Adding second inverter

[prfleming]

In our 2016 210 I have the underhood generator (aux alternator) and the "minimum 2500 watt" inverter which I think is actually a 3000 watt Power Star LW3000-12 sine wave inverter. In testing that I have done, it can handle about 2000 watts, but as you approach 2500 watts, the voltage drops off considerably. Also, when looking at the waveform on a scope, the sine wave approaches a square wave over 2000 watts. This inverter draws about 6 amps with no load, which limits extended use while dry camping.

I had a Xantrex 2000 watt sine wave inverter collecting dust in the garage so I have installed that and wired it to the Power Star 12V terminals with 2/0 gauge welding cable, and ran a surge protector power strip to the kitchen counter area.

https://www.amazon.com/Xantrex-PROWa...+wave+inverter

The added advantage of this inverter is the low idle current of 800 milliamps, so we can charge our cell phones overnight without worrying about draining the house batteries.

[booster]

What is the purpose of doing that. If the Xantrex is a pure sine wave (you mentioned sine wave) and the other is obviously a modified square wave, who knows what will happen if both are running at the same time. You also now would have two AC power sources, so neutral bonding could get wierd.

The voltage drop you see with the original inverter is typical, especially if you read it with a true RMS meter and is why you get less actual power out of a modified sine wave. The wave form normally gets progressively worse as you approach max output, and the lower quality the unit, the sooner it happens and the worse it gets.

IMO, if you need more output and better wave form, find one inverter that will do the job, and that may be the Xantrex by itself, but I would get rid of the second one.

[prfleming]

Yes, I have considered just replacing the (cheap) Power Star sine wave inverter/charger with a higher powered better quality unit, but I think I will wait a year or 2 as we are still under warranty.

Adding the Xantrex is just temporary, mainly for the low idle current while dry camping. There should be no issue with neutral conflicts, I am just plugging in griddle, induction hot plate, wok, hibatchi grill and keurig on the separate powerstrip when cooking (not all at once of course...! ha ha)

[BBQ]

Originally Posted by prfleming

In our 2016 210 I have the underhood generator (aux alternator) and the "minimum 2500 watt" inverter which I think is actually a 3000 watt Power Star LW3000-12 sine wave inverter. In testing that I have done, it can handle about 2000 watts, but as you approach 2500 watts, the voltage drops off considerably. Also, when looking at the waveform on a scope, the sine wave approaches a square wave over 2000 watts. This inverter draws about 6 amps with no load, which limits extended use while dry camping.

I had a Xantrex 2000 watt sine wave inverter collecting dust in the garage so I have installed that and wired it to the Power Star 12V terminals with 2/0 gauge welding cable, and ran a surge protector power strip to the kitchen counter area.

https://www.amazon.com/Xantrex-PROWa...+wave+inverter

The added advantage of this inverter is the low idle current of 800 milliamps, so we can charge our cell phones overnight without worrying about draining the house batteries.

+1

800 milliamps is good. Much better than 6 Amp.

[wincrasher]

sounds like your original inverter is a pile of junk. 6 amps at idle! yikes.
my Magnum 2812 has minuscule draw at idle and seems to be large enough to carry all loads in the van. It's rated for a surge of 4500watts. I'd say it's a much easier project to swap out your existing with a better inverter than trying to add a second one.

also, I doubt you are really preserving your warranty adding a second inverter - you pretty much are throwing out your electrical warranty by what you've done.

[markopolo]

I doubt that warranty is affected as the auxiliary inverter is not integrated. It's just a stand alone unit at this point. It would be easily disconnected.

The ProWatt is basically a light duty unit.

A direct link to Xantrex is better than an Amazon link: Power Inverter, Pure Sine Wave Inverter, Marine Inverter, PROwatt SW

The 1800 watt continuous rating is likely at PF .95 so suitable for resistive loads but not suitable to run an Air Conditioner as a long term solution for example.

Thanks for confirming that the Power Star is basically a low budget solution. It works but wouldn't fair well if tested against a Magnum or Outback or even Samlex. Maybe one day Roadtrek will install a high quality brand name inverters in their new coaches.

A Magnum would be a nice upgrade.

I recently opted for a Samlex for a project. 2 amp no load draw or 700 milliamps in power save mode.

For charging your phones, an automotive 12V adapter would likely waste much less power than running an inverter overnight. I'm assuming your newer coach has USB outlets so that's probably much more efficient than using an inverter also. Note: those USB outlets are likely another source of continuous parasitic loss.

[GeorgeRa]

I have 2 inverters; the main higher power is Magnum MMS 1012 and lower power is Mornigstar 300W. Both are on separate circuits and have their own bonds. Shore power goes through Magnum built in transfer relay. I started with 1000W one but due to rare use and standby draw of 420mA I decided to get and additional 300W with 55mA idle draw, that is a drop from about 20-30% of my daily Ah needs to practically nothing. The 300W is clearly identified as shown on the picture and it became mine main unit. Doing a conversion again I would just have a 300W one plus a good battery charger.

Both inverters are pure and clean sine wave so my addition was not due to improvement from a modified square wave, I always found calling it a modified sine wave a marketing ploy, I guess sine looks better in marketing terms.

[Phoebe3]

OK, my ignorance is going to show here and I'm sort of hijacking the original post so I could start a new thread, if that's more appropriate...

A while back I asked about adding an inverter to run our computers. Initially, the advice was to use a 12v car charger for the laptops, but it turns out they want a minimum of 15v and sometimes I need to use a tower for work. Also, don't know if this is important, but at home, I use a surge protector.

The second use would be to run a 900W microwave for about 10 minutes a day. Turns out we miss having that option. Particularly when we want coffee at 5am. We drive every day so I don't think the batteries will be a problem.

Do you all have a recommendation for brand and size of inverter? Sounds like Zantrex or Magnum would be best. Anything else I should be looking for?

[markopolo]

The 1800W Prowatt should do it. Power Inverter, Pure Sine Wave Inverter, Marine Inverter, PROwatt SW

A 2000W PSW Samlex should do it as well. The fan runs whenever some models are on so might be annoying.

Add an inline transfer relay for convenience: Inline Transfer Relay

After those you get into the heavier transformer based units at 50+ lbs in weight. They're much more able to handle heavy loads without failure but likely overkill for the usage you describe.

[GeorgeRa]

Originally Posted by Phoebe3

OK, my ignorance is going to show here and I'm sort of hijacking the original post so I could start a new thread, if that's more appropriate...

A while back I asked about adding an inverter to run our computers. Initially, the advice was to use a 12v car charger for the laptops, but it turns out they want a minimum of 15v and sometimes I need to use a tower for work. Also, don't know if this is important, but at home, I use a surge protector.

The second use would be to run a 900W microwave for about 10 minutes a day. Turns out we miss having that option. Particularly when we want coffee at 5am. We drive every day so I don't think the batteries will be a problem.

Do you all have a recommendation for brand and size of inverter? Sounds like Zantrex or Magnum would be best. Anything else I should be looking for?

I agree with Xantrex, one thing to remember is that microwaves are rated at cooking power output, the actual draw could be 40-60% higher. My 600W microwave takes practically 1000W input.

So, your 900W microwave will dwarf your computer needs for which 300W is sufficient. The difference in wiring between 1800W and 300W inverters will be AWG 1/0 versus 10, battery bank also needs to be able to deliver 150A draw. Microwave doesn’t come for free, let’s say $50. But, infrastructure required needs expensive cables and about 500 Ah of AGM or flooded batteries, so batteries alone, for exmaple4 x 115Ah12V Fullrivers will cost you over $1K.

The cost ratio of microwave to needed infrastructure is about 1:30 ($50/$1500).

[BBQ]

.

RT is installing 2 inverters in their current crop of RVs.

[booster]

I just took a look at the manual for our MS2000 Magnum inverter/charger to check on the parsitic load they spec. I had remembered two numbers but never really worried about it because we have ours off unless in use, so not an issue for us.

I remembered two numbers because there are two given.

One is the load the inverter itself is consuming while inverting, and that is given a less than 25 watts, so about 2 amps

The second is how much it consumes when it is in standby mode and that is given at less than 8 watts, or about .6 amps.

This is the typical system in a lot of decent inverters in which they turn off the inverting electronics but monitor the output for an AC load coming on, at which time they turn on the inverting electronics.

All of this is fine and dandy, and nice low parasitic, with the unit in standby, and no loads, but some users may get bit by bigger parasitics than they would expect from the very low amps they measure with nothing on because even a tiny load will kick the parasitic loss up to 2 amps or so.

I think this points out the wisdom of some users of big, and expensive, inverters, who use very small additional inverters for running small loads, especially if they are over extended periods and the big inverter is normally left off (no power used), or even if in standby (.6 amps used).

Folks that may be running CPAP machines all night, charging small things like phones, etc would be typical places an add on inverter may be desirable. We have a 100 watt pure sine wave inverter that we run the 110v DVD player of off (we didn't have room for the 12v without the brick LG when our native 12v automotive style DVD player died. It has very tiny parasitic in use or just on, but we normally leave it off. No reason to have 10-20 times the loss from the big inverter just to watch a DVD.

At .8 amps, the Xantrex may be doing the same thing, as that is pretty low for parasitic in a big inverter. It is also hard to check because you would need to know exactly how much output is being used by your load to calculate if the parasitic goes up when inverting. Tough because the efficiency also plays into it. The Magnum can be overridden to full time on so you can see what the on parasitic is. Apparently, they get complaints that users want it on full time so they can have an accurate electric clock, or keep the microwave from flashing. It would be interesting to see if the parasitic does go up when actually inverting a small load in the Xantrex, as if it doesn't that makes it much more universally good for various loads, including little ones over long periods.

[Phoebe3]

Originally Posted by GeorgeRa

I agree with Xantrex, one thing to remember is that microwaves are rated at cooking power output, the actual draw could be 40-60% higher. My 600W microwave takes practically 1000W input.

So, your 900W microwave will dwarf your computer needs for which 300W is sufficient. The difference in wiring between 1800W and 300W inverters will be AWG 1/0 versus 10, battery bank also needs to be able to deliver 150A draw. Microwave doesn’t come for free, let’s say $50. But, infrastructure required needs expensive cables and about 500 Ah of AGM or flooded batteries, so batteries alone, for exmaple4 x 115Ah12V Fullrivers will cost you over $1K.

The cost ratio of microwave to needed infrastructure is about 1:30 ($50/$1500).

The microwave draws 1100 watts (rated at 900) so I get that part, but are you saying that running it for 10 minutes will draw down my batteries by 150A?

What if I run the Transit engine while using the microwave? It is a lot quieter than the Onan generator.

[booster]

Originally Posted by Phoebe3

The microwave draws 1100 watts (rated at 900) so I get that part, but are you saying that running it for 10 minutes will draw down my batteries by 150A?

What if I run the Transit engine while using the microwave? It is a lot quieter than the Onan generator.

This goes back to our very common term confusion that happens here regularly.

The 150 amps is the amount of current flowing at an instance in time, it is not a measure of power, which the battery has stored. The stored energy stored is in units of amp-hours, which is just flowing amps over a time period. 150 amps for 1 hour would use 150 amp-hours. In your case 150 amps for 10 minutes would be 150 amps times 1/6 hour or 25 amp-hours out of your battery.

You would be better to run the Transit while using that large an amount of power, unless you have lots of batteries and fast charging available. It is much easier and efficient to not use the power from the battery in the first place, than to put it back in later. You would need to confirm how big the wiring and circuit breakers or fuses are in you alternator to coach wiring, though, as you likely wouldn't have 150 amp capability stock. If the van is just idling, it might reduce the amps available to stay within the wiring capacity, though, as most stock alternators aren't good for much more than 100 amps at idle.

Using an Onan for a quick microwave run is not great, IMO, for all the reasons many have often mentioned. We took our Onan out once we could run the microwave off the batteries or engine easily.

[Phoebe3]

Ok, I'm done trying to understand the theory. I've read every post in this forum, had you and MarcoPolo and BBQ and everyone explain things to me and I really wanted to figure this out and do it myself, but I still don't get it. So I'm just going to ask:

I have a 230 amp alternator and 2 x 12v 100ah AGM batteries (ambulance prep package) on the Transit chassis; then I have 2 x 12v 105AH wet cell batteries for the house.

I want to run 2 x 15v computers for several hours a day and I want to run a 120AC 900w (1100 watt pull) microwave for 10 minutes (about 5 minutes at a time).

What is the best way to go about it?

[booster]

Originally Posted by Phoebe3

Ok, I'm done trying to understand the theory. I've read every post in this forum, had you and MarcoPolo and BBQ and everyone explain things to me and I really wanted to figure this out and do it myself, but I still don't get it. So I'm just going to ask:

I have a 230 amp alternator and 2 x 12v 100ah AGM batteries (ambulance prep package) on the Transit chassis; then I have 2 x 12v 105AH wet cell batteries for the house.

I want to run 2 x 15v computers for several hours a day and I want to run a 120AC 900w (1100 watt pull) microwave for 10 minutes (about 5 minutes at a time).

What is the best way to go about it?

Unfortunately, there is likely not an answer we can just give you, as the system you have right now is not really conducive to what you want to do without some modifications.

If I understand the description correctly, the ambulance prep gave the big alternator and two AGM batteries that are basically in place of the van starting battery? If so, you wouldn't want to run stuff off them for very long because if you kill them, you wouldn't be able to start the van.

You also have a mix of wet and AGM batteries, so even if they were all available to the coach, they would need to be used and charged separately due to the mismatch of chemistries and style.

To know if you can run the computer, it would be necessary to measure the amount of 12 volt power to the inverter is needed to run it, which could then give an accurate time and affect on the batteries.

Is there a wiring diagram or schematic that the manufacturer would be willing to give you for your van, so we could tell better what you have and what would be the best way to proceed? You might also need the Ford wiring diagram for the ambulance package, which is likely available in the upfitters information pack from Ford.

My guess is that you would need a good inverter charger, like a Magnum MS2000, which improve both your inverting and charging capacity. Getting all the batteries tied together, and not starting the van with them, would be great if you can get a single smaller battery to start the van mounted somewhere (it may already have on as part of the ambulance package, too). You would need to change the wet cells to AGM to do all of the above so the batteries match and charge and discharge together well.

My guess is also that it will be a pretty big job to do, as there would be wiring changes and big cables to be installed in a finished van.

In reality, you would be winding up with a setup similar to what Avanti, Boxster, and I have in our vans, so probably a similar amount of work.

Are you in an area where you are near any of the members here that might be able to look at your setup and collect some information, maybe pix, for you to provide? That would be really nice if you are that lucky. Getting a hold of the manufacturer to check on wiring diagrams would also be a good place to start. The hardest part of all this is always to get it all correct the first time, so the more information that is available up front the better.

Sorry there isn't a basic answer for you, but you have just too many unknowns at this time to do much more than speculate. I do think that 400ah of batteries will be enough for you, depending on how many days you need without charging them, as long as you can come up with a separate battery to start the van.

[GeorgeRa]

Originally Posted by Phoebe3

Ok, I'm done trying to understand the theory. I've read every post in this forum, had you and MarcoPolo and BBQ and everyone explain things to me and I really wanted to figure this out and do it myself, but I still don't get it. So I'm just going to ask:
I have a 230 amp alternator and 2 x 12v 100ah AGM batteries (ambulance prep package) on the Transit chassis; then I have 2 x 12v 105AH wet cell batteries for the house.
I want to run 2 x 15v computers for several hours a day and I want to run a 120AC 900w (1100 watt pull) microwave for 10 minutes (about 5 minutes at a time).
What is the best way to go about it?

Some explanation of electrical terms -
Electric current, like water flow in the river, measured in [A]
Battery capacity, like lake size above a water fall, measured in [Ah]
Voltage, like height of the water fall, measured in [V]

Some correction - your 900W microwave will like be pulling 1260W (900W + 40%)

Let’s assume your computers are rated at 100W each. I assume by stating 15V you are planning to power them via 115V power supplies. For 100W AC you will draw 100W / 12V / 0.9 inverter efficiency = 9.26A x 2 computers = 18.5A or approximately 20A DC. You mentioned several hours per day, let’s say it is 8 hrs.; so, 20A x 8hrs. = 160Ah.
Your rated batteries capacity is 210Ah, common wisdom states to not use more than 50% of this capacity to keep up with battery life but discharge of 80% is OK with shorter battery life so you have from 105 to 170Ah capacity. Not much room for microwave left.

If you forgo microwave powered by batteries an excellent inverter with high efficiency and low standby draw for your PCs is venerable Morningstar 300W - https://www.morningstarcorp.com/products/suresine/

[Bud]

Originally Posted by Phoebe3

Ok, I'm done trying to understand the theory. I've read every post in this forum, had you and MarcoPolo and BBQ and everyone explain things to me and I really wanted to figure this out and do it myself, but I still don't get it. So I'm just going to ask:

I have a 230 amp alternator and 2 x 12v 100ah AGM batteries (ambulance prep package) on the Transit chassis; then I have 2 x 12v 105AH wet cell batteries for the house.

I want to run 2 x 15v computers for several hours a day and I want to run a 120AC 900w (1100 watt pull) microwave for 10 minutes (about 5 minutes at a time).

What is the best way to go about it?

Phoebe3, this stuff can make my head hurt too. booster has been helpful.

The coffee at 5:00am can be had without a microwave, good coffee. I use the microwave, but not for coffee and only have a need for the microwave during 'appropriate times for the LOUD onan'. I do Dislike the LOUD onan, but for 5 minutes folks are understanding where all day use for a/c can be inappropriate some places.

All my other 110 volt applications are with a 600 watt inverter.

I also like to 'have my cake and eat it too'. But without another application except coffee at 5:00 am, I'm also lazy............. So I would probably stay as is, as that is what I'm doing.

Bud

[Phoebe3]

Thanks, everyone!

In response, the current wiring is undocumented at this point. I have mapped the fuses at the converter and found about 30% were marked incorrectly and there's still one that I can't figure out what it goes to. We removed the seat cover so we could look at the back of the converter panel and found that all the wires to the 15a and 7.5a fuses were white and not marked with any way to differentiate them.

There is a second, PrecisionPlex panel in the front of the RV with about 20 fuses and I haven't mapped those yet. I have asked Coachmen for the ladder diagram as it appears that the bathroom light should always be hot (controlled with a wall switch) but that does not appear to be the case. They have forwarded a request to Precision and have not heard back. I'll ping them again.

WRT the solar panels, we know they are wired "backwards" insofar as the Batt1 should be the house battery set and Batt2 should be the Transit battery set. We have confirmed with GoPower that these should be reversed and have instructions on how to do that - just haven't found the time.

I will go looking for the Ford diagram - it's probably online.

I would prefer not to link the house and Transit batteries. If necessary, I think I could replace the two house 100 ah wet cells with two 200ah AGMs, so that I could have 400ah to play with, but if we aren't going to put in an inverter, that probably isn't necessary (I'll do it when these fail and I'm going to replace them anyway).

I'm still in negotiations with DH, but frankly I'd rather play with our new toy than work on it and we can make coffee with propane - it just takes longer and is a bit more work.

I do thank everyone for your efforts at my education. Don't know why electricity is so hard - I can sew, do woodwork, and mechanical stuff is easy, but those darned little electrons are so small, I just can't seem to get my hands on them.

[booster]

Good plan. If you can avoid going to more batteries, big inverter, and such, all of it gets much easier to deal with.

At that point, you just need to figure out how long you will be able to be off grid, compared to what you want, based on your other usages, which will probably be mostly the computer stuff. 200ah is not a tiny battery capacity, but might be close if you need more than a day or two without charging.

Do you have a gas or 12v compressor frig?