Re: [Paddlewise] battery life

Ulli,
I like this idea. How did you connect the batteries in series? Did they all
go in a single line or did you rig them in a bundle? If in a bundle how were
they each connected to the next (I understand series vs paralell). I'm gonna
fabricate one similar to yours.
Sid Taylor
-----Original Message-----
From: Ulli Hoeger <uhoeger_at_is.dal.ca>
To: PaddleWise_at_paddlewise.net <PaddleWise_at_paddlewise.net>
Date: Wednesday, March 14, 2001 1:22 PM
Subject: Re: [Paddlewise] battery life


>>               AA Alk.   2850 MAH = Milliampere Hours.
>>               C Alk.   7800 MAH
>>               D Alk.   15,000 MAH
>
>>To translate what this means, if you put a AA Alk. battery in a
>>circuit that uses 40 milliamperes to operate, the battery will have
>>a useful life of 71.25 hours. At the same rate (40 MA) a D size
>>would run for 375 hours.
>
>OK,
>lets see if I got the theoretical background right.  My rule 500 bilge
>pump draws according to the manufacturer's data sheat 1.9 A.  I
>run it on alkaline AA batteries (8 in line to get up to the 12 V).
>Theory: Based on the math the pump should work for ~1.5 hours
>on those 8 batteries.  2850 mAh/1900mA = 1.5h
>
>Practice: In fact I burned 1 battery set during the last season
>during my rescue practice being to lazy to use the hand pump -I
>carry one as back up.  At the end of the season the pump
>performance went a bit down, i.e. took longer to get the water out
>due to the lower voltage, but still sufficient fast. I never stopped the
>life time of the batteries, but I was already wondering for how longer
> they will last.  Initially I gave them a couple of minutes life and was
>surprised how long they finally lasted.
>Maybe I should mentioned that I use 2 packs of batteries, one
>while doing rescue drills, and another fresh one for real life paddling.
>
>Conclusion:  I will keep my battery solution, in the beginning I was
>looking for other power sources like motocycle batteries and
>rechargable stuff. But since battery life, the costs of AA batteries,
>space and weight are absolutely sufficient and the whole assembly
>fits into my cockpit behind the seat I decided to stick with that
>solution.  Switching to C or D cells (still a good space and weight
>option) are for another reason 2nd choice.. I carry a bunch (~10) of
>spare AA are anyway in my EVAC-bag, since GPS and VHF use
>the same size -advantages if all electronics uses the same battery
>size are obvious.
>A similar size/capacity Atwood pump draws 1.4 A and should
>therefore last for 2 hours on a battery pack.  I think I will get one of
>those for my new boat what is currently under construction (S&G,
>reduced the beam from 25 inch to 22 inch, and reduced the profile
>above the waterline, 2 more weekends and it should be done and I
>will see how tippy it is).
>
>Cheers
>
>Ulli
>
>P.S. The switch, batteries and wiring are in a Nalgene bottle.
>Drilled a hole in the lid to mount the switch and another hole to
>guide the wire to the pump.  Switch outside covered and sealed
>with a rubber cap, waterproofed with Sikaflex and Silicone.
>Connection pump to power unit with a waterproof trailer connector.
>Price tag for the whole construction ~ 50 CAD.   So far after one
>summer no problems with waterproofness and corrosion.
>
>
>(All spelling errors are intentional and are there to show new
>and improved ways of spelling old words.)
>
>Ulli Hoeger
>Dept. Physiology and Biophysics
>Dalhousie University
>Halifax, B3H4H7, Nova Scotia
>Canada
>
>Phone I : 902-494-2673
>Fax: 902-494-1685
>Phone II :902-488-6796
>http://is.dal.ca/~uhoeger
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