Re: Requesting list wisdom re gel battery and Battery Tender Plus

[Bruno Valeri <bvaleri@xxxxxxxxxxxx>]

Steve,

From: "Steve Makohin" <wateredg@xxxxxxxxxxxx>

> What is the list wisdom regarding a gel battery and a Battery Tender Plus? 
> I
> am aware that the makers of the Battery Tender tell you you need a special
> Tender, as does BMW.

I'd expect a battery manufacturer to list the charging requirements on their 
website. From memory, a gell cell requires a lower charging voltage than an 
AGM, but I don't remember the specifics.

Apparently, a true gel cell requires a charging cycle (algorythm) that is 
different from wet cell and slightly different than AGM type batteries. Much 
has been written over the years, and I've also researched it some. Since 
I've had very good service from my AGM battery, I don't keep all the info on 
my main memory banks. <G>

The gist of what I remember is charging voltage requirement. Voltage is 
pressure. If a battery (ie like gel cell or AGM)requires a higher charging 
voltage to fully charge (ie higher pressure), it may not fully charge with a 
lower output charger. So you have a battery that charges, say, to 80% or so 
of its capacity.

On my AGM battery, I use a regular 2/10amps automotive automatic charger . I 
monitor charging voltage typically in the high 14 ie 14.97 etc. Sometimes 
(initially) over 15 volts. When my charge is done, my battery voltage 
settles down to 12.79-12.80 after surface charge wears off. this is with a 
52 month old battery. But it only goes on the charger during the off season 
and then only for a couple of hours every 4-6 weeks. I monitor before and 
after voltage and this seems to work out fine. Wet cell batteries require 
more frequent care, hence the need for BT. I have no experience with gel 
cells.

Incidentally, some AGM manufacturers recommend hooking their batteries to an 
automatic automotive charger set on 10amps. This clearly goes against the 
traditional wisdom of using low amps ie 1 or 2 to charge a motorcycle 
battery.
So looking at the mnfg website is a good starting point.

> My mechanic says the gel batteries have not been in the
> field long enough to conclude if there is any harm done by using a 
> standard
> Battery Tender, and that he knows of no cases where he can attribute a gel
> battery's demise to using a standard Tender vs a special gel Tender.

The literature and writing suggests not harm but rather less than complete 
charge. If true, I'd expect more frequent ABS faulting.

> What's your take? I live in a part of the country where we see several 
> weeks
> of 90'F temps, as well as sitting dormant over the winter at below 
> freezing
> temps.

Heat is bad for all batteries. Extended use in high heat cuts short battery 
life. But we're talking heat as in over 100F. Any battery should take heat 
in the 90's in stride.

Cold weather is actually good for batteries. Though it does decrease 
cranking ability, it also slows down self discharge rate. A battery likes 
cool and cold. All that is required is to monitor charge to prevent it from 
freezing if the temps go significantly below 0C/32F. It never gets -really- 
cold out in your area.  <G>

What I would do is take the battery in out of the cold. If an AGM ie with 
much slower self-discharge, I just put in on the charger every 4-6 weeks (or 
whenever I remember) for a couple of hours. But the basics still apply.


hope that helps some

Bruno
Montreal, Canada
CBR 929
http://pages.videotron.com/mcrides

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