HELP mains transformer running VERY hot!

[michaelmorris]

aandncaravan - 2018-05-14 8:02 AM

 

If the battery is heavily discharged and/or damaged and the Halfords Car battery charger is only low power then even on charge the charger may not reach it's charge voltage very quickly. That is why we need info about the chargers you have.

 

Does the charger get hot and did the battery get warm?

 

 

It does look like you have an issue with the charging systems not keeping the battery charged, and as a result the battery has maybe over discharged. That would explain why the BCA Leisure battery charger was working so hard.

 

 

Are you sure the Habitation battery was fully charged before you left home for this holiday? A Varta LFD90 should have been up around 12.9v off EHU.

 

Is it possible that the Alternator charging fuse had blown before you left, so there has been zero charge during the journey to your holiday destination?

Maybe you had the Fridge on 12v so you were actually discharging the habitation battery as you drove because of the blown Alternator fuse?

Maybe you then arrived at site with an over discharged battery which the charger had to work really hard to bring back up?

 

But that doesn't explain the 12.5v that you said the battery held off charge for several hours and how it then dropped sharply to 11.2v? Unless the Fridge discharged the battery on the way home as well?

 

A real puzzle.

 

Does the charger get hot and did the battery get warm?

When the Halfords battery charger is charging the leisure battery the battery isn't getting warm and the charger is slightly warm.

 

 

Are you sure the Habitation battery was fully charged before you left home for this holiday?

No, I didn't check

 

Is it possible that the Alternator charging fuse had blown before you left?

Yes

 

Maybe you had the Fridge on 12v so you were actually discharging the habitation battery as you drove because of the blown Alternator fuse?

If it is that than that is a really poor design flaw.

 

But that doesn't explain the 12.5v that you said the battery held off charge for several hours. But remember that was on vehicle's own voltmeter with both batteries attached and quite possibly with a blown 15A fuse for the vehicle battery. Also this was with the vehicle voltmeter reading identical voltages for both the leisure and vehicle batteries. With the leisure battery out of the van and the vehicle battery 15A fuse replaced the vehicle volt meter is now reading 13.4v for the vehicle battery (same as the multimeter) The 11.2 volts was with the leisure battery out on a work bench and measured with a multimeter.

 

[aandncaravan]

I had forgotten about the Voltmeter display not changing when selecting 'Starter'.

It is likely that the Alternator/Starter battery fuse failure had already occurred and the Power Controller could not 'see' the Starter battery, hence no change in voltage.

Now the fuse has been replaced and you are seeing 13.4v on the display, that pretty much confirms it was already blown.

 

 

You are right, the way most British converters wire the Fridge from the habitation battery is a bit mad.

Hymer, Burstner, etc wire it direct from the Starter battery with it's own, separate fused supply. That not only avoids the issue, which I think you had here, but usually results in faster habitation battery charging.

 

 

If you want to do a health check of the vehicle charging, then :

 

Make sure the Habitation battery is fully charged for at least 36 - 48 hours, to 12.9v. Then :

 

Record the Starter battery voltage after the vehicle has been off EHU for about 12 hours.

With it off EHU, make sure the Fridge is not on 12v and start the engine (never start your engine while it is on EHU).

Rev the engine at a fast idle for a few seconds, let the revs drop but keep the engine idling and record the voltage of the Starter battery again. We are hoping for 14.4v.

Record the voltage of the habitation battery. We are hoping for 14.4v.

With the engine still running, switch the Fridge to 12v and record both Starter and Habitation voltages again. Voltage drop from the extra demand should show a small fall, but we are still hoping for close to 14.2v.

Turn off the engine and 12v Fridge, wait an hour and then connect EHU.

Record both battery voltages again. We are hoping for 14.3v.

 

 

Make sure all voltages are taken using the same device, i.e. all multimeter unless you are sure the Display and multimeter have the same accuracy.

 

 

Post the details on here along with the details of the chargers you have.

 

 

Note : the test must start with good, full batteries or that can skew the results.

 

[michaelmorris]

Thanks, unfortunately it'll probably be tomorrow or Wednesday before I can do this.

 

Thinking ahead, if the fridge does turn out to be the problem, would a viable short term option be to simple put some freezer blocks in the fridge and simply turn the fridge off rather than on 12v when travelling?

[aandncaravan]

The Fridge is unlikely to be the problem. The problem will be to do with charging from the Alternator, just that the fridge can complicate any Alternator charging issue.

 

Not using the Fridge on 12v won't resolve any charging issue you might have, hence the health check to find out what issues there are.

 

A local auto sparky (rather than a Caravan repair man) will be able to do a health check for you and it shouldn't cost much at all.

 

[Alanb]

Michael,

 

In general I agree with Allan, and as I and others appreciate, he has a wealth of experience in this area.

 

However if you wish to investigate further yourself, may I restate my suggestion of a careful check of connections under the bonnet.

 

As has been suggested, it seems that your fridge is discharging the habitation battery as you drive.

 

The possibility of corroded connections, a blown fuse, or perhaps even a faulty relay should be eliminated.

 

As I have previously stated, it seems to me that there must be a relay controlling the fridge supply, preferably operated by D+. (If this relay is not present, what is to stop the fridge being switched to 12V, and draining the vehicle battery?)

 

Under the bonnet, I would also expect you to find two or three inline fuses. One perhaps 20A for the fridge, another of similar value for the connection to the control panel, and perhaps a 2A fuse for the relay coil.

 

The fuses should be OK, but please do check the connections to the vehicle battery. At the same time the it would be sensible to check the connection to the vehicle battery negative for the habitation 12v electrics.

 

One of the possible locations for the relay and perhaps fuses is under the plastic cove,r that is secured by two M6 bolts at the centre of the engine bay.

 

You may wish to note that there have been at least two previous threads on this forum, with similar problems,

 

Alan

[aandncaravan]

Alanb - 2018-05-14 11:37 AM

 

Michael, The possibility of corroded connections, a blown fuse, or perhaps even a faulty relay should be eliminated.

 

 

 

Alan

 

 

Alanb, I agree there are a number of areas that might be investigated, but I don't think Michael is as technically able as you, so the collection of diagnostics, easy to take voltage readings, will help us point him in exactly the right direction of where any faults may lie.

 

What voltages we get when running on Alternator, particularly when the Fridge is switched to 12v, will tell us a lot about what is going on.

Depending on how far the voltages are away from 14.4v will give a clue to corrosion and bad connections.

 

The size of the voltage drop when the Fridge switches to 12v will also tell us the state of the relays/connections, and even if the relays are working at all.

The voltages of the chargers and their spec will also speak volumes about the very first issue he reported.

 

 

Clearly Michael is fed up and struggling with the problems he has encountered, including the delamination of the floor from another thread. I am not sure throwing lots of possible solutions at him when we don't know the extent of the problems (like has the Alternator got an issue and is only charging at 13.1v?) is the ideal approach to help him.

 

While the text for carrying out the diagnostics might look daunting on first read, it is just recording voltage readings. So followed step by step shouldn't be hard. If you can improve their readability, and/or suggest other easy to take diagnostics I am sure he would appreciate that.

 

[michaelmorris]

aandncaravan - 2018-05-14 12:44 PM

 

Alanb - 2018-05-14 11:37 AM

 

Michael, The possibility of corroded connections, a blown fuse, or perhaps even a faulty relay should be eliminated.

 

 

 

Alan

 

 

Alanb, I agree there are a number of areas that might be investigated, but I don't think Michael is as technically able as you, so the collection of diagnostics, easy to take voltage readings, will help us point him in exactly the right direction of where any faults may lie.

 

What voltages we get when running on Alternator, particularly when the Fridge is switched to 12v, will tell us a lot about what is going on.

Depending on how far the voltages are away from 14.4v will give a clue to corrosion and bad connections.

 

The size of the voltage drop when the Fridge switches to 12v will also tell us the state of the relays/connections, and even if the relays are working at all.

The voltages of the chargers and their spec will also speak volumes about the very first issue he reported.

 

 

Clearly Michael is fed up and struggling with the problems he has encountered, including the delamination of the floor from another thread. I am not sure throwing lots of possible solutions at him when we don't know the extent of the problems (like has the Alternator got an issue and is only charging at 13.1v?) is the ideal approach to help him.

 

While the text for carrying out the diagnostics might look daunting on first read, it is just recording voltage readings. So followed step by step shouldn't be hard. If you can improve their readability, and/or suggest other easy to take diagnostics I am sure he would appreciate that.

 

Thank you again folks for your help with this one.

 

Okay, firstly some voltage figures

The good news is that it looks as though the leisure battery is still servicable (but may have sustained some damage due to the low voltage). The charge fell from 12.49 to 12.11 in 6 hours (It wasn't fully charged when the test started). A further session of charging will hopefully get it back to full voltage.

 

On the alternator the voltage at the battery is 13.2 volts, falling to 13.0 volts when the fridge is turned on. So it looks as though the leisure battery is being charged form the alternator - good news.

I took the van to our motorhome engineer to see if the problem was the charger he fitted 5 months ago.

The engineer didn't think the problem was the charger, but swapped it over for a new one and the over-heating disappeared ;-). He said he still wasn't convinced the charger was faulty and swapped it back for the original and hey presto, no overheating ??? (Picture of charger box attached)

 

He said that his best guess is that the MCB covering the charger had been a bit corroded internally, and that switching it on and off numerous times may have scrapped off some of the corrosion. Anyway the excessively high charger temperature seems to have gone. This still doesn't address the problem as to why the battery had been drained and he concurred that fridge set to 12v when we were travelling was the cause of the drain. Obviously, the hunt for why it is draining the leisure battery is still very much an open question.

 

Anyway, we seem to now have a more or less working system apart from the fact that we probably shouldn't have the fridge on 12 volt when we travel. Working on this assumption, I now feel happy enough to still go to France in 2 weeks time. We'll turn the fridge to 'off' rather than '12v' when travelling and pack some ice packs into the freezer compartment and move them down into the main body of the fridge when travelling. This then gives us time to work out what the longer term problem is until after we get back. He said his best guess at the moment is a dodgy relay.

 

Our plan to test this theory that the fridge is running off the leisure battery when in 12v mode is to do before and after voltage reading on the leisure battery after 1 hour runs with the fridge turned off and switched to 12v. However we won't have the opportunity to do this before we go to France and I don't want to risk the leisure battery further by doing this test in France. We'll probably do this on the journey home back up the M5 in 4.5 weeks time.

 

Just in case we are wrong, we're going to carry a battery starter, jump leads, battery charger, battery powered LED lights, a pack of 20 x15A fuses and a Gaz regulator so that we can run the fridge on gas for an extended period if the habitation electrical system fails altogether.

 

 

[aandncaravan]

Michael, Without all the voltage readings we suggested that should be taken, it is hard to know the true state of things, but 13.2v charging from the Alternator is really, really low.

 

A good system will be 14.4v. You have a 13.0v battery, so charginge it at 13.2v, will take forever as the charger voltage should be least 1.0v above the battery voltage.

It is likely the current going into the battery will be very small, much less than is being taken out when driving.

Even without the Fridge on, I don't think the battery will get any meaningful charge.

 

The mains charger you have is the very low power P116 we suspected would be installed. It is listed on the box in the photo as a Power Supply/charger (not a proper battery charger) and will get very hot trying to charge up a battery that is low.

I suspect it no longer overheats because the battery has charged up quite a bit so is placing less load on the unit?

They were designed as power supplies for Caravans, we don't think they are suitable for a Motorhome. There is a 20amp version, with a cooling fan, for Motorhomes

 

 

 

So I think the guess work that all your problems were caused by the battery being discharged while driving, is correct.

You probably got to site with a very flat battery that overwhelmed the Power Supply which subsequently overheated.

 

 

If your battery has dropped such a lot of volts in just 6 hours, I would say it hasn't survived and will make things worse.

 

If the Alternator is charging the Starter battery at the same voltage, it probably won't have enough ooomph to even keep the Starter battery charged if you have to use Head Lights, wipers, etc.

 

Can I suggest that before you go you find out why the Alternator isn't properly charging the habitation battery. It may be as simple as just needing a new Earth strap.

At the very least, fit a decent mains charger, the Sargent PX300 isn't the best charger going, but at least it is cheap and more than double the power of the one you have?

 

 

[Keithl]

Michael,

 

As a very quick test of the alternator try the following:

 

1. Turn off all habitation electrics.

2. Start the engine and allow to idle. What is STARTER battery voltage?

3. Rev engine to approx 1,500 to 2,000 rpm. What is STARTER battery voltage?

4. Hold revs and turn on headlights, heater blower, etc to load alternator. What is STARTER battery voltage?

 

If you do not see above 14 V for test 3 you need to investigate why.

 

Keith.

[michaelmorris]

Keithl - 2018-05-15 2:43 PM

 

Michael,

 

As a very quick test of the alternator try the following:

 

1. Turn off all habitation electrics.

2. Start the engine and allow to idle. What is STARTER battery voltage?

3. Rev engine to approx 1,500 to 2,000 rpm. What is STARTER battery voltage?

4. Hold revs and turn on headlights, heater blower, etc to load alternator. What is STARTER battery voltage?

 

If you do not see above 14 V for test 3 you need to investigate why.

 

Keith.

 

Thanks, I'll try to get this done this later evening when I get back from work.

[michaelmorris]

Keithl - 2018-05-15 2:43 PM

 

Michael,

 

As a very quick test of the alternator try the following:

 

1. Turn off all habitation electrics.

2. Start the engine and allow to idle. What is STARTER battery voltage?

3. Rev engine to approx 1,500 to 2,000 rpm. What is STARTER battery voltage?

4. Hold revs and turn on headlights, heater blower, etc to load alternator. What is STARTER battery voltage?

 

If you do not see above 14 V for test 3 you need to investigate why.

 

Keith.

Okay here are some voltage figures for the vehicle battery.

1. - with engine off and key not in the ignition. Has been sitting idle since yesrday at 6:30pm =12.9v

2 - engine idling = 14.19v

3 - engine at 2,000 revs = 14.2v

4 - engine at 2,000 revs with headlamps, indicators and heater fan on full blast = 13.88v

 

[Keithl]

Fantastic!

 

So that basically proves your alternator IS working quite decently.

 

Now you need to work out why you where only getting 13.2 V at the leisure battery and you may be getting somewhere.

 

Try measuring the voltage at various points starting with the relay and fuses which feed the leisure battery and earth the black meter probe to a good clean ground every time. Follow the wire and test at as many points as you can until you find the voltage drop 14.2 V to 13.2 V.

 

Keith.

[michaelmorris]

Keithl - 2018-05-15 8:04 PM

 

Fantastic!

 

So that basically proves your alternator IS working quite decently.

 

Now you need to work out why you where only getting 13.2 V at the leisure battery and you may be getting somewhere.

 

Try measuring the voltage at various points starting with the relay and fuses which feed the leisure battery and earth the black meter probe to a good clean ground every time. Follow the wire and test at as many points as you can until you find the voltage drop 14.2 V to 13.2 V.

 

Keith.

 

Thanks Keith, your (and everyone else's) help with this issue really is VERY gratefully received.

This has given me some (perhaps false) reassurance that my planned strategy of not running the fridge on 12v and using hook ups every night whilst we are away is (hopefully) likely to reduce the risk of further problems during our stay in France. When we get back I can then work out whether to try to tackle the investigation myself (probably significantly beyond my capabilities and time available) or bite the bullet and pay some else to do it.

[Keithl]

michaelmorris - 2018-05-15 9:55 PM

 

This has given me some (perhaps false) reassurance that my planned strategy of not running the fridge on 12v and using hook ups every night whilst we are away is (hopefully) likely to reduce the risk of further problems during our stay in France.

 

Michael,

 

You could always run it on gas whilst on the road, just do not enter any fuel filling station without first stopping and turning it off though! (It's not only illegal but downright dangerous!).

 

Keith.

 

PS If you can spend a few minutes with your meter you may find your fault is as simple as a corroded connector or faulty relay.

[michaelmorris]

We're off in a week ;-) and I've been having a think about our proposed temporary fix of simply turning the fridge off when we travel.

Would an alternative strategy of when we travel be to disconnect the leisure battery and turn the fridge to 12v work or does that risk draining the vehicle battery?

[Alanb]

Michael,

 

Isolating your auxiliary or habitation battery will of course prevent it becoming discharged while travelling, but it will also prevent it being charged. You will be reliant on EHU for battery charging. Further as your fridge is not receiving a good supply from the alternator, it is probable that your fridge will not cool adequately.

 

To elaborate, your 12V supply while in motion is provided by the vehicle alternator. The alternator B+ is connected as the name suggests to the starter battery positive, probably via a high value fuse. On my X244 Fiat Ducato the starter battery negative is connected to the battery and engine earth cable, which connects to the chassis inboard and below the front (negative) end of the battery. The cable continues under the radiator, and connects to the engine block near the starter motor. The return circuit to the alternator is completed via the engine block, to which the alternator is bolted.

 

From the starter battery voltage readings taken by you, there does not seem to be a serious problem with the vehicle standard connections and alternator.

 

The habitation 12V electrics are typically connected to the positive and negative terminals of the starter battery, but the negative connection could be made to the vehicle chassis. Other voltage readings taken by you indicate a significant voltage drop somewhere in the habitation circuit.

 

One method that should help in localising the fault is to use a long negative connection lead for your multimeter. This lead could be made fron four or five metres of thin electrical flex as follows. Strip both ends of the flex as necessary. push one end into the COM or -ve socket of your multimeter. Secure it with electrical tape, masking tape, string, or even adhesive plaster, so that it will not come tree from the meter accidentally. Secure the free end to the starter battery negative connector.

 

Now take the following voltage readings with the fridge on 12V, and the engine running at 1500 to 2000 rpm.

 

1. Starter battery positive.terminal.

 

2. Habitation battery positive terminal.

 

3. Habitation battery negative terminal.

 

The difference between 1 and 2 above will indicate the volts drop in the positive connection.

Reading 3 indicates the voltage drop in the negative connection. Both voltage drops should be small fractions of a volt. The drop on the positive side will probably be slightly higher, due to the extra circuitry involved (fuse & relay contacts).

 

Alan

[michaelmorris]

Okay, here is the latest update.

The good news - running the van for over 2 weeks with fridge turned off and the leisure battery disconnected when travelling meant that the leisure battery held it's charge fine. It was topped up when we were on hook up.

On the way home we ran a test.

Start voltage 13.3v

Run for 2 hours with leisure battery connected and fridge OFF = final voltage of 13.7v

Run for further 1.5 hours with leisure battery connected and fridge ON (12v) = final voltage of 13.2v

 

Conclusion - Either

1 - Vehicle is not supplying enough power to leisure battery to charge it and run fridge on 12v

or

2 - Fridge is drawing more power when on 12v than it used to,

or

3 - Something else is drawing more power then it used to which now no longer leaves enough power to run the fridge on 12v.

 

 

 

[Keithl]

Michael,

 

What is your leisure battery voltage with engine running and fridge both Off and On please?

 

Keith.

[Alanb]

Michael,

 

I regard your conclusions 2 & 3 above as unlikely, and suggest that you ignore these until investigations indicate otherwise.

 

That leaves your conclusion 1, but may I rephrase it to read :- Insufficient power is being received from the vehicle to charge the habitation (leisure) battery and power the fridge on 12V.

 

May I restate my advice of 25/05/18 to use a trailing negative lead with your multimeter, this should quickly indicate the area where the cause of your problem is.

 

Alan

 

 

[michaelmorris]

(Hopefully) fixed! :-)

We've just brought the van up to North Wales for Allan to have a look at. He diagnose the problem in around 40 minutes. It was simply a knackered earthing lead. New one fitted and now we have over 14v going to both the vehicle battery and leisure battery.

Result.

 

[aandncaravan]

We looked at the BCA equipment, checked the habitation battery and the Starter battery voltages.

 

We then ran the engine, with the Fridge off, and the voltage at the habitation battery struggled to reach 13.3v, see photo

 

The Starter battery showed the same voltage.

 

As per our guidance at the bottom of the add a Battery web page, http://www.aandncaravanservices.co.uk/add-a-second-battery.php I put a jump lead between the chassis and the engine block and the voltage immediately rose to 14.1v, indicating that the power could not get out of the Alternator.

 

We fitted a new 'made up' earth lead to go between the chassis and the Engine block and the Starter battery voltage rose up to 14.2v and just on 14.1v at the habitation battery.

When the Fridge was operated on 12v the voltage plummeted to 13.6v, exactly in line with expectations for the BCA power control set-up, but close to what it would have been out of the factory.

 

One very happy Michael who said he had been quoted £450 for a new BCA controller. but went away with a bill for just 2 hours labour. And that included a full 12v survey.

 

 

I suspect the Engine Earth strap has been failing for some time and the duff battery finally overloaded the failing wiring resulting in more power being taken out by the Fridge than was being put back by the Alternator while driving.

This resulted in a very low battery at destination which then over whelmed the 10amp mains charger, hence it running hot to destruction trying to handle a very tired, very discharged battery.

 

 

As we have said before corroded Engine earth straps doesn't just affect Starting, which was perfect.

 

 

 

 

 

 

[Keithl]

And hopefully taught you some basic troubleshooting lessons in the process!

 

Good result Allan.

[Alanb]

Allan,

 

On my 2006, x244 Ducato, the earth cable runs from the battery negative clamp, to an earthing point below the battery, (flag terminal lug) and continues to a starter motor stud.

 

Please was the earthing on Michael's vehicle the same or different?

 

Thanks,

 

Alan

 

 

[aandncaravan]

On this 2003 Peugeot it ran from the battery down to a chassis point, but stopped there.

There is then a separate cable from chassis to Gearbox housing.

 

Even if the Earth straps are good, they are to the gearbox housing, not the engine/cylinder head.

In addition there are several lumps of metal with potentially poor connectivity between the alternator and the engine block.

By at least going to the engine block/head you stand a better chance of reasonable Alternator connectivity.

 

 

 

 

 

[michaelmorris]

Okay, we ran the fridge on 12v for the 3.5 hour journey home on Tuesday. This morning (over 3 days after we got back) I've measured the battery voltage at 12.66v. Is that figure okay?