Deka AGM Batteries [RE-wrenches]

[Brad Bassett]

Here's what I've been able to find out about commercial quality sealed 
VRLA batteries. East Penn, aka: Deka, sold by MK, makes both gel and AGM 
batteries. I believe the AGM batteries are less expensive than the gels, 
and are not as highly recommended for use in solar systems. I think Deka 
quality is good enough that they are probably as good as most other AGM 
batteries. My experience is that gel batteries are good if they are of 
high quality, and I have heard that the Deka batteries have held up 
well, I don't have alot of experience myself. There is one East Penn gel 
battery that is somewhat different than most of them, the 8GGC2. This 
battery was designed and made to be an advanced electric vehicle 
battery. The tests indicate that it is almost in the realm of industrial 
batteries when it comes to cycle life. I have not heard of any failures 
yet in the field in the past few years that it has been put to use in 
solar systems (Not that I hear all that much, I would like to hear of 
any long term experience with these). It is the same form factor as the 
T-105, 6 volt, 200 Ahr. 

The GNB Sunlyte 12-5000 (100 Ahr AGM) that we sold many thousands of 
over the years seem to have a moderate lifetime of 2-4 years in solar 
service, but seem somewhat short lived when used in hot conditions. This 
may be true of sealed batteries in general. 

We also used many Concorde batteries in northern Africa that seem to 
have held up quite well, possibly as long as 5 years though we mostly 
lost touch with the users after 3-4 years of use. I have noticed that 
Concorde advertises very high cycle life for their batteries and on 
looking into this find they tend to skew the parameters of the testing 
to enhance their numbers, very high rate discharge (therefore not really 
as deep a discharge) etc. Very rarely is is possible to find oranges to 
oranges tests on cycle life in commercial quality batteries, so I 
recommend to take them all with a grain of salt. Solar systems tend to 
use batteries differently than in any of these tests anyway, and fail 
from different mechanisms (sulfation, grid growth, etc). Keep in mind 
that the Concorde 2 volt batteries are not the same as 2 volt industrial 
cells in any way, they are the same construction and plates as the other 
Concorde batteries, but the cells are just put in parallel instead of 
series, so will probably not have much longer life, though maybe less 
wiring problems than using a bunch of 12 volt bateries.

I think all of the sealed commercial batteries are probably simiar in 
cycle life (with the possible exception of the 8GGC2), with higher 
quality winning out over poorer quality in preventing premature 
failures, and type of useage being the largest factor. We ran into some 
very poor gel batteries a number of years ago that failed miserably (not 
East Penn) and probably contributed to the still heard complaint that 
gel batteries are not very robust.

I hope this is useful and not too long winded. Let me know if it's not 
that useful.

Brad Bassett
Schott Applied Power 
Tumwater, WA office
bsbassett at earthlink.net

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