Running a fridge of an invertor

ZootHornRollo

I've looked into them before but it was years ago. Unless much has cbanged they tend to be very small and the larger ones tend to be a chest style which wouldn't be practical.

Gloomendoom

ZootHornRollo wrote: »

I've looked into them before but it was years ago. Unless much has cbanged they tend to be very small and the larger ones tend to be a chest style which wouldn't be practical.

Larger ones are available. My sister-in-law lives totally off grid and had six foot upright versions. From memory, they were well over £1k each though.

She has since swapped them for standard electric compressor types that run from batteries via an inverter. However, the battery bank fills up half a shipping container and is fed from a fairly large solar set up.

forgotmyname

Inverters are not very efficient. It may state 80% but that will be at a fairly precise power input/output. Outside that range it could be just 60% efficient.

Also as stated they dont like high current startup items. I have a 600W inverter that wont even run a small electric staple gun. The stapler requires instant power where the inverter requires a startup period to get to the correct voltage.

250W fridge at 12 volts will be over 20amps running for approx 8 hours = 160amps. Using a lead acid battery = double that unless you want to replace batteries every few months. SO an excess of 320Ah batteries.

So your looking at 4 x 100Ah decent quality leisure batteries just for 8 hours worth of power. If you choose cheaper brands then you may need double that. I purchased a budget green one from the camping shop, supposedly 100Ah. Yet its real capacity was less than that of a 42Ah car battery.

Your best option are deep cycle batteries, but decent ones are even dearer.

Fill the freezer with as many ice packs as you can and bring the food from home each day. That way when you start the generator it should still be below zero.

May help to add extra insulation to it.

Gloomendoom

A firm called Rose make reasonably priced wet cell deep cycle batteries.

Would agree with what has been said about leisure batteries as I have made the same mistake. They won't last long if deep cycled. If there is a starting current given in the specs, they are very unlikely to be true deep cycle batteries.

Another thing you have to watch with inverters is voltage drop. When I turn on the toaster in our caravan, admittedly a high load, the voltage drops from 240v to around 195. Some units are better at compensating for this than others.

psychic_teabag

Perhaps a stupid question, but rather than putting the DC through an inverter to drive an AC compressor, is it possible to get a DC-powered freezer ? (or even just replace the compressor in your existing freezer with a DC one ?)

ZootHornRollo

As already pointed out, fridges and freezers don't run constantly. I suspect the best way forward here may be to get a meter, as suggested, to monitor the actual power usage of the fridge and freezer in their real life operation and get a more accurate figure.

Another solution for me may be a small fridge van that I could run back and forth with?
Part of the problem I am trying to solve is also to do with recruitment. Anyone who passed their driving test after 1997 needs to sit a separate test to tow my trailer. Whilst this only costs around £350 I have done it twice only for said employee to leave a couple of months later.
A fridge van could be driven on a standard license making it easy to recruit people who can open up the business without my presence.

forgotmyname

One of my inverters only puts out 160volts under load.

Correct they don't run constantly, but the startup current can be a lot and even 250watts = over 20amps @ 12volts. A fairly decent 100Ah leisure battery will be fairly dead with just 3 hours use (motor running). Below the charge point to keep the battery healthy and have a long life.

that

batteries + cold weather does often not equal maximum a/h charge and long running times. it may lead to duff (possibly broken - if it get cold enough) battries too