How to wire up a PMS4

[Ronha11]

Hello Funsteres, ive been a silent reader member for quite a time and enjoyed the banter etc. but need help with wiring please Ron

 

[Lenny HB]

What is a PMS4?

 

[tonyidle]

I had to Google PMS4 but still uncertain of make. There's a ton of info though.

 

[Two on Tour]

Hello Funsteres, ive been a silent reader member for quite a time and enjoyed the banter etc. but need help with wiring please Ron

The PMS4 has been around for donkey's years, on which van it's fitted to or going to be fitted to and photos will give us an idea what your up against.

 

[Ronha11]

I was really thinking of somebody who has actually fitted one of these and can tell me how the 12 volt leads go, not sure that these pics will help

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[Ronha11]

I`m converting a Merc xlwb into a motorhome, i`m a joiner by trade but electronics baffle me so was looking for HELP

 

[Lenny HB]

It appears to be a Plug in Systems unit that was used in caravans many years ago (early to mid 90's). Looks fairly simple so should be possible to trace the wiring back from the connectors. Do you have a friend who is more aware of electrics that could help you? You may have better luck on caravan forums.
If you have the spec on it worth checking the charger as I suspect it only charges to 13.8 volts which means your batteries will never get a full charge and that will shorten their life considerably.

 

[Ronha11]

Thanks Lenny, I bought this about 18 months ago brand new so reluctant to not use , it does say it will charge at 18 volts for a short time so will try to make use of it.

 

[Ronha11]

While i`m here how do I change my details please?

 

[newcamper]

Hi just wondering if you managed to sort this? I have just recently bought a van to convert and been given a pms4 from an old caravan to use just wanting to gain some information sorry to jump on thread

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[NicM]

This may help you… https://www.olearymotorhomes.co.uk/ekmps/shops/olearys/resources/Other/pms3-instructions.pdf

 

[Ronha11]

A friend finally sorted it for me but he had to pull the blocks out to comprehend how the wires were connected. The recent post PSM3 gives a lot more idea of how to connect the unit but the units are completely different

 

[newcamper]

Could you help with The 12v charger side? Do u know of this takes a separate wire to run to as I couldn't see anything on the psm3 diagram that shows the charger just 240v and 12v output to components

 

[Ronha11]

I`m afraid that is the part I coulden`t fathom out, when you connect the charger to the batteries that then appears to be the feed back to run the 12 volt system.

 

[Two on Tour]

We had a PVC fitted with a PMS unit and I was using a CTEK MSX10 charger directly to our leisure battery for 240v charging and a voltage sensing split charge relay for 12v charging to the leisure battery.

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[NicM]

Found this.. maybe some help, sorry got the first one wrong!

 

[Ronha11]

This might or not help but these are the only instrutions that came with the new PMS4

 

[Itsmcb]

I have a very similar unit in my 1996 van. Your confusion may be because you think the charger has to be connected to the battery and then a seperate cable back to the distribution panel. Actually the built in charger is also a power supply so is connected directly within the distribution panel with only one positive feed cable running to the battery. It's definitely a 13.8v maximum output charger nominally 12 amps output but will supply up to 18amps for a short while before shutting itself down. I have recently fitted a seperate sterling 12/30 battery charger in my van to allow the batteries to be charged fully. This is connected directly to the battery and feeds the distribution panel through the original positive cable. I have just switched off the built in charger using the red switch on top of the distribution box therefore I still have it as a backup.

 

[Ronha11]

Thank you, that clears things up