david lloyd Posted October 7, 2023 Share Posted October 7, 2023 Whilst investigating the voltage drop on my Eberspacher heater recently the auto electrician fitted two new relays. The first picture is, I think, a split charge relay to energise the fridge on 12v when driving. Not sure what the two near the front of the engine bay are for - one of which they replaced. I am wanting to fit a Vanbitz Battery Master but not sure if any of these would be suitable to wire it into and, if so, which terminals to use. David Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 7, 2023 Author Share Posted October 7, 2023 Actually, I think the TEC3M relay in first picture was installed with the new towbar so may be supplying power to the 13 pin socket. David Quote Link to comment Share on other sites More sharing options...
Keithl Posted October 7, 2023 Share Posted October 7, 2023 That would make sense! And the other two are separate relays for split charge and fridge. Keith. Quote Link to comment Share on other sites More sharing options...
Labby Posted October 7, 2023 Share Posted October 7, 2023 Although the Vanbitz instructions suggest using the split charging relay, if the leisure and starter batteries are not too far apart, it is just as easy to fit the connections direct to the batteries. But if you do need to use the split charge relay a wiring diagram for your Motorhome should show which colour wiring are for starter and leisure battery cable connections at the split charge relay. (or a multimeter used to show which are the correct cables to use, they may be the brown/green and brown/blue cables, with the red/yellow being connected to the fridge relay) Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 7, 2023 Author Share Posted October 7, 2023 Keith/Labby thank you - very helpful. The starter battery on my x244 based Peugeot is near these relays under the bonnet and the leisure batteries are about midway down the motorhome beneath the near side settee - cable run of about 3 - 4 metres but it may be easier to lengthen the cables than try and connect them into the relay. I have also looked at the Votronic version which only has two cables (one to each battery positive) and delivers up to 3amp but does need fusing and would still need longer cabling whereas the Vanbitz is already fused. Looks like the Vanbitz BM placed inside near the leisure battery and longer cabling to the starter/chassis would be the best bet. David Quote Link to comment Share on other sites More sharing options...
Labby Posted October 7, 2023 Share Posted October 7, 2023 There may be a starter battery connection at the PSU which is closer . Quote Link to comment Share on other sites More sharing options...
Alanb Posted October 7, 2023 Share Posted October 7, 2023 David, does your vehicle have Sargent electrics? The wire colours in your photos are a close match for those used by Sargent to connect to Fridge and Split Charge relays. The only difference is the use of black for the relay coil negative connections. Brown, brown/green, brown/blue, and red/yellow for the fridge all appear in that part of Sargent wiring diagrams, with blue being used for the D+ connection to the relay coils. I am inclined to question as to why your auto electrician changed, either the split charge, or fridge relays, when investigation the Eberspacher supply. Perhaps you are able to operate the Eberspacher with the engine running? Otherwise these relays would not be operated, and not in the Eberspacher supply circuit? Unless the connections to your battery master are short, they should be fused as close to the respective batteries as is practicable. A possible connection site would be at a B2B, but the presence of the split charge relay suggests that a B2B is not fitted. Alan Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 7, 2023 Author Share Posted October 7, 2023 Thanks Alan, it is a 2006 Pioneer Renoir so no smart alternator and I’m pretty sure no B2B. As I mentioned above, thinking about it the new split charge relay in first photo was fitted by the towbar company rather than the Eberspacher agent. Hi were, they did fit a new relay (the LH one in photo two) and removed a wobbly connector block near the leisure battery permanently connecting the wires as that is likely to have been the cause of the low voltage to the heater and yes the heater can be used when driving. However, you are right it is a Sergeant PSU unit - EC200 PSU2007 mated to an EC328. This does allow me to switch the 240v mains charger (which I had changed to a six stage charger by Apuljack Electronics) to charge the starter battery but we rely heavily on solar charging on sites - which only charges the leisure side. All the info I have read about the Vanbitz BM says it doesn’t need fusing at the live connections as it has a built in fuse. David Quote Link to comment Share on other sites More sharing options...
Alanb Posted October 7, 2023 Share Posted October 7, 2023 Hi David, Thanks for the informative reply. Our 2006 IH Tio R, is based upon a Ducato 2.8jtd, so almost identical in engine and cab area. The relay associated with the towbar is probably, as I believe you already suspect, for fridge supply and battery charging in a caravan. I am not clear as to whether the Eberspacher is part of the MH conversion, or a retro fitted base vehicle option. If the latter I would expect it to be powered from the starter battery, which is not the best idea when using when parked. As regards fusing, I was referring to your proposal to run a cable for the habitation battery side of the battery master. This cable should be protected against possible short circuit, by a fuse close to the battery. The internal fuse in the battery master will not give such protection. However if you can make the tee connections at the Sargent unit with short lengths of cable, the additional fuse(s) could be omitted. Alan Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 7, 2023 Author Share Posted October 7, 2023 Yes Alan the Renoir is all but identical to your IH including having the rare 2.8HDi engine. The Eberspacher was part of the original spec for this model. I guess it would be prudent to fuse a long run of cable - so, of the various methods for installation, I have to think which one I (as a confident but amateur DIY person when it comes to electrickery) feel most comfortable with. David Quote Link to comment Share on other sites More sharing options...
Alanb Posted October 7, 2023 Share Posted October 7, 2023 I somewhat disfavour the term "electrickery". It makes us professional electrical engineers seem like magicians, when the profession is soundly based on science.🙂 In a PVC, finding space for a new item is always problematical, doubly so if it has a display or LEDs that need to be visible. With some of my modifications, I have had to create new cable routes by running cable trunking across the top of the inner rear wall of cupboards. I have also used brown trunking in a corner behind the driving seat. The result is not visually intrusive. Alan Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 8, 2023 Author Share Posted October 8, 2023 My sincere apologies Alan. I would never seek to diminish in any way the learned experience and knowledge of any professional. But to me it is nothing short of magical seeing such professionals diagnosing and resolving electrical issues that confound me. It is, perhaps, why the phrase “tricks of the trade” was coined. Please keep advising as it is most welcome by many members of the forum I suspect. David Quote Link to comment Share on other sites More sharing options...
Alanb Posted October 8, 2023 Share Posted October 8, 2023 David, Please do not be too concerned, I did add a smiley face. Another pet hate of mine is the use of the term "Flea Bay" to denote Ebay. Longer, and rather childish in my opinion. Users seem to forget or be unaware of the origins of an alternative supplier. Enough, I am hijacking your thread. Alan Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 8, 2023 Author Share Posted October 8, 2023 So, what I have gathered so far is that the TEC3M relay in picture one is likely to be for the towbar electrics to allow charging a leisure battery and run the fridge on a caravan, for instance. In picture two the upper relay would be for split charging the leisure and starter batteries. The lower relay is to supply 12v to the fridge when travelling. It was the upper relay that was changed by the Eberspacher agent as the heater fault was to do with low voltage that was likely to be the ill fitting connecting block but I know the pins on the relay were quite corroded so may have been a precautionary measure. Perhaps Alanb could just confirm for me which wires to the split charge relay are starter/leisure battery cables what the three fuses on this relay protect? Grateful for all the interest and advice. David Quote Link to comment Share on other sites More sharing options...
Alanb Posted October 8, 2023 Share Posted October 8, 2023 (edited) David, In order to avoid an attack of vertigo, due to twisting my ancient head around while examining your photos, peraps it is easier if I send you an extract of a Sargent wiring diagram. Unfortunately this is in pdf format so I would need a PM with your email address. I am not currently into converting pdf into a format compatible with the forum. From the above extract taken fo help with understanding a slide out step problem I have the following. Red/yellow = Fridge 12V element supply. Brown = Starter battery fused separately at 40A and connecting to both relays terminal 30 and also to 20A fuse after which it becomes brown/green. Brown/green is fused starter battery to Sargernt EC200. (From above). The so called "LeisureBattery" is shown as being fused close to the battery by a 20A fuse. The wire colour changes from red to brown/blue. This connects via an adjacent 20A fuse to the split charge relay terminal 87., and to the EC200. The above information is derived from a diagram relating to a more recent ECxxx unit, and may differ in detail, but the colour codes seem to hold. Hope that helps, Alan Edited October 8, 2023 by Alanb minor alteration Quote Link to comment Share on other sites More sharing options...
Brian Kirby Posted October 8, 2023 Share Posted October 8, 2023 21 hours ago, david lloyd said: ...........................I guess it would be prudent to fuse a long run of cable - so, of the various methods for installation, I have to think which one I (as a confident but amateur DIY person when it comes to electrickery) feel most comfortable with. David David, with apologies, but the underlined above made me wonder whether there may be a misunderstanding regarding the purpose of the fuse? The fuse (or more probably an MCB) is actually there to protect the circuit wiring from overload. If a fault (possibly a short circuit, but equally just a connected load that exceeds the safe current carrying capacity of the wire itself) overloads the wire, it will heat up. The greater the overload the more rapidly it will heat, ultimately to the point at which it just melts and possibly starts a fire. Unless I'm misunderstanding you, the length of the wire itself has no bearing on the need for, or position of the fuse. The fuse should be of lower capacity than the actual wire to ensure that if an overload occurs the fuse "blows" before the wire overheats. It is therefore imperative that the wire is of the correct gauge for the load it is to carry, and that the fuse is interposed between the supply point (in this case the battery) and the wire. That way, an overload will blow the fuse before the wire heats dangerously. Where the length of the wire becomes critical, especially with 12V systems, is its total resistance, which causes voltage drop. The thicker the wire the lower its resistance, so, for long circuits, to ensure the desired current is delivered to its end, it's gauge needs to be increased in proportion to its length. But this really is Alan's field - I understand the principles to some extent, but am not equipped to give advice on what gauge for what load over what length! Apologies for the intrusion! 🙂 Quote Link to comment Share on other sites More sharing options...
david lloyd Posted October 8, 2023 Author Share Posted October 8, 2023 Yes thanks Brian. I think my confusion stems from the installation advice on the Vanbitz BM which refers to it already having a built in fuse but, if I have to run longer cables than are supplied with the BM (due to the distance between the two batteries) it is sensible to place a fuse at the start of the long run near the battery. Always learning. David Quote Link to comment Share on other sites More sharing options...
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