Hi, I hope someone on here can set my mind at rest. We usually plug the van into the house electric supply before our trips out, like a lot of people do. It is (or i should say was) plugged in today when i went under the seat for something and realised the charger was hot. And I mean hot. Not just warm. I unplugged from the supply and left the seat up to let it cool down. Surely its not meant to be so warm is it, I havent noticed it before. Are we going to need a new charger?
Caravan Battery Charger
- Thread starter MagsAlan
- Start date
Hello Mags,
Chargers will run warm when in use. The temperature is generally proportional to the load it is supplying., So running hot could indicate that something is loading it substantially. This could point to a failed battery. But also it could point to a faulty charger.
You could try disconnecting the battery, and then see if the charger heats up. If it dosent it suggests the battery could be the culprit.
Chargers will run warm when in use. The temperature is generally proportional to the load it is supplying., So running hot could indicate that something is loading it substantially. This could point to a failed battery. But also it could point to a faulty charger.
You could try disconnecting the battery, and then see if the charger heats up. If it dosent it suggests the battery could be the culprit.
Could it also be that something which draws a fairly heavy current is switched on? Can't think what it would be that you wouldn't have noticed, but I thought I'd throw it in.
What would happen if the fridge was left in battery mode when the car wasn't plugged in?
What would happen if the fridge was left in battery mode when the car wasn't plugged in?
Hello Gozza,Gozza said:
Unless someone has wired it up incorrectly, the fridges 12V element should not be connected to the caravans 12V circuits. It is designed only to be supplied with power direct from the towing vehicle.
The main reason for this is because it will use a considerable amount of 12V power. which will be excessive for the caravan battery and charger to supply.
That's what I thought - but if someone had wired it incorrectly, in the way you describe, would it produce the symptoms Mags is experiencing?
Hi again. Well I disconected the charger from the battery then turned the power back on and the charger didnt heat up. When we have got the battery out of the box we notices a fine powdery substance (a bit like fine castor sugar) around the terminals - is that indicative of anything?
Do you have a test meter? if so set it to 20v dc disconnect from EHU disconnect battery, connect meter to pos & neg leads from caravan & reconnect EHU. this should show no more than 13.8 volts which is the normal charge rate Now disconnect ehu. leave battery disconnected for several hours & then connect the meter across the battery terminals , this should read 12.7 for a fully charged battery, even better if you have a battery with removable caps first check the battery water levels & then buy a hydrometer,about £5 using this check all battery cells they should all read the same if not then the battery has a dead cell & needs replacing actualy using a hydrometer is a much better way of checking a battery
J-Nevil said:
It difficult to be specific, as it depends on the makers decisions about cooling within the charger. But generally the components on circuit boards are generally commercially rated to 70C so the external casing of an electronic rated electronic circuits should not exceede that, and should be much lower.
MagsAlan said:
Prof John
Is there anything relevant in the above statement that may cause "overheating" in the charger?
Dustydog said:
hi DD
sorry to interject but yes there is, the deposits are caused by electrolisis (the passing of a current through different materials) ie brass clip and lead terminal, petoleum jelly usually stops it,
this deposit causes a barrier though the connection and an increases the resistance for the current to pass through this makes the charger work harder and as a result generates more heat, the more the work the hotter it gets until the integrated componants fail. this is why things like computer PSU's have a fan, most charges dont have fans and use convection to dissipate heat if the charger get warm the air around it gets warm so the charger gets warmer ect, increasing air circulation helps, but seeing as how the charger is in a confined space this is difficult, how hot can it get, good question!! (using the Profs statistic of 70 degrees C) about the same as very hot water, or a electric kettle 10 mins after being boiled.
I can't disagree with Colin's description of the cause of the powder deposits, but I can't fully agree with his logic regarding the charger having to work harder to compensate for the powder. This is in fact wrong.
If the powder introduces or increases the contact resistance of the connection to the battery, it means the charger will deliver less current to the battery.
In a series connected circuit (such as the battery and charger) the current is the same at all parts of the circuit. So if there is less current being delivered to the battery because of contact resistance, then there is less current passing within the the charger.
The resistive heating effect in a circuit is directly related to the current passing through it, consequently less current to the battery means less current to heat the charger.
In Mags case, the fact the charger is not getting hot when the battery is disconnected, strongly points to the battery at fault.
Using a hydrometer will certainly show if the electrolyte has the correct Specific Gravity but battery specialists may have the means to check the battery for discharge and charge rates.
If the powder introduces or increases the contact resistance of the connection to the battery, it means the charger will deliver less current to the battery.
In a series connected circuit (such as the battery and charger) the current is the same at all parts of the circuit. So if there is less current being delivered to the battery because of contact resistance, then there is less current passing within the the charger.
The resistive heating effect in a circuit is directly related to the current passing through it, consequently less current to the battery means less current to heat the charger.
In Mags case, the fact the charger is not getting hot when the battery is disconnected, strongly points to the battery at fault.
Using a hydrometer will certainly show if the electrolyte has the correct Specific Gravity but battery specialists may have the means to check the battery for discharge and charge rates.
hi all.
sorry John, logic is all I have to work with not being a professor or anything, that and experiment or course
.
2 points, first so resistance doesn't cause heat eh! erm, I thought it was something to do with thermal dynamics and all that, you know the one, the bit about how a light bulb and elecric fire works, the senario you propose is of course correct if the zig unit is of the smart charger type and reduces the current as the resistance in the state of battery charge becomes higher, trouble is zig units are not smart chargers,
second, experiment we all have some sort of charger at home, place on flat suface connect a battery and plug into the mains, leave for 1hour, turn off then check the temprature of the charger, next do the same thing but this time place the charger in a box fit lid and cover with insulation, run again for an hour,(if the charger lasts that long without blowing a fuse) check the temp again it will be considerably warmer due to the lack of air circulation.
I do agree however that the main reason the charger would heatup considerably would be due to a duff battery and not electrolisis alone, but it doesn't help.
sorry John, logic is all I have to work with not being a professor or anything, that and experiment or course
2 points, first so resistance doesn't cause heat eh! erm, I thought it was something to do with thermal dynamics and all that, you know the one, the bit about how a light bulb and elecric fire works, the senario you propose is of course correct if the zig unit is of the smart charger type and reduces the current as the resistance in the state of battery charge becomes higher, trouble is zig units are not smart chargers,
second, experiment we all have some sort of charger at home, place on flat suface connect a battery and plug into the mains, leave for 1hour, turn off then check the temprature of the charger, next do the same thing but this time place the charger in a box fit lid and cover with insulation, run again for an hour,(if the charger lasts that long without blowing a fuse) check the temp again it will be considerably warmer due to the lack of air circulation.
I do agree however that the main reason the charger would heatup considerably would be due to a duff battery and not electrolisis alone, but it doesn't help.
Hello Colin,
Lets clarify some factual information as your last post carries a number of points that need to be addressed.
I'm not sure where you think I gave that impression. The fact is that where a current passes through a resistance it will generate heat. But the heat will be generated where the resistance is located, in this case the sulphation is on the battery terminals not in the charger.
There are various resistance throughout the circuit some inside the charger, and other such as the wiring, and the sulphation and battery, but if any series resistance increases, it adds to the whole circuit resistance and the current in it will drop proportionally. if the current drops, the heating effect in each resistive element also drops.
No where in the OP's posting does it mention ZIG. In fact the OP mentions the caravan is a 2007 model, which means the power supply will be one with a stablised 13.8v output model. In this case the current passing through the circuits will deminish as the batteries terminal voltage rises as it is charged.
It is inevitable that where an electronic device and especially where a power switcher is concerned, it it has restricted access to ventilation, it will heat up more, but in the OP's case the access to ventilation is unchanged, so your reference to the enclosure in this instance has no relevance.
Lets clarify some factual information as your last post carries a number of points that need to be addressed.
colin-yorkshire said:
I'm not sure where you think I gave that impression. The fact is that where a current passes through a resistance it will generate heat. But the heat will be generated where the resistance is located, in this case the sulphation is on the battery terminals not in the charger.
There are various resistance throughout the circuit some inside the charger, and other such as the wiring, and the sulphation and battery, but if any series resistance increases, it adds to the whole circuit resistance and the current in it will drop proportionally. if the current drops, the heating effect in each resistive element also drops.
colin-yorkshire said:
No where in the OP's posting does it mention ZIG. In fact the OP mentions the caravan is a 2007 model, which means the power supply will be one with a stablised 13.8v output model. In this case the current passing through the circuits will deminish as the batteries terminal voltage rises as it is charged.
It is inevitable that where an electronic device and especially where a power switcher is concerned, it it has restricted access to ventilation, it will heat up more, but in the OP's case the access to ventilation is unchanged, so your reference to the enclosure in this instance has no relevance.
Hi all. Crikey, I didnt mean to cause such a complicated discussion.
We put the battery on charge using the charger that Alan keeps for the car. It took 3 days to 'fully' charge. Our mobile engineer came yesterday and tested the battery and the charger and couldnt find anything wrong with either. He suggested that the overheating was caused by the battery charge being so low. (It had been stood for 4 weeks without any charge)
The van has been plugged into the domestic power all day today and there was a gentle warmth to the charger at first but then it gradually cooled.
Thank you everybody for your input, I appreciate you all taking the time to help.
This caravanning business is a lot more complicated than we thought 5 years ago when we started - there always seems to be something going wrong and it doesnt help that we are not the most technical minded of people.
Thank you again
Mags
We put the battery on charge using the charger that Alan keeps for the car. It took 3 days to 'fully' charge. Our mobile engineer came yesterday and tested the battery and the charger and couldnt find anything wrong with either. He suggested that the overheating was caused by the battery charge being so low. (It had been stood for 4 weeks without any charge)
The van has been plugged into the domestic power all day today and there was a gentle warmth to the charger at first but then it gradually cooled.
Thank you everybody for your input, I appreciate you all taking the time to help.
This caravanning business is a lot more complicated than we thought 5 years ago when we started - there always seems to be something going wrong and it doesnt help that we are not the most technical minded of people.
Thank you again
Mags
As this particular query seems to be satisfactorily settled, I wonder if (without wanting to appear to be hi-jacking the thread) if I could post a very similar query. In my caravan I have a Thetford fridge with automatic fuel selection. One of the requirements of the fridge that at all times when it is operating, it must have a constant 12v supply for the control panel to function. On a site about a fortnight ago, on EHU, I noticed that the fridge had switched itself off. Repeated attempts to get it going only resulted in it switching itself off again after a mere 1 or 2 seconds. Thinking that possibly the battery voltage was down, I checked on the voltmeter which I have permanently installed and found to my great surprise that it indicated a charge level of 14.35V whereas I (mistakenly I believe) thought it should not exceed 14V, and that the fridge was in fact switching of because of over-volting. After switching off the battery charger, normal service was resumed.
Subsequent closely observed sessions with the battery charger 'on' have never exceeded 13.7V. Do I really have to go through life constantly having to take charge-rate readings, or is there some simple explanation.
Subsequent closely observed sessions with the battery charger 'on' have never exceeded 13.7V. Do I really have to go through life constantly having to take charge-rate readings, or is there some simple explanation.
MagsAlan said:
Hello Mags
I hope you have had your question answered.
What else has followed is not a reflection on your question, or you, but thank you for asking in the first place.
Ultimately it seems the battery probably was to blame, as you say having stood discharged for some time, so now it is charged hopefully all will be fine.
I bought one of these recently
Non-Contact LCD IR Laser Digital Infrared Thermometer Gun -50℃ to 380℃ UK
£9.99 inc post
http://www.ebay.co.uk/itm/290926936157?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Very useful gadget. Last trip out I did a quick zap of all 6 tyres and wheel hubs at a motorway service station looking for anomolies.
Sorry about the font, could not see how to change it.
Non-Contact LCD IR Laser Digital Infrared Thermometer Gun -50℃ to 380℃ UK
£9.99 inc post
http://www.ebay.co.uk/itm/290926936157?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Very useful gadget. Last trip out I did a quick zap of all 6 tyres and wheel hubs at a motorway service station looking for anomolies.
Sorry about the font, could not see how to change it.
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