Well, if the six batteries are wired in series to get 48 volts, the
capacity of the six is essentially the capacity of the smallest-capacity
battery of the lot. As the smallest-capacity battery discharges, its
internal resistance increases, which prevents the discharge through it
of the batteries with greater capacity. If the six are identical,
however, then the capacity in amp-hours of the six in series is the same
as the capacity of any one of them alone. Only the voltage changes.

Or is that more confusing?

Chuck



Peter Bennett wrote:
On Sun, 29 Jan 2006 19:34:10 GMT, "Dennis Pogson"
wrote:


Thomas Wentworth wrote:


Now,, if he had 6 batteries and each one is an 8 volt .. does this
mean he has 8x6 = 48 volts of possible power? And how does this work
out to amps. ?


For the six batteries you mention to give 48 volts they would have to be
wired in series, i.e. each one positive to negative, whereas in parallel
(positive to positive and negative to negative) they would give you 12
volts, but the capacity would be the sum of the six batterys' capacities.


The OP's suggested 8 volt batteries - if he connects them in parallel,
they'll still give him 8 volts.

On Mon, 30 Jan 2006 00:56:53 GMT, chuck wrote:

Well, if the six batteries are wired in series to get 48 volts,

8 volt batteries are not that common except on boats with 32 volt
electrical system like the older Hatteras motor yachts.

Much more common on sailboats are banks of 6 volt batteries wired in
series-parallel to yield high capacity 12 volt battery banks.

Four 6 volt golf cart batteries in series parallel will give you about
440 amp-hours of capacity but in actual practice it is a bad idea to
discharge below the 50% level since that will greatly shorten batter
life. You can get a rough idea of discharge level by looking at a
digital voltmeter when the batteries are under load. 12.6 volts is
fully charged, 11.6 volts is about 50%, and 10.5 is fully discharged.

Yeah. Should've mentioned that. I was trying to respond to the original
question as posed. He seemed to be asking about the capacity of
series-connected batteries.

Chuck

Wayne.B wrote:
On Mon, 30 Jan 2006 00:56:53 GMT, chuck wrote:


Well, if the six batteries are wired in series to get 48 volts,


8 volt batteries are not that common except on boats with 32 volt
electrical system like the older Hatteras motor yachts.

chuck wrote:
Yeah. Should've mentioned that. I was trying to respond to the
original question as posed. He seemed to be asking about the capacity
of series-connected batteries.

Chuck

He would be better reading a copy of "The 12-volt Doctor's Practical
Handbook", a must for all who find boat electrical technology difficult.
Sadly, any .pdf copies seem to have disappeared from the Web, and you have
to pay around $30 for a hard copy.


Dennis.

snip

Four 6 volt golf cart batteries in series parallel will give you about
440 amp-hours of capacity but in actual practice it is a bad idea to
discharge below the 50% level since that will greatly shorten batter
life. You can get a rough idea of discharge level by looking at a
digital voltmeter when the batteries are under load. 12.6 volts is
fully charged, 11.6 volts is about 50%, and 10.5 is fully discharged.

I thought 12.2v was 50% charged (12v lead acid battery). No idea were I got
that idea from, but it would explain why I struggle to keep my batteries
above it. I have 4 x 12v 135amp batteries connected as two pairs of 12v
batteries wired in series then wired together in parallel, to give 24v.
Something I have often wonder about is if I should connect them to the
electrical system with both positive and negative coming off one pair, or
the positive off one pair and the negative off the other.