[tincan]

Next month we are taking to the Canal du Midi to meet up with friends for a week on the canal. As I use a CPAP pump for sleep apnoea I am wondering about the best way to get power to the pump. The only power on the boat is a 12volt outlet about 6 meters from our berth. I successfully use a 300 watt inverter in Tincan but with just the short leads on the inverter (600mm)and the pump(1500mm). Question is do I use a 12volt or a 230 volt extension? Which is going to be more efficient? My intent was to wean off the pump before the trip but my weight loss ambition was too optimistic and I just may need it, so I need to figure the best way to so do.

Noel

 

[pippin]

Extend the 240V, there will be less voltage drop than if you use a 12V extension.

 

[sallytrafic]

As a rule the 230V extension option best but how little power does your pump use? It may be too small to matter either way. I am assuming that as you use it at night the voltage will be not much more than 12 volts so 14V charge not a problem for the pump.

 

[RogerAndHeather]

Hi Noel

The simple answer is that you will get less of a volt drop using a 230volt extension lead than with a standard 12 volt one.

The basic rules are - the higher the voltage the less drop (that is why transmission lines are up above 14Kvolts) plus AC, 'travels better' than DC using convenient cable sizes.

Hope this helps without getting technical.

Regards, Roger

 

[tincan]

Thanks for all the replies. 230 volt extension lead to be added to things to pack list. The makers specification advises 300 watt inverter with 500 watt surge, just hope I dont flatten the boat battery as my swimming would not be good enough to power a push start

Noel

 

[Boff]

Hi!

just hope I dont flatten the boat battery as my swimming would not be good enough to power a push start

Don't worry. Boats have, like MHs, separate habitation and starter batteries.

Best Regards,
Gerhard

 

[Damchief]

You will have to use a 240v ext lead. You won't find a suitable 12v one as it would have to carry 40 amp for the 500w surge recommended.

 

[RogerAndHeather]

Hi again Noel

I presume that you have checked what type of 12volt outlet is provided on the boat. 500 watts is a lot of power (as stated 40 amps) and most 12vi outlets are fused between 10 and 15 amps - you would knock them out cold. The cables on most inverters over 150 watts are designed to be connected directly to the battery, so you might need direct access.

It might be worth checking that the storage capacity of the batteries are equal to that on your own motorhome and have means (solar?) of recharging without running the engine. If you need to work out the total power you use during the night then the Mains Power and Monitor from Maplins is a good investment.

Sorry if I'm gibbering a load of rubbish, you've probably covered it all, good luck, Roger

 

[tincan]

Hi again Noel

I presume that you have checked what type of 12volt outlet is provided on the boat. 500 watts is a lot of power (as stated 40 amps) and most 12vi outlets are fused between 10 and 15 amps - you would knock them out cold. The cables on most inverters over 150 watts are designed to be connected directly to the battery, so you might need direct access.

It might be worth checking that the storage capacity of the batteries are equal to that on your own motorhome and have means (solar?) of recharging without running the engine. If you need to work out the total power you use during the night then the Mains Power and Monitor from Maplins is a good investment.

Sorry if I'm gibbering a load of rubbish, you've probably covered it all, good luck, Roger

Nope Roger, I have not checked out fully whats on the boat. I did enquire and was advised that a single 12 volt outlet was positioned next to the steering wheel, I assumed this to be a cigar lighter type but will check further when the boat is back from its present hire on Saturday. If I'm really pushed I can survive without the pump but it also makes life better for everyone else as I dont snore when using the mask. You may well be gibbering but in the absence of a strong repost from some of our leccy types in the forum I bow to your superior knowledge

Noel