On most boats the fridge is the biggest continuous electrical load, so marine refrigeration is as much about power as about cooling: a 12- or 24-volt compressor unit, wired with adequate cable and protection, supported by a battery bank and charging that can keep up. We install, rewire and fault-find boat fridges and freezers on board.
When a boat fridge stops cooling, the cause is frequently electrical. Low voltage at the compressor, caused by thin or long cable runs, tired batteries or poor connections, makes the controller cut out to protect itself. The fridge appears dead or struggles to hold temperature, while the refrigerant side is perfectly healthy.
Refrigerant gas work, such as regassing and pipework repairs, requires a refrigeration engineer. We handle the electrics and the system design around the fridge, and will tell you if the problem lies on the gas side.
A compressor fridge cycles on and off, so its daily consumption depends on box insulation, ambient temperature, how often it is opened and what is put in warm. In summer, and with a poorly insulated box, the compressor can run for a large part of the day. That makes the fridge a key figure in any battery bank calculation.
Improving insulation and ventilation around the compressor and condenser often reduces consumption more than any electrical change. We look at both when advising on an upgrade.
Compressor controllers are sensitive to voltage drop. The manufacturer specifies minimum cable sizes for given run lengths, and these are often larger than people expect. We run a dedicated, correctly fused supply from the distribution, use sound marine terminations and check the voltage at the compressor while it is running, not just at rest.
The faults we see most often:
If the fridge is flattening the batteries, the fix may be a bigger or better bank, more charging, or both. LiFePO4 batteries, such as the Fogstar range we supply and fit, hold their voltage well as they discharge, which suits compressor fridges. Solar can offset much of a fridge's daytime use in summer. Victron monitoring shows exactly how much the fridge is taking, which takes the guesswork out of the decision.
Replacing an ageing unit, converting an icebox, or adding a freezer or drinks fridge all come down to the same questions: where the compressor and condenser can breathe, how the cable will run, and whether the battery and charging system has capacity. We work that out before anything is fitted, then install and commission the system.
Our approach is to measure before replacing anything. We check the voltage at the compressor terminals with the unit trying to start, read any fault indication from the controller, confirm the condenser fan runs, and look at the fuse, switch and connections along the supply. Many controllers signal the cause with a flash sequence, which narrows the fault quickly.
Only once the supply is proven good do we look at the compressor or controller itself. If the electrics are sound and the unit still will not cool, that points to the refrigerant side, and we will say so.
No. Refrigerant work needs a refrigeration engineer. We handle the electrical side and diagnosis, and tell you if the gas side is at fault.
Often because battery voltage falls under load once the charger is off. Cable size, battery condition and connections are the usual suspects.
They can. LiFePO4 holds voltage well as it discharges, reducing low-voltage cut-outs, though cabling and charging still need to be right.
Yes, as long as there is space for the compressor and ventilation and the battery system can support the extra load.
Tell us the unit and what it is doing, and we will find out why.