Battery Monitoring in Our RV

Just before sunrise Ketchum ID

Debbie and I have lived in our 25’ travel trailer year-round the past five years. It’s not too big, not too fancy, doesn’t have too much storage. And until recently didn’t have too much spare battery capacity.

We mentioned visiting QuartzFest 2012 in our post last January and how we’d dry-camped in the desert with good friends Herb and Lois. Lucky for us, their motor home generator has excess capacity and they were willing to share.

Trimetric 2025-RV

Truth is, we really didn’t know how much battery capacity we had at any given time. Sure, we’re starting with 460 amp/hours at full, but what about ten or twenty hours after full charge? We’ve just added a Trimetric 2025 battery monitor from Bogart Engineering into our trailer, and we are rapidly gaining a good understanding of our batteries’ charging and discharging patterns.

A couple of key measurements include days since full-charge, number of amp-hours from full, and most interesting to me, incremental watts or amps of each connected load.

My very compact ham station

My ham station, consisting of a VHF radio, HF radio, Hear-It speaker, Kantronics TNC, and LDG illuminated meter adds 1.5 amps load. Lowering the antenna requires 0.4 amps, raising it takes 0.8 amps, and tuning it takes 0.3 amps. I haven’t measured transmitting yet, but will.

I look forward to learning the observed ampacity of our loads and better understanding the capacity of our 460 amp-hours of batteries (four 6v Interstate batteries).

Debbie looks forward to my being less cranky about saving battery energy when we probably have lots to spare. She’s using 8.2 amps right now — I should go check into it, right?

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6 responses to “Battery Monitoring in Our RV

  1. It sounds like a lot of the extra battery related equipment would not be necessary if you almost always camped where 30 amp service was provided. How long are you dry camping? Would a post on “Advantages of Dry Camping” be in order?

    • Richard
      Absolutely grand topic, Advantages of Dry-Camping. I’ll follow up on this later.

      We dry-camp nine days for Sun Valley Jazz Jubilee (another great topic for soon blog), 5-10 days for QuartzFest, several times for one to three days during caravans, and often overnight when moving our house cross-country.

      A couple on our Alaska caravan this summer claimed they could not endure even one overnight without AC power. Many folks nowadays are spending lots of dollars converting incandescent lights to LED in their trailers and motorhomes.

      I believe anyone considering changing battery configurations or adding solar to their RV should FIRST install a battery monitor and see their usage patterns and values. They may not need to double their battery capacity, or like us, they may not need any more LEDs. We seem to have scads of battery capacity now.

      So the answer my good friend is, “It depends”. I say you need enough battery to carry what you need, including your furnace, overnight. A battery voltage meter does not tell you anything about your battery capacity, and may be without value to you except to tell very low voltage and very high voltage. You probably spend the least time at these extremes, so the battery voltage meters serve little routine purpose.

      A battery monitor, even for a small system with a single battery, tells you everything you are using and how much battery capacity you have remaining, among other things useful to maintaining your batteries.

      Yes, most needed for dry-camping multi nights. But for me, instrumental to maximizing battery operating life. Be green, don’t waste precious (and contaminating) resources. Make your batteries last, and let them serve you the best they should.

      Thanks for the idea on “Dry Camping Advantages”. Look for it soon on your favorite dreamstreamr blog site.

  2. When we bought our Airstream in 2006, I wanted to add solar panels to enable some extended dry camping, but I’m glad now we didn’t. The extra weight and cost wouldn’t have been worth the expense. Dry camping in the southeast isn’t really practical for us. Mostly it’s too hot and humid to not have 30amp for the AC. And, if the climatology of the the last two years persists, it may be too hot to dry camp anywhere in the lower 48 in the summer. On our travels these last five years, we thought about stopping in a Walmart, etc. for the night but always found it too hot to be comfortable. We did dry camp in an RV park overflow site one night in New Mexico on our way home this year, but we were high enough that it was cool during the night.

    Our two batteries and factory installed charging system has served us well. I may add the monitor you have recommended above, just for the better insight as to their condition. BTW: We went to Alaska on 30 month batteries that were 36 moths old. I have always kept them on a battery tender when not in-use, and had them tested at an Interstate store in Melbourne before the trip. Their report was, “They tested like new.” Here we are five months later and they are still going strong.

    Nearly home now. See you again at FL State. Randy

    • The only place we simply had to have air conditioning was in Bakersfield CA in mid-August a few years ago. Sustained daytime temps over 100F challenged our endurance, and our A/C kept the trailer interior under 90F. Otherwise we are good without A/C year-round, largely because we are chasing 75 degrees all year.

      Jim & Deb

  3. is the seller we purchased the Trimetric meter and shunt from. Great people to deal with, speedy service, very helpful folks.

  4. Pingback: Solar Charging Stuff for RVs We Should Have Known | Dreamstreamr Odyssey

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