Re: (ET) Battery help needed

["David Roden (Akron OH USA)" <roden ald net>]

On 6 Jan 2003 at 9:26, SteveS wrote:

> The golf cart batteries are built for
> deep discharge - automotive batteries are not, and will not perform well 
> over
> the long haul. Marine batteries are somewhere in between, but I get the 
> sense
> they are more like automative than golf cart.

You got it.  An automotive starting battery (the industry term is SLI, for 
"starting, lighting, ignition") is designed to have maybe 5-10% of its 
capacity used to start the vehicle, and then be immediately recharged.  In 
a 
cyclic application an SLI battery will be good for between 20 and 50 
cycles, 
depending on how deep they are.

Marine batteries vary.  The ones that claim to be combination deep-cycle 
and 
starting batteries are almost 100% the latter and worthless for our use.  
(Usually, if the battery specs state cranking amps instead of reserve 
capacity, walk away -- those are not suitable for cyclic applications.)

Others, such as the Trojan 27TMH and US Battery 27TMX, are true deep cycle 
batteries.  But they don't have the same plate design as the golf car 
batteries.  Cycle life is rated at 250-300, compared to the 450-750 cycles 
you can expect from a good golf car battery.

Golf car batteries are intended for loads of around 75 amps average.  
Marine 
batteries are meant for powering trollling motors, which means they like 
loads of around 25 amps -- one-third as much.  Applying large loads to 
them 
will further reduce their already short cycle life.

BTW, don't confuse marine batteries with floor sweeper batteries such as 
the 
US Battery EV-145 and Trojan 5SHP.  These are big, heavy 12v batteries 
with 
plates similar to those in golf car batteries.  They weigh around 85 lb 
instead of around 55 lb.  In high current applications these will last 
nearly as long as golf car batteries (but they won't fit in ETs, so I 
guess 
it's a moot point).


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea 36vdc
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