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HELP mains transformer running VERY hot!


michaelmorris

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We're away in the van at the moment. I've just noticed that the mains PSU is very hot. It smelled, was very hot to the touch Would burn your skin!) and you could feel the heat it was giving off on the other side of the piece of wood it is screwed to.

It was replaced with a new one late last year after the last one failed. I also replace the leisure battery with a new Varta LF90.

Before I replaced the battery the 15A fuse marked van batt used to blow every few weeks. No problems with the fuse or the PSU since I fitted the new battery at around christmas. The same 15A fuse blew earlier today

I've tripped the MCB that covers the charger as a safety precaution so we're also having to run the fridge on gas as it's on the same MCB as the mains PSU.

 

Any ideas as to the cause?

 

We're supposed to be going to France in less than 3 weeks!

 

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Only a guess, Michael, but I think the fault may lie with the battery, new or not.

 

Not familiar with the Varta LF90, though it seems well reputed.

 

Starting point would be to see if you can remove any of the cell inspection caps (ideally all) to see if the electrolyte level covers the plates. But first, try you hand on the battery to see if its hot. If it is, I think it may be wise to leave it to cool off charge before getting close to it, as there is a possibility that the smell you noticed is coming from the battery which may indicate it is at some risk of exploding.

 

Hope I'm not needlessly scaring you, but it has been known to happen, and the last thing you want is a face full of hot battery acid!

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Brian Kirby - 2018-05-11 7:15 PM

 

Only a guess, Michael, but I think the fault may lie with the battery, new or not.

 

Not familiar with the Varta LF90, though it seems well reputed.

 

Starting point would be to see if you can remove any of the cell inspection caps (ideally all) to see if the electrolyte level covers the plates. But first, try you hand on the battery to see if its hot. If it is, I think it may be wise to leave it to cool off charge before getting close to it, as there is a possibility that the smell you noticed is coming from the battery which may indicate it is at some risk of exploding.

 

Hope I'm not needlessly scaring you, but it has been known to happen, and the last thing you want is a face full of hot battery acid!

 

Thanks Derek

It's a sealed unit so no way of inspecting electrolyte levels.

No sign of it being hot, but it's been off charge for about 30 minutes so no idea whether it was hot when connected to charger.

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Michael,

 

It sounds like you have a short or bad connection somewhere in your wiring, probably between the mains transformer and the fuse, which is overloading the mains transformer and blowing the fuse to protect the battery and its wiring.

 

Keith.

 

 

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Okay, I think we may have sussed out a potential work around so that even if we can't get it fixed before we go away to France, we should still be able to function.

 

1. - disconnect mains PSU so that we can run the fridge on 230v.

2. - connect the leisure battery up to a mains battery charger for two or three hours every evening, running the battery charger off a plug socket in the van. (This assumes the leisure battery isn't damaged)

 

Would I be correct in my assumption that running the van engine will charge still charge the leisure battery a bit?

 

Does this sound like a sensible plan?

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Have you made any other modifications recently ? Particularly fitted anything with screws to the walls ?

 

Last year my charger ran very hot, with the thermostatically conrolled fan running almost constantly. It turned out that I had inadvertaently put a screw through a cable when fitting some Fiamma garage securing rails - it hadn't crossed my mind that the garage wall would be anything other than a solid panel, but it transpired that it was two thin skins with lats between them and the bathroom light wiring ran in the gap. One screw (out of 48 !) shorted the wiring, causing the heavy load on the 12v circuit.

 

Nigel B

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mgnbuk - 2018-05-11 9:11 PM

 

Have you made any other modifications recently ? Particularly fitted anything with screws to the walls ?

 

Last year my charger ran very hot, with the thermostatically conrolled fan running almost constantly. It turned out that I had inadvertaently put a screw through a cable when fitting some Fiamma garage securing rails - it hadn't crossed my mind that the garage wall would be anything other than a solid panel, but it transpired that it was two thin skins with lats between them and the bathroom light wiring ran in the gap. One screw (out of 48 !) shorted the wiring, causing the heavy load on the 12v circuit.

 

Nigel B

I fitted a reversing camera a few weeks ago and that involve putting a few short screws into two areas of the van exterior wall, but nowhere near any cabling (as far as I can tell). The camera and screen are both powered from the electrics in the cab.

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Michael, if the battery is not even warm it suggests the battery isn't taking the current.

 

My guess would be something is drawing around 14amps, maybe a single item, maybe several and the charger is meeting the demand, not the battery.

 

Is there any chance the Fridge has been left on the 12v setting and the charger is supplying the power for that due to some internal issue in the Power distribution box?

 

Or that a combination of Heater fan, LCD TV, Laptop charging, phone charging, etc all combined, is drawing a few amps each so totalling about 14 - 20 amps or whatever the charger max limit is?

 

 

 

Turning off the charger will most certainly protect the charger but obviously something is drawing a significant amount of power. Just turning the charger off won't be a complete cure as the power will now be taken from the battery. At that level, maybe draining it inside 4 hours?

 

What charger is it, that would give an idea of it's capability and the likely load being placed on it?

 

 

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aandncaravan - 2018-05-11 10:05 PM

 

Michael, if the battery is not even warm it suggests the battery isn't taking the current.

 

My guess would be something is drawing around 14amps, maybe a single item, maybe several and the charger is meeting the demand, not the battery.

 

Is there any chance the Fridge has been left on the 12v setting and the charger is supplying the power for that due to some internal issue in the Power distribution box?

 

Or that a combination of Heater fan, LCD TV, Laptop charging, phone charging, etc all combined, is drawing a few amps each so totalling about 14 - 20 amps or whatever the charger max limit is?

 

 

 

Turning off the charger will most certainly protect the charger but obviously something is drawing a significant amount of power. Just turning the charger off won't be a complete cure as the power will now be taken from the battery. At that level, maybe draining it inside 4 hours?

 

What charger is it, that would give an idea of it's capability and the likely load being placed on it?

 

I'm pretty certain the fridge was on 230v.

The only things turned on were the fridge and the telephone charger (which seemed to be working g okay)

The voltmeter in the motorhome says both the vehicle and leisure batteries are running at 12,5 volts over 4 hours after I isolated the charger by turning g off the relevant MCB.

 

 

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michaelmorris - 2018-05-11 10:58 PM

 

I'm pretty certain the fridge was on 230v.

The only things turned on were the fridge and the telephone charger (which seemed to be working g okay)

The voltmeter in the motorhome says both the vehicle and leisure batteries are running at 12,5 volts over 4 hours after I isolated the charger by turning g off the relevant MCB.

 

 

 

12.5v on a Varta LFD90 is not far off 50% discharged, that is as far as it is recommended you discharge a battery, suggesting that something is taking some current?

 

 

Just done some research and the normal charger in that age of Eldiss seems to be a BCA/PS 10 amp power supply/charger. It isn't very powerful so will get hot if you are drawing more than about 7 amps, so you don't actually need to be taking that much current for it to get hot.

 

For example :

Charging the battery - 2 amps

TV - 3 amps.

Lights - 2 amps

Heater blower - maybe 2-4 amps depending on age and efficiency of the bearings?

Laptop/Phone charger - maybe 1 amp?

 

Total - 10 - 12 amps.

 

 

 

You say you had a new charger, did you fit an uprated unit or the same model?

 

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aandncaravan - 2018-05-11 11:44 PM

 

michaelmorris - 2018-05-11 10:58 PM

 

I'm pretty certain the fridge was on 230v.

The only things turned on were the fridge and the telephone charger (which seemed to be working g okay)

The voltmeter in the motorhome says both the vehicle and leisure batteries are running at 12,5 volts over 4 hours after I isolated the charger by turning g off the relevant MCB.

 

 

 

12.5v on a Varta LFD90 is not far off 50% discharged, that is as far as it is recommended you discharge a battery, suggesting that something is taking some current?

 

 

Just done some research and the normal charger in that age of Eldiss seems to be a BCA/PS 10 amp power supply/charger. It isn't very powerful so will get hot if you are drawing more than about 7 amps, so you don't actually need to be taking that much current for it to get hot.

 

For example :

Charging the battery - 2 amps

TV - 3 amps.

Lights - 2 amps

Heater blower - maybe 2-4 amps depending on age and efficiency of the bearings?

Laptop/Phone charger - maybe 1 amp?

 

Total - 10 - 12 amps.

 

 

 

You say you had a new charger, did you fit an uprated unit or the same model?

As far as I am aware it was a like-for-like swap. The name BDA does ring bells.

We don't have a TV in the van and our 1kw fan heater wasn't even plugged in.

In short (no pun intended) the only loading on the PSU should have been

The leisure battery charging

The fridge

a telephone charger

The TV aerial amplifier (don't know why we don't turn this off!)

 

We haven't turned on the hot water boiler this holiday.

 

According to the internal volt meter in the van, the vehicle and leisure batteries are still holding at 12.5v (6 hours since my last posting).

 

The planned holiday in France in 2 weeks is going to be a much needed high point in an otherwise truly horrible year. However, if we can't get to the bottom of what is going on and/or come up with a workable workaround we will just have to cancel it :-(

 

Trying to look on the bright side, at least this didn't happen on our first day in France!

 

 

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Okay, sitrep.

Good news is that battery voltage is stable at 12.5 v overnight.

I've discovered three severed wires. All are small, one 2 core grey, one 2 core black and a white 3 core cable with blue yellow and black wires in it. They as though they may have been cut rather than ten and the cuts do not look fresh. (Copper is oxidised).

 

I have no idea what these wires feed and everything appears to be working.

 

At the moment I'm loathed to reconnect them until I understand what they are.

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Michael,

 

Now that you have found some loose damaged wires, may I suggest that you test with a multimeter, or preferably a simple 12V test lamp, to see if any of the cut ends are live at 12V to earth (battery -ve).

 

If no live wires, then probably not cause of your main problem.

 

Like you I would want to know what they had been connected to.

 

If the above checks locate no live wires, you could at least partially eliminate the charger by disconnecting the charger output, and then switching the mains input ON. The charger should not overheat in this no load condition.

 

Alan

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Okay, further sitrep.

Disconnected battery and turned MCB back on and fridge and lights working okay and PSU not getting hot (just slightly warn as usual).

Reconnected leisure battery and PSU starts to get very hot again.

Now disconnected leisure battery and I'm charging it from a 230v battery charger. As I don't have a multimeter with me I can't test the leisure battery voltage.

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Michael,

 

I am trying to create a hypothesis for the cause of your problem. So far there seem to be three possibilities to explore.

 

1. Your relatively new battery has failed. (Bill Kirkby suggested this earlier in the thread.)

 

2. The charger has developed a fault and is giving a slightly too high voltage and trying to overcharge the battery. (Batteries have low internal reistance, and a small increase in voltage will result in a large increase in charging current.)

 

3, You have lost the main connection to the vehicle battery, either due to a blown fuse or corroded connections, probably under the bonnet.

 

I am not fully familiar with the 2003 Autoquest 12V connections, but there may be fuses and relay(s) under the bonnet. Certainly the fridge control relay is not shown on the wiring diagram.

 

Is it possible to check whether the vehicle battery is available by selecting it briefly on the control panel?

 

If you have lost the vehicle battery connection, it seems possible that the fridge relay would operate from the D+ when the engine is started, this will in turn operate the split charge relay. It seems to me that the fridge would then draw its 12V power from the habitation battery when the engine is running. This will discharge the habitation battery at quite a high rate. Then when on EHU the charger struggles to recharge the battery as well as supplying other loads. At least worth checking before incurring serious costs.

 

I am sure that you will welcome any further suggestions proffered.

 

Alan

 

 

 

 

 

 

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I am not familiar with your setup so this may be a bit of a long shot, but do you have a battery sense wire that is missing/open?

 

My battery has a separate wire to the EBL protected by a small (2A) fuse. As there is only a very small current in this wire, the voltage at both ends are the same and so it is used by the EBL and charger to read an accurate battery voltage (the heavy current carry cables will have a small voltage drop on them). I am not sure what happens to your charger if this wire is lost since it may not be reading the correct voltage and be trying to overcharge the battery maybe? I would hope that it was designed to fail safe but this may not be the case. There should not be anything else attached to this wire.

 

Measuring the actual voltage on the battery terminals and comparing it to your displayed reading would rule this out.

 

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Firstly, a huge thank you for those trying to help with this.

 

You mentioning the vehicle battery has reminded me that the volt meter one the lounge area is reading IDENTICAL voltages for the leisure and vehicle batteries. There is not the tiniest flicker when I operate the switch that selects AUX. and VEH.to switch between the two batteries. I thought this was a bit weird. Could this help with diagnosing the fault?

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I assume this is not normal for your van, Michael? Also, is this the case with the habitation battery disconnected as described above, or have you re-connected it?

 

In passing, be a bit careful what 12V appliances you turn on with the hab. battery disconnected as you will be pulling all the 12V power direct from the charger unit (PSU), without the battery acting as a buffer to smooth the peaks and troughs. It would be very easy to overload the PSU with the battery out of circuit. I'm not suggesting you re-connect the hab. battery, just to take care to keep the 12V current draw from the PSU within its capabilities until you find the actual fault.

 

That said, I wonder if the changeover switch has failed with both circuits closed, so the PSU is trying to charge both starter battery and hab. battery simultaneously? I imagine that might well overload the PSU, depending on the states of charge of the two batteries.

 

If you decide to check that switch I suggest you first also disconnect the starter battery, as you will otherwise have a live feed from that in play. You won't want to short that into the bargain - could be messy! :-)

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Michael, In response to your other thread asking if you can run without a Leisure battery in circuit - In your instance with the very low current draw you have and the BCA/PS 'charger' actually being designed as a Power Supply, then yes you can.

 

More modern chargers do not like the sudden change from providing a 1/4 of an amp one second to providing 18 amps the next, without help from a battery. The old BCA 'charger' we think you have is actually a 13.5v power supply that has a Saturday job of charging batteries, so was designed to handle big variances in load. Can you supply more info about the replacement charger you bought so we can confirm this?

 

So you can use running without a Habitation area battery as a backstop, but before we adopt that, can we try and help you some more? Alanb and other contributors on here are brilliant so don't give up yet.

 

 

You have the other Car battery charger you are using, can you tell us more about that as we might be able to use that to identify if you have a charger/battery issue? As much info on it as you can?

 

 

You say you are using the substitute charger for a couple of hours at night, does that overheat when it is used?

Would you be able to connect it up for longer and monitor it closely (and the battery temperature) while it is operational?

Information such as Voltages when it first starts up (does it kick in at 14.4v or 13.5v) then voltage and temperature info after 30 mins, after 1 hour, etc

 

 

If you have the time, lots of people on here have the will to help you.

 

Any chance you can acquire a cheap multi-meter to take voltages of the batteries when the engine is running, but mains disconnected?

That way we can tell if the Alternator charging is working.

 

 

 

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Michael,

 

I will defer to Allan's vast practical experience as regards the suitability / nature of the BCA charger for running without a battery. It is labelled as Charger Power Supply in the handbook.

 

Looking at your query about voltage reading change when selecting batteries. The battery selection is performed by the upper of the three relays shown towards the LHS of the diagram. This relay must be energised to select the vehicle battery, so failure of switch,wiring, or relay would result in failure to select the vehicle battery, hence no change in voltage.

 

Alan

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When we got home after our 3 hour journey (wirh the battery hooked up) I took out the battery and measured the voltage at just 11.1v! I immediately put the battery on charge with our Halfords smart charger.

It's now 6:00am and the battery voltage is up to 12.32 volts. My plan is to wait until it gets to 12.5volts the see how it holds charge. Does this sound sensible?

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michaelmorris - 2018-05-14 6:10 AM

 

When we got home after our 3 hour journey (wirh the battery hooked up) I took out the battery and measured the voltage at just 11.1v! I immediately put the battery on charge with our Halfords smart charger.

It's now 6:00am and the battery voltage is up to 12.32 volts. My plan is to wait until it gets to 12.5volts the see how it holds charge. Does this sound sensible?

 

Michael,

 

Was the 12.32 Volts with or without the charger connected?

 

If with then something is not right as the charging voltage should be well over 13 Volts.

 

If without then was it immediately after disconnecting the charger or how long after?

 

Keith.

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Keithl - 2018-05-14 7:20 AM

 

michaelmorris - 2018-05-14 6:10 AM

 

When we got home after our 3 hour journey (wirh the battery hooked up) I took out the battery and measured the voltage at just 11.1v! I immediately put the battery on charge with our Halfords smart charger.

It's now 6:00am and the battery voltage is up to 12.32 volts. My plan is to wait until it gets to 12.5volts the see how it holds charge. Does this sound sensible?

 

Michael,

 

Was the 12.32 Volts with or without the charger connected?

 

If with then something is not right as the charging voltage should be well over 13 Volts.

 

If without then was it immediately after disconnecting the charger or how long after?

 

Keith.

When charging the voltage was around 12.6 volts.

Off charge it is now 12.47v. I will monitor this over the next few hours.

 

Just checked the vehicle battery. Voltage is 13.4 volts. Found out that the vehicle battery fuse had blown as well, probably some time yesterday. There is something fundamentally b*ggared with the electrics in this van! This is so depressing!

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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.

 

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