Keyline Voltage Sensitive Relay (VSR) Vs. TRIK-L-START/AMP-L-Start)

[imnprsd]

I keep seeing threads from people who want to charge there house batteries off the alternator.

...And the most common answer (belief) is that you should buy an AMP-L-START (for lithium batteries) or TRIK-L-START module and wire it to your coach solenoids.

...What I would like to know is if this Trik system only works with the key-on?

Apparently, people seem to be happy with this approach, but I have read about these things failing. Or maybe I'm mixing that up with the B.I.R.D. systems installed on older RVs?

If we accept the TRIK-L or AMP-L works when you are driving to keep your chassis and house batteries charged, will it also work when you put your RV in storage and the key is off?

MY SET-UP IS DIFFERENT

I have been using the Keyline VSR to join my 2 battery banks together for over 5 years and it has been working flawlessly. However, I can only recommend this approach if your house and chassis battery banks are right next to one another -- so your connection cables are only a few feet long.

...And when I put my coach in storage I use a Victron 17A battery charger, connected to my house battery bank only, which doubles as a battery maintainer. And with shore power in storage, I just turn off my BDS and both my battery banks (chassis and house) are fully charged when I return to pickup my coach 6-7 months later.

The cost of the KeyLine is in the $85 range, but there are less expensive knockoffs on Amazon too. However, I would still by the KeyLine VSR over these other brands, that look the same BTW, just to be sure I got "qualified" vendors in China who build this stuff.

...And I love the Victron 17A charger too!

The Victron is now my primary charger when I have shore power for 2-3 or more days... and using the Victron means I turn my Dimensions charger off.

Another reason I like the Victron is that I hope this will extend the life of my Dimensions inverter side since it's the Dimensions charger side that is more likely to fail over time. Plus a slow charge from the Victron is always better vs. a fast FLA battery charge off the Dimensions, but I can still use the Dimensions to fast-charge my battery bank when I need to. I just rarely do.

And since I have a "Tip Out-Window" in my bedroom this makes it real easy to fish an extension cord into the bedroom where my Victron is mounted. (Note: If you go this route, I recommend you add a 1/8" plastic spacer so the Victron is not touching the wood.)

Back to the Keyline function: The term "VSR" is not that common. Blue Sea calls their device a "battery isolator" but I think they function the same.

Summary: Help me understand how these BIRD devices work?

* Is a a Trik-L or Amp-L also called a B.I.R.D.?

* Does a Trik-L or Amp-L need the key to be on in order to join the 2 battery banks together?

* Is there any benefits to installing a Trik-L or Amp-L? The only once I can think of is if your batteries are hard to get to and if your solenoids are mounted in the front of your coach.

Note: My solenoids are mounted behind a metal plate and it's somewhat of a pain to access vs. installing the Keyline next to my battery trays which are stacked on top of each other.

==> So maybe your choice of devices will depend on access and installation difficulty?

* In order for the Trik-L or Amp-L to work, do you need 3 solenoids as shown in the picture below?

...Or can you get away with just 2 solenoids (a BDS and Boost solenoid) which is what I have in my 2004 Itasca Horizon 40AD.

* How much do these Trik-L or Amp-L cost?

I'm asking these questions, because I would think the goal is to find a battery isolator that is cheap, reliable, and will last a long time.

==> And I would also like to think I do not have to hook up 2 battery maintainers when my coach is put in storage.

==> I do not own a Trik-L or Amp-L device, but I can tell you I satisfied these goals buy installing a Keyline VSR for $80 and a Victron 17A charger/maintainer for $135, and with the Victron I now have bluetooth control and display information on my cell phone, which I like very much!

So if there is an advocate out there who to explain why the Trik-L or Amp-L is better than the Keyline VSR, please let us know why?

=== Parts ===

Victron IC67 (17A) Charger/Maintainer ($135):

https://www.amazon.com/Victron-Blue...=1&keywords=Victron+17A&qid=1618249706&sr=8-1

KeyLine VSR ($80)

https://www.amazon.com/Dual-Battery...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[cbeierl]

...
Summary: Help me understand how these BIRD devices work?

* Is a a Trik-L or Amp-L also called a B.I.R.D.?

No, Trik-l-Start/Amp-L-Start are different from a B.I.R.D. (Bi-Directional Isolator Relay Delay). You can see details about each at these links: Trik-L-Start Intellitec Product DataSheet

...
* Does a Trik-L or Amp-L need the key to be on in order to join the 2 battery banks together?

No.

...
* Is there any benefits to installing a Trik-L or Amp-L? The only once I can think of is if your batteries are hard to get to and if your solenoids are mounted in the front of your coach.

Note: My solenoids are mounted behind a metal plate and it's somewhat of a pain to access vs. installing the Keyline next to my battery trays which are stacked on top of each other.

==> So maybe your choice of devices will depend on access and installation difficulty?

The whole point of the Trik-L-Start/Amp-L-Start is to charge the chassis batteries whenever the coach batteries are being charged. Once installed, there is no need to access the device at all.

...
* In order for the Trik-L or Amp-L to work, do you need 3 solenoids as shown in the picture below?

...Or can you get away with just 2 solenoids (a BDS and Boost solenoid) which is what I have in my 2004 Itasca Horizon 40AD.

No, you don't need ANY solenoids to install the Trik-L-Start (or Amp-L-Start). The solenoids just happen to be a convenient spot and where Winnebago installs/recommends installing the Trik-L-Start. (You can see my install in the left front compartment of my 2005 Vectra in the two pictures attached below--no solenoids involved!)

...
* How much do these Trik-L or Amp-L cost?
...

Current price on the LSL Products page is $54.95 for the Trik-L-Start. It looks like the Amp-L-Start is $72.95.

 

[imnprsd]

Cbeierl: Thanks for clarifying the BIRD is not the same as a TRIK-L or AMP-L.

* Is the TRIK-L or AMP-L considered a "battery isolator?"

* When one of these is installed, and your coach goes in storage, and you connect a battery maintainer to the one battery bank, will it charge the other battery bank too?

I.e., does the TRIK-L or AMP-L join both battery banks together just like the KeyLine VSR (aka battery isolator)?

Also, I see your 2005 Winnebago Vectra 36RD has a 12V chassis fuse panel located in front of the driver's side tire. And the pictures you posted above show the front of the panel and the back side. Are there 3 wires: Blue, Black & Yellow? ...What fuses did you connect the TRIK-L wires to?

Better still, do you have have a circuit diagram on how you connected your TRIK-L device you can share?

Do have solenoids in the inverter bay located behind the driver's side rear tire?

Are your batteries up front (passenger side) or back by the water tank in the rear?

Finally, since the gauge of the wire to the TRIK-L is not that thick, how many amps do you think are being passed through? ...And how many driving hours do you think it would take to recharge 200AH (which is about 50% of a 420AH house battery bank)?

 

[cbeierl]

Cbeierl: Thanks for clarifying the BIRD is not the same as a TRIK-L or AMP-L.

* Is the TRIK-L or AMP-L considered a "battery isolator?"

* When one of these is installed, and your coach goes in storage, and you connect a battery maintainer to the one battery bank, will it charge the other battery bank too?

I.e., does the TRIK-L or AMP-L join both battery banks together just like the KeyLine VSR (aka battery isolator)?

Also, I see your 2005 Winnebago Vectra 36RD has a 12V chassis fuse panel located in front of the driver's side tire. And the pictures you posted above show the front of the panel and the back side. Are there 3 wires: Blue, Black & Yellow? ...What fuses did you connect the TRIK-L wires to?

Better still, do you have have a circuit diagram on how you connected your TRIK-L device you can share?

Do have solenoids in the inverter bay located behind the driver's side rear tire?

Are your batteries up front (passenger side) or back by the water tank in the rear?

Finally, since the gauge of the wire to the TRIK-L is not that thick, how many amps do you think are being passed through? ...And how many driving hours do you think it would take to recharge 200AH (which is about 50% of a 420AH house battery bank)?

No, I don't think the Trik-Ls would be considered 'battery isolators'.

If you connect a battery maintainer to the coach/house batteries, then yes, the Trik-L-Start would charge the chassis batteries. It only does that when the coach batteries are actually being charged, so it can't run down your coach batteries when they're not being charged. If however, you connected your maintainer to the chassis batteries the Trik-L-Start would NOT charge the coach batteries--it's a one-way-only smart device.

Just three wires on the Trik-L-Start. I have both Coach and Chassis battery buses available to me in that compartment (see attached wiring diagram).

Yes, my solenoids are in the left rear powercord compartment. My batteries are to the rear of the right rear tires.

The original Trik-L-Start would charge at 5amps, but the LSL Products web site indicates the the current version of the Trik-L-Start charges at twice that (10amps).

Driving hours don't make an difference, since when the engine is running the battery banks are connected together via the Boost Solenoid and both banks are thus charged by the alternator. Remember, the Trik-L-Start just siphons a small charge from the Coach batteries to the Chassis batteries, BUT only when the former are being charged. My coach is plugged in next to my house when not in use, and the Trik-L-Start keeps the Chassis batteries topped up nicely.

 

[imnprsd]

I'm still not complete sure how this TRIK-L works. ...So if I'm following you right:

The TRIK-L is a relay that joins the chassis battery to the house battery when the alternator is producing more than 13.2V.

Does the TRIK-L get any trigger from the ignition key switch?
...I'm guessing not. IDK?

What do the 3 wires from the TRIK-L go to:

Yellow ==> ??? House battery
Black ==> ??? Ground
Blue ==> ??? Chassis Battery

Note: Those wires look a little light to be pushing 10A through them! ...Maybe your model is a 5A version. Do you know?

I know a 12V battery will never be above 13V at rest. So anytime the voltage is above 13V this applies there is some sort of charging source involved.

And if the TRIK-L is a one way relay then I'm guessing you would want to put your battery maintainer on the chassis side battery (engine battery) when you store your coach; and then, presumably, some amount of charging current will also charge your house batteries thru the TRIK-L relay.

Cbeierl: Is this what you do when you put your coach in storage? ...You put your 110V charger/maintainer on the engine battery?

So what happens when your solar charge controller is connected to the house battery? ...Does the TRIK-L open so the engine battery can also get some of this charging current? (Apparently not if it is a one what relay that only senses the voltage of the engine battery to decide if it opens the relay to join the two batteries together.)

As for driving time. I think this matters a lot. I.e., if you want your alternator to charge your house batteries while you drive, and I do, then it begs the question: If my house batteries are down 200AH, because I just pulled away from my dry camping spot, and I want my alternator to charge the house battery when I am driving; then it would take 20+ hours of driving time at 10A of TRIK-L leakage current to bring my house batteries up to full charge. And that does not sound good to me, because I only drive about 4-6 hours/day... and in-between overnight stops.

Note: If the TRIK-L only passes 5A then it would take 40+ hours of driving time to replenish 200AH in your depleted house battery bank. And I really don't like the sound of that!

Have I got that right?

 

[cbeierl]

See the attached wiring illustration (from the Trik-L-Start link posted earlier). The Trik-L-Start doesn't join the battery banks together--it's a one-way link from the Coach/House batteries to the Chassis batteries that sends a 5amp (original version like I have or 10amp for the current Rev F 'Mega' version) charging current to the Chassis batteries ONLY when the Coach batteries are being charged. I would recommend reading the Trik-L-Start FAQ on the LSL Products site--lots of good info there.

You would put your battery maintainer, converter, charger, etc. on the Coach/House batteries and then let the Trik-L-Start trickle charge the Chassis batteries.

My coach is always plugged in next to my house, so the 3 Coach/House Deep Cycle AGM batteries are maintained by the Inverter/Charger in my coach (a Xantrex RS2000 Pure Sine Wave unit which replaced the OEM Dimensions unit). The Trik-L-Start then acts as a trickle charger for my 2 Chassis Maintenance Free Starter batteries, keeping them topped up as well.

The Trik-L-Start would also pass along a little bit of charge from the little OEM solar panel as well, as it would for any other charging source for the Coach/House batteries. [It looks at the voltage on the Coach/House batteries, NOT the Chassis batteries, to determine if it will charge the Chassis batteries. (Actually, I don't know if it looks at the Chassis battery voltage as well, but this is effectively what it does.)]

To repeat, the Trik-L-Start ISN'T INVOLVED when the engine is running. In that case the Coach/House and Chassis batteries ARE connected together by the Battery Boost Solenoid and the Alternator charges both sets of batteries. [If the Battery Boost Solenoid has failed, as it has in many older coaches, this charging won't happen until the solenoid is replaced.] [This is the way our Winnebago's are set up.]

 

[imnprsd]

THANK YOU FOR SHARING THE TRIK-L DATA SHEET WITH US! (See pdf attached.)

This is what it says:

HOW DOES TRIK-L-START™ WORK? TRIK-L-START™ is a "diversion charger" - Basically, it "steals" a little bit of current from your house battery charger, diverting it to keep your engine starting battery(s) charged. Since it is DC-powered, it does not require any direct connection to AC power - No extension cords or AC wiring required.

WILL TRIK-L-START™ WORK WITH MY DIESEL (OR GASOLINE) STARTING BATTERIES? Yes, TRIK-L-START™ is designed for both diesel and gas engines, and works with either single or multiple starting batteries. Its robust 10 amp maximum output is powerful enough to keep even the largest Cummins/Cat/Detroit Diesel dual-battery bank fully charged, but won't overcharge the single starting battery used with most gas-engine motorcoaches.

DOES TRIK-L-START™ EVER NEED TO BE TURNED OFF OR DISCONNECTED? No, most owners leave TRIK-L-START™ connected all the time. Unlike most AC-powered chargers, TRIK-L-START™ causes no significant drain on your batteries when it's not charging. When you're dry-camped, no current is allowed to flow in the reverse direction (i.e., from the starting to house batteries), so your engine always has full cranking power - even if your house batteries are completely discharged. Finally, TRIK-L-START™ does not interfere with the normal operation of your engine alternator while you're driving. It's completely worry-free - Install it, and forget it!

WILL TRIK-L-START™ OVERCHARGE MY BATTERIES? No, TRIK-L-START™ maintains your starting battery(s) at approximately 0.2 volts below your house battery voltage. This is considered to be the ideal setting for starting batteries, and virtually eliminates water loss and gassing. Maintained in this manner, your starting battery(s) should last for many years.

I STORE MY MOTOR HOME WITHOUT ANY AC HOOKUPS. CAN TRIK-L-START™ BE USED TO DRAW POWER FROM MY HOUSE BATTERIES TO KEEP MY STARTING BATTERIES CHARGED? No, TRIK-L-START™ only works when there is a house battery charging source (i.e., DC power converter, inverter/charger or solar panels) present. In the absence of this charging source, TRIK-L-START™ is effectively disconnected, and doesn't supply any charge to your starting battery(s).

===== MY CONCLUSIONS ====

* The TRIK-L or AMP-L are not battery isolators. They are as their name implies, simple trickle devices, but now apparently can deliver up to 10A of current... from the house battery to the engine battery. However, I don't see what 10A will do better than 5A if this is only a one way device.

* And that means your Alternator does not charge the house batteries at all.

* So why people keep pushing these TRIK-L devices over the KeyLine VSR is beyond me.

I guess it's just for storage! I.e., when you hook up a charger to your house battery the TRIK-L will maintain your engine battery. (And 5A is plenty for this purpose.)

NOW WE ALL KNOW. BUY THE KEYLINE VSR if you want your alternator to charge your house batteries.

And here's another data point, when you join the House Battery to the Engine Battery through a KeyLine VSR, then the two banks will fight each other for the available charge current. And when one is full the other will take that charge.

So when I get done boondocking and hit the road with a full engine battery...thanks to my solar panels and the Keyline VSR... I drive 4-6 houre and when I arrive at my overnight spot, on my way to ????, I always start with a fully charged house battery to get me through the night.

A) I'm guessing my Alternator is pumping 20A through the Keyline VSR to the house batteries, but I really don't know.

However, I will measure it the next time my house batteries get depleted by 200AH and I will let you know.

My 400W of solar is putting out 0-20A depending on the amount of sun and other factors, but lets say I get 100AH/day out of this setup.

So this is why I only need to drive 4-5 hours to completely recharge 200AH with my alternator, with my solar panels working together.

And as mentioned earlier, this is why I always start every day on the road with a fresh battery bank, and when the sun is not shinning I need to run my generator.

===

Now that I have read the TRIK-L Data Sheet (see attached) I have to say, everyone who has one of these needs also needs a KeyLine VSR... and they really need one of these if they have solar on their roof.

And if you store your coach outside, then the solar power will keep both battery banks charged if you install a KeyLine VSR too.

[BIMHO, I would say the Keyline is far superior to the TRIK-L or AMP-L device; and I don't know why people keep recommending the TRIK-L or AMP-L?[/B]

...And frankly, would remove the TRIK-L box if you install the KeyLine VSR, because you don't need it any more.

...The KeyLine VSR is a bi-directional battery isolator that will open whenever either battery bank is above 13.3V and cuts out at 12.8V. See more information below; and if I miss quoted or made any false claims, please let me know.

Note: The diagram below is for a Blue Sea Battery Isolator that has slightly different Voltage cut-in and cutout numbers vs. the KeyLine VSR, but the principles are the same. And either the Keyline or the BlueSea is a good choice. The Blue See is much more expensive, but with competition from Keyline their prices have come down a lot. And if you don't see BlueSea that much, it's because they focus on the sailboat and power boat market.

 

[Bones2003]

===== MY CONCLUSIONS ====

* The TRIK-L or AMP-L are not battery isolators. They are as their name implies, simple trickle devices, but now apparently can deliver up to 10A of current... from the house battery to the engine battery. However, I don't see what 10A will do better than 5A if this is only a one way device.

* And that means your Alternator does not charge the house batteries at all.

* So why people keep pushing these TRIK-L devices over the KeyLine VSR is beyond me.

I guess it's just for storage! I.e., when you hook up a charger to your house battery the TRIK-L will maintain your engine battery. (And 5A is plenty for this purpose.)

On both my 2003 and 2021 coaches, the house batteries automatically charge from the alternator when the engine is running so I don't need any other special device for that purpose. But my chassis battery is not charged from the generator, shore power, or solar when the engine is off. That is why I added a Trik-L-Start. Now while in storage, solar keeps all batteries topped off and during an extended stay at an RV park, shore power keeps all batteries topped off.

 

[imnprsd]

Bones2003: Thanks. Are you saying your ignition key switch "triggers" a relay to join the house battery to the engine battery... when you are driving?

And so... when you park your RV and have genertor or shore power providing 120V to a charger, with the Trik-L device, then you keep both your house and your engine batteries charged up. This confirms the Trik-L is a one-way relay which passes charging amps from the house battery to the engine battery... but at what rate.

Others have said the rate of charge is 5A. And the AMP-L puts out 10A (unverified).

The idea being, the charger will provide 0-100A of charge and the Trik-L will syphon off 5A to maintain the engine battery at full charge.

Okay. This is clear to me. What is not clear is how your house batteries get charged by the Alternator when you are driving. I seriously doubt the house battery is directly connected to the engine battery, because if you ever have a short, then both your house and your engine battery would go dead... leaving you stranded... which would be a bad design.

So there has to be a battery isolator in the circuit since the Trik-L is not going to let charging amps from the battery (alternator charge) to get to the house battery, since we have confirmed the Trik-L is a one way device.

So I'm still looking for answers as to how the house battery gets charged by the alternator in Winnebago RV that came from the factory with this capability?

 

[Bones2003]

Bones2003: Thanks. Are you saying your ignition key switch "triggers" a relay to join the house battery to the engine battery... when you are driving?

Yes, my ignition key triggers something to join the house and engine batteries. I think it uses the "Aux Start Solenoid" which is the same device that is used to connect the house batteries to the engine starter via a switch if the engine battery is dead.

And so... when you park your RV and have genertor or shore power providing 120V to a charger, with the Trik-L device, then you keep both your house and your engine batteries charged up. This confirms the Trik-L is a one-way relay which passes charging amps from the house battery to the engine battery... but at what rate.

The Trik-L-Start is definitely a one way device. It is not a mechanical relay but some type of solid-state electronic device. I ordered my Trik-L-Start in February of 2021 it is labeled Mega Trik-L-Start rev F2 and is rated at 10 Amps maximum charge.

Others have said the rate of charge is 5A. And the AMP-L puts out 10A (unverified).

The idea being, the charger will provide 0-100A of charge and the Trik-L will syphon off 5A to maintain the engine battery at full charge.

Okay. This is clear to me. What is not clear is how your house batteries get charged by the Alternator when you are driving. I seriously doubt the house battery is directly connected to the engine battery, because if you ever have a short, then both your house and your engine battery would go dead... leaving you stranded... which would be a bad design.

So there has to be a battery isolator in the circuit since the Trik-L is not going to let charging amps from the battery (alternator charge) to get to the house battery, since we have confirmed the Trik-L is a one way device.

So I'm still looking for answers as to how the house battery gets charged by the alternator in Winnebago RV that came from the factory with this capability?

As stated above, I think it is via the "Aux Start Solenoid" but that is how my two Ford gas engine Winnebagos have been setup from the factory. I am sure they have used a variety of methods on various motorhomes over the years.

 

[imnprsd]

Then you are saying the house battery is directly connected to the engine battery when driving?

Okay, I buy that.

...I guess my concerns about a short leaving you stranded are not real, because a short while you are diving will only deduce the alternator's ability to charge both the house and engine batteries; and when you are not driving the boost solenoid is isolated from the BDS so any short will only affect that system. I.e., a chassis short (when parked) will drain the engine battery; while a coach system 12V short will only affect the house battery.

That said, a direct connection relies on the internal resistance of each battery bank to resist the charging current, and because of this a Flooded Lead Acid (FLA) battery self-regulates itself. I.e., you can force more current (amps) into a battery than it will allow.

This not true with LiFeO4, which is why there are a number of thread indicating you need a battery isolator to protect your charging circuit.

 

[Journey cat]

Some one made this statement to me .

Those Key line chargers are only good to connect two start batteries together
They have no way to control the current to the second battery .
140 amp is to much current to charge deep cycle batteries .
Also if your ideling when you start up it will overheat your alternator

I contacted KeyLine on that This was there reply

Our isolator reads upstream voltage from the primary battery - the isolator will engage when the voltage of the primary battery is over 13.3 volts and disengage when the voltage of the primary battery is lower than 12.8 volts isolating the start battery from the auxiliary system. In regards to amperage, Our isolator is rated at a constant 140 amps, with a peak of 200 amps. The vast majority of applications will draw a maximum of 40-60 amps at any one time. 220 amps is the maximum output for the alternator that we recommend use with. For reassurance, a 140 amp breaker or fuse to protect the isolator can be used. The only instance of the unit charging in both directions is with a solar panel: when the auxiliary battery is above the start battery in voltage and is above 12.8 volts, the light will remain on and the auxiliary system will be powering the main system. Regardless of if the alternator is engaged or not, the isolator will not isolate until both start and auxiliary batteries are below 12.8V. I hope this helps.

 

[imnprsd]

JourneyCat: I waited answering you until I talked to Keyline designer. .Plus I wanted to take some direct voltage and amp measurements off my house and start battery with the Keyline VSR (Battery Isolator) hooked up and disconnected. And I will get to that conclusion below.

First, I would like to say, the term "Isolator" implies the start battery is "isolated" from the house battery (aka Aux Battery) by a patented Keyline design which has both "cut-in" and "cut-out" voltages as previous discussed.

Note: The Keyline VSR patent expired just a few years ago this is why you are now seeing some Keyline "Knockoffs" on the market for less money, but IMO you should stay with Keyline so you know your VSR is being built by Keyline approved vendors, and to buy from the original company that brought this device to us. Plus the price difference is only $10-$15. So buy the original VSR from Keyline on Amazon or direct from Keyline.

JourneyCat said... another Winnebago Owner made these statements so I will put my rely answers below the following questions:

Those Key line chargers are only good to connect two start batteries together...

==> This is false. The Keyline VSR is NOT a charger and has now boost or buck circuitry in it.

==> There is no such thing as start, house, Aux batteries. They all look like 12V storage devices to the Keyline VSR.

They have no way to control the current to the second battery.

==> True. A "battery isolator" is just a fancy switch, but by design if you have a short in one system that current drain will not decrease the other battery bank, because the "cut-out" voltage limit "opens" and "isolates the two battery banks.

==> When you install the Keyline VSR it basically "joins" positive battery posts, much like what happens whey you jump-start a car; only the VSR add protection circuitry and when you jump a car you have to physically remove the battery cable. With the Keyline VSR you just hook it up and leave it. No ignition switch or trigger switch is needed. So it's "smarter" than a typical relay or non-latching solenoid.

==> The current out of your alternator will not go over what the wires will carry, because the internal resistance of FLA batteries will resist "current runaway."

140 amp is to much current to charge deep cycle batteries .

==> Someone doesn't know what they are talking about. As stated in previous threads your 160A "rated" alternator only put out 45% of that value... if that much. So for simplicity call it 70A and it's regulated DC output is more like 14.2V @ 5-20A.

==> Today I woke up and my house batteries were at 50% SOC. So I started my engine and measured 11A on the wires into and out of the Keyline VSR.

==> With FLA batteries that have high internal resistance, which only increases as the SOC increases -- so you never have to worry about your 160A diesel RV alternator burning up due to too much current flowing to a bank or banks of FLA batteries.

KEYLINE COMMENTS

Today I specifically asked why their literature implies the Keyline VSR only senses the voltage off the primary-start battery... like a one-way switch -- when I know for a fact my Solar Charge Controller increases the house battery voltage from 12.7V to 13.2V when I attach the Keyline VSR cable to my start battery?

==> Keyline's answer: When this VSR was first designed about 15+ years ago there weren't any solar cells on the market; and so all the literature was based on having 2 battery banks (like in a boat) where both can be used as start batteries or one can be a start battery and the other can be an AUX battery used to power your radio. So the concept of a "primary" battery was borne.

==> Keyline confirmed that if you have a Solar Charge Controller, which is a smart battery charger, albeit not always that great of one, then your VSR will pass charge from the house battery bank, thru the KeyLine VSR, to the start battery bank.

==> When my solar panels were putting out 14.8V at 15A... I measured 11A thru my VSR wires; and since the higher voltage source was the solar side, I think it's save to conclude 11A were going from the solar panels to the start batteries.

And since my 2 start batteries are in parallel, that means only 5.5A will go to each battery.

OTHER COMMENTS

==> LiFeO4 batteries do not charge like the FLA batteries and therefore it is recommend you use a DC-DC converter when installing LiFeO4 batteries or be sure your LiFeO4 bank has some BM circuitry built in.

The purpose of the DC-DC Converter are: 1) To isolate and protect; and 2) Increase the output voltage to match the LiFeO4 upper limit of 15.2V (or there bouts) in order to fully charge your LiFeO4 bank.

Note: Normal alternators have internal voltage regulators that will not put out 15.2V, or will burn up the voltage regulator if you run at this upper threshold for a long time.

Note: I need to do some more research on this subject before I comment further. And if I install a LiFeO4 bank of batteries in my RV this year, then I will be able to offer you my feedback.

...But today, I can honestly say, I am completely sold on using the KeyLine VSR over all other isolators on the market that cost less or cost more!

Note: Keyline is in the process of releasing a DC-DC Converter and when this product hits the market I will let you know if I install one.

PS
Maybe after my conversation with Keyline today they will update their Keyline VSR instruction manual, to address comments like those mentioned in this thread. TBD

Many thanks to everyone on both sides of the learning curve! These types of debates helps everyone!