Engel Fuse - can i replace with normal fuse

Submitted: Saturday, Mar 09, 2013 at 18:21
ThreadID: 100991 Views:27908 Replies:10 FollowUps:15
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My engel fuse has blown (im responsible for that)
Do people replace these with normal fuses, or should I go and see the bank about borrowing money for a engel thermal fuse.
I have a 4 year old 40l engel.

Any assistance will be much appreciated.

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Reply By: Shaker - Saturday, Mar 09, 2013 at 18:52

Saturday, Mar 09, 2013 at 18:52
I would imagine they use a thermal fuse for a reason.
Hardly a big deal at $9.00.
AnswerID: 506425

Reply By: Member - Old Girl - Saturday, Mar 09, 2013 at 19:06

Saturday, Mar 09, 2013 at 19:06
We keep a spare Engle fuse in the glove box. Above got a deal. Ours was $12. Small price for a great fridge.
AnswerID: 506426

Follow Up By: aboutfivebucks (Pilbara) - Saturday, Mar 09, 2013 at 19:34

Saturday, Mar 09, 2013 at 19:34
What im really asking is - can i use a normal fuse while i wait for my new one to be shipped to me.
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Reply By: Member - J&R - Saturday, Mar 09, 2013 at 20:26

Saturday, Mar 09, 2013 at 20:26
Probably. If it never blew a fuse before you caused it to blow it is usually safe to replace with a fast blow type.
AnswerID: 506428

Reply By: Tim - Saturday, Mar 09, 2013 at 20:37

Saturday, Mar 09, 2013 at 20:37
At the risk of being shot down.... Yes u can. A thermal over load/ fuse (TOL) allows for short bursts of start up current (up to 6 times normal operating current) for short periods of time because thats what a motor does. So a 3A motor might draw 18A on start up but it wont trip a 5A thermal fuse.
So, if ur confident u stuffed the old fuse and there is nothing wrong with the fridge, go for it but u might need to up the current rating on the fuse.
And its an engel so its tough as nails!
AnswerID: 506429

Follow Up By: Allan B (Member, SunCoast) - Sunday, Mar 10, 2013 at 14:05

Sunday, Mar 10, 2013 at 14:05
You are confusing a thermal fuse with a slow-blow fuse.
A thermal fuse responds to the temperature of its environment, in this case the cigar plug.

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Follow Up By: Tim - Monday, Mar 11, 2013 at 12:57

Monday, Mar 11, 2013 at 12:57
A thermal fuse /TOL and even a normal fuse respond to temp. The temp of the conductor causes a specific action. Being either a thermal fuse or slow or even fast blow fuse, once the conductor heats to a certain temp, the conductor will melt and hence blow the fuse. A proper TOL can be reset, they are usually made from a bimetal strip which bends once the current heats it up beyond its limits.
Any breaker or fuse will be de-rates with higher ambient temps. A slow blow or thermal fuse will require a long period of excessive current before tripping, similar to a type D circuit breaker in industrial applications.
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Follow Up By: Allan B (Member, SunCoast) - Monday, Mar 11, 2013 at 17:40

Monday, Mar 11, 2013 at 17:40

I'm afraid that you still have not grasped the function of a Thermal Fuse. It is not comparable to a normal wire fuse, slow or fast blow, or to a Thermal Overload Circuit Breaker (TOL).
Wire fuses and TOL's are designed to respond to the current passing through them and interrupt the circuit if that current exceeds the design limit. As the current generates some heat within the device in order to activate it, the ambient temperature may have some small undesired effect upon the operating point, but it is the electrical current which is the significant operating parameter, not the temperature.

Conversely, a Thermal Fuse is designed to respond to the temperature of the environment surrounding it and to protect the appliance from overheating. They are manufactured in a range of temperature responses. Their operation has nothing to do with the magnitude or duration of the electrical current. There may well be a maximum current specified for each device but only to indicate the limit that the device can safely handle.

A commercial description may be found here.

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Reply By: Trackerdog - Saturday, Mar 09, 2013 at 20:40

Saturday, Mar 09, 2013 at 20:40
Yes, you can just use a standard fuse. Been running a standard fuse for 2 years now and there has been no problems at all.
AnswerID: 506431

Reply By: The Bantam - Saturday, Mar 09, 2013 at 22:04

Saturday, Mar 09, 2013 at 22:04
Like a great many things...people have a lend of us.

This " thermal fuse"..have we got a picture of it?

Does it fit in a normal fuse holder?

Does it look more or less like a normal fuse but with sort of springy bit in side.

Perhaps it is just a standard off the shelf slow blow fuse????

$12 for a single fuse.....oh please.

AnswerID: 506435

Reply By: The Rambler( W.A.) - Saturday, Mar 09, 2013 at 22:19

Saturday, Mar 09, 2013 at 22:19
I can see no problem in replacing a thermal fuse which was designed for the engel for around$10 as they should last many years.Ihave been running 2 engels in my camper trailor for years without replacing fuses.The biggest culpret for blowing the fuse is the standard cigarette lighter plug.Replace this with a Engel plug and you should never have a problem.
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Reply By: Member - Old Girl - Saturday, Mar 09, 2013 at 23:17

Saturday, Mar 09, 2013 at 23:17
Crap. I wont bother posting here anymore.
AnswerID: 506440

Follow Up By: Rod W - Tuesday, Mar 12, 2013 at 09:32

Tuesday, Mar 12, 2013 at 09:32
I fully agree with you Old Girl. I'll still post, but some people go absolutely over the top and blow everything out of proportion.
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Follow Up By: Rockape - Tuesday, Mar 12, 2013 at 10:54

Tuesday, Mar 12, 2013 at 10:54
don't worry about it. There are many different people out there and I guess that is what makes the world go round.

Chin up or was that finger up, I can't remember which one is the appropriate.

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Reply By: Allan B (Member, SunCoast) - Saturday, Mar 09, 2013 at 23:37

Saturday, Mar 09, 2013 at 23:37
An Engel thermal fuse is not the same thing as a 'normal' wire-type fuse.
A thermal fuse disconnects supply when its surrounding temperature reaches the design limit. It is not designed to protect against over-current. They are typically 'buried' in the windings of transformers to protect against overheat. Once activated they do not reset.

The Engel thermal fuse is positioned within the cigar plug of the 12v cable to protect against heat produced by the notoriously poor contacts of this type of plug. It operates at 168C. Additionally the Engel thermal fuse contains a diode to protect the refrigerator from a reversal of supply polarity.

The refrigerator will work satisfactorily with a suitably-fitting 'normal' wire fuse of appropriate rating (10A or 15A), but without the temperature and polarity protection described above.

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AnswerID: 506441

Follow Up By: Member - OnYaBike - Monday, Mar 11, 2013 at 00:17

Monday, Mar 11, 2013 at 00:17
yes I found out about the reverse polarity protection when I was careless one time. Luckily a spare was included with the fridge and I replaced it the first chance I had. A few dollars is a small price to pay to protect a thousand dollars.
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Reply By: The Bantam - Sunday, Mar 10, 2013 at 01:55

Sunday, Mar 10, 2013 at 01:55
OK I've done a bit of research......this thing is pretty well unnecessary.....its only used with a cigarette lighter socket....if you buy an engel power cord that does not have a ciggy lighter plug...this "thermal fuse" is not encorpirated.......correct me if I am wrong.

AND, nobody else uses one but Engel.

The spiel on the Engel site is BS at best.

They claim that this fuse measures cable resistance......it can't do anything of the sort

As far as I can see its a standard 3AG fuse case that has been fitted with a standard thermal fuse $3.50 retail and a diode for polarity protection.

as far as I can see the only possible function of the thermal fuse part is to stop the ciggy lighter socket melting.

The diode is suposedly for polarity protection........why would anybody install polatrity protection that can be installed wrong way around.
If polarity protection is required why is it not fitted in the main body of the fridge in a permanent way that can not be tampered

From what I understand Engel fridges have a power supply fuse in the main body of the fridge.

Now......one thing that interests me is small fridges generaly draw around 3.5 ish amps continuous.....I'm a technician by trade & Ive made a few funny fuse devices in the past......buggered If I know where I would get a 5 amp rated diode that would fit inside a 3AG glass fuse envelope........remember this is a motor and will have a start surge way higher than 5 amps

My expectation is that the diode may present a reliability issue.....if anybody has one of these blown thermal fuses ...I'd be interested to see if its the diode or the thermal eliment that has failed.

A standard 3AG fuse will work just fine...if there is the correct fuse in the main body of the fridge, the value of the replacement fuse will not matter as long as it is above the rating of the main fuse.

BTW...the going retail price for these things is $9.00...if you are paying $12 someone is having a big lend.

If ya still want this thermal protection and can live without the polarity protection......go to any good electronics parts store and buy a 10 or 15 amp fuse that has soldered ends wot 50c retail and a Grey coded thermal fuse about $3.50 retail.
sweat the ends off the fuse, desolder the normal fuse wire, insert the thermal fuse.....and with a fast hand and a hot iron, solder the thermal fuse into the fuse holder.

hope this helps

AnswerID: 506448

Follow Up By: Sand Man (SA) - Sunday, Mar 10, 2013 at 09:46

Sunday, Mar 10, 2013 at 09:46
That is a lot of buggering about to save $9.00.

I just trust the Engel techo's know what they are doing by incorporating the thermal fuse in the patch lead.

The only thing I have done is remove the original plug and change to a merit plug to standardize all my 12 volt equipment with the one style of plug/socket.

I haven't had a problem with either a blown thermal fuse in the patch lead, or the standard blade fuse on the fridge itself, but I would not concern myself with forking out $9.00 for a new fuse, should the need arise.

Perhaps some people are just miserly!


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Follow Up By: Allan B (Member, SunCoast) - Sunday, Mar 10, 2013 at 11:08

Sunday, Mar 10, 2013 at 11:08
If you have replaced the original Engel cigar plug with a Merit plug then you certainly won't have "a problem with a blown thermal fuse" as it has gone with the removed plug.
So you are actually not "trusting the Engel techo's" knowhow. LOL

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Follow Up By: The Bantam - Sunday, Mar 10, 2013 at 11:30

Sunday, Mar 10, 2013 at 11:30
I'm afraid I am not such a trusting soul.

Particularly when that manufacturer tells me a diode and a thermal fuse " measures cable resistance" I know there is a bucket of BS in the corner.

Sticking a standard fuse costing 50c retail in place of this device is hardly a lot of buggering around.

for those of us who can solder well, making your own thermal fuse minus the unnecessary diode for $4 retail is hardly a lot of buggering round...particularly when the bits can be had in any good electronics parts store.

As I say...correct me if I am wrong but the Engel plug supply lead does not have such a fuse in it, and no one else uses such a device in a ciggy plug........looks pretty superfluous to me.

Unless they are just trying to cover up for a fundamental failing in the ciggy plug.

Speaking of the ciggy plug......the ciggy plug is fundamentally flawed as power supply connector......

When the ciggy plugs and sockets are as good as can be baught, they are fundamentally unreliable.

When they are less than top shelf( most I've seen) they are just trash.....introduce a fuse into ciggy or merit plugs and they just get less reliable.

The best and most reliable versions of both ciggy and merit plugs I have come across, do not have provision for a fuse in them.

Personally I would not run a fridge on a ciggy plug unless I had no other choice......If I did, I'd be checking it every time I stopped to make sure the plug had not fallen out & was still pushed in tight.


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Follow Up By: Sand Man (SA) - Sunday, Mar 10, 2013 at 11:55

Sunday, Mar 10, 2013 at 11:55
Allan B,


You are so right mate:-)
Removing the Engel plug also removed the thermal fuse.

I changed over to the merit style plug/socket many years ago.
I just like the positive method of connection.

I have a 75Ah Thumper that I use when taking the tent in lieu of the camper. This device has two merit sockets and one cigarette style socket.
By standardizing on the one type of plug, I can connect the fridge, one or two fluro lights and just add the red collar to one plug if three devices are connected concurrently.
The solar panel connects to a 50A Anderson connector also incorporated in the Thumper, along with a larger Anderson connector for jump starting if the need arises.


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Follow Up By: The Bantam - Sunday, Mar 10, 2013 at 12:54

Sunday, Mar 10, 2013 at 12:54
The truth is the cigarette lighter was never designed to be a DC supply socket and as such performs very poorly.

The outer connection gets fair contact quality but the inner point relies on the friction of the outer for the contact pressure.....there is no wiping action to clean the contact of this center and thus the whole thing is poor.
10 times worse if the socket has ever used to light cigarettes...due to corrosion.

many ciggy lighter sockets may be fused at 15 amps......but even in good condition 5 amps continuous is about as far as they can be trusted..and only then if the particular combination holds in well.

Merrits are a far better proposition, but only if the good quality plugs and sockets are used.
Look for a complete outer ring that snaps into the socket firmly.

The combination Merrit/ciggy plugs I have found to be only margianlly better than the standard ciggy plug.....most of the ones I have seen are hard to terminate decent sized wires into and the encorpirated fuse and the way its fits is a joke.

I know a lot of people are suspicious of merit plugs and sockets.......but I put that down to so many of them being these cheapy combination things.

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Follow Up By: Allan B (Member, SunCoast) - Sunday, Mar 10, 2013 at 14:53

Sunday, Mar 10, 2013 at 14:53
Bantam, I agree with you about the misapplication of cigar-lighter sockets as 12v accessory sockets. They were historically installed as cigarette lighters but then were pressed into use to supply the newly-developing accessories. And as you say, the Merrit plugs are only marginally better. We really need a new, decently designed, 12v accessory outlet but the cigar plugs have become the standard and we are stuck with them if for no other reason than the advent of accessory power units of 5 volt and the like that are built-in to a 'cigar' plug. They are not convenient to remove and be replaced with a better plug. You and I may do it but it would be beyond most.

For my own part, my fridge is directly connected with no plug other than at the fridge end, a couple of Andersons for heavy users, and my assortment of accessory charger/supplies just have to get by with cigar sockets.

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Follow Up By: The Bantam - Sunday, Mar 10, 2013 at 17:30

Sunday, Mar 10, 2013 at 17:30
There are any number of plugs that are better for the job but none of them have become standardised.

The fridge makers don't help, both the major fridge makers have their own non standard for the connection at the appliacne end or the supply end or both.

The T plug, ( same as our 240v mains plug but with 2 pins arranged in a T) has been a standard DC supply plug in this country for decades.
They are well and truly capable of handling 15 amps continuous when in good condition and they are pretty reliable......but people turn their noses up against them...on the basis of price or size..some even clam them to be unreliable..sorry I cant see it.

The film and television industry world wide has been using the 4 pin XLR plug for DC supplies since valves went the day of the dodo in video cameras......the 4 pin is used to prevent confusion with the 3 pin used for professional microphones......the 4 pin is rated at 7.5 amps continuous per pin.....and they are about as reliable as a plug gets.

If there is no issue with confusion with microphone plugs, the 3 pin XLR is an excelent connector...redily available tough as, excelent strain relief and good for 15 amps continuous...and it is a latching plug.

Yamaha used to have a special non standard 2 pin version made for its CP series portable electric grand painos.....its a pitty it was never widely made or standardised.

While we are in the audio market.....the SPEAKON would make an excelent DC connector....good contact resistance good current and voltage capacity and a very strong strain relief.

There is the CB radio microphone plug....available in 2,3,4, 5 and rarely in 6 pin.....a great little plug, good for about 7.5 amps in the 2, 3 & 4 pin.....these are used extensivly in DC power supply leads for low to mid range sound equipment....they have a threaded locking ring and excelent strain relief.
They are also used for connecting all sorts of stuff to a wide range of buggeryboxes in all fields of electronics

There is the marine bi-pin, that has a large and a small pin, in both a push in version...which while a little chincy works well...and a threaded ring locking version with a metal body .....looks crude but they are reliable and good for 15 amps.

Then there are the Amphinol and Cannon milspec connectors that have been around for decades, nice plugs made by Hirshman, Hirose and others.

There is even a 2 pin version of the 5,6 & 7 pin trailer connector.

But nothing standardised.

In my view one of the most rediculous things is connecting a 3.5 amp current drain item using a 50 amp anderson plug...a plug way too big for the cable, no strain relief and massivly bulky.

There is a lower rated version of the anderson plug that comes in single pole connectors..red & black, that can be linked together into build multi pin plugs...these are a great little thing but no one seems to use em or even know about em

I can certainly see a very good case for hard wiring a fridge cable into the vehicle......but most people cant be bothered doing it prorperly.
A little screw top junction box with a cord clamp strain relief.

after all there is a plug on the fridge end...buy another cable f you want to plug it into a ciggy lighter.

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Follow Up By: Allan B (Member, SunCoast) - Sunday, Mar 10, 2013 at 20:22

Sunday, Mar 10, 2013 at 20:22
Some of those plugs & Sockets may be sort of OK for the 12v power application but I'm not so sure about others. Many of those you mention have pins too small for a decent cable and are fiddly to assemble.
I also do not consider it a good idea to be using dedicated comms plugs such as microphone and speaker types for power supply purposes, it simply extends the corruption of standards.
What is needed is a new, dedicated, economical 12v/24v auto connector. And not the clumsy Clipsal t-pin 402/32v plug which is nearly as old as me!
It's still not too late.

I agree about the oversize Anderson plugs. Lack of strain relief is a real shortcoming. And very open to the elements when used outside of the cabin. Yes, yes I know.......there are covers available but water and dust can still ingress at the cable entry unless sealed with silicon. But they do have good contacts.

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