Re: (ET) Battery questions....

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

On 14 Jan 2002 at 21:57, Christopher Zach wrote:

> As to using Gel cells in a high current job like an ET... 
> 10amps for 6 hours? No problem. However when
> you draw on them hard, the voltage output drops like a rock. 

Maybe it depends on the battery design and how they're connected.  I use 
East Penn group 24 Deka Dominators in my E15 and they work fine.  
However, I'm using six 12-volt batteries in series parallel, so each 
battery sees half the current.

One note, though; my six group 24s have apreciably less capacity than six 
golf car batteries (they also weigh less).  For my lot this isn't a 
problem; I have never drawn them below 50%.  For others it might be.

Generally, if you compare capacities of flooded, gel, and AGM (absorbed 
glass mat, such as Concorde, Hawker, or Optima) batteries, similar size 
and weight batteries will look like this:

Flooded:  highest energy, fairly high power
Gel: lowest energy, lowest power
AGM: moderate energy, highest power

By energy I mean available watt-hours; by power, I mean current they will 
deliver without too much voltage sag.

And it's correct, using the crude ET charger on gel or AGM batteries will 
ruin them in short order.  I doubt that they would explode; more likely 
they would gas excessively.  They would then vent (they have release 
valves to prevent excess pressure buildup) and lose their internal 
moisture.  Since they're sealed, the water can't be replaced; so after a 
few cycles of this abuse, they are useless.


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1970 GE Elec-trak E15 36vdc
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