Current draw while towing

CanadianTabber

Hi all!
After a couple of successful trips with our 2021 Tab 320 BD, I have noticed a few things which baffle me.
My tow vehicle has a dedicated 12V line connected, yet the Victron Solar Controller shows full charging on the app history while I am towing.
Is it the electric brakes that draw down the battery and the solar kicks in?
I don't have the fridge running while towing and I am sure the other components (Jensen, sensors etc) would be negligible in current draw.
Any ideas or am I seeing this the wrong way?

Thanks!
Brent

Dutch061

Verify that you TV is actually charging.

Simple method:

1. Turn of  charging in the solar controller
2. Turn on interior light
3. Start TV
4. Turn off master switch

Does interior light stay illuminated?

A couple of screen shots of that you are looking at on the Solar Charge Controller would help, I am assuming that you are using the Bluetooth App.

Brad

pthomas745

What do you mean about "full charging?"  If the battery is being charged, the voltage reading of the battery will read 13 something no matter what the "actual" status of the battery is.  The only way to find a more accurate battery state of charge is to remove all charging sources and turn off the battery switch so you can measure a "rested" battery.

What you are seeing is normal.  If you unplug the trailer from the battery, turn off the battery switch, and look at your Victron, what does your voltage read then?

CanadianTabber

I suppose the real question i am asking is what is the the major draw on the battery while towing? I will try hooking my tow vehicle up to the trailer, turn off the battery switch and solar charger and see, first of all, if i am getting 12 volts from the tow vehicle.

pthomas745

My trailer is sitting just outside on a sunny day, with the solar panel plugged in.  Haven't had the trailer running anything in several days, the battery switch is on.  The battery voltage is reading 13.69.....which is normal for a battery being charged.  There is no draw at all on the trailer, except for whatever parasitic drain there happens to be, which for me winds up to being about 1/4 of an amp.   So, just seeing a big "voltage" number while charging does not necessarily mean there is a major draw.

CanadianTabber

So this screenshot shows the day (2 days ago) I was travelling back home...full solar panel on in Bulk mode to charge battery...my thinking is, why does the battery need such charging if there is no heavy load (perhaps maybe only electric brakes?) if everything is basically off, excluding parasitic drain and if there is a 12 volts constantly feed to the trailer from the tow vehicle? electric brakes?) if everything is basically off, excluding parasitic drain and if there is a 12 volts constantly feed to the trailer from the tow vehicle?

TomCanada

Is your battery state of charge under 100%?  If so, the TV and solar panels will both attempt to charge the batteries at the same time. This is expected behaviour..  if the batteries are full, the charge from the solar is significantly lower.  I only see large bulk charges from my solar when the batteries are discharged below full.

TomCanada

Here is an example from my setup.  The two days on the left the battery was mostly full - just a little discharged from overnight parasitic draw.  The three on the right were days I had drawn the battery throughout the day (fan, lights, etc).  You can see the bulk charge from solar is significantly higher those days - which is why I suspect you're towing with a less-than-full battery and you're simply charging up using solar while on the road..

CanadianTabber

Yes, my battery was less than full when i left the campsite (12.64v) and i had minimum sun while camping.
Its good to know everything seems normal🙂
Thank you everyone for your help!

Brent