Udo, if the light bulb is receiving the same heat dissipation in both cases
(hanging freely in the same ambient air temperature), the time to discharge
to a particular voltage should be proportional to the AH rating of similarly
constructed batteries (batteries with similar discharge curves).

Bob

"Udo Rumpf" wrote in message
.. .
I used a 12 volt Halogen light rated at 5 watt.
The two batteries were set up at the same time and
each had the identical 12 volt light, the discharge lasted for 51/2 hours
and ended at 12.00 volts for the smaller battery and 12.05 volt with the
bigger one. both started at 12,70 volts no resistor attached.
Udo


"COLIN LAMB" wrote in message
nk.net...
"If a 7 amp/h battery shows 12.00 volts exactly, after 5 hours
with a 5 Watt resistor, what voltage should a 10 amp/h battery show?
Both batteries are of the same type and starting from
the same voltage with surface charge removed.
Udo"

Something seems mixed up here. Wattage is determined by multiplying the
current times the voltage. Excatly 5 watts would only be dissipated
during a brief period, since the voltage and the current will be
changing
during the discharge cycle. I am wondering if the 5 watt rating of the
resistor is misleading you.

What is the resistor value in ohms? The manufacturer should have a
curve
showing the voltage at various discharge rates vs. time.

Colin