Date: Tue, 19 Jun 2007 11:58:09 -0300
Reply-To: David Etter <detter@MAIL.AURACOM.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Etter <detter@MAIL.AURACOM.COM>
Subject: Re: Low-voltage alarm
Content-type: text/plain; charset=us-ascii; format=flowed
Hi TC ? ? :
Yes, you are right 11.7 Volts is low,and represents as you
say 25% battery power remaining. If repeated too often, that is
fatal for a 'Wet-Cell' and although also low for a Gel-Cell, they are
designed to handle that.
True, battery life (number of recycles) is somewhat shortened
when taken down that low but in the case of AGMs, not unacceptably
shortened. And one would hope that dropping to 10.5 volts is NOT done
on a regular basis but rather the exception.
Among the "Deep Discharge" Battery manufacturers, it's a very
competitive world out there and they are stretching the limits (and
credibility too) all the time. It is becoming more common to see
advertised 'extended recycling numbers' even when taken down to 0%
discharge. (1.7 - 1.75 volts per cell depending on the company)
Extending your use of the battery until reaching 10.5 Volts
instead of only 11.7 Volts may give someone an extra 25% time with
light to effect a repair or other critical period and still have the
assurance that the battery is not unduly harmed.
And if the mfrs say it's all right then who am I to argue.
David(dsl82westy)
P.S.: Perhaps left out of all this debate is the point that we are
referring to Gel-Cell's and in my particular case, AGMs. We are after
all working with RVs.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TC <trclark@shaw.ca> wrote
>Please explain! I thought that 11.7v was about when a 12v battery
>has 25% charge
left, 12.8-13.2v is ~ full charge, & fully discharged is about 11v.
So 11.7v is really low discharge pt even on deep cycle batteries if
you want optimal life of the battery.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David (dsl82westy) <wrote>
> > Yes, but it cuts out at 11.7 volts.... too high to be of any use for RV's.
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >Tom <wrote>
> > >Would this sort of low voltage cut-off gizmo do the trick ??
>
> >>http://canadiantire.ca/browse/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524
>443294641&FOLDER%3C%3Efolder_id=1408474396672454&bmUID=1182208017428
|