12 volt Fridge power consumption!!!

[Mark M]

Hi Guys

I am wondering how long my fridge should run before it flattens my battery

I have a old 12 volt Electrolux fridge in the boat that I purchased last year, and have never used the fridge up to now.
Its fed from a new house battery which is rated at 120 Amp Hours, but the fridge flattens the battery within approx 10 hours if the engine is not running and charging the battery.
I did measure the current to the fridge on a multimeter and it was drawing approx 5 amps when first switched on, so i thought I would at leat get 20 hours use from it.

How long does you guys fridge run before flattening the battery?, or can you recommend a good efficient fridge

Cheers

 

[boatone]

Its fed from a new house battery which is rated at 120 Amp Hours, but the fridge flattens the battery within approx 10 hours if the engine is not running and charging the battery.
I did measure the current to the fridge on a multimeter and it was drawing approx 5 amps when first switched on, so i thought I would at leat get 20 hours use from it.

Heavy drain fridge and inadequate battery capacity I'm afraid.

The following is an explanation I gave earlier on here:

Also, many people fail to recognise that 110Ah doesn't mean that is what you get! In fact, in a well managed battery setup you should only assume useable power of about 1/3rd actual stated capacity so my 4 x 110Ah = 440Ah actually gives me about 150Ah 'sweet' battery power without pushing the batteries too far. Reason for this is that even in a well managed charging routine pushing the charged level up above 85% is difficult and letting them discharge below 50% is best avoided on a regular basis so we get to use 35% (85-50) with confidence.

On our boat this 150Ah is enough to stay somewhere for up to 3 days without need to run engines, generators or shore power and we run an electric fridge 24/7 as well as computer/TV/cabin lights/hifi etc etc. I can even run a complete music setup with 300watt+ PA system for several hours using the boat 12v supply thru a 240v inverter.

My alternator is not huge - about 50A I think - but it copes quite happily You do need to make sure the charge cable from alternator to battery is man enough for the job. If it is too small it will offer high resistance and severely restrict charging.

The only 'battery' management I employ is this simple approach to battery capacity. I worked out that I needed 50Ah per 24 hours to run all electrics generally in use and then installed the 4 x 110Ah's to make sure I got it.

I would suggest beefing up your battery bank for the domestics because, even if you get a more efficient fridge it is likely to draw about 4 Amps when running.

Your 120AH battery is really only going to supply about 40AH of sweet power and your recharging regime will be critical as well.

 

[Dave_Seager]

The old Electrolux 3-way refrigerators (230v, 12v, gas) are totally unsuitable for use on boats.

They used to be popular when they could be run on gas but the new safety regulations now make that almost impossible. I am not knocking the BSS on this point as I experienced a fire on a boat caused by such a refrigerator.

When running on 12v there is no thermostat and they draw 8 amps. continuously. If you track down the original instructions, they clearly state that they are not intended to run on 12v unless the engine is running to maintain the charge. They also state that they are not recommended for boats and if installed on a boat the guarantee would not apply.

The only practical option is to fit a refrigerator with a compressor and thermostat designed to run on 12v. Our boat had an Electrolux fitted when we bought her which flattened 3 110Ah batteries in a single afternoon and evening. I replaced it with an Isotherm which only draws 2.7A when it is running and, because of the thermostat, only 0.6A average.

 

[joejo]

12 volt fridge

I had exactly the same problem, about 10 hours max, and fitted an Isotherm Cruise 49 with ASU. The ASU bit means it has a capacitor that charges up either when under engine power or shore power. When you stop you switch over to ASU mode and it takes the stored power with minimal drain on your batteries. Mine has worked really well, never had a drained battery, and even in hot conditions the fridge is nice and cool. Have had mine on over 24 hours with no external power and works a treat. If you Google Isotherm Cruise 49 ASU you will get a better explanation from their web site.
They do come in a range of sizes but in my opinion it is worth paying the extra for the ASU bit which is the key to low battey drain.
In true marine style they are fairly expensive

 

[miket]

Isotherm

I endorse the Isotherm thoughts.

 

[boatone]

Whatever the type of fridge, one 120AH domestic battery is still not enough for good battery life/performance if running a fridge 24/7 as well as other stuff. There's nothing worse than wondering if the battery is going to hold up.

By all means get a new fridge - I think you should and the Isotherms are good - but IMHO you should still beef up your battery capacity.

 

[Tom Price]

12V boat fridges

Both Isotherm and Waeco brands incorporate Danfoss compressors resulting in power consumption of only 0.6 A average, 2.7A max. Not cheap but worth it!

 

[Mark M]

Cheers guys

I am going to add a few batteries into the bank as well, but the
Isotherm Cruise 49 ASU fridges sound a good idea as well, as we dont have AC power at our mooring, we are relying on the alternators to do all the charging, so the lowest power consumption fridge sound pretty efficient

Thanks again for all the input

 

[DWT]

Fridges and gas

I am confused about the current position with gas and the BSS? A previous owner of my boat had the gas fridge disconnected, presumably to get through the examination, which meant I had the same problems as others running it off the battery. Following a chat with the engineer I use for my boat (he is also a BSS examiner) he told me the rules on gas have changed and he was happy to reconnect the fridge to the gas.

I assume their are rules about ventilation and flues which must be complied with, but I don't think there is anything unusual about my boat which means a gas fridge will comply with the regulations where other boats will not.

As a result I never need to use the battery option, either gas when away from shorepower or mains when in the marina. This was a much cheaper option than buying a new fridge.

 

[Dave_Seager]

It appears that the BSS rules regarding LPG refrigerators have been relaxed. I have a copy of the BSS Guide from January 2002 which states that almost all gas appliances apart from cookers must be room-sealed. This effectively banned most gas water heaters and refrigerators that had previously been common in boats.

The current version of the BSS Guide only seems to require room-sealing for gas refrigerators in boats with petrol propulsion. Water heaters seem to be permitted without room-sealing regardless of the fuel used for propulsion.

This is only my interpretation of the rules and I would speak to a boat safety examiner before changing any gas appliances on my boat.

 

[Mark M]

Thats interesting

Gas would be good as an option during the day (with a gas leakage alarm fitted as back up) then i could switch it over to battery at night, this would solve a lot of my battery consumption problems,
I dont like using gas on the boat but if its only used during the day with a back up of an alarm, it should be ok, but well worth checking with a BSS Boat Safety Examiner

 

[apollo]

Thats interesting

Gas would be good as an option during the day (with a gas leakage alarm fitted as back up) then i could switch it over to battery at night, this would solve a lot of my battery consumption problems,
I dont like using gas on the boat but if its only used during the day with a back up of an alarm, it should be ok, but well worth checking with a BSS Boat Safety Examiner

i have found after running the fridge on mains, that you have to let it settle a bit before you can put the gas on. Otherwise doesnt seem to work?

...or maybe my fridge is duff...

 

[DogsBody]

Our previous boat had a gas fridge which I used to run on gas all the time, even for trips down to the Medway / London.

I do vaguely recall reading something in the manual about not running it on gas if it has been moved / shaken around recently but it always seemed to work ok, although did seem to take longer to cool down than the electric one on our current boat does.

 

[Mark M]

Cheers Guys

I think as I have no shore power my best option is to buy a new fridge as i wouldnt trust the old electrolux 3 way fridge on gas, and use the new fridge during the day on gas and on battery at night time as I dont like the idea of gas appliances running when we are sleeping.

The 12 v isotherm fridge looks great but unfortunately the budget might not strech that far!!!

Thanks everyone for all the input

 

[macanante]

We recently came across an A'vanner with problems getting his Electrolux fridge to run cold enough when on the move. On closer inspection we found he was running his fridge from the 12 volt accessory socket in the back of his 4WD. His auto electrician suggested this and made up the lead! We were horrified! It is absolutely essential to wire fridges in separately using 6 mm wires with fuse/self reset overload to another outlet straight from the battery, both positive and negative. This is to prevent voltage drop. If the standard wiring is too small, instead of getting a full 12.8–13.2 V or more to the outlet, you may only get 11–11.5 V. In Engel 12 volt motor driven type fridges this causes them to run inefficiently and even burn out from running under voltage. Voltage drop is probably the biggest cause of portable fridge problems followed closely by outback caravan parks running their own diesel generators, sometimes causing voltage spikes.

 

[Momac]

Our one ordinary 110Ah leisure battery easily deals with the fridge for a 24 hour stop over.

 

[Mistroma]

True that a new well charged 110Ah would cope with an efficient fridge over 24 hours.

It all depends on actual battery capacity & power consumption.

Starting at % charge level below and dropping to 50% charge you get:

% Charge Capacity Ah
95 55
90 50
85 44

My own fridge uses about 6A when running but has a duty cyle of around 25% (Scottish summer). So daily usage is 6 x 0.25 x 24 = 36

So OK if weekending and on shorepower in between. 95% > 50% leaves 19Ah spare on 1st day.

Without shorepower you'd be close 85% > 50% leaves 8Ah spare on 1st day.

As soon as you factor in other loads you can see that 105Ah won't really cut it unless you are very frugal, mainly use shorepower and do limited cruising.

It sounds as if the OPs fridge isn't as efficient as your installation.

 

[Momac]

The battery certainly needs to be in good health.
The present battery has had two seasons use. The previous leisure battery was somewhat tired (despite tests suggesting it was fine) and it struggled with an overnight stay.

 

[watson1959]

We recently came across an A'vanner with problems getting his Electrolux fridge to run cold enough when on the move. On closer inspection we found he was running his fridge from the 12 volt accessory socket in the back of his 4WD. His auto electrician suggested this and made up the lead! We were horrified! It is absolutely essential to wire fridges in separately using 6 mm wires with fuse/self reset overload to another outlet straight from the battery, both positive and negative. This is to prevent voltage drop. If the standard wiring is too small, instead of getting a full 12.8–13.2 V or more to the outlet, you may only get 11–11.5 V. In Engel 12 volt motor driven type fridges this causes them to run inefficiently and even burn out from running under voltage. Voltage drop is probably the biggest cause of portable fridge problems followed closely by outback caravan parks running their own diesel generators, sometimes causing voltage spikes.

Welcome! Just Surprised that your first post replies to one from 2 yrs ago.....come and say hello!

 

[oldgit]

We have two 120amp leisure batteries on board,this gives us about 24 hours of average use on our boat.
Fridge/lights/TV/radio/hair dryer etc etc etc etc.
As mentioned elsewhere,normally we turn off fridge last thing at night and power it up during day.
Unless its really really hot and vital v. important supplies to keep one sane needs to kept cool...............like wine and beer.