How long will my batteries last when I go camping?
How large is your Deep Cycle battery.............Expressed in Amps over 20hrs
To protect your battery try to maintain a 30% safety buffer (never totally discharge your battery.
Next part is what are you running?
Typical camping needs
Waeco 45 42litre fridge
(runs at 45 watts per hour 32% running at 30° C)
Ie 45 watts x 8hrs divide by voltage 12v = 30 amps per day
2 x 13 watt fluoro about 3 hrs a day
26w x 3 divided x 12 = 6.5 amps per day
Television via an inverter
35watt x 90% efficiency for inverter say 2.5 hrs a day
35 w x loss = 39w x 2.5 divide x 12v = 8 amps per day
Radio / player
10 watts 2 to 3 hrs say 2 amps per day
Total daily load 46.5 amps per day
Divide 70 % of the battery rating by the daily load
A 100 amp battery will provide approximately 1 and ½ days power in this situation.
How can I extend my camping trip?
Well you could take a generator but many parks do not generators to be run because of the noise and it does stress wildlife or use Solar power
A 75watt solar module will provide an average of 5.5 peak sun hours in NSW maybe 6 in Qld (This figure also can depend on location, shading, angle of mounting and direction of module).
75 watts X 5.5 hrs divide by voltage (12) = 34 amps per day
Not enough to run all your power needs
Now try "sun tracking" put the panel on an angle to maximise sun power facing North east in the morning, Due North in the middle of the day and North-West in the afternoon. You will collect possibly 7 – 7 ½ hrs per day
75watt x 7 divide by voltage = (12) Almost 44 Amps
That replaces almost all your daily needs
Start with a fully charged 100-amp deep cycle battery Power Bank
So on the first day you use 46.5 amps of 70/100amps 53.5 amps
Second day replace 44 amps back to 97.5amps, Second night use 46.5 amps 51 amps
Third day replace 44 amps back to 91 amps, Third night use 46.5 amps 44.5 amps
Fourth day replace 44 amps back to 88.5amps, Fourth night use 46.5 amps 42 amps
Fifth day replace 44 amps back to 86amps, Fifth night use 46.5 amps 39.5 amps
Sixth day replace 44 amps back to 83.5amps, Sixth night use 46.5 amps 37 amps
Seventh day replace 44 amps up to 81amps, Seventh night use 46.5amps 34.5 amps
Eighth day replace 44 amps back to 78.5amps, Eighth night use 46.5 amps 32 amps
(Now very close to buffer suggest you are starting to overcycle the battery)
Ninth day replace 44 amps up to 76amps, Ninth night use 46.5amps 29.5 amps
Ten days camping on a single battery!
Pack up go home its probably raining and boy, do you need a shower!
Check electrolyte levels & put the battery onto long charge cycle say min 3.5 amps for 20 hrs ASAP.