Battery Upgrade

Denny16

Sharon_is_SAM said:

@RFraer - I know you planned to rearrange your wiring, but I don’t see where your battery switch is located in your diagram in this thread:  https://tab-rv.vanillacommunity.com/discussion/14637/battery-inverter-charger-upgrade#latest

Sharon, your question seems to have been lost in the discussion.  The battery switch is at bottom of the diagram, circled in blue.

Cheers

elbolillo

ScottG said:

elbolillo said:

ScottG said:

There is a rough schematic of the 400 wiring here. This shows that--as is the case for the 320--the battery switch must be ON for the brakes to be powered if the trailer is separated from the tow vehicle.

You could certainly rewire things to make this not be the case, but this is the way every stock T@B has been wired since battery switches became standard equipment.  

Scott. Thanks so much for your comments. You seem to be well versed on the electrical system of the Tabs. So if I wanted to add an additional 12v battery to only operate the brakes in case of breakaway I would need to remove the wires from the bus bar and connect directly to that aux battery, correct?

@elbolillo, yes, that approach would work. Alternatively, if you didn't want to carry a separate battery just for this purpose, you could do the same thing but just wire the breakaway brake switch leads directly back to the existing house battery.

Another option--albeit one that is a bit more complicated--would be to relocate the battery switch to the line between the junction box and the power center. That was where I placed mine back before battery switches were standard equipment. This arrangement allows you to disconnect only the power center while leaving the battery connected to the breakaway brakes (for safety purposes) and the tow vehicle (for charging purposes) at all times.

Or you could just remember to leave your battery on at all times when towing.  :-)   

Thanks for the tips. I’ll probably go the second route and direct wire into the house battery. With my tow vehicle connected and the battery switch on it draws down the two Battleborn batteries on my Tab.

VictoriaP

So for those of us who know nothing at all about wiring: is there not a way to control power through the 7 pin so that power only flows from TV —> Trailer and not from Trailer —> TV?

AnOldUR

elbolillo said:

With my tow vehicle connected and the battery switch on it draws down the two Battleborn batteries on my Tab.

I'm not that good with electronics, but this doesn't seem to be right. Anyone know why this would happen?

Denny16

@VictoriaP, and @elbolillo, electricity can flow both directions, but normally from a source to a load.  The source in this case is a battery, either the TaB’s or the TV.  When two battereis are connected together, as when you connect the TV to the TaB, the battery with the higher voltage will charge the one will less voltage, until they equalize.  When a load is applied, lights, brakes, fridge… power will flow from the batteries to that load.  

You can regulate direction, in the case of a TV connected to the trailer, so power only goes from TV to the trailer, and the TV will not get power from the trailer — you add a diode regulator/controller between the TV and trailer, to prevent power from flowing to the TV from the trailer.  The diode works like a check valve, only allowing electrons to flow in one direction.
cheers

RFraer

VictoriaP said:

So for those of us who know nothing at all about wiring: is there not a way to control power through the 7 pin so that power only flows from TV —> Trailer and not from Trailer —> TV?

The only thing that I have some experience with would disconnect the batteries. Victron Orion-Tr Smart 12/12-18A DC-DC Charger. It has engine shutdown detection, when you turn off your vehicle the charger senses the voltage drop and turns off the connection between the batteries. Last week I installed an Orion-Tr Smart 12/12-30A DC-DC Charger but I did not go through the 7 pin because the wire gauge would not support 30A. I added a Anderson connector between the Tow and camper. The engine shutdown detection works great and is completely adjustable through Bluetooth.

pthomas745

The question is: does your tow vehicle have an "isolation relay" that prevents drawing power from the tow vehicle or having power drained from the trailer battery when the trailer and tow vehicle are connected. (Batteries of different charge states will try to "balance" their charges until they are equal.)

How to test for an isolation relay in this comment..the Mouseketab comment:

https://tab-rv.vanillacommunity.com/discussion/comment/138756/#Comment_138756

elbolillo

pthomas745 said:

The question is: does your tow vehicle have an "isolation relay" that prevents drawing power from the tow vehicle or having power drained from the trailer battery when the trailer and tow vehicle are connected. (Batteries of different charge states will try to "balance" their charges until they are equal.)

How to test for an isolation relay in this comment..the Mouseketab comment:

https://tab-rv.vanillacommunity.com/discussion/comment/138756/#Comment_138756

The interesting thing is that the tow vehicle only starts to draw down the camper batteries when I am actively towing. At idle it does not happen. 

JeffroNC

@Dutch061 I just did this mod with the stock batteries. i got the 30a version. I went from 2 to 25 amps with the trailer battery at 60%. 

RFraer

elbolillo said:

pthomas745 said:

The question is: does your tow vehicle have an "isolation relay" that prevents drawing power from the tow vehicle or having power drained from the trailer battery when the trailer and tow vehicle are connected. (Batteries of different charge states will try to "balance" their charges until they are equal.)

How to test for an isolation relay in this comment..the Mouseketab comment:

https://tab-rv.vanillacommunity.com/discussion/comment/138756/#Comment_138756

The interesting thing is that the tow vehicle only starts to draw down the camper batteries when I am actively towing. At idle it does not happen. 

This is complete speculation on my part but what might be happening is that you have a smart alternator on your Honda Pilot so it shuts down when it senses a full vehicle battery charge and runs totally off the battery. Your Lithium batteries have a higher voltage then the vehicle battery so your camper batteries also providing current to the vehicle. When the camper and tow batteries equalized and drop to a set voltage the alternator senses the voltage drop and turns back on. Putting a charge controller particularly a smart one between the camper and tow might solve this. The Victron Orion can be set for a smart alternator giving it a load so it stays on.  

elbolillo

RFraer said:

elbolillo said:

pthomas745 said:

The question is: does your tow vehicle have an "isolation relay" that prevents drawing power from the tow vehicle or having power drained from the trailer battery when the trailer and tow vehicle are connected. (Batteries of different charge states will try to "balance" their charges until they are equal.)

How to test for an isolation relay in this comment..the Mouseketab comment:

https://tab-rv.vanillacommunity.com/discussion/comment/138756/#Comment_138756

The interesting thing is that the tow vehicle only starts to draw down the camper batteries when I am actively towing. At idle it does not happen. 

This is complete speculation on my part but what might be happening is that you have a smart alternator on your Honda Pilot so it shuts down when it senses a full vehicle battery charge and runs totally off the battery. Your Lithium batteries have a higher voltage then the vehicle battery so your camper batteries also providing current to the vehicle. When the camper and tow batteries equalized and drop to a set voltage the alternator senses the voltage drop and turns back on. Putting a charge controller particularly a smart one between the camper and tow might solve this. The Victron Orion can be set for a smart alternator giving it a load so it stays on.  

Yeah. Who knows. Seems like this is an issue that knows no end. I was just trying to avoid having to add one more thing to my setup. IDK

ChanW

@VictoriaP,
Commonly, when the is no 'isolation relay', the TV electrical system and the trailer electrical system are interconnected so that the batteries work in tandem, both discharging and charging together, depending on the overall draw (or lack of) in the system.
So if your Tab is drawing on the system, it's drawing on both the Tab battery and the TV battery together.
This can be a problem if, for example, you leave the three-way fridge turned on in 12V and shut off the TV's engine for lunch. The 11A draw of the three-way can deplete your car battery over a long lunch! (BTDT)
The isolation relay will shut off the connection to the trailer if the TV's alternator is not putting out enough voltage to charge the Tab's battery - ie: when the engine is not running.
If your TV doesn't have an isolation relay, as ours didn't, you can install one. The one we have is "Blue Sea Systems", and works well. Any good auto-electrical mechanic could install it for you.

VictoriaP said:

So for those of us who know nothing at all about wiring: is there not a way to control power through the 7 pin so that power only flows from TV —> Trailer and not from Trailer —> TV?

Dutch061

To help better understand the reason current flows from the RV to the Tow Vehicle when you have Battleborn (or other Lithium batteries) instead of using voltage and amperage use pressure and flow.

Where Voltage = Pressure and Amperage = Flow

The Battleborn batteries (and other Lithium batteries) have a higher voltage (pressure) than your TV, so the tendency is for the "pressure to equalize". Which in this case unfortunately means that the current flow will be from the RV to the TV instead of the other way around. 

This is caused mainly by 1 thing but amplified by a combination of others.

The main cause would be the charging voltage (pressure) for your TV is at a lower rate of voltage (pressure) than your Lithium batteries desire. The exception would be if you were in a very cold ambient temperature which causes the charging system voltage to increase. However, by the time you get to a low enough temperature, your Lithium battery BMS (Battery Management System) should have triggered the Low Temperature Cut-Out to prevent charging and damage.

Things that amplify or add to this.

1. Smart Alternator - some newer vehicles will actually reduce the charging system voltage below what is considered normal for improved fuel economy. Yes, it takes some power to spin an alternator, especially when the amperage output (flow) is high.

2. The gauge of wiring between the 7-pin connector at the rear of the vehicle and the source

3. Isolation relay - in other words is the power source of the 7-pin connector removed if the TV engine is not running.

4. Quality of connection in all of the contact points

Things to consider and or correct the issue.

1. What gauge of wire is used between the source and the 7-pin connector on my TV? On my 2021 F-250 it is 12-gauge wire.

2. Is there an isolation relay on my TV, if not do I need to add one or can I remember to disconnect the 7-pin connecter each time I stop to prevent battery discharge. 

3. Is my vehicle equipped with a "smart alternator"?

4. How much amperage can I safely pull from my TV to charge the batteries? This will be limited by either the gauge of wire between the source and the 7-pin connector and/or the alternator.

Simplest Solution - (Brad's opinion)

Since NuCamp already uses Victron for a Solar Charge Controller, and many have added a Victron BMV-712 Shunt to their RV; the simplest and most flexible solution is to use a Victron Orion DC-to DC Charge Controller. There are several versions offered with the biggest difference being "Isolated VS non-Isolated".

This simply means this: Isolated has 4 terminals and non-Isolated only has 3. The non-Isolated shares a common ground while the isolated has a separate ground for each circuit. However, the Bluetooth (Smart Series) is on available in the Isolated Version (as far as I was able to determine, but I didn't spend loads of time looking either). 

Since I didn't want to have to buy anything else (IE Serial Cable or other) for programming the Controller, I opted for the Smart Series that is Isolated. Even though I tied the 2 grounds together and connected them to the same ground location. 

The Victron Smart Series (Orion) is easily configured using the Victron App on any smart phone or tablet. Set up is simple, a matter of setting output voltage and times. There are also settings for the type of Alternator and an engine running detection that is easy to configure. In my case where I have an isolation relay between the source and the 7-pin connector, I turned the engine running detection off because it is not necessary. 

This device does the following things.

1. It sets the output voltage to the proper level (which is 14.6 volts for Battleborn) to charge Lithium batteries

2. It adds isolation relay functionality to those vehicles that are not equipped, no more concerns about TV battery discharge if you forget to disconnect the 7-pin.

3. The Controller limits the amount of amperage that can be drawn from the TV, which is very useful if you have upgraded the wire size between the source and 7-pin connector on your TV; or if you have bypassed it and added an additional power and ground wire to the rear of your TV. 

For my application, I chose the 18 Amp DC-to-DC Charge Controller since my TV is equipped with 12-gauge wiring from the source to the 7-pin connector. To use the 30-amp version, you would want to have a minimum of 10-gauge wiring and depending on the distance, possibly even as large as 6 gauge. 

Bottom line, I was able to go from 1 to 3 amps of charging rate to the full 18 amps. The installation and configuration took less time than it took to clean my 7-pin connector. 

***Disclaimer*** I do not work for nor am I compensated by Victron; I like their stuff because it simply works!

Brad

elbolillo

Dutch061 said:

To help better understand the reason current flows from the RV to the Tow Vehicle when you have Battleborn (or other Lithium batteries) instead of using voltage and amperage use pressure and flow.

Where Voltage = Pressure and Amperage = Flow

The Battleborn batteries (and other Lithium batteries) have a higher voltage (pressure) than your TV, so the tendency is for the "pressure to equalize". Which in this case unfortunately means that the current flow will be from the RV to the TV instead of the other way around. 

This is caused mainly by 1 thing but amplified by a combination of others.

The main cause would be the charging voltage (pressure) for your TV is at a lower rate of voltage (pressure) than your Lithium batteries desire. The exception would be if you were in a very cold ambient temperature which causes the charging system voltage to increase. However, by the time you get to a low enough temperature, your Lithium battery BMS (Battery Management System) should have triggered the Low Temperature Cut-Out to prevent charging and damage.

Things that amplify or add to this.

1. Smart Alternator - some newer vehicles will actually reduce the charging system voltage below what is considered normal for improved fuel economy. Yes, it takes some power to spin an alternator, especially when the amperage output (flow) is high.

2. The gauge of wiring between the 7-pin connector at the rear of the vehicle and the source

3. Isolation relay - in other words is the power source of the 7-pin connector removed if the TV engine is not running.

4. Quality of connection in all of the contact points

Things to consider and or correct the issue.

1. What gauge of wire is used between the source and the 7-pin connector on my TV? On my 2021 F-250 it is 12-gauge wire.

2. Is there an isolation relay on my TV, if not do I need to add one or can I remember to disconnect the 7-pin connecter each time I stop to prevent battery discharge. 

3. Is my vehicle equipped with a "smart alternator"?

4. How much amperage can I safely pull from my TV to charge the batteries? This will be limited by either the gauge of wire between the source and the 7-pin connector and/or the alternator.

Simplest Solution - (Brad's opinion)

Since NuCamp already uses Victron for a Solar Charge Controller, and many have added a Victron BMV-712 Shunt to their RV; the simplest and most flexible solution is to use a Victron Orion DC-to DC Charge Controller. There are several versions offered with the biggest difference being "Isolated VS non-Isolated".

This simply means this: Isolated has 4 terminals and non-Isolated only has 3. The non-Isolated shares a common ground while the isolated has a separate ground for each circuit. However, the Bluetooth (Smart Series) is on available in the Isolated Version (as far as I was able to determine, but I didn't spend loads of time looking either). 

Since I didn't want to have to buy anything else (IE Serial Cable or other) for programming the Controller, I opted for the Smart Series that is Isolated. Even though I tied the 2 grounds together and connected them to the same ground location. 

The Victron Smart Series (Orion) is easily configured using the Victron App on any smart phone or tablet. Set up is simple, a matter of setting output voltage and times. There are also settings for the type of Alternator and an engine running detection that is easy to configure. In my case where I have an isolation relay between the source and the 7-pin connector, I turned the engine running detection off because it is not necessary. 

This device does the following things.

1. It sets the output voltage to the proper level (which is 14.6 volts for Battleborn) to charge Lithium batteries

2. It adds isolation relay functionality to those vehicles that are not equipped, no more concerns about TV battery discharge if you forget to disconnect the 7-pin.

3. The Controller limits the amount of amperage that can be drawn from the TV, which is very useful if you have upgraded the wire size between the source and 7-pin connector on your TV; or if you have bypassed it and added an additional power and ground wire to the rear of your TV. 

For my application, I chose the 18 Amp DC-to-DC Charge Controller since my TV is equipped with 12-gauge wiring from the source to the 7-pin connector. To use the 30-amp version, you would want to have a minimum of 10-gauge wiring and depending on the distance, possibly even as large as 6 gauge. 

Bottom line, I was able to go from 1 to 3 amps of charging rate to the full 18 amps. The installation and configuration took less time than it took to clean my 7-pin connector. 

***Disclaimer*** I do not work for nor am I compensated by Victron; I like their stuff because it simply works!

Brad

Brad. Yeah I have been investigating the Victon Orion but just didn’t want to add yet another piece of hardware. But this might be my best bet.