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Battery Question

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Posted by RE Newbie on July 1, 2005, 10:24 pm
12 volt Interstate sealed AGM deep cycle battery.  Rated: 100 AH (20 hr rate to
1.75 volts per

I have been draining my battery down to 11 volts before I put it back on charge.
 How deeply am I
discharging it?  I guess I could be draining it down to 10.5 volts as the
sticker says I can and
which coincides with the low voltage warning alarm setting on my inverter.

Posted by Bill Darden on July 17, 2005, 3:32 am
It is not so much "how much are you draining your battery?" but rather
"how much are you reducing the battery's life with sucha deep
discharge?"  Please see Section 11.3 in the FAQ on www.batteryfaq.org
if that is your real concern.

Kindest regards,


1.75 volts per

charge.  How deeply am I

sticker says I can and

Posted by Bill Kaszeta / Photovoltaic Re on July 18, 2005, 1:40 am

1.75 volts per

charge.  How deeply am I

sticker says I can and

11.0 Volts is about 94% discharged (you did not specify a model and I do not
have detailed
         battery data)

11.6 Volts is about 80% discharged, and you will get about 25% more cycles out
of the battery

A lot depends on getting the battery fully charged at least every 2 weeks.  
Read your battery manufacturer's recharge instructions carefully.

Bill Kaszeta
Photovoltaic Resources Int'l
Tempe  Arizona  USA

Posted by RE Newbie on July 18, 2005, 7:27 am
 Hi Bill, they are Interstate PC121000 models.

I had no idea that I was discharging them down that much.  I couldn't find any
information such as
recharge and discharge levels on these batteries as I got them 2nd hand from
work.  I use them to
run a 15 watt CF lamp.  So far I use them for about 5 hrs/night for the past 3
weeks and the battery
voltage reads 12.2 volts while running the CF.


have detailed

of the battery

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