It is useful to be able to monitor the power in your Motorhome. But monitoring power uses power, but how much? I decided to check on my system before I get it all ready for trips out once the weather is warmer 🙂
I have a Victron setup for monitoring everything. This includes a bunch of Victron BMVs and a Cerbo GX Unit, as well as various chargers and controllers. All these devices take some power, and even if each is very little it all adds up, but question is how much?
This is a view of 12 hours at a time where the solar is not harvesting, so the numbers are not affected by any charging going on
The orange line is the current.
This is the draw for all the Victron Monitoring, plus some little random devices such as an Opto-isolator (for monitoring IO circuits); temperature relay controller (to activate cooling fan for electrics cupboard when needed); an 18A Victron DC-DC Converter for regulated Hab Electrics voltage; and a couple of USB Sockets that stay active (nothing plugged into them).
The current is bouncing between 0.6A and 0.7A – so this is the residual current when the van is laid up doing nothing.
In terms of draw from the battery, the Battery bank dropped from -300.5Ah to -308Ah in the 12 Hours.
So this would be 15Ah/Day being taken out the battery, and more than likely around 13Ah a day more than a system that has no monitoring and is ‘factory fresh’. Is the extra load worth it? That would be up to the individual 🙂
There is one device that I usually leave on 24/7 but was off in the numbers above…. The Internet Router. This is a chart of the router current draw over a 24 hour period, with the flat line between around 5PM to 8AM being the time it was unplugged
The 0.1A draw when the router was unplugged is the general load on the Habitation side (so the DC-DC Converter and USB Sockets). Note that this 0.1A is already included in the Hybrid current draw at the top.
This graph is showing the router is pulling between 0.2A and 0.3A (once that 0.1A baseline is removed) – Around 3-4 Watts. Call it 2.5A average, which makes it around 6Ah/Day an Internet Router takes from the battery.
So having the ability to fully monitor my electrics system AND remotely report it via the Internet adds up to a total of about 21Ah a Day. More than might be expected actually. I thought it would be less.
Right now solar is still poor and is only just keeping up with the load (33Ah brought in in the last 24 hours). Come the spring it will be a different picture and that 21Ah load will be much more insignificant.
I do have some other minor loads also which I would usually leave on (motorhome security system) which will add more load as well. I need to do the numbers for that as well.