Waeco B40

[Bro]

Has anyone experience of the Waeco B40 they would like to share? in particular how much juice it uses when running on 240V.

[Tony Brooks]

From the manual on http://td.dometicgroup.com/_pdf/b40-b-15s-01.pdf

 

47 watts on DC so say 4 amps,

65 watts on AC so say a draw of 7 amps from 12V batteries when on an inverter.

 

The mains compressor appears to be thermostatically controlled so say about 84 Ah per day

 

The DC is almost certainly a Peltier device and the manual makes no mention of a thermostat so assume 4 amps for 24 hours = 96 Ah per day. This could be reduced by turning off at night BUT how fast it will cool a full load of food is open to question so it may need leaving on 24/7.

 

A typical 12V compressor fridge uses maybe 40 to 50Ah per day. An A++ mains fridge plus inverter probably similar.

 

The B40 will gain a little by being top loading so the cold air stays inside.

[Alan de Enfield]

Probably of no use, but, maybe useful for a comparison :

 

I have a Waeco CR80 (78 litres fridge with 8 litre ice-box)

12v

With a thermostat

Fridge at 5^o C on thermostat setting 2

Runs approximately 18-20 minutes per hour (less at night)

Rated at continuous consumption of 40w

Actual usage approximately 1.1 amps (25Ah per day)

Cost £550 - £600

 

From the manual :

 

Intended use : The refrigerator is suitable for cooling and freezing foodstuffs. The appliance is also suitable for use on boats.

 

When used on boats the refrigerator can be subjected to a constant inclination of 30°.

 

You can use the continuously variable thermostat to set the desired temperature.

 

Installation : If the cable run is up to 4 metres use at least 8mm² cable. and for 8mt run a minimum of 12mm².

[Bro]

From the manual on http://td.dometicgroup.com/_pdf/b40-b-15s-01.pdf

 

47 watts on DC so say 4 amps,

65 watts on AC so say a draw of 7 amps from 12V batteries when on an inverter.

 

The mains compressor appears to be thermostatically controlled so say about 84 Ah per day

 

The DC is almost certainly a Peltier device and the manual makes no mention of a thermostat so assume 4 amps for 24 hours = 96 Ah per day. This could be reduced by turning off at night BUT how fast it will cool a full load of food is open to question so it may need leaving on 24/7.

 

A typical 12V compressor fridge uses maybe 40 to 50Ah per day. An A++ mains fridge plus inverter probably similar.

 

The B40 will gain a little by being top loading so the cold air stays inside.

 

I am confused.

 

Take for example figures for the 240V unit. The manual says 65W (as you say Tony) but of course it is not running all the time so let's suppose it runs it runs for 1/3rd the time ie. 8hrs /day. Would it not then use in a day just 8x65 = 520W(approx.) and 520/12 = 43A (approx.) per day not 84 you suggest?

 

More confusing even, to me, is manual statement saying annual consumption is 99Kw. Now if we divide that by 352 days in the year it equates to 280W per day which equals 280/12 = 23A per day.

 

I am simple numpty not electric and shall be grateful if someone will sort this out for me. Is the take from battery roughly 84A, 43A or 23A per day? Please keep answers simple and in round numbers.

[CaneyJ]

Whilst I agree what the B40 would probably draw high amps using its 12V Peltier [which would unlikely have any form of thermostat control]; I think it would draw a lot less than 84-Amps a day using its AC compressor and an Inverter.

 

The only reason the B40 has a 12V peltier is to just maintain the fridges temperature for a short time whilst it is sat inside a motorhome or caravan when driving between home [where is will be connected to the mains to bring it down to temperature initially] and its destination camp site which would most likely have a hook-up.

 

It’s not designed to run 24/7 on the peltier alone. Its cabinet is too large compared to the tiny 48-Watt peltier plate which is meant to run little 5-Litre coke can fridges and nothing more.

 

My 32L equivalently sized LEC freezer has a sticker that specs the compressor to 60-Watts but I’ve found this to be a conservative estimate and measured it to actually be running at 52-Watts average.

 

The insulation on the B40 is of a similar thickness to my counter-top freezer [minus the lid which would explain why it’s only rated as a 3-Star -15°C freezer].

 

Your calculations of 7-Amps an hour I assume is based on an Inverter with a 12V conversion efficiency of 80%?

 

Let’s assume the compressor does indeed run at 65-Watts. A conversion to 12V at 80% is 6.5Amps. I assume the slack is made up with an Inverter standby of 0.5Amp per hour to get 7A?

 

Your calculation of 84-Amps assumes the Fridge would need to be running for 30-mins or 50% of an hour for 24-Hours? Even the worst fridges don’t run this often on its compressor or it would burn out.

 

Here is a closer estimate on running a B40 when set at 5°C. Based off my 32L LEC freezer as it has a similar cabinet size and insulation grade; I reckon it would only run for 12-minutes every hour in perhaps 2x 6-minute compressor cycles.

 

I also think the conservative figure on the compressor puts it closer to an actual running wattage of 58-Watts.

 

At a 20% Inverter conversion loss; this would draw 70-Watts or 5.8Amps at the battery. At 12-Mins an hour, that means 5.8[Amps] / 5[th of an hour] = 1.16AH.

 

That puts the B40 fridges consumption at a more realistic demand of 28-Amps per day [+ 12AH Inverter Idle].

 

The inverter idle however can be solved by using a temperature controlled relay to switch the inverter on and off with fridge demand so 28-Amps is all you’re going to draw [+ cable losses?].

 

The same principle could be applied to a better suited domestic freezer to run as a fridge only costing £100. There is no reason to use a Waeco B40 on a boat. Dedicated Freezers are often designed to run in out-buildings and garages with similar conditions to unoccupied boats.

 

The added benefit here is that even with a worst case consumption of 30-35 Amps per day running an AC freezer [as a fridge]; the combined outlay for an 80L freezer and Inverter can be just £250 whilst a Waeco CR80 costs over double that.

[Tony Brooks]

This all depends upon how ready you are to rise damaging your batteries by excessively discharges. I assume a fridge will run for 12 hours a day, some may run more and some may run less. I never take a makers (marketers) blurb as gospel. It seem generally accepted that for mains powered equipment fed via an inverter dividing the power (watts) by 10 to allow for an 80% inverter efficiency (remember it will be drawing power when the thermostat has turned the fridge off).

 

So 65W/10 = 6.5 amps. 6.5 amps X 12 = 78Ah. I rounded the 6.5 up to 7 giving 7 x 12 = 84.

 

It is far better to over estimate electrical consumption than to underestimate it. You will note that we are not given the ambient temperature data for the manufacturer's test. You can bet it was one that suited them, not the 70 degrees plus you can get inside a narrowboat on a hot summers day!

 

Did the yearly figure test include any allowances for cooling food as and when it is placed in the unit or was it calculated from the consumption? However it was done I am cynical enough to believe it is not far short of a lie made for marketing purposes.

[bizzard]

If Waeco took all their fridges to the North or South Pole or even to the Smithfield meat markets deep freeze to test and procure the consumption figures they could honestly say that ''Our fridges are incredible they use no power at all''. They wouldn't even have to plug em in there to find out, but I suppose they'd have to, to do it honestly.

Edited October 8, 2015 by bizzard

[Tony Brooks]

If Waeco took all their fridges to the North or South Pole or even to the Smithfield meat markets deep freeze to test and procure the consumption figures they could honestly say that ''Our fridges are incredible they use no power at all''. They wouldn't even have to plug em in there to find out, but I suppose they'd have to, to do it honestly.

 

Yes, honestly - like a certain car maker!