Just last week, I had written an article regarding my episode with my RV batteries and what has happened over the first winter of owning an RV. You can check out the article here: Winterizing Your RV Batteries
I wanted to add to that original article because as luck would have it, I was able to sit down and listen to a lecture given by someone in our local RV dealership. It was very informative and I really wanted to relay what was mentioned there for you to use as a reference in your RV.
The Gas That Drives The Engine – Amp-Hours
Whenever we think batteries and what they do for us, they really are just fuel tanks for electrical energy. So as we use our electrical appliances, it will take energy out of the batteries. When we run the RV’s engine, connect to shore power or use a solar panel, we put energy back into the batteries.
Now, we are very familiar with the idea of putting a liter of gas or for our American friends, a gallon of gas into the tank. With a battery, we use the word, amps-hours. You will find batteries rated best by what is known as amp-hours. It comes down to, how many amps you can use for how many hours.
If a battery is rated for 100 amp-hours or AHs, then that means we can take out 100 of those AH”s and the battery is depleted and needs to be charged.
Now, all of the electrical devices in your RV will use these AH’s to do what you want them too. For example, for every light bulb you light, it will use up 1 AH per hour. Or in other words, 1 AMP per Hour.
Now all the devices have ratings and below you will see roughly what those rates are per hour.
| Appliance | Rating In AH |
| Furnace Fan | 4 |
| Light | 1 |
| Propane Alarm | .2 |
| Radio | 1 |
| Refrigerator (Running On Propane) | .4 |
| Refrigerator (Running On Electrical) | 3 |
| TV | 3 |
| Water Pump | 4 |
| Drip Coffee Pot | 67 |
| Laptop Computer | 12.5 |
| Microwave Oven | 167 |
So there’s a short list for you. Now, you notice that I don’t even mention air conditioning in that list. The point is simple. You should NEVER run air conditioning on your 12V system unless you’ve beefed it up to support it. The power draw is very high and for extended periods of time.
Now looking at our list above, we can estimate what we will use on an average day with our RV if we are only using our batteries.
Now, let’s say I go camping when the nights are still a little chilly and the furnace comes on here and there.
For an average 24 hour period I may use:
- furnace for about four hours – 4 x 4 = 16 AH
- Lights – three lights for three hours = 9 AH
- Propane Alarm runs 24 hours per day = 4.8 AH
- Radio for about four hours per day = 4 AH
- Refrigerator runs on propane 24 hours per day = 9.6 AH
- Water pump probably about one hour per day = 4 AH
- Laptop computer for about four hours per day = 50 AH
Now if you add all of that up, we are looking at a pretty clear need for 97.4 AH per day!! If I knock off the laptop, we are sitting around a reasonable 50 AH per day.
So, next let’s look at the fuel container in this mix, the battery.
We have two 6 volt batteries that together can supply 12 Volts at around 225 AH.
So if we do simple math, that 225 divided by 50, I can get about 4.5 days out of the batteries before I have to charge them somehow. If I run the laptop too, then we are into about 2 and 1/4 days before I’m in trouble.
How Did I Get In Trouble Over The Winter?
Now you may be asking yourself, why do my batteries bleed to nothing and then possibly freeze over the winter, if I”m not using anything? I wondered that too. But I was using something without even thinking about it. The propane detector. That propane detector/alarm using up about 4.8 AH per day will bleed my new shiny batteries down in about 47 days.
So within a month and a bit, my batteries were totally depleted. Because a battery is made up of acid and water in it, and it turns mainly to water when depleted, the batteries froze! Yes, I do feel like a bonehead.
Now, this helpful person did also tell me the truth. If you freeze your batteries and they bulge like they are pregnant, then you may as well thaw them out and get them replaced. At the very best, you’ve got 50% capacity left in them. And honestly, that’s a waste of time.
So, now you can figure out how much power you use and some exciting things like how can you keep your batteries charged for the long term. Ahhh, but you have to wait until I start talking about solar!