Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rating: Thread Rating: 10 votes, 5.00 average. Display Modes
Old 01-06-2013, 16:12   #1
Registered User

Join Date: Nov 2012
Location: Jupiter, FL, USA
Boat: Seidelmann 37
Posts: 31
SCUBA tank to drive a batt charger motor

I have a (3000 psi) SCUBA tank, primarily for pleasure and/or bottom-work. I wonder if I could use this as an energy source to drive an alternator/charger, for the (hopefully never-occurring) event when I have dead batteries that will not start my diesel engine. I assume (?) that a full/near-full tank could run a small motor (alternator/charger) quite awhile, long enough to adequately charge a engine-starting battery.

There are many pneumatic tools on the market, but I would like to find/build a pneumatic (SCUBA-driven, ~150 psi available) generator/alternator (not sure proper name). Aside from my diving regulator, I have an old "1st stage" regulator that has an output hose that can deliver the 150psi to whatever.

Any of the experts out there have insights into this? I've done a fair amount of googling, but can't come up with anything useful.... Especially if it has not been done by others, this may be cost-prohibitive, but it would be great if there's something simple/useful out there. Thanks.
ephyraboater is offline   Reply With Quote
Old 01-06-2013, 16:18   #2
Registered User
 
Teknav's Avatar

Join Date: Jul 2012
Location: Texas - USA
Boat: Twin Otter de Havilland Floatplane
Posts: 1,838
Re: SCUBA tank to drive a batt charger motor

Use the SCUBA tank for diving ONLY. These air tanks were not designed to be used in anything else.
Mauritz <PADI Dive Master>
Teknav is offline   Reply With Quote
Old 01-06-2013, 16:27   #3
Registered User
 
Therapy's Avatar

Join Date: Jul 2007
Location: W Florida
Boat: Still have the 33yo Jon boat. But now a CATAMARAN. Nice little 18' Bay Cat.
Posts: 7,086
Images: 4
Re: SCUBA tank to drive a batt charger motor

having trouble with the image............

I am sure it could be done but you may have to build something.

great idea.

I cannot for the life of me take a image I find on the net and get it in here.
Therapy is offline   Reply With Quote
Old 01-06-2013, 16:28   #4
Registered User

Join Date: Nov 2012
Location: Jupiter, FL, USA
Boat: Seidelmann 37
Posts: 31
Re: SCUBA tank to drive a batt charger motor

Thanks for expressing your safety concern. However, the tank doesn't care where the air is delivered - absolutely zero impact on the SCUBA tank (unless it's bled too quickly w/ subsequent temperature-induced condensation on outside - but not gonna happen here). If anything, use of a SCUBA tank to drive pneumatic "tools" is an expensive way to go!
ephyraboater is offline   Reply With Quote
Old 01-06-2013, 16:30   #5
Registered User

Join Date: Feb 2013
Location: Oregon
Boat: Seafarer36c
Posts: 5,563
Re: SCUBA tank to drive a batt charger motor

Air motors don't seem very efficient and I don't think you would get much run time out of 1 fill. Plus when you factor filling the air tank up I think it would be a looser.
An air tank is an air tank so why would it make a difference what it was made for?
model 10 is offline   Reply With Quote
Old 01-06-2013, 16:32   #6
Registered User

Join Date: Sep 2009
Location: on board, Australia
Boat: 11meter Power catamaran
Posts: 3,648
Images: 3
Re: SCUBA tank to drive a batt charger motor

as there not an Indian car designed to run on compressed air. Try google.
downunder is offline   Reply With Quote
Old 01-06-2013, 16:35   #7
Registered User
 
Therapy's Avatar

Join Date: Jul 2007
Location: W Florida
Boat: Still have the 33yo Jon boat. But now a CATAMARAN. Nice little 18' Bay Cat.
Posts: 7,086
Images: 4
Re: SCUBA tank to drive a batt charger motor

Forget Electric Cars, This One Runs on Compressed Air - John Metcalfe - The Atlantic Cities

I want one of them.
Forget Electric Cars, This One Runs on Compressed Air - John Metcalfe - The Atlantic Cities
__________________
Who knows what is next.
Therapy is offline   Reply With Quote
Old 01-06-2013, 16:54   #8
Registered User
 
Capt.Alex's Avatar

Join Date: Jan 2013
Location: St. George's, Grenada
Boat: Nordhavn 50
Posts: 315
Re: SCUBA tank to drive a batt charger motor

An 80 CuFt scuba tank only lasts me about an hour while taking a breath every few seconds. I would guess that it would be empty in a matter of a few minutes trying to operate some sort of pneumatic generator. My little DA sander needs an amazingly large volume of air to run, I would think at least as much as a generator contraption. I don't think you would get much a charge before you run out of air. Of course I have been known to be wrong once in a while too....
Capt.Alex is offline   Reply With Quote
Old 01-06-2013, 16:59   #9
Moderator Emeritus
 
capngeo's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Key West & Sarasota
Boat: Cal 28 "Happy Days"
Posts: 4,210
Images: 12
Send a message via Yahoo to capngeo Send a message via Skype™ to capngeo
Re: SCUBA tank to drive a batt charger motor

A standard full tank has 80 cu ft... if your motor used 10cfm, you have 8 minutes; not much charge there. A more efficient use would be an air starter..... or carry a small Honda genny!!!!
__________________
Any fool with a big enough checkbook can BUY a boat; it takes a SPECIAL type of fool to build his own! -Capngeo
capngeo is offline   Reply With Quote
Old 01-06-2013, 17:35   #10
Registered User

Join Date: Nov 2012
Location: Jupiter, FL, USA
Boat: Seidelmann 37
Posts: 31
Re: SCUBA tank to drive a batt charger motor

I hear you, capngeo and Capt.Alex. My assumption that I could run a small alternator-type motor from one tank is fundamental. There are multiple unknowns (to me), but some sanders (using 90psi input) state that they run on ~2 cfm (I don't use air tools, so not sure of the importance of specs relating to 15-second vs full-load runtime, effect of input pressure, etc).

An 80 cuft tank could supply about 40 minutes of run-time if I assume the alternator/generator consumes about 2 cfm; BUT I have no idea what the friction/load requirements are of an alternator/generator, i.e., whether 2 cfm is anywhere in ballpark. Nor whether that time could charge a dead/near-dead battery enough to just-barely-crank my diesel (& glow-plugs)!

Sounds like the physics may(?) mean that no-one bothers with any consumer-product. Just a crazy-idea of mine I guess.

Nevertheless, I'd love to hear from others regarding the feasibility - I could get a second SCUBA tank ($80 used) if things were marginal - then I would also not be w/o a tank for actual diving.... ;-)
ephyraboater is offline   Reply With Quote
Old 01-06-2013, 17:58   #11
Registered User

Join Date: Dec 2008
Location: ontario canada
Boat: grampian 26
Posts: 1,743
Re: SCUBA tank to drive a batt charger motor

You would be further head configuring your engine to start on the compressed air stored in the Scuba tank.
perchance is offline   Reply With Quote
Old 01-06-2013, 18:00   #12
Registered User
 
resilientg's Avatar

Join Date: Jul 2012
Location: Townsville, Qld, Australia
Boat: William Bollard, Gypsy Wave, 28'
Posts: 144
Re: SCUBA tank to drive a batt charger motor

As most trucks and heavy equipment start their engines on compressed air starters, is that not a better alternative than trying to charge a battery to do the same thing?

Yes if you wanted to make an air powered battery charger for some other purpose i can understand but it all you want to do is to start your motor, maybe look in a truck wreckers and save yourself some headache.

Plus you would still have most of your scuba tank full for diving.

Matthew
__________________
Do but once what others say you cant, and you will never be judged by their limitations again.
resilientg is offline   Reply With Quote
Old 01-06-2013, 18:57   #13
Registered User

Join Date: Feb 2013
Location: Oregon
Boat: Seafarer36c
Posts: 5,563
Re: SCUBA tank to drive a batt charger motor

A truck starter would use up a tank of air in just a few minutes. Where would you get the compressed air anyway? Sitting in an anchorage listening to a gas powered scuba compressor run for an hour makes me think this is not a sound idea.
model 10 is offline   Reply With Quote
Old 01-06-2013, 18:58   #14
Jd1
Registered User

Join Date: Aug 2011
Location: Victoria, BC
Boat: Catalina 36 MKII
Posts: 1,108
Re: SCUBA tank to drive a batt charger motor

I think the best option is to just buy a second battery. Isolate it so that it charges when the house battery is full but doesn't deplete with the house battery and if you need it you have MUCH more energy available than trying to generate electricity from compressed air.
As a side story, I have a small diesel motor that I start with compressed air / air motor. The air motor is rated at about 4 hp and sucks down a 60 gallon 125 PSI tank in no time flat. The motor can only handle about 100 PSI but needs a huge amount of air. I use a 1/2" hose to feed it but should really be using a 3/4" hose for best use of the available air. I would think that a big issue would be the regulator freezing up as you try to go from 3000 PSI to 100 PSI - 80 cu ft used up in something like 30 seconds or less.
Ok, looked it up, my Gast motor uses 128 CFM at top speed !!!!
Jd1 is offline   Reply With Quote
Old 01-06-2013, 19:27   #15
Registered User

Join Date: Oct 2005
Location: Cruising NC, FL, Bahamas, TCI & VIs
Boat: 1964 Pearson Ariel 'Faith' / Pearson 424, sv Emerald Tide
Posts: 1,531
Re: SCUBA tank to drive a batt charger motor

Yes, a second battery or maybe a solar panel... You will not get far on turning an alternator with a scuba tank...

... Do you have a dedicated start battery with a switch?
s/v 'Faith' is offline   Reply With Quote
Reply

Tags
charger, motor, scuba

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Advertise Here


All times are GMT -7. The time now is 11:41.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.