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TEC3M Split charge relay

marc674

Active member
Messages
190
Location
East sussex
After the garage letting me down for the second time today "Oh the guy who was going to do that has gone home" thats ok just waste my time mate !!! I have decided to fit it myself which I should of done in the first place! Looks easy enough from instructions but I am not sure what sort of wire I should use

been thinking 30amp wire should

Be ok ?? ( the holes for relay switch are very small) I know i should use a inline fuse just after van battery but what amp should this be? any advice on this would be much appreciated. I have attached a few pics of the relay switch. Thanks

View attachment 6998

View attachment 6999

 
30 amp tri-rated cable will be fine by the meters you require - usually 5 or 6 meters.

Don't forget to order some black as well for the leisure battery earth to chassis.

Short length of 1.0 or 1.5mm black cable to earth the relay.

2 x inline fuse holders with 20 amp fuses. If you do blow a 20 amp fuse then you could upgrade to a 25 amp, but no higher.

I like these;

Standard Inline Splash Proof Blade Fuse Holder for Auto Fuses 12V / 30A/ 30Amp

Order a few fuses as spares. First fuse holder close to starter battery, the second close to the leisure battery - so on either side of the SCR.

Order an assortment of eye or ring terminals. Usually 6.4 and 8.4 are enough.

You will need a soldering iron to join cables and eye terminals and a couple of lengths of heatshrink or electrical insulation tape to insulate cable joins. You could use 30 amp strip connectors but they always look ugly.

 
Thanks Spruce that really helps.

So the relay earth is just to the van body and not the battery?

as for the leisure battery earth to chassis is that connected direct to the chassis or will the van floor be ok?

On the left of the relay at the front there is a small hole with a screw in it,do you have any idea what this is for? Only got a basic wiring diagram with the relay

 
Thanks Spruce that really helps.
So the relay earth is just to the van body and not the battery?

as for the leisure battery earth to chassis is that connected direct to the chassis or will the van floor be ok?

On the left of the relay at the front there is a small hole with a screw in it,do you have any idea what this is for? Only got a basic wiring diagram with the relay
To chassis would also be to a screw on the van floor. You just have to make sure you have a good earth by removing the paint so the terminal is in contact with clean metal. Once its all tightened down then you can paint over it.

I wouldn't bother with a black earth cable all the way back to the starter battery. You will just need a good contact on the van's body which is just as good.

You won't need to concern yourself with that small hole with screw behind it on the pc board.

Its an adjustment to change the cut in/cut out voltage settings. I can't find a spec with this detail on your TEC3M but my VSR (voltage sensitive relay) will only connect the Leisure battery to the van's starter battery when the van's starter battery is fully charged and is 13.7V or over (engine running being charged by alternator) and will cut out if the van's starter battery falls below 12.8V (engine switched off - no alternator charging). (When charging the batteries the alternator can push out around 14.4 to 14.5 volts. Newer vans will charge at a higher voltage than 14.5v).

Cutting out at 12.8v ensures that the leisure battery can never drain the van's battery.

I would imagine yours is similar. If the setting 'wanders off' then it can be reset by adjusting this screw either clockwise or anticlockwise. You probably won't be able to adjust this yourself without a multimeter. Setting the cutout at 12.8v will be the place to start

 
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Hi Guys, I appreciate this is an old post, buti just got my TEC3M switched relay today, but unsure on how to wire it up to the leisure battery. I can see the 12v connects to the Positive terminal on the van battery as does the second 12v if a high voltage drop occurs?? don't really understand all that, anyway, i know the Ov goes to the chassis/body but unsure of the remaining connections no6? no4? no2?. I have googled it and it appears to be for providing power to a towbar. I don't know what connection goes to the leisure battery positive, any help would be greatly appreciated..

Relay wiring.jpg

 
Thanks for the help guys
You can use either 6 or 2 from the relay to the leisure battery.

In the world of caravan electrics 2 is for charging the battery and 6 is for powering the 12v fridge whilst the engine is running.

4 is a straight through power source for powering the lights in the caravan if you stop at night.

You need a fuse close to the leisure battery as well.

You mustn't forget to earth your leisure battery to the vans body either. If you don't the SCR will not work.

 
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Can you charge your battery with a normal charger when the split relay is connected up or do you have to disconnect it?
You just leave it in place. If you do start your engine up the charger will see the battery as fully charged and switch off. It will switch back on again when you have switched the engine off and the voltage across the leisure battery stabilises.

The VSR (Voltage sensing relay) I have is bi-directional which means to say that the leisure battery charger will also top up the van battery at the same time.

I leave my battery in place and plug the charger into the van with an extension lead.

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Spruce, a quick question please my round is 95% within 5 minutes drive to and 5 minutes back home obviously little stop and start between do you think installing a scr on my transit connect would be that beneficial ATM I'm using a smart charger a couple times a week which literally just takes seconds to connect so isn't a problem.

 
Spruce, a quick question please my round is 95% within 5 minutes drive to and 5 minutes back home obviously little stop and start between do you think installing a scr on my transit connect would be that beneficial ATM I'm using a smart charger a couple times a week which literally just takes seconds to connect so isn't a problem.
We are in the same boat as you although we will be around 10 minutes drive from the majority of our work.

If you look at the maths then no, its not worth the trouble and cost of fitting one tbh, especially if you have to employ the services of an auto electrician.

Our experience is that we just don't get enough charge going back to the battery when the engine is running. As I said before, after a day's work the van's alternator will be charging our 110 amp leisure at between 7 and 8 amps on the way home. If our return home is a 10 minute drive, then all that's gone into the battery is just over one amp. According to our amp meter our Shurflo pumps draw about 4.5 amps at the flow we use. So if my pump as a single operator works for 3 hours that day (just pumping water onto the glass) then I have taken 13.5 amps from my battery and replaced 1 amp. If I've driven about a bit and run my engine for another 10 minutes during the day I might have added another amp, two at the most. Driving to work the following morning will add another amp.

Whatever the actual figures are, my battery will be in deficit that day by more than 10 amps.

However, that original SCR saved us once on a big job. It was 15 miles away and would take 2 of us 3 hours each to do. Our leisure battery decided to pack in barely half an hour into the job. Being able to run the engine in a secure environment meant that we were able to complete the job. That SCR saved a wasted day and us having to return back to complete the job after we had sourced another battery. That relay in those days was less than £10 plus my own fitting time, so paid for itself many times over.

The first SCR I fitted was to my first wfp trailer system. I often had the run my Suzuki van in the street with a crook lock on my steering wheel to keep the pump going. The electric fan took more current than the alternator generated so when that kicked in, flow to my pump died. I just stood there and waited for the cooling fan to cut out. I had a terrible time with leisure batteries on that trailer system and that SCR got me through a fair amount of work.

We have many posters say that they have never had to charge their leisure battery since fitting an SCR. This certainly hasn't been our experience with 2 Citroen Relays, a Peugeot Partner or a Ford Transit Connect. My son in law with the Connect was about a 25 minute drive away and used his van a lot privately, so his battery got more of a charge between cleans. He had to recharge his battery about every 3 weeks.

We have 1 customer who is 25 miles away. Just before Christmas I completed 2 jobs 10 miles from us and then pushed on to our furthest customer 25 miles away, cleaning my daughters house on the way. That day I did about 70 miles and the alternator did not replenish the charge I used cleaning those 4 houses by the time I got home.

My first SCR on my van mount burnt out after about 6 years in the van. I didn't hesitate to replace it with a bigger one.

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Thank you so much, has I realise that answer would have taken quite a while to write up just for my single question and that's really appreciated, after reading and the way you have explained in great detail makes it so easy to understand. For me to learn and have the understanding of voltage, amps, wiring and mathematical expertise you have would have taken me another life time to master, once again for answering another thought in my limited nodle.

So grateful that you and other members offers so much to this forum, would have been lost without you guys.

 
Thank you so much, has I realise that answer would have taken quite a while to write up just for my single question and that's really appreciated, after reading and the way you have explained in great detail makes it so easy to understand. For me to learn and have the understanding of voltage, amps, wiring and mathematical expertise you have would have taken me another life time to master, once again for answering another thought in my limited nodle.
So grateful that you and other members offers so much to this forum, would have been lost without you guys.
Thanks. I'm glad to be able to help. I know of other experienced posters who feel the same way as I do. At one time I needed help in wfp as well and there were people around then who helped me.

So many questions asked aren't easy to answer with a simple yes and no. The SCR question you asked is one of them. Many of the answers I give are from my own experience and may not tally with the experience someone else has, so its important for me that I try to clarify why I see something the way I do. Its then up to you to decide if that answer has any substance for you. If it doesn't then you just simply ignore it.

If I had a new generation van with a smart alternator and regenerative charging then I would think twice about fitting a £350 battery to battery charger in place of my SCR I have now. I just couldn't justify that kind of price, because, like you, its easy for me to plug in my leisure battery charger. I don't remove the battery and takes less than 5 minutes to set up.

But if recharging my battery wasn't easy as I only had street parking, then this weighs toward spending that extra money. I might even try to supplement that charge with the addition of a couple of 100 watt solar panels on the roof of the van with an MPPT controller. The van would probably also end up at son's house over a weekend to boost charge the battery. I might try to find a way of throwing a cable out of an upper window and attach it to the roof rack to keep it off the pavement as and when I could get parking outside my front door.

I might even add a change over switch and run a cable from my van battery. If my leisure battery went flat, then this switch would allow me to use the van's battery to finish the days work using the van's battery. If I had to wait for a replacement leisure battery to arrive, the van's battery would get me through a couple of days.

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Fortunately I have the luxury of my own driveway and external plug so a extension lead to the van only takes literally seconds, in all honesty thinking about it a solar panel would probably be better as an alternative with regards to the miles I do.

Many thanks again spruce.

 
Fortunately I have the luxury of my own driveway and external plug so a extension lead to the van only takes literally seconds, in all honesty thinking about it a solar panel would probably be better as an alternative with regards to the miles I do.
Many thanks again spruce.
I don't think there is a perfect solution except to put a charger on the batteries from time to time. The motorhome guys say that solar panels aren't the solution to their power needs in the UK winter but are good enough to keep an already charged battery topped up. The other thing with solar is that to catch the sun's rays the panels need to be angled correctly. On a van's roof they will not do this as they will be secured flat.

Some say that solar is their complete charging solution. There was a discussion on this subject about 6 months ago on here. But would I spend £300 putting 2 x 100 watt panels on the roof if I found they had limited success all year round?

We have a flashing 30 MPH speed warning sign on the entry into our town which is solar driven. I'm amased at how many times a minute that sign flashes up as most motorists tend to drive higher than the speed limit. That solar panel isn't very big. I appreciate that the LED lights are very low current but they operate for many hours without sunlight to recharge the batteries. I've only seen it not working a couple of times in the last few years its been up.

One day I'm sure the technology will be cheap enough for fast charging batteries like Formula 1 use that will fully charge up in a few miles and solve all our charging problems. /emoticons/wink.png

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So first few days my new split charger was working great then today I noticed it wasn't switching on, so I got my volt meter out and put it on my van battery, before starting the value it reads 12.26 and then it goes down to 12.19 after starting, the spit relay says cut in is 13.3. What is going on? Peugeot expert 2012.

 
Hey guys I’ve just wired in my tec3m and it seems to be working fine (14v with engine running) but should I still be getting 12.6v to my pump if I bypass the liesure batty with the engine off? Is this not drawing power from my starter battery? 
Thanks in advance ?

 
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