Amps from/to TV?

[Silver Hawk]

Could use a little insight from those more experienced. Hooked up my TV today prior to a trip - it wasn't what I expected. Using my Trimetric monitoring system this is what I get:
1. -.06 amps draw when everything is unplugged and turned off.
2. -1.6 amps draw when I plug into my TV - engine not running.
3. +2.4 amps charge when I turn on the engine - same at 800 rpm idle or 2000 rpm - normal travel rpm.
Questions:
1. -.06 isn't much, but what do others get? is it normal?
2. what's the -1.6 draw from the TV? Is this normal - what can it be from? do others experience this draw.
3. +2.4 charge - (seems it would be 4.0 charge if you add the -1.6 draw and the 2.4 charge) - is this the normal amount of charge on can expect from a TV? I expected more.
Would appreciate replies as to what is normal and what others experience to see if I have a problem or can improve my situation.
Thanks for amy reply as this is my first time with a TT and don't know what to expect.

[idroba]

The -0.06 draw is 60 mA and the tri metic itself may be taking that amount. Other parasitic losses such as radios which are always "hot" to keep stations on, Television anetnna amps etc could cause this.

The -1.6 when you plug into your TV simply means that for a while the batteries in the AS are at a higher charge state than your TV battery. They will equalize with a bit of time. I see this on my sensetive metering system too. After siting plugged together the current will drop to near zero.

The + 2.4 amp charge you are seeing when you start the TV simply says that some current is flowing from the TV to the AS. If the battery(s) in the AS are pretty much charged, fully, there is no real need or possibility for the TV to push more. A battery only takes as much charge as it needs, and if full, not much will go into it.

Now, you probably will never see much more than about +10 amps from the TV to the AS due to the wiring resistance and distances involved. TV charging is fairly minimal in most situations due to those issues.

All said, your numbers don't concern me at all. They are not far from what I see on my own rigs.

[Tom Nugler]

I agree that a slight parasitic draw can be expected under most circumstances and the readings would appear to be within reason.
Quick Question.
Is that –1.6 amp draw on the coach batteries with the ignition on or off?
Ignition on would make sense if the trailer batteries had been recently charged by the converter and feeding the TV battery.
Most of the factory tow packages would have an isolation relay to separate the truck’s B+ circuit from the trailer charge circuit when the ignition is off. The idea is to prevent accidental discharge of the trucks staring battery if the umbilical is connected, and, there’s a excessive draw or fault in the trailer.
That 1.6 +/- draw seems too high even considering the coil current limiting diodes and capacitors found in automotive relays.

Just wondering,
Tom

[Silver Hawk]

Thank You IDROBA!
Very clear -
My batteries were fully charged - what your saying, it's really a balance between the two sets of batteries.
Thanks

[Silver Hawk]

The 1.6 draw was with the key off. I didn't try it with the key on, but without the engine started. What your saying is I seem to be missing a " isolation relay" on my truck. It was a factory insulation - Dodge RAM. To get around this I would have to unplug it whenever I stop - pain.

[Jammer]

Originally Posted by Silver Hawk

The 1.6 draw was with the key off. I didn't try it with the key on, but without the engine started. What your saying is I seem to be missing a " isolation relay" on my truck. It was a factory insulation - Dodge RAM. To get around this I would have to unplug it whenever I stop - pain.

Not unusual, not a cause for concern, and no need to unplug when stopped. The cause varies widely. Having an interior light on in the truck would be enough to create a little more draw. Or as suggested it may be the batteries equalizing.

The only reason you would want to unplug would be if you are spending a night or more without shore power and are concerned that the power draw from the trailer may deplete the truck battery to the point where it won't start.

[RickDavis]

.06 amps (100 amp shunt) is what I see on mine also and I assume that is what the trimetric itself draws.
Everything else sounds normal. Don't expect much charge from your tow vehicle as others have said.. Probably 2 to 5 amps would be normal .
I think Ford has an isolation relay but I know my 99 dodge did not. I wouldn't worry about unplugging unless you are parked for days.
Actually I did put an isolation switch in my Dodge, but only because I was delivering trailers and the new trailers usually didn't have a battery and all the lights would be on inside and want to run off my truck. Since I have solar I rarely turn the charge line on.
I guess this is pretty much what everyone else has said.
Just as an aside if I disconnect the cord or put the jack down while stopped somewhere with out unhooking I will wrap the seat belt around the steering wheel as a reminder I need to do something.

[Tom Nugler]

Got your TV info from your profile. Pulled up the wiring diagrams from Alldata.
I don't see any indication of an isolation relay. Lots of relays with fuses in the Power Module for running lights and turn signals though.
If your concerned it would be fairly easy to install a relay in the charge line.

Tom.

[Silver Hawk]

Sounds like it's a issue (or non-issue) of the two battery systems trying to equalize. The TT was fully charged and the TV wasn't. Normally the TV will be charge up and the TT will be low on the road. When parked I just have to unplug the cable. I'm going to look in to having a relay in line since it's a pain to remember to unplug every time I stop.
Thanks for all the help; once again Air Forms comes through! Started knowing nothing - with your help - ended understanding. RobertC