Inverter/charger vs separate components question

[rmcrowe]

Hi all, I've been watching the forum for a while but this is my first post.

I'm begining to plan out a system for my travel trailer which is a grand design imagine 2500rl with 30amp service. I'm considering the merits of a inverter/charger vs going with separate charger/inverter/transfer switch. One of the perceived benefits is that the inverter/chargers seem to be able to vary the charge amps to the battery based on what is available... I.e if running the AC or other high load appliances it reduces the charge current to the battery so as to stay within the 30amp total capacity (from shore power/generator) Is there a way to get this capability with separate components? Do most combined inverter chargers support this capability (I think the multiplus does). Finally, if the AC power leg is not through the inverter/charger (I could use a 2000watt inverter in this case) how can I ensure I am not exceeding 30amps ? Thanks for your thoughts,

Bob

 

[John Frum]

Hi all, I've been watching the forum for a while but this is my first post.

I'm begining to plan out a system for my travel trailer which is a grand design imagine 2500rl with 30amp service. I'm considering the merits of a inverter/charger vs going with separate charger/inverter/transfer switch. One of the perceived benefits is that the inverter/chargers seem to be able to vary the charge amps to the battery based on what is available... I.e if running the AC or other high load appliances it reduces the charge current to the battery so as to stay within the 30amp total capacity (from shore power/generator) Is there a way to get this capability with separate components? Do most combined inverter chargers support this capability (I think the multiplus does). Finally, if the AC power leg is not through the inverter/charger (I could use a 2000watt inverter in this case) how can I ensure I am not exceeding 30amps ? Thanks for your thoughts,

Bob

The only inverter/charge I know that does this is the Samlex Evo.
Victron probably does to but I don't pay much attention to their kit.
I know of no discrete components that do this.
If they do, expect vendor lockin and a big price tag.

 

[mapguy525]

Many Inverter charger units marketed to mobile applications usage have load support features. Look for units that have UL458 certification. These models are not cheap, but they have provisions to ensure grounding and bonding are maintained during operation.

Xantrex, Magnum, Aims/Signeer, Victron, Kisae and others have these units available. Load support functions like provided by these hybrid inverter chargers is not available out of the box with separate components.

 

[John Frum]

Many Inverter charger units marketed to mobile applications usage have load support features. Look for units that have UL458 certification. These models are not cheap, but they have provisions to ensure grounding and bonding are maintained during operation.

Xantrex, Magnum, Aims/Signeer, Victron, Kisae and others have these units available. Load support functions like provided by these hybrid inverter chargers is not available out of the box with separate components.

mapguy525 The samlex supplements/tops up other charge sources because those charge sources pass their power through the samlex inverter which has a shunt/hall sensor to determine the current differential.
How do the other devices do it?

 

[John Frum]

@rmcrowe I reread your post and It seems I misunderstood.
I am talking about a different feature.
@mapguy525 ^

 

[mapguy525]

Can't speak for all the options available on how their circuitry is designed. I have looked at the Magnum, xantrex, victron and Kisae. Of the four, the Victron seems to be the best all around solution regarding load support and charger prioritization. Victron also uses the pass through function to make these features work. Victron is on on the higher price side of market.

There are other more esoteric brands with hybrid functions , too. Like Mastervolt and Outback.

 

[rmcrowe]

Thanks all for the feedback so far. I was looking at the Victron Multiplus, it looks great but it seems the output is pretty significantly derated as the ambient temperature raises. Considering the 12/3000 - that would mitigate the power loss I guess. I'll probably start up another thread with any specific questions on that model later on after I do more research.

 

[Sojourner1]

@rmcrowe what batteries and size of bank are you considering?

 

[rmcrowe]

Im strongly considering 4s of the 280ah Lifepo4 for 280ah @ 12v. that i would build myself. Not really enough to push a 3000w inverter for long and I might consider the 2000 model.

 

[HaldorEE]

Thanks all for the feedback so far. I was looking at the Victron Multiplus, it looks great but it seems the output is pretty significantly derated as the ambient temperature raises. Considering the 12/3000 - that would mitigate the power loss I guess. I'll probably start up another thread with any specific questions on that model later on after I do more research.

That is because Victron doesn't lie.

Every bodies product has to be derated at higher temperature. Most people just ignore this.

 

[rmcrowe]

As a follow on to my original question - doesn't seem to be a very good way to current limit inbound, I guess the way most folks do this is just to put a breaker in place and if it pops you know you need to turn something off and flip the breaker back on. Thats workable.

@HaldorEE thanks I realize things derate at temperature, I was a bit surprised by how much the Victron claims but they are probably being conservative.

At the risk of hijacking my own thread - The Multiplus 12/3000 will fit in the space I have available better than the 12/2000 - Even though I don't have the battery to really push that thing the to fullest (now), would it be a problem to use that instead of the 12/2000 ? What are the downsides? Is there a way to tell the Victron to limit inbound amps from the battery (looked through the manual it was not obvious) ? Obviously I would have a BMS and fuse to prevent catastrophe, but I'd rather not have that tripping regularly. I don't really need more than 1800 watts or so at any one time, and typical usage will be far below that.

 

[Airtime]

@HaldorEE thanks I realize things derate at temperature, I was a bit surprised by how much the Victron claims but they are probably being conservative.

Fully agree with @HaldorEE. Many vendors just specify power at 25C and let you figure out that it can't supply that on a hot day when it trips. Providing thorough specs including derating is an indication of solid engineering to me.

At the risk of hijacking my own thread - The Multiplus 12/3000 will fit in the space I have available better than the 12/2000 - Even though I don't have the battery to really push that thing the to fullest (now), would it be a problem to use that instead of the 12/2000 ? What are the downsides? Is there a way to tell the Victron to limit inbound amps from the battery (looked through the manual it was not obvious) ? Obviously I would have a BMS and fuse to prevent catastrophe, but I'd rather not have that tripping regularly. I don't really need more than 1800 watts or so at any one time, and typical usage will be far below that.

Upsides of 3000 vs 2000 include of course higher peak load capability, you could run more parallel loads for example a microwave in parallel with an induction cooktop on high. Realistically you'll only do that for a few minutes at a time in actual usage so you wouldn't drain your 280Ah bank much. You would also have 120A charging instead of 80A, if that's important to you, and that's less than 0.5C charging on your 280Ah bank so it can easily handle that.

Only downside I'm aware of is 2X the idle current draw and slightly higher cost. Many people turn off the inverter except when using it to eliminate that battery drain.

Also, Victron also does a good job of specifying surge. You can do 130% of nominal power for 30 minutes, and max power for 2 minutes (not 1 second as some specify). It can surge higher than max power at reduced voltage output for up to 5 seconds, for example when starting a motor. This Victron goes into some depth, but if you start at 8:14 up to about 11:50 minutes he talks specifically about surge numbers:

FInal comment... not sure what you are planning for BMS for your bank, but if you want separate remote control of Inverter and Charger controlled by your BMS, I think Victron is the only product that offers that.

 

[rmcrowe]

@Airtime Thanks for the information. I am leaning towards the 3000, esp since it fits where I want to put it physically. I'm still figuring out what my master plan for this thing is going to be, and I will open a new thread on my specific Victron questions in the appropriate place when I get a bit further along. Thanks all for the feedback!

 

[HaldorEE]

@Airtime Thanks for the information. I am leaning towards the 3000, esp since it fits where I want to put it physically. I'm still figuring out what my master plan for this thing is going to be, and I will open a new thread on my specific Victron questions in the appropriate place when I get a bit further along. Thanks all for the feedback!

Let us know if you find anything unexpected. I am thinking about using a Victron Multiplus 24/1600 on my van conversion. I want to be able to power a small microwave oven. Does anyone have any experience with the 1600 VA Victron inverters? I plan on using a 900 W rated microwave oven (1300 to 1400 W input power). With cheap Chinese inverters I wouldn't try this with anything that had less than a 2000W rating and I am leaning towards 3000W. The Victron is certainly pricy though.

 

[Airtime]

Let us know if you find anything unexpected. I am thinking about using a Victron Multiplus 24/1600 on my van conversion. I want to be able to power a small microwave oven. Does anyone have any experience with the 1600 VA Victron inverters? I plan on using a 900 W rated microwave oven (1300 to 1400 W input power). With cheap Chinese inverters I wouldn't try this with anything that had less than a 2000W rating and I am leaning towards 3000W. The Victron is certainly pricy though.

Are you familiar with low frequency vs. high frequency inverters? You will get usable surge on the LF inverters, not on the HF. As for price, the Victron is actually pretty competitive on price relative to other LF inverters.

You will also need to derate cheap inverters to get a fair comparison. That 1600 Multiplus unit you are looking at has 3000W peak power, and what that means from Victron is 2 full minutes at 3000W. Peak power on a cheap HF inverter likely means some milliseconds--not useful even for a motor transient.

 

[HaldorEE]

Are you familiar with low frequency vs. high frequency inverters? You will get usable surge on the LF inverters, not on the HF. As for price, the Victron is actually pretty competitive on price relative to other LF inverters.

You will also need to derate cheap inverters to get a fair comparison. That 1600 Multiplus unit you are looking at has 3000W peak power, and what that means from Victron is 2 full minutes at 3000W. Peak power on a cheap HF inverter likely means some milliseconds--not useful even for a motor transient.

That is exactly what I was trying to say.

I think the issue is more related to honest ratings than it is to HF vs LF. There is no reason a HF inverter can't be designed to deliver any level of power desired. Variable frequency drives are high frequency inverters that have special features to permit them to drive motors at variable speeds. VFD's can be had that will drive motors in the 100's of HP. Data point, a 300 HP motor is almost a 1/4 million watt load (1 HP = 750W). Being able to deliver over 400A at 500VAC (3 phase) is no joke and this is from an inverter operating with a switching frequency between 2 KHz to 4 KHz.

https://cdn.automationdirect.com/static/specs/gs4drives.pdf

Keep in mind that Honda generators are high frequency inverters also and I never heard anyone claim these don't deliver rated power.

Question I have is if a 1600W Multiplus has the capacity to comfortably operate a 900W microwave oven (the biggest load I desire to operate). I think it should, but I hate to spend $1200 on an inverter only to find out it won't do what I want. DC Inverters are kinda like audio equipment in that ludicrous claims are made for cheap crap and miraculous claims are made for old technology (tube amps being the analog for LF Inverters).

I am an electrical design engineer (focused primarily on high precision signal processing) and I understand how these products work and why products cost what they cost. The issue for me is cutting through the marketing BS and outright lies bandied about by almost everyone involved in this industry.

Victron ticks my engineer boxes. They seem to have well engineered, conservatively specified products which explains why they are pricey (good quality, conservatively rated engineering means more expensive products). Cheap inverters claim double their continuous ratings for surge also (1500W rated, 3000W surge), but I take their claims with a very big grain of salt. I was looking at one inverter on Amazon that clearly stated they couldn't deliver their rated "continuous" power into a light bulb which is about as benign and real world a load as you could find. What that means to me is that the power rating specified has no relationship to the actual product being sold. It is like computer speakers that claim to be "200W" but come with a 12V, 1A power supply (12W).

 

[Airtime]

Question I have is if a 1600W Multiplus has the capacity to comfortably operate a 900W microwave oven (the biggest load I desire to operate). I think it should, but I hate to spend $1200 on an inverter only to find out it won't do what I want. DC Inverters are kinda like audio equipment in that ludicrous claims are made for cheap crap and miraculous claims are made for old technology (tube amps being the analog for LF Inverters).

Sorry didn't see your reply earlier. The answer to this question is yes, absolutely no problem operating a 900W microwave from a Victron Multiplus 1600. Looking at the specs in the manual, it will run 1300w continuous (as in 24/7), 1600W for 30 minutes, and 3000W for 2 minutes. And Victron does deliver on their specs.

You could run two of those microwaves in parallel, for the amount of time you need to run a microwave at full power... BTW you can do better than $1200. For that you could almost get a Multiplus 3000.

 

[Airtime]

I think the issue is more related to honest ratings than it is to HF vs LF. There is no reason a HF inverter can't be designed to deliver any level of power desired.
...
I am an electrical design engineer (focused primarily on high precision signal processing) and I understand how these products work and why products cost what they cost. The issue for me is cutting through the marketing BS and outright lies bandied about by almost everyone involved in this industry.

I meant to comment on this. BTW I am an EE as well. Your comment on HF vs LF may or may not be accurate in a theoretical sense. But practically speaking, for the inverters you can actually buy, the LF inverters have huge magnetics that store a lot of energy. The HF inverters you can buy do not have the same energy storage nor do they have the kind of design you're describing. If you buy any of the HF inverters, you will find that the so-called 2X surge they claim is specsmanship and not actually useful for anything, it is marketing BS. Your choice...

 

[gnubie]

It sure is rubbish, but if the desire was there a HF inverter can be made that will hold up just as well as a big transformer design, but it wouldn't sell for $100 any more.

*edit to fix typos*

 

[HaldorEE]

I meant to comment on this. BTW I am an EE as well. Your comment on HF vs LF may or may not be accurate in a theoretical sense. But practically speaking, for the inverters you can actually buy, the LF inverters have huge magnetics that store a lot of energy. The HF inverters you can buy do not have the same energy storage nor do they have the kind of design you're describing. If you buy any of the HF inverters, you will find that the so-called 2X surge they claim is specsmanship and not actually useful for anything, it is marketing BS. Your choice...

Turns out there are HF inverters that aren't lying. They just start at $700.

I have about decided to get one of these. Xantrex 24V, 2000W inverter. 4000 W surge rated for 2 seconds (not 40 mS like the crap inverters). Fully configurable low voltage cutoff voltage and recovery so it won't hurt your battery pack. Automatic transfer switch for shore power. They specifically mention running a microwave oven and chop saw. This looks like the real deal to me.

Xantrex Freedom X 2000 True Sine Wave Power Inverter - 24VDC - 120VAC - 2000W

Freedom X 2000 True Sine Wave Power Inverter - 24VDC - 120VAC - 2000W True sine wave 120VAC inverter with built-in transfer switch. Designed for recreational and commercial applications.The Freed...

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