Re: LEAD ACID BATTERY

john wrote:
Hi,

I have to design a voltage source ( +/- 18volts, 13A ) using lead acid
batteries. My circuit draw is 700mA and requires plus minus 18 volts
to operate efficiently. I need batteries that can atleast run for 10
to 12 hours before the voltage drops to +/- 17 volts. I am thinking
of adding three 6 volts, 13AH ( rated for 20AH ) batteries in series
to produce +18 volts and adding three 6 volts to generate -18 volts.
I choose the battery ( BP13-6V ),
http://www.zbattery.com/zbattery/ub13-6.html.

Can anybody advice me that am I doing the right thing that will these
six batteries last for 10 to 12 hours maintaining +/- 18 volts @
600mA.

Thanks
Regards
John

You won't have much fun with lead batteries, if you repeatedly discharge
them all the way down. Even if you choose deep cycle or gel cells. If you
have to depend on this kind of cheap technology, choose them to have at
least double the capacity needed, so you discharge never more than 50%. Then
you also don't need to worry about the voltage drop. Well maintained they
will
then last for 10yrs instead of 10 months.
The charger will be another challenge for you, I doubt you will find one for
36V. So you have to take them apart each time and charge them in parallel or
better one at a time, because otherwise you won't get them full. If you have
50% left, this will take 7h each, so you can set your alarm clock every
night. :-(
Ian suggested the right thing, take a single 12V battery with sufficient
capacity(60-70Ah) and operate a switching dual supply from that.

--
ciao Ban
Apricale, Italy



.

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