Deep Cycle BatteriesDeep cycle batteries are basically a fuel tank for the 12-volt system. We start by understanding amp hours available from our typical batteries. Amp hours are the amount of time our batteries will provide a charge at a certain draw known as amperage. Here are the typical amp hours for batteries at a 25 amp draw:
Group 24: 140 minutes
Group 27: 175 minutes
This means you only have about 2.5 hours of usage drawing 25 amps on a Group 24, or just about 3 hours on a group 27. In a 12-volt system, adding a second battery parallel (positive to positive) will double the amp hours. However, connecting two 6-volt batteries in series (negative to positive) will give you 12-volts, but does not double the amp hours!
AGM BatteriesEven Absorbed Glass Mat (AGM) batteries give the same or slightly less amp hours for the corresponding group rating! The advantage of AGM is they are less likely to sulfate, therefore lasting longer. They are also maintenance free, and can be installed sideways in tight compartments. To get higher amp hours, you will need to add more batteries. There are some AGM battery companies, such as Lifeline, that offer a higher-capacity AGM with 330 amp hours on a 12-volt or 692 on a 6-volt, but you would still need two, and these are much higher prices!
Battery ConditionOnce you understand what kind of batteries you are using, you need to determine the condition of your batteries. Lead acid batteries require a multi-stage charge every month that creates a high voltage “boil” for a specified amount of time and then an equalizing and float stage. Most RV owners simply plug the unit in and leave them, thinking the on-board converter keeps them conditioned. Not so! Battery sulfation is a big problem in the RV industry and most batteries are not operating anywhere near their rated capacity. So if you have batteries rated at 175 minutes for a 25-amp draw and they are sulfated and only providing 60% capacity, you only have 105 minutes. It’s important to get your batteries tested correctly. A digital tester is not the answer; the only way to truly test battery capacity is to charge them up and test with a 25 amp draw machine and document the time it takes to bring them down.
One product on the market that helps condition batteries is the Battery Minder, available online at www.batteryminders.com or from your local dealer. This product sends high-impact waves into the battery and breaks up the sulfation and will extend the life of your batteries as well as the available amp hours.
Drawing PowerLastly, it is important to figure out what is drawing power from your batteries. Typical 12-volt components are interior lights, water pump, vent fans, and any appliance that is running on LP as they will draw battery power to open and close the gas valve and other operations. A refrigerator with an icemaker usually uses 12-volt power to heat the tray before ejecting the cubes. Smaller inverters will draw power from the battery to run the TV and DVD player. Larger inverters will draw a lot of power to run a residential refrigerator and other appliances. You can spend a lot of time trying to calculate the amp draw from each appliance and the amount time each gets used every day. However, a basic understanding of good battery capacity and what the “energy hogs” are is easier.
Tips for Conserving 12-Volt PowerNow that you know the basics, we’ve got some other tips on how to maximize your power efficiency when camping!
1. Change your routine! Adjust your activities according to natural light, read during the day, go to bed earlier, and get up earlier when natural light is available.
2. Use more portable, rechargeable solar lights. There are several products on the market for solar LED string lights for outside, rechargeable puck lights for inside, and lanterns. Instead of sitting inside reading, eating, or playing games, go outside and use the campfire light, portable lanterns, and LED string lights. It’s all free power!
3. If you are camping in colder temperatures, invest in a portable catalytic heater that runs off a small bottle gas canister. This provides safe supplemental heat without CO2 gassing and extends the propane and 12-volt power.
4. Change to LED bulbs. Incandescent bulbs used in the older light fixtures draw 1.5 amps; halogens draw about 1 amp. The newer LED bulbs draw about .01 amp (ten times less)! And they provide better light so you don’t have to have as many on!
6. If you are using an inverter to charge accessories such as cell phones and laptops, unplug then after they are charged. An empty cord will still draw power if plugged into an outlet.
7. Charge all electronic accessories such as cell phones and laptops from the automotive battery system while driving.
8. Manage heat and cool temperature the old-fashioned way! Open windows for cross-ventilation, utilize shade from trees, determine the cool mornings and hot afternoons, and park accordingly.
Need some more information on boondocking? We’ve got a great free video on Running 12-Volt Appliances on Generator While Boondocking.