Intermittent electrical issue ; Sargent EC155 / EC51 related

[Keefe]

I have a fairly standard new T6 conversion with a solar panel, CTEK 250SE & Sargent EC155 / EC51. It recently started to show a problem.

When I switch the van electrics on via the EC51 control panel, sometimes it comes on perfectly, and sometimes comes on at low voltage (showing 6 -7 volts on a 12V socket monitor) - under this condition the van lighting will not come on or will come on dimly. If I switch it off and back on again (maybe a few times) via the control panel, then it will come back to normal operation. If I use the control panel to select the vehicle battery, I see the same behaviour - ie if it is normal, then the vehicle battery gives me normal operation, if it is in its faulty low voltage mode, then the voltage remains low.

The fridge & the heating which are independent come on normally under all conditions.

My thoughts are:
It is not a battery or charging problem - or else it would not come back on normally operating the on/off on the control panel and I would not see the same behaviour with the vehicle battery.
It could be an intermittent electronics failure in either the EC51 or the EC155 (maybe a solid state relay failing or something similar)
It could be an iffy connection to or from the EC155 or maybe a poor ground connection somewhere - this feels less likely as I am moving nothing when I switch the control panel off & back on again - also - I don't fancy the idea of having to chase down wiring behind all of the nicely finished paneling.

I tried asking Sargent & they suggest that it could be a connection issue between the leisure battery & the EC155 - but that would not explain why it can come back to life by turning the EC51 off & back on - or why I also see the issue with the vehicle battery (I probably did not give as much detail when I asked Sargent).

Does anybody here have experience of such a fault? - my next steps are going to be to swap out the EC51 & the EC155 - which is not going to be cheap - so it would be nice to think I'm not going down a blind alley.

Thanks in advance
Keefe

 

[roadtripper]

Welcome to the forum

As a first thought I doubt it's anything to do with the connection between EC51 <> EC155 - though if it's easy to get to the connections and check them then no harm in that. I think it's an a 8 Pin RJ45 connection so a couple of plug and unplug cycles should clean any surfaces.

I'm not sure this unit will be using an SSR, I suspect all the switching is done by normal mechanical relays. And the symptoms you describe do sound like a classic damaged/dirty relay contact that either has some corrosion or spark damages on it such that some times when it closes it has a high resistance.

Do you have pictures of your install?

 

[roadtripper]

Can't find any images of the guts of an EC155 but there is this one of a EC325 and those are classic mechanical relays doing the heavy lifting of battery connections - mid left marked "Sun Hold RX1-1240 40A 12v coil"

There are also some small relays bottom middle (orange - text fuzzy)



The source of the image seems to be a company that do repairs on the units:

Unit Gallery

www.apuljackengineering.co.uk

 

[DXX]

I probably did not give as much detail when I asked Sargent

I suggest you copy and paste the the thread and ask Sargent, you may well save yourself some time and money.

 

[Keefe]

Welcome to the forum

As a first thought I doubt it's anything to do with the connection between EC51 <> EC155 - though if it's easy to get to the connections and check them then no harm in that. I think it's an a 8 Pin RJ45 connection so a couple of plug and unplug cycles should clean any surfaces.

I'm not sure this unit will be using an SSR, I suspect all the switching is done by normal mechanical relays. And the symptoms you describe do sound like a classic damaged/dirty relay contact that either has some corrosion or spark damages on it such that some times when it closes it has a high resistance.

Do you have pictures of your install?

Hi Roadtripper & others.

Thanks for the very prompt input and advice. I've attached a couple of photos of the install (which I don't think give away very much). The control unit is opposite the sliding door, right of the sink; the CTeK & battery are in front of the offside rear wheel arch (a bit awkward to get at) and the Sargent unit itself is in a cupboard behind the offside rear wheel arch (quite difficult to get at the RHS of this).

 

[oldiebut goodie]

I know the angle may make this seem closer but worth checking:

 

[roadtripper]

I'd certainly check out that terminal @oldiebut goodie highlights, even if it's just the angle having that unprotected so near other terminals makes me tense.

Also the terminals seem very "busy" with a lot of ring terminals and a relay (with piggyback terminals) also tied into the wiring loom. I'm uncomfortable using charger terminals as distribution points, really there should just be dedicated battery connections there and distribution done by a bus bar, fuse board or similar.

Do you know what that additional wiring and relay are for?