly high voltage peak suggests there is a link?.

Maybe something is placing a big load on the charger preventing it reaching Float mode, until the load suddenly drops and the Charger reaches a peak close to 15v before stabilising at 13.6v??

 

 

Allan,

 

That is the best hypothesis at the moment, particularly as the charger instructions effectively state that it will not switch to float mode if it is supplying a load as well as charging the battery.

 

 

Mark,

 

Is it possible that you have a standing 12V load on your habitation electrical system, e.g. lights switched ON when carrying out your tests?

 

Another thought Is to doubly exonerate the habitation battery and charger, by "bench" testing the battery and charger combination on their own. This would probably require custom made test leads, but could be carried out with the battery and charger still in the vehicle. DO NOT ATTEMPT THIS IF YOU ARE NOT EXPERIENCED IN ELECTRICAL WORK.

 

If the above test were carried out, and as is to be expected the charger functions correctly, the fault must lie either in the PSU, or the vehicle wiring.

 

Alan