Our Travato, Lance, is a pretty customized machine. At some point this year, we’ll make a video about it, and I can promise you I’ll forget things that have been done to him because there are so many. One of the areas where there have been extensive modifications is the electrical system. He’s had quite a few gadgets installed – an inverter, Auto Generator Start, various cut-off switches, and a Battery Monitor Kit.
But I’m not writing about any of those today – at least not directly. You see, the Battery Monitor Kit (a Magnum BMK, if you’d like to investigate this for yourself) is capable of giving us a whole bunch of data about the Travato’s electrical system. One of the things it can tell me is exactly how many amperes, with 0.2 amp accuracy, are going into or out of the batteries at any given moment.
Since we’re running our Travato with the two stock AGM batteries, this information is pretty valuable. We have 200 amp-hours to work with, but you should really only use half of that. So the information from the BMK lets us answer that old question “How long could I run this on battery power?” very precisely. Where we have the same electrical appliances or fixtures that you do, these loads should be the same in your coach. But obviously, this is going to be the most accurate for other Travato owners.
Determining the Loads
The procedure for determining the various loads is pretty simple:
- Take a reading of amps in/out.
- Turn on the load in question.
- Take another reading.
That’s it. I resorted to a number of methods for turning loads on and off. For something simple, like a light, I would just use the switch. But for something like the entertainment system, I would pull a fuse.
Before I could take the readings, I needed to disconnect the solar panels on Lance’s roof. The variable output from the solar panels would have made it impossible to get an accurate or repeatable reading. Fortunately, the Winnebago solar option has pluggable solar panels and a 3 port box on the roof, so this was really easy.
So, without any further ado, here are the loads I found. Except where I’ve indicated, they’re not additive.
|Background load, with coach battery disconnected. For me, this is the Auto Generator Start, and the display for the Battery Monitor Kit itself.||0.2 A|
|Enabling Coach Battery (with all other fuses pulled)||Undetectable|
|Propane Leak Detector||0.2 A|
|Other Background Loads (Vampire loads for Jensen, Truma, LEDs on USB outlets, etc.)||0.2 A|
|Truma Control Panel (backlight on)||Undetectable|
|Jensen JWM 990 - Radio ON. Volume 25/40||1.0 A|
|TV Switch On||Undetectable|
|TV on (local station)||1.4 A|
|DVD playing through TV Jensen at Volume 40/40 (A Fist Full of Dollars)||2.4 A|
|External speakers – Full Volume (Peg, by Steely Dan)||1.6 A|
|Truma Fan – Vent 2||0.4 A|
|Truma Fan – Vent 10||3.4 A|
|LED tube/strip Light Over Cab Entry - Low setting||0.2 A|
|LED tube/strip Light Over Cab Entry - High setting||1.0 A|
|LED Puck Lights (each – though each switch runs two lights)||0.1 A|
|LED Exterior light||0.6 A|
|Propane Solenoid – Enabled||1.0 A|
|Fresh Water Pump||1.4 A|
|Shower Waste Water Pump||1.6 A|
|Awning Motor - Extend||1.2 A|
|Awning Motor - Retract||2.6 A|
|Maxx Air Fan – lowest speed||Undetectable|
|Maxx Air Fan – Highest speed||2.2 A|
|Refrigerator on 12v||14.0 A|
|Fan for composting toilet (Most won't have this)||Undetectable|
|Inverter on (Standby – all 120V breakers off. Magnum MS 2000)||1.6 A|
|Inverter on (Microwave clock, 120V phantom loads)||2.0 A|
|Inverter on – Refrigerator on 120V – just out of curiosity (Total Load)||19.6 A|
|OnePlace Monitor panel – awake, displaying meters||Undetectable|
|WeBoost Drive 4G-X Cell Signal Booster||1.0 A|
|Tank heaters switched on (Grey, black, and macerator)||9.0 A|
|Water Line Heat Tape (My install only)||0.4 A|
|Circular Bathroom Fan – Running||1.4 A|
|Refrigerator on Gas (Not including Propane Valve)||Undetectable|
|LED Running Board Lights||.8 A|
|Typical Dry-Camping “standby” (All fuses in. Propane valve open. Truma and Jensen powered but dark. Fridge running on Gas) Total Load. (I've subtracted my Magnum accessories.)||1.4 A|
Things I Found Interesting
It takes one amp to keep the propane solenoid open. This means, to keep propane available in the coach all the time is costing me 24 amp-hours a day. That’s roughly one fourth of my usable battery capacity. Rather than leave it on all the time, it would make more sense to only have the propane valve open when I need it.
But I usually can’t… because we usually camp without hookups. When we do, we run the refrigerator on propane. While the propane fridge doesn’t use much electricity itself, another way to look at it is that the propane fridge requires 24 amp-hours a day to run, in addition to the propane.
And speaking of running the refrigerator on propane – you’re certainly going to want to do that! The 14 amp draw for the refrigerator was the biggest single 12 volt load I found. We’ll leave the fridge on 12v sometimes when we stop for lunch. (OK. Usually not on purpose. We usually forget.) Unless you’re going to be doing some more driving, you probably don’t want to leave it on 12v for very long unless you’re running the engine.
And just for grins, I ran the fridge on 120v off the inverter. I don’t know what I expected to see there, but I was just curious. The good news is that it with losses from the inverter and additional 120v phantom loads, it was more efficient to just run it on 12v. Good.
The LED tube light was sort of a surprise. The difference in draw between the low and high settings was 5 times – but the light certainly doesn’t seem 5 times brighter on high. So the lesson there is, if we’re really trying to stretch our battery life, use that light on “low”.
The results from the MaxxAir fan were kind of neat too. On the lowest speed, I couldn’t pick it up. This tells me that there’s very little energy cost to leaving it running for some ventilation while we’re out. Good to know.
And the Truma fan. Wow. Usually, it’s dead silent, and we never hear it. But if you turn it on “vent” and crank it up all the way… WOW! I didn’t know it could spin up that much! I don’t know if it was moving more air than the Maxx Air fan, but it was certainly using more Amps. But like I said, in actual use, the fan never runs that hard.
The good news from all of this – for us, anyway – is that with 300 watts of solar power on the roof, most of the minor loads are a wash. On a sunny day, we really don’t think much about our battery state of charge. And considering we drive most days, the alternator keeps us topped off, and it’s all pretty academic anyway. Still I found it interesting to go through the exercise. Hopefully, there’s something here you can use.