Will the cigarette lighter outlet support a small DC fridge?

[Chris Meyer]

We were thinking of adding some fridge capacity for a cruising trip this summer.   Found a reasonably priced one that plugs into a cigarette lighter outlet  

This fridge is made to be used in a car.

There must be a way for me to figure out if this outlet can support this small fridge without blowing fuses.

Just checked the wiring diagram.   The cigarette  lighter is on a 10 amp fuse.  The fridge draws about 5.

What do I need to look for?

[seattledale]

Well, the fridge is is 5A x 12V = 60watts.  The fuse is 10A so it's good for 10A x 12V = 120watts.  So you should be good, Chris.  However, if it's a compressor-type of fridge (Freon with a compressor motor) then there may be some surge current as the motor starts up.  If that's the case and you're blowing the fuse you could replace it with a 10A Slo-Blo type fuse which can usually hold in during a motor start.

However, seeing how the fridge is designed for a car I suspect it's one of those solid-state type coolers.  I seem to recall it's called the Peltier Effect although I could be wrong.  It's a solid state device that when current is passed through it, one side gets cold and the other side gets warm.  Bolt it to a heat sink and the hot side of the heat sink is on the outside of the case, the cold side is on the inside.  They're not particularly efficient and they only cool down to maybe 30 degrees or so below ambient temperature.  Good for keeping some soda cans cool but I don't think it's going to give you ice cubes.  I've got one; sort of looks like an Igloo cooler with some vents on the top.  The good news is, there is no compressor motor that's going to draw a large amount of current when it starts up.  So I think you won't have any problem blowing fuses.

Or I could be completely off base....

Dale

[Chris Meyer]

Apr 29, 2024 2:31:46 GMT seattledale said:

Well, the fridge is is 5A x 12V = 60watts.  The fuse is 10A so it's good for 10A x 12V = 120watts.  So you should be good, Chris.  However, if it's a compressor-type of fridge (Freon with a compressor motor) then there may be some surge current as the motor starts up.  If that's the case and you're blowing the fuse you could replace it with a 10A Slo-Blo type fuse which can usually hold in during a motor start.

However, seeing how the fridge is designed for a car I suspect it's one of those solid-state type coolers.  I seem to recall it's called the Peltier Effect although I could be wrong.  It's a solid state device that when current is passed through it, one side gets cold and the other side gets warm.  Bolt it to a heat sink and the hot side of the heat sink is on the outside of the case, the cold side is on the inside.  They're not particularly efficient and they only cool down to maybe 30 degrees or so below ambient temperature.  Good for keeping some soda cans cool but I don't think it's going to give you ice cubes.  I've got one; sort of looks like an Igloo cooler with some vents on the top.  The good news is, there is no compressor motor that's going to draw a large amount of current when it starts up.  So I think you won't have any problem blowing fuses.

Or I could be completely off base....

Dale

Thank you Dale!

[rene460]

Hi Chris, I ran a small compressor fridge in my previous boat for many years, though it was wired in by a three pin plug similar to that on a computer power supply.  I believe it was only 4 A but it was intended as a car fridge, and I also used it as such at times.  It was a compressor type. 

Those cigarette lighter style outlets are rated for 10 amps and if you have any fuse problems when the compressor starts, a slow blow type as already suggested should solve the problem.  Get a resettable fuse to replace your 10 A fuse, a useful trouble shooting aid for your tool kit anyway, and try it before buying a special fuse.

The main characteristic which suggested it was a car fridge was that it had very little insulation, so when in the car so tended to be heavy on power consumption.  I enclosed it in a plastic storage box which gave about 50 mm clearance all around which I filled with polystyrene blocks and filled the gaps with expanding foam.  I left the compressor end out of the end of the box for the required air flow.  My wife made a padded cover to better insulate the lid.  This way I reduced the power consumption to where I operated with a single battery and a 55 W panel with careful aiming the panel at the sun and unplugging at night and making sure it ran as much as possible when the sun shone.  Mind you a 100W panel would have been better.  I was stretching the limits.

If you are still looking to buy a suitable type, I suggest you look for a compressor type with plenty of insulation all around, preferably 50 mm or more, and a padded cover.  There are several brands available here in the usual camping and fishing supply houses, but I am sure you will be able to find similar ones.  And obviously the outside dimensions need to fit the space where you intend to keep it.  I found the portable one a good option as it is also easy to take it with you for use in the car for picnics or camping when you are not on board the boat.  The Peltier type Seattledale mentions are also available, but as he mentions the efficiency is not great, so power consumption is high, and compressor fridges tend to perform better.  The very best compressor fridges even have a variable speed compressor which I believe minimises the startup current drawn by the motor.

I hope this helps.

rene460

[Chris Meyer]

Apr 29, 2024 12:10:20 GMT rene460 said:

Hi Chris, I ran a small compressor fridge in my previous boat for many years, though it was wired in by a three pin plug similar to that on a computer power supply.  I believe it was only 4 A but it was intended as a car fridge, and I also used it as such at times.  It was a compressor type. 

Those cigarette lighter style outlets are rated for 10 amps and if you have any fuse problems when the compressor starts, a slow blow type as already suggested should solve the problem.  Get a resettable fuse to replace your 10 A fuse, a useful trouble shooting aid for your tool kit anyway, and try it before buying a special fuse.

The main characteristic which suggested it was a car fridge was that it had very little insulation, so when in the car so tended to be heavy on power consumption.  I enclosed it in a plastic storage box which gave about 50 mm clearance all around which I filled with polystyrene blocks and filled the gaps with expanding foam.  I left the compressor end out of the end of the box for the required air flow.  My wife made a padded cover to better insulate the lid.  This way I reduced the power consumption to where I operated with a single battery and a 55 W panel with careful aiming the panel at the sun and unplugging at night and making sure it ran as much as possible when the sun shone.  Mind you a 100W panel would have been better.  I was stretching the limits.

If you are still looking to buy a suitable type, I suggest you look for a compressor type with plenty of insulation all around, preferably 50 mm or more, and a padded cover.  There are several brands available here in the usual camping and fishing supply houses, but I am sure you will be able to find similar ones.  And obviously the outside dimensions need to fit the space where you intend to keep it.  I found the portable one a good option as it is also easy to take it with you for use in the car for picnics or camping when you are not on board the boat.  The Peltier type Seattledale mentions are also available, but as he mentions the efficiency is not great, so power consumption is high, and compressor fridges tend to perform better.  The very best compressor fridges even have a variable speed compressor which I believe minimises the startup current drawn by the motor.

I hope this helps.

rene460

 
Very thoughtful response.    Thank you.
I am thinking about one of the new well insulated coolers and just put ice in every other day.   Our current fridge and freezer works well.  Just looking for a little bit of auxiliary space!

[rene460]

Hi Chris, for a little extra cool storage space, the moulded polythene cooler boxes with the very thick sides work very well.  The electric fridge I mentioned above broke down one year in our mid summer.  No way to get it fixed at a holiday town in peak holiday season.  With some 35 degree days forecast, I bought one of those polythene boxes expecting to need to put a new ice block every couple of days.  It exceeded all my expectations and the ice lasted several days.  

Here they are called Tropical Cooler boxes, but I notice the camping outlets have a couple of alternative brands these days.  I still have the box some 20 years or more later and it’s great for drinks at parties or to keep the food cool for picnics and so on or keeping the fish catch on ice for the trip home.  They work way better than the cheap ones with only minimal air space instead of insulation, and don’t squeak when you pack it in the car like the polystyrene ones.  Apart from the squeak, all the ones I have ever seen have only about an inch of wall thickness.  They need a good 2 inches to keep ice for more than a few hours on a hot day.

For a useful bit of extra cooler space, the cooler boxes with none of the moving parts of a refrigeration unit are a good simple solution.

rene460

[Chris Meyer]

May 2, 2024 11:52:10 GMT rene460 said:

Hi Chris, for a little extra cool storage space, the moulded polythene cooler boxes with the very thick sides work very well.  The electric fridge I mentioned above broke down one year in our mid summer.  No way to get it fixed at a holiday town in peak holiday season.  With some 35 degree days forecast, I bought one of those polythene boxes expecting to need to put a new ice block every couple of days.  It exceeded all my expectations and the ice lasted several days.  

Here they are called Tropical Cooler boxes, but I notice the camping outlets have a couple of alternative brands these days.  I still have the box some 20 years or more later and it’s great for drinks at parties or to keep the food cool for picnics and so on or keeping the fish catch on ice for the trip home.  They work way better than the cheap ones with only minimal air space instead of insulation, and don’t squeak when you pack it in the car like the polystyrene ones.  Apart from the squeak, all the ones I have ever seen have only about an inch of wall thickness.  They need a good 2 inches to keep ice for more than a few hours on a hot day.

For a useful bit of extra cooler space, the cooler boxes with none of the moving parts of a refrigeration unit are a good simple solution.

rene460

Thank you again for your support.
I have doing some reading about YETI coolers as well as RTIC.    They both seem to hold ice for a long time and no electrical plug in needed!
I have not heard about Tropical Cooler Boxes, but maybe these are not marketed here in the USA.
I have coolers that are very old.  One I bought in college 50 years ago.  Time for an upgrade!
Chris

[MartyB]

My daughter gets 3+ days with her Yeti cooler, even if temps are approaching or over 90F.

I would be really shocked frankly, if a good quality plug in, with the proper fuse etc behind or is that in front of the plug in, could not handle on the plug-in fridges. I had one, now X has it, as she used it to keep things cool in her mini-van for the kids to eat or drink while on day trips etc. I would not think twice about doing this in my 85 Jeanneau. Just have not gotten around to it, as it is not used enough for more than 3 days of floating about normally. Buying ice here and there makes about as much sense as buying a plug-in cooler.

Marty

[Chris Meyer]

May 5, 2024 4:38:09 GMT MartyB said:

My daughter gets 3+ days with her Yeti cooler, even if temps are approaching or over 90F.

I would be really shocked frankly, if a good quality plug in, with the proper fuse etc behind or is that in front of the plug in, could not handle on the plug-in fridges. I had one, now X has it, as she used it to keep things cool in her mini-van for the kids to eat or drink while on day trips etc. I would not think twice about doing this in my 85 Jeanneau. Just have not gotten around to it, as it is not used enough for more than 3 days of floating about normally. Buying ice here and there makes about as much sense as buying a plug-in cooler.

Marty

thank you Marty.

Our coolers are decades old so we are going to upgrade to a Yeti.
Have measured and we know which one fits the best.
Appreciate all the comments.
fewer electronic gadgets are usually better!
Chris