Roadtrek RS Adventurous Inverter Upgrade

[markopolo]

I don't see a problem with 11.4A use on a 15A circuit either. You mentioned also running a Keurig on the same circuit so there could be times when you'd exceed 15A and trip the breaker. You'll know soon enough if running the Keurig on that circuit is a problem or not.

[engnrsrule]

I did some testing on the system operation. The Keurig is on one of the outlets previously fed from the Tripplite. Those outlets are now fed directly from the breaker "F" that originally powered the Tripplite. The new charger is taken directly from ABT 1 output to a single plug outlet, with its own 15a breaker mounted in the box.

I once managed to make coffee off the inverter, but tested today and it tripped the DC breaker feeding the inverter. The microwave also trips the inverter off, so I now know neither of those appliances will run off the inverter.

[booster]

How big is the breaker? We used to run the Dometic microwave in our 190 off a 1500 watt PSW Samlex inverter without issue. I think I had a 250 or 300 amp fuse in the line to it. I think I would get a check on what the amps are at startup to see what is going on. I have been using more fuses lately instead of breakers because of the inaccuracy and sensitivity of most of the reasonably priced breakers I got to try. Good 200-300 amp breakers a into the the triple digit price in most cases.

[engnrsrule]

I was mistaken, my DC breaker is 180a, though the inverter input rating says 150a. A 50a would only support 600w. I will take another look at it, may try replacing it with a fuse and see. Thanks.

[booster]

Originally Posted by engnrsrule

I was mistaken, my DC breaker is 180a, though the inverter input rating says 150a. A 50a would only support 600w. I will take another look at it, may try replacing it with a fuse and see. Thanks.

Generally, on things with starting surge as much as 100% over rated might be needed in a fast blow breaker or fuse. Slow blow and you can go much closer. I would go at least 200 amps for a test.

[Road Toad]

Originally Posted by engnrsrule

I did some testing on the system operation. The Keurig is on one of the outlets previously fed from the Tripplite. Those outlets are now fed directly from the breaker "F" that originally powered the Tripplite. The new charger is taken directly from ABT 1 output to a single plug outlet, with its own 15a breaker mounted in the box.

I once managed to make coffee off the inverter, but tested today and it tripped the DC breaker feeding the inverter. The microwave also trips the inverter off, so I now know neither of those appliances will run off the inverter.

That is how we did ours too.
https://mightytext.net/zELnAM

[markopolo]

Just for clarification, I was referring to converter plus Keurig use while plugged in to grid power. That's where it could be problematic if both are on the same 15A circuit. A switch that turns the converter on or off might be the easiest workaround if the timing of converter & Keurig use causes the breaker to trip.

[engnrsrule]

Ok, not sure I am understanding you. The Inverter (DC to AC) is powered by the battery with an inline 180a DC breaker. The Converter/Charger (AC to DC) is powered by a new separate branch line from ABT 1 on a 15a AC breaker. Even when the old Tripplite was on same circuit as the keurig, it never tripped the AC breaker when on shore or generator power.

It should be obvious that in no case can the inverter supply power to the charger. (If it could I would be a wealthy man). ABT 2 isolates the grid power feed to the charger when grid power not present.

What happens now is the 180a DC breaker supplying the inverter trips. Per Booster, this is probably due to the low quality of these breakers. In fact the reviews of the one I bought include complaints that it does not carry the rated load. I am going to replace it with a slow-blow fuse that should allow the inverter to run at its peak capacity and see how that goes.

One indicator that this theory is correct is that the inverter never even reaches a point where its fan comes on.

I can run keurig, charger and microwave when RV is plugged into a single 15a at home. Also, although my new charger is rated 5a more than the Tripplite (60 vs 55) that would only be associated with boost mode after batteries are significantly depleted. My normal scenario with Boondocking would have me on the road a few hours, and that usually brings batteries back to 100%. For example, 7 days without grid power had me at 78%. Four hours into trip home batteries were 100%.

[booster]

It just occurred to me that your inverter said it had a 3000 watt surge capacity. That is going to take 250 amps a 12v and 100% efficiency and over 300 amps at 80% efficiency. Add to that the fact that you will likely not come anywhere near close to holding 12v at those kinds of power levels and you would have even more amperage needed.


The 150 amp rating appears to come from using 12v and 80% efficiency to get the 1500 watt 110v output. Again you would probably use much more than that because of voltage drop.


It is looking like you really need to have 4/0 cable from the batteries to inverter and a 300 amp fuse in that line.


You should be able to reduce the voltage drop by running the van engine as long as you have adequate wiring to carry whatever amount the alternator will provide. If a stock Roadtrek that had a Tripplite you may only have 80 amp breakers in that line so you might trip them.


Our Dometic microwave uses in the 90s for amps when running when the voltage holds or the engine is running, and will go up to about 120 when the voltage gets in the 11.0v range, but probably double that when starting. I don't have a meter fast enough to catch the actual peak, though, so just a guess from what I can see.

[markopolo]

Originally Posted by engnrsrule

Ok, not sure I am understanding you. ...................... Even when the old Tripplite was on same circuit as the keurig, it never tripped the AC breaker when on shore or generator power....

Originally Posted by engnrsrule

...........I can run keurig, charger and microwave when RV is plugged into a single 15a at home. Also, although my new charger is rated 5a more than the Tripplite (60 vs 55) that would only be associated with boost mode after batteries are significantly depleted. My normal scenario with Boondocking would have me on the road a few hours, and that usually brings batteries back to 100%. For example, 7 days without grid power had me at 78%. Four hours into trip home batteries were 100%.

I'm not referring to inverter use at all. That's a separate issue which should be solvable.

I'm just not certain of your understanding of this so thought it was worth mentioning. You're doing some advanced stuff here but also mentioned watts when amps were being referred to.

Originally Posted by engnrsrule

........................The old charger was 55W 3-stage and the new one is 60W and 4 stage. So I see that as one might a light bulb. .....................

I assume it was just a typo because I consider what you're doing to be advanced and well beyond the basics.

The Tripp Lite would have a 45A (not watt) charger section and the PD9260C is a 60A (not watt) charger.

On AC
Tripp Lite: 9.3A max
PD9260C: 11.4A max

If running the Tripp Lite plus the Keurig simultaneously was problem free in the past then there's a good chance the PD9260C plus the Keurig simultaneously will be OK. If it turns out that the breaker gets tripped often then adding a switch that turns the converter on or off (off when using Keurig) would be an easy workaround.

Note that the Tripp Lite might be smart and reduce charger output automatically based on throughput when necessary. It's a common feature of inverter/chargers.

I had a coach that had two high current AC items on the same 15A circuit. From memory, it was the water heater and the microwave oven. There was a factory installed toggle switch that enabled one or the other but never both items at the same time.

[booster]

I think Marko is referring to the original setup that had the charger on the same circuit as the inverter circuits of the Roadtrek. I also mentioned this earlier and there was another modification done to put the charger on a standalone 15 amp breaker directly off the first transfer switch so it is not with any other uses.


The changes are shown in an earlier post with a PDF so don't show in the post itself like the other drawings did.

[markopolo]

OK so what was a issue on Dec 1 (my post) was solved by Dec 5 but then queried on Dec 13 by the OP.

If a new circuit was added then the problem was eliminated.

[engnrsrule]

Booster, the GoWise inverter came with relatively light cables. Installation instructions said these were suitable for small loads, and for larger loads consider increased cable size. I installed 4 AWG. Most of the DC cables are 4 or 6 AWG per the system drawing. The Tripplite DC connections were also 4. Those were retained as the output for the PD charger. The main battery negative terminal to shunt and shunt to vehicle ground are 0 AWG. The cables coming from engine into and out of the 12v transfer switch are 6awg.

My thought at this point is to install the 200a fuse just to see if the inverter is capable of running the keurig or microwave. I believe it should be able to without tripping. Recall when the 180a breaker was brand new it did run the keurig. But I also realize that doing so (assuming it is safe electrically) with any regularity is probably costly to my batteries and boodocking capacity. I think based on the cable size I ought to stay with not more than a 150a slow blow. I am not inclined to run 4/0 and go to 300a serving the inverter that says its rating is 12v 150a.

So if not confused enough, lets go back to N-G bonding. I asked GoWise tech support and their answer said a moving vehicle can't be grounded to earth (yea I got that). Seems like they did not understand the question so I do not know if the inverter establishes this bond or not. I can also advise that both my ABTs are H-N switches with a shared ground bus bar.

So starting with ABT1, without shore tie connected, Generator on, makes a NG connection, no problem; connect shore tie (which I believe is the dominant source) with generator still running its active shared ground connection would have a path back to the shore tie neutral, while its hot and neutral would be disconnected. Turn off generator or unplug shore tie, the duplicate path is broken. ***Important to note that this is the "factory" configuration, with the inverter being a downstream subsystem operating on a single circuit.***

Now consider ABT2. The ABT1 (dominant) input is coming with or without a duplicate NG connection as described above. I still don't know if the inverter establishes NG connection, but if it does the shared ground would also have a path to the Inverter's neutral. I see where 3-conductor ABTs would totally eliminate alternative N-G pathways.

But in practice, no one would normally operate with 2 or 3 (or 4 if solar too) of their 110v sources connected/running, and the ABTs prevent their simultaneous connection of Hot and Neutral to the system. I may not be grasping what the real risk/danger is associated with multiple N-G continuities. I have one other observation...in researching ABTs that transfer all 3 poles, I found them mostly in the 50a and above rating, with those less than 50a are all 2-pole. And since these 50a models also have a grounding bar inside, the question becomes are these really designed for a 220v 50a (or higher) application, where the grounding bar continues to be shared across all sources connected to the box, and therefore the potential for multiple N-G connections would continue to exist? My rig is a 30a, 110 only, single bus panel.

[booster]

As I mentioned, the 1500 watts would be 150 amps at 12.0v and about 80% efficiency AT THE INVERTER, and that would not cover the double output of a 3000 watt surge so figure 3000 watt surge will pull about 300 amps if it held the 12.0v.


Now figure that that the batteries will not be able to sustain that kind of load at 12v and will probably be closer to 11.0v and you would be at 170 amps and 340 amps.


Now figure in maybe 1.5v drop in the undersize wiring and you have 9.5v and the inverter will likely go into low voltage shutdown.


I would suggest going to a voltage drop calculator and get the voltage drop per foot for the various cable sizes and amps. Be sure it is a one wire calculator, not a two way, which I got fooled on lately.


Inverters rapidly drop in efficiency with % of rated output and with voltage drop so you could be having lots of issues that way. If the starting surge of the appliance drops the voltage to the inverter you may be getting a distorted sine wave out to the appliance which can cause them to not start or malfunction.


I think you may want to start with getting an AC clamp on meter a see what the Keurig and microwave each use at startup surge and when running. You can then calculate roughly how many DC amps they will use including after putting in efficiency.


It is obvious, I think, that the rating on inverter is not possible if there really is startup surge or even the running rating if the voltage is lower than 12v. That, and not knowing what neutral bonding is quickly would tell me they don't really know what they are doing, sad to say.


As I said, we ran probably the same microwave on a low/mid priced Samlex 1500 PSW inverter without any issues. I think Marko may still have that inverter, even.



With proper wire sizes on both the feed and ground wires to the inverter from the batteries and adequate fusing, a decent PSW inverter should be able to do it.


I may be time to take a step back and start from scratch on specing the system. As Marko said, be sure you fully understand the units being used like watts, amps, volts, ohms etc and how to use the e=ir formula to figure out this stuff. You will be able to calculate the information you need to choose the right wire sizes based on amperage and lengths, including the grounds. At this point, just doing stuff to see if the microwave will run and using that as an AOK is just not a good idea as undersized and mismatched wiring is a definite hazard.


The biggest risk of having a second bonded neutral to ground onboard is in the fact that most of the RVs have the ground for the 110v on the chassis of van with the neutral and hot run as wires. Shore power comes in as 3 wires and then the ground is tied to the chassis. If there is a neutral to ground on board the shore power neutral and bond are as one wire and both will be carrying the neutral current back to the post.



Now imagine that the post develops an open neutral for some reason (a common occurrence). All the neutral current is then running in the ground and through the chassis of the van. If the resistance of the ground is much the voltage of the skin of the van will go to positive compared to earth. If the ground goes open, which is also common, the skin of the ground will go to 110v and be able to seriously injure anyone who touches it while grounded to earth like being is puddle or such. If the resistance of the ground is just high you would get tingled but not dead. The hazard is real, even though a couple bad things have to happen together.


Please don't see this as overly harsh as it is not intended to be, but one thing that has gotten many people into bigger problems is trying to fix a small problem or error with and inadequate fix on top of other fixes. Trying to find a single way to get the system in question to be completely good is probably going to require a full evaluation. My guess is that wiring sizing and fusing will need some changes and perhaps the inverter is just not up to the task. Lots of help available here to take advantage of as all of this is often not totally logical or obvious.

[engnrsrule]

No problem Booster. Must not forget that main motivators here were (1) getting pure sine to run light loads - TV, VCR, Computer, phone chargers, and not necessarily higher loads, directing the inverter output to the whole panel adds flexibility to plug in wherever convenient; and (2) eliminating the GFCI problem inherent in the Tripplite. If my arrangement means I only use 20 or 30% of this inverter's capacity then that's OK.

Bear with me,,,I am still confused over the N-G configuration since original ABT uses a shared neutral which would seem to allow duplicate NG bonds in the scenario you described. So when I imagine an open neutral on the campground post, say the white wire comes loose from the neutral bus, the service to the RV would be interrupted and the RV would go dark, would it not? It would seem to me the last thing you would want on the RV would be any neutral ground connection, if the open neutral at the source was downstream of the grounded neutral, an NG connection on the RV would allow a path to close the circuit via the ground.

[booster]

Originally Posted by engnrsrule

No problem Booster. Must not forget that main motivators here were (1) getting pure sine to run light loads - TV, VCR, Computer, phone chargers, and not necessarily higher loads, directing the inverter output to the whole panel adds flexibility to plug in wherever convenient; and (2) eliminating the GFCI problem inherent in the Tripplite. If my arrangement means I only use 20 or 30% of this inverter's capacity then that's OK.

Bear with me,,,I am still confused over the N-G configuration since original ABT uses a shared neutral which would seem to allow duplicate NG bonds in the scenario you described. So when I imagine an open neutral on the campground post, say the white wire comes loose from the neutral bus, the service to the RV would be interrupted and the RV would go dark, would it not? It would seem to me the last thing you would want on the RV would be any neutral ground connection, if the open neutral at the source was downstream of the grounded neutral, an NG connection on the RV would allow a path to close the circuit via the ground.

Yes, if you have an ABT that uses common grounds and common neutrals you have the potential for a second bond and the hazard that goes with it. I think those setups are why the major generator and inverter makers have made their units autobonding, but even that doesn't eliminate the issue is you forget it on. The certain way is switch both lines like I think you are saying the newer on does as that makes it for sure OK. I think I would replace that first ABT with a double pole version.


Using just a limited amount of the capacity is absolutely OK, it is done all the time. All you do is follow the same procedure as you would for using all the power. Determine the wire size from the usage maximum you need to run and then fuse the wiring to protect the wires from overload. The only problem you will have is that if you have the entire van on the main panel and inverter but with it fused down, you will blow the fuse if someone turns on something larger. This would be normal and needed to protect the wiring. Normally, the inverter would then be on a limited amount of outlets to prevent too many things from running or starting, like Roadtrek did in the OEM wiring for the Tripplite inverter.


On your example if the neutral at the post goes open the van will go dark, unless there is a bonded neutral to ground in the van, that is exactly the point I mentioned. I also mentioned the ground running the load then, but it is also putting whatever voltage is on the ground due to line resistance of the ground to it's full earth ground upstream someplace. If all the ground connections are perfect zero resistance, it will just be the distance of the wiring that sets the voltage, but the resistance is usually much higher than that as even the earth reference ground rods have resistance to the earth and get worse with age. In a good case of open neutral and bonded van you would get tickled if you touch the van skin while touching a good ground, like a water spigot at the campground or such. If the ground line resistance is high the voltage in that same condition can be high enough to injure or kill people. When the inspector came to inspect my shop when I built it, it was required to have it's own earth ground at the building as a ground rod, and he checked the building ground to earth resistance with special test rig. It is considered an outbuilding from the house so is required to NOT have the main breaker panel bonded, just like and RV and for the same reasons.



We have the whole van on our 2000 watt PSW inverter, but for small loads we have two 120 watt PSW inverters, one running a device charging station that has 110vAC and USB and the other to audio cabinet. We only have whatever inverter we need to use turned on at any given time to prevent parasitic losses. The big inverter has a 1.4 amp idling load so that counts up in a hurry and will use as much as our frig in a 24 hr period. With them all off we have zero parasitic from the inverters and with one small one it is only .3amps but still better at zero when it only used a couple hours a day max.

[markopolo]

re: testing for neutral ground bond in an inverter from notes I saved from a rv.net forum topic

I think the test or at least one test to check for NG bond is using a digital (not analog) multimeter on the AC volts setting and the inverter turned on.

If it shows approx 60V hot to ground and approx 60V neutral to ground then it's not bonded.

If it shows 120V from hot to ground and 120V from hot to neutral then it's bonded.

My current understanding is that you can't check for continuity to check for NG bond in an inverter as there are internal components like capacitors that make that type of check unreliable or inconsistent.

Not sure how this helps with the current discussion but hope that it might be useful.

[booster]

Originally Posted by markopolo

re: testing for neutral ground bond in an inverter from notes I saved from a rv.net forum topic

I think the test or at least one test to check for NG bond is using a digital (not analog) multimeter on the AC volts setting and the inverter turned on.

If it shows approx 60V hot to ground and approx 60V neutral to ground then it's not bonded.

If it shows 120V from hot to ground and 120V from hot to neutral then it's bonded.

My current understanding is that you can't check for continuity to check for NG bond in an inverter as there are internal components like capacitors that make that type of check unreliable or inconsistent.

Not sure how this helps with the current discussion but hope that it might be useful.

I have messed a bit with checking with a meter and it is pretty difficult as how much voltage you get on each line if they are bonded can vary a lot based on their actual resistance to ground or to the bonding point. The important part is to check when on shore power, as that is biggest hazard I think and when on shore power you should have no real amount of voltage on the van chassis when measured to earth ground. If neutral and ground are bonded on the van, you will see some voltage based on the line resistance. Probably easier to just look for current on the ground line coming from the van, but you would have to make a cheater cord to get the individual wires to measure the current. If there is any current in the ground to shore outside the van you have a bonded neutral and ground in the van.


The best way of all to know is by having the manufacturer tell you how their bonding is set up. Most are eager to tell you as they know it is a safety thing that can cause them trouble if it goes wrong. That the seller/manufacturer of the unit in this thread couldn't say how it is set up makes one wonder about the whole unit

[engnrsrule]

Originally Posted by markopolo

re: testing for neutral ground bond in an inverter from notes I saved from a rv.net forum topic

I think the test or at least one test to check for NG bond is using a digital (not analog) multimeter on the AC volts setting and the inverter turned on.

If it shows approx 60V hot to ground and approx 60V neutral to ground then it's not bonded.

If it shows 120V from hot to ground and 120V from hot to neutral then it's bonded.

My current understanding is that you can't check for continuity to check for NG bond in an inverter as there are internal components like capacitors that make that type of check unreliable or inconsistent.

Not sure how this helps with the current discussion but hope that it might be useful.

I tested voltage on shore tie and on inverter. H-N 110, H-G 110, N-G 0.

[booster]

Originally Posted by engnrsrule

I tested voltage on shore tie and on inverter. H-N 110, H-G 110, N-G 0.

As Marko said, that should mean it is bonded somewhere, but it won't say where. If you are not plugged into shore power the bond would have to be in the van, but if you are plugged in to shore power it could be either place or both.



I think as long as the neutral of the inverter gets interrupted with the hot, and I think that is what is happening in your second transfer relay, you should be OK even if the inverter is full time bonded or bonds at power on. If the inverter had van power feedthrough, that would be a problem, but it doesn't appear you have anything like that. The transfer relay priority should take care of it.


This doesn't mean, though, that if the autobonding in the generator sticks on it would also be OK. The first transfer switch, if it only switches the hot, would allow bonding at the generator and shore at the same time, I think.