(ET) Battery choice (was Elec-trak Digest, Vol 15, Issue 41)

["David Roden" <etpost drmm net>]

On 22 May 2017 at 17:04, Robert wrote:

> First, my recommendation for the ET is AGM batteries, not lithium and
> not open L/A. Lithium's advantage is in power to weight, in a tractor
> weight is in your favor so the extra expense has little benefit 

I agree, lead batteries are a good choice for the ET.  The weight is not a 
negative.  :-)

If flooded batteries are charged carefully, there isn't much reason for 
them 
to make a mess.  Regrettably most engineers / chargers view floodies as 
forgiving (which they are) and the tendency is to overcharge them.  (As 
I've 
said before, in my experience far more batteries die from overcharging 
than 
from undercharging.)

Golf car batteries also still about the most economical in this 
application. 
Some kinds of lithium (LiFePO4) might last longer in theory.  That may 
make 
a difference for road EVs.  For the use an ET gets, it's less apt to 
matter.

AGMs are nice for the low maintenance.  I've used Hawkers and Concordes. 
They were pretty good.  If you slam Hawkers (I think they're now called 
Odyssey) with a good hard initial charge every cycle, they can last a long 
time.  They also deliver FEROCIOUS currents, if that's what you need.

Gel batteries should be fine for this application too, if you aren't doing 
tractor pulls or whatever, and don't need the huge peak currents that AGM 
can supply. 

IN fact I've used East Penn (Deka Dominator) gel batteries now for 20 
years, 
and by that I means the same ones.  Twenty years.  They're just now 
starting 
to lose capacity.

IMO for most people who don't need raw power, gel batteries of this 
quality 
are probably a better choice than AGM.  They're starved-electrolyte, which 
admittedly means lower specific energy.  However, it also means that as 
long 
as you don't reverse a cell, they self-limit their discharge to minimize 
over-discharge problems.  The acid is gone before the grids can be 
damaged.  
This also help to reduce grid corrosion.

You do have to be careful not to overcharge them, but limiting the 
on-charge 
voltage to 14.2v or 14.3v (East Penn recommends 14.1v) takes care of that 
problem.


David Roden - Akron, Ohio, USA

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