Re: [Paddlewise] Electric Pumps ??

I looked at the referenced guidebook.  I don't think there is an
inconsistency between the experience of the many PW readers who use gel cell
batteries and the guidebook.  The guidebook is concerned about continuous
discharge for a one hour period, pumping out a kayak is a 2.3 to 6 minute
discharge with hopefully a long rest period until the next use.

The exception to the long rest period I have experienced is when I am
practicing rolling, bracing and rescues.  To date I have not had a battery
fail due to excessive rate of discharge.  I don't doubt that my 2.2 AH
battery will fail eventually and that it will fail sooner that it would if
the discharge were at a lower rate.  Again there is a trade off here.
Larger batteries are heavier, bulkier and initially more expensive.

FWIW, and although I don't recommend it, I also tried a 1.2 AH battery with
a 3 amp draw.  The trial was during a practice session so the battery got a
workout.  The battery did not fail.  If it had failed I would have used my
backup manual pump.

Dana Dickson 


 > -----Original Message-----
 > From: owner-paddlewise_at_paddlewise.net
 > 
 > Date: Wed, 13 Mar 2002 12:39:05 -0500
 > From: "Michael Daly" <michaeldaly_at_rogers.com>
 > Subject: Re: [Paddlewise] Electric Pumps ??
 > 
 > From: "Gerald Maroske" <gum_at_exmail.de>
 > 
 > > Doubling amps can mean that your battery pack cannot 
 > provide enough 
 > > current. Normal PANASONIC NiCD 2,2Ah cells failed when 
 > currents of 4,5 A 
 > > were needed in my tests. [...]
 > > 
 > > When those are used and your pump requires 12V here is the 
 > next problem. 
 > > If you charge/recharge those cells, each cell has a 
 > slightly different 
 > > capacity which may result in HALF of the given Ahs after several 
 > > load/reload cycles.
 > 
 > When investigating sealed lead acid and AGM cells for use in 
 > a pump, I 
 > stumbled on this web page (it's a pdf document):
 > 
 > http://www.stagewireless.com/PDFs/Battery_Selection_and_Maint
 > enance_Guidebook.pdf
 > 
 > It is intended for the theatre and music business, but the 
 > battery info seems
 > good in general.  It explains what Gerald has experienced - 
 > that batteries 
 > have a discharge rate limit (no more than twice the amp-hour 
 > rating) and
 > rules on charging, discharging etc.  Since I'm not an 
 > expert, I can't vouch
 > for the accuracy, but it seems reasonable and is easy to 
 > understand.  It
 > made me realize I needed a bigger battery than I initially thought.
 > 
 > Mike
 > (Now if I could only find a local source for such batteries...)
 > 
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