183 replies to this topic

[Jon R]

A few centimeters of #6 AWG wire is no issue at all, your wire is already oversized for the job, and you don't care about voltage drop anyway as you have a DC-DC charger.   

This is not at all a problem in your system as your wire is all more than sufficient, but in general it is more important that the wires between the DC-DC charger and the battery are fat (and short), as opposed to the wires between the truck and the DC-DC charger.   The charger will compensate for voltage drop on the wires to the truck, but not between the charger and battery.

I've ordered a Victron Orion-Tr 12/12-30 isolated DC to DC charger.  The wire run from the engine compartment to the charger in the battery compartment will be about 26 feet.  The truck is a 2021, so I assume it has a smart alternator.  The truck hasn't arrived yet so I can't measure the alternator output.  I was planning to use Ancor Type 3 marine tinned copper 6AWG wire for that 26 foot run.  While that wire size is certainly adequate for the current the Orion will draw, I'm hoping that size wire will limit the voltage drop sufficiently to allow the engine running detection logic of the Orion to work properly without using a dedicated wire to provide an engine running signal.  Can anyone tell me from experience whether 6AWG will be sufficient for that?  Thanks

 

Edited by Jon R, 10 March 2021 - 08:20 AM.

[Vic Harder]

Using this DC voltage drop calculator - Voltage Drop Calculator (rapidtables.com)   I suspect you will see about a 0.7V drop feeding 35A into that Victron using 6AWG wire, or around 5%.  Without the DC2DC, you would want to aim at 3% or less.  With it, it really doesn't matter if the wire can handle the current, which it can.

[rando]

I've ordered a Victron Orion-Tr 12/12-30 isolated DC to DC charger.  The wire run from the engine compartment to the charger in the battery compartment will be about 26 feet.  The truck is a 2021, so I assume it has a smart alternator.  The truck hasn't arrived yet so I can't measure the alternator output.  I was planning to use Ancor Type 3 marine tinned copper 6AWG wire for that 26 foot run.  While that wire size is certainly adequate for the current the Orion will draw, I'm hoping that size wire will limit the voltage drop sufficiently to allow the engine running detection logic of the Orion to work properly without using a dedicated wire to provide an engine running signal.  Can anyone tell me from experience whether 6AWG will be sufficient for that?  Thanks

 

Full disclosure, I don't have an Orion-Tr.   However, looking at demo on the Victron connect app, you can adjust the engine running detect parameters to work with the voltage drop in your cables, unless your alternator output is REALLY low.  

[Ruck_and_Roll]

I have the 6awg and the last time I checked I was getting about 25amps.  Was good enough for me.

[CatButt]

Slightly confused on adding a portable to a series wired roof configuration. If all the panels are running via the controller why is a portable a no go here? Isn't just additional current into the controller? 

[Jon R]

Full disclosure, I don't have an Orion-Tr.   However, looking at demo on the Victron connect app, you can adjust the engine running detect parameters to work with the voltage drop in your cables, unless your alternator output is REALLY low.  

Agreed, the engine running detection parameter can be adjusted, but you can't set the engine running detection voltage to be lower than the voltage at the Orion from the truck battery when the truck is shut down and the Orion is drawing no current.  Otherwise the Orion will cycle on and off while the truck is off.  So you need the voltage at the Orion with engine running and the Orion drawing 35 amps to be high enough above the voltage at the Orion with the truck shut down so that the engine running detection voltage can be set between the shutdown no-current voltage at the Orion and the voltage at the Orion when drawing 35 amps with the engine running.  Otherwise you need a dedicated engine running detection wire to the Orion.  

 

The cable resistance data can be used to estimate the voltage drop (as Vic did), but the connections probably add some resistance as well.  Based on Vic's figures and similar calculations using the data provided for that specific wire I'm probably good with the 6AWG for the entire run.  However, I was hoping for someone to be able to tell me they have a similar setup and confirm it works without the engine running detection wire.  Thanks for the helpful responses. 

[rando]

Slightly confused on adding a portable to a series wired roof configuration. If all the panels are running via the controller why is a portable a no go here? Isn't just additional current into the controller? 

 

If your existing panels are in series, that would mean that a portable would need to be put in series with the roof panels.     To do that, you need to disconnect the wiring to the roof panels and connect the portable into the circuit, and the reverse to disconnect the portable panel.   Furthermore, all the current from all your panels would be running through the wiring to your portable panel.   

 

So yes it *could* be done, but practically it would be much easier to either run everything in parallel or run a separate charge controller for your portable.

Edited by rando, 11 March 2021 - 07:13 PM.

[rando]

Agreed, the engine running detection parameter can be adjusted, but you can't set the engine running detection voltage to be lower than the voltage at the Orion from the truck battery when the truck is shut down and the Orion is drawing no current.  Otherwise the Orion will cycle on and off while the truck is off.  So you need the voltage at the Orion with engine running and the Orion drawing 35 amps to be high enough above the voltage at the Orion with the truck shut down so that the engine running detection voltage can be set between the shutdown no-current voltage at the Orion and the voltage at the Orion when drawing 35 amps with the engine running.  Otherwise you need a dedicated engine running detection wire to the Orion.  

 

The cable resistance data can be used to estimate the voltage drop (as Vic did), but the connections probably add some resistance as well.  Based on Vic's figures and similar calculations using the data provided for that specific wire I'm probably good with the 6AWG for the entire run.  However, I was hoping for someone to be able to tell me they have a similar setup and confirm it works without the engine running detection wire.  Thanks for the helpful responses. 

 

My understanding is that Victron thought of this situation and have this engine running detection algorithm where they periodically briefly pause the charging (which removes the voltage drop) and see if the resting voltage is above the turn on threshold.  

[Jack]

I've ordered a Victron Orion-Tr 12/12-30 isolated DC to DC charger.  The wire run from the engine compartment to the charger in the battery compartment will be about 26 feet.  The truck is a 2021, so I assume it has a smart alternator.  The truck hasn't arrived yet so I can't measure the alternator output.  I was planning to use Ancor Type 3 marine tinned copper 6AWG wire for that 26 foot run.  While that wire size is certainly adequate for the current the Orion will draw, I'm hoping that size wire will limit the voltage drop sufficiently to allow the engine running detection logic of the Orion to work properly without using a dedicated wire to provide an engine running signal.  Can anyone tell me from experience whether 6AWG will be sufficient for that?  Thanks

I had cycling problems with the stock 10 AWG and the Vic DC-DC. Replaced it with 25' of 8 AWG braided speaker wire direct from truck to the DC-DC (with two 50A thermal breakers and an Anderson connector inline) and it works just fine. 6 AWG should give you plenty of margin.

Edited by Jack, 11 March 2021 - 05:02 PM.

[Tom S]

Help!!!
I just put the camper on and ran the heater all night. It worked great, 25 ah consumed in 14 hours. So 80% remaining. I started the truck and went for a drive. Sure enough it said 78% remaining. Huh? Looking at the monitor with the truck running I am showing negative amps at 14.8 volts. I checked the polarity and it is correct. There is continuity from the the breaker in the engine compartment to the input terminal on the dc2dc charger. Input voltage at the charger is 13.6 compared to 13.7 at the truck battery so that seems correct. Output from the dc2dc charger is 14.8 volts. I checked the shunt and it is wired correctly and I show a positive charge with both solar and shore power. The alternator light comes on on the charger as it should. I just can’t figure out why I get a negative reading on alternator. The battery voltage on the truck doesn’t change so it’s not seeing the 14.8 volts from the charger so the isolation seems to be working.
I have not connected the ignition sensor as I didn’t think this was necessary as I didn’t think my 2015 Tacoma alternator was “smart”. I’m thinking that could be it?
But it also could be that the dc2dc is defective. And also it could be that I’m just not getting the reading correctly on my monitor but I think the odds of this are slim as it is reading correctly in all other modes.
So any ideas? I’m going to read up on the ignition sensor and try a quick and dirty jumper to see if it comes on line. Cheers and thanks in advance.