Medical Devices

CPAP Machines

In order to clarify the situation with running critical medical equipment on boats we hope the following will help.

Although the boats have 3 x 110Amp batteries supplying the domestic systems, only approximately 33% is actually usable. This is normal for most battery types in ideal conditions (ie, temperature and age). In the above case this means that there would be approximately 100 Amps of power available providing the batteries were fully charged. Below this battery level, lights will be very dim and motors will either run very slowly or stop completely. THIS WILL INCLUDE THE ELECTRIC FLUSH TOILET. In the case of other sensitive electronic equipment these will probably stop working and may be damaged.

In the case of portable CPAP machines, we have been informed that these units draw approximately 25 Watts which equals just over 2 Amps on a 12 Volt system. This would in theory give you 50 hours of usage but when you add in the other electrical appliances on the boat all using the same battery supply (each light approx 2 Amp, TV approx 4 Amp, water pump approx 10 Amp, shower pump approx 8 Amp, Refrigerator etc. – albeit not all running continuously, etc) the available power supply drops dramatically. As you can see, the more lights that are on, the longer the TV is on and the more often the fridge door is opened will all have an effect on the available power. As we have no control over how this equipment is used, it does mean that we cannot guarantee critical equipment being able to work for extended periods once the boat engine is switched off and no longer recharging the boat batteries.

The only way to be absolutely sure of a CPAP working correctly overnight is to have a Portable CPAP Battery Pack.

This should be able to be recharged via the boats 240 Volt system when the engine is running, in fact the CPAP will run similarly, it is only when the engine is switched off that the potential problem arises. We say "should", because it depends on the electronics in your your charger; please be aware that the inverter that converts the boats 12v battery system to the 240 Volt supply is a Modified Sine Wave (sometimes called Quasi Sine Wave) type and may not work with your specific charger. You should check with your equipment supplier that it will work with this type of inverter.

I hope that this helps in understanding why we cannot guarantee a continuous supply of 240 volt electricity over extended periods when the boat engine is not running. We cannot be responsible for any loss of available power and any life threatening condition that requires a CPAP machine. In our opinion it MUST have it’s own backup power supply.

Napton Narrowboats

4th October 2024