jim s 34 Posted January 18, 2018 Share Posted January 18, 2018 Hi all, I've invited a very likeable old salt sailing in the sounds next month but it turns out he has a machine he needs to bring that helps him breathe at night ... i understand it runs constantly at night and draws 3.8 amps at 24 v. our on board capacity wont handle this at all (trailer sailer with car battery and 80w of solar panels) so i'm looking for suggestions as to how i can store enough power to run this thing for 4 nights or so. i don't mind spending a few dollars if for example a couple of fancy lithium batteries will do the job... thanks, jim Quote Link to post Share on other sites
mcp 32 Posted January 18, 2018 Share Posted January 18, 2018 Is it a 24 volt machine or does it have a 240v plug? Quote Link to post Share on other sites
jim s 34 Posted January 18, 2018 Author Share Posted January 18, 2018 It plugs into the mains and has a transformer/rectifier? that then plugs into the actual unit Quote Link to post Share on other sites
mcp 32 Posted January 18, 2018 Share Posted January 18, 2018 Also, how many hours with this device run for? Is the car battery, also the start battery for the yachts motor? There is a motor in your yacht with an alternator? Quote Link to post Share on other sites
jim s 34 Posted January 18, 2018 Author Share Posted January 18, 2018 the breathing assist machine would need to run about 9 hrs per night using 90 odd watts the whole time. The yacht has a pull-start outboard - the car battery normally runs a little waeco fridge and a few other bits but i know i'll need a separate system for this outing. I'm not familiar with the latest in battery technology and am hoping someone can point out a possible solution. Quote Link to post Share on other sites
Fish 0 Posted January 18, 2018 Share Posted January 18, 2018 The only options I could think of is a suitably sized 24 v battery ( and some means of charging it during the day), or a fuel cell. I don't know anything about fuel cells. I'd imagine you'd be hard push to hire one, although it may be possible. An impractical option would be a generator. They make noise and would be difficult to sleep with. And for a temporary job, setting one up so the exhaust fumes aren't a hazard would need some consideration. You could potentially source a 24 v battery big enough to do the trip without charging. In flooded lead acid they would be very big and heavy. In lithium a lot lighter but also much more expensive. I've never heard of anyone with a need to hire batteries, but in this situation you may be able to borrow some off a charitably minded boatie (assuming people have big house batteries in their boats). If only 12 v batteries are available, put them in series and hay presto, 24 v. Tie cables are about $20 from SCA. You'd want two the same type and age of batteries if you are tieing them together though. Not mix and match from different boats. You might be better to investigate the machine some more and see if you can get a 'portable' version with inbuilt batteries. The machines are moderately common, and I know having them portable is a common constraint for the users, so that they can travel in just this example. A mate of mine designed the original nasal mask that goes with them. Quote Link to post Share on other sites
Fish 0 Posted January 18, 2018 Share Posted January 18, 2018 A quick example, 4 x 6v batteries at 220 amp/hr would weight 120kg cost to buy is $1,100 This supplier is Chch based and free delivery. The pricing is good for these batteries (I sussed and brought new over Christmas). You would need about 140 amp / hrs to cover 4 nights (3.8 amps x 9 hrs per night). You shouldn't go past 50 % depth of discharge on FLA batteries but 140 amps out of a 220 Amp / hr battery is 64% so not too bad for a 1 off. This type of battery (FLA) is the cheapest option based on purchase price. Lithium would probably be in the order of $4,000 (substantially more) Note, I'm not entirely sure I have converted amp hrs properly from 12 to 24 v. It is likey other boaties have suitably sized house battery banks (to borrow). You obviously need to install them securely in a water tight space, the main reason for me posting this is for you to understand the weight required, and general capacity for 4 nights without charging. If you took a portable generator to charge during the day, a substantially smaller batter would be required, which could be an option. http://www.caravancamping.co.nz/Our-Products/Motorhome-Caravan-Boat/DEEP-CYCLE-BATTERIES/DEEP-CYCLE-BATTERIES/WET-DEEP-CYCLE-BATTERIES/Crown-Deep-Cycle-Battery-6-volt-220ahr-x-4/ Quote Link to post Share on other sites
jim s 34 Posted January 18, 2018 Author Share Posted January 18, 2018 Thanks Fish - i have thought about the size and weight of lead acid batteries and it isn't really an option for our little boat . the machine itself i understand is about 2.5 k complete with data-logging thats reviewed from time to time so i suspect it could be potential drama if a different machine is used and something unfortunate happens...possibly i may need to consider a base we return to each night that has mains power... Quote Link to post Share on other sites
grant 40 Posted January 18, 2018 Share Posted January 18, 2018 you could find a bach to rent to stay ashore and then day trip from there, we have used these people in the past and had a great holiday http://www.kulakrentahouse.co.nz/ many places will have a jetty or mooring as well 1 Quote Link to post Share on other sites
mcp 32 Posted January 18, 2018 Share Posted January 18, 2018 The easiest solution is to get one of these, get up after a few hours and top up the tank...at 58db it's pretty quiet and likely useful for other adventures. --> https://www.trademe.co.nz/business-farming-industry/industrial/generators-power-supply/petrol/auction-1516551735.htm?rsqid=ac886b8242ae4a91b74ac1538b239977 Maybe buy a 30 meter extension cord and an anchor for the dinghy. Quote Link to post Share on other sites
mcp 32 Posted January 18, 2018 Share Posted January 18, 2018 Note, I'm not entirely sure I have converted amp hrs properly from 12 to 24 v. If you convert to watts it is easy. Voltage x amps = watts. Divide watts by voltage you will apply, to get the correct amps for this new voltage. Quote Link to post Share on other sites
jim s 34 Posted January 18, 2018 Author Share Posted January 18, 2018 Hmmmm mcp thats a bloody good idea - only trouble is i can see a new thread starting in a few weeks time "generator left running in dinghy all night" In actual fact its easy to find an anchorage with no houses or other boaties for miles in the Pelorus 1 Quote Link to post Share on other sites
mcp 32 Posted January 18, 2018 Share Posted January 18, 2018 Hmmmm mcp thats a bloody good idea - only trouble is i can see a new thread starting in a few weeks time "generator left running in dinghy all night" In actual fact its easy to find an anchorage with no houses or other boaties for miles in the Pelorus You will be fine mate. A small generator in a dinghy. Worst case is it will catch on fire and the dinghy will sink and put the fire out. Honestly, that is what I would actually do in your circumstance. It ticks all the boxes and allows for the future. Quote Link to post Share on other sites
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