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Old 10-04-2018, 04:29   #46
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Re: Inverter/Charger Recommends

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Originally Posted by missourisailor View Post
How this plays into this discussion is with a inverter/charger combo unit, that technically is both a charge source and a load, where do you place it in the system? On the charge buss or the load buss?

Being that lead acid batteries are still pretty much the norm, all of this is a mute point. But for only a couple of cases, there is no reason to have a split buss on a normal lead acid system.

Barring an internal failure of some sort, can an inverter/charger with its own internal automatic transfer switch ever be a load and a charge source simultaneously?

And/or perhaps the issue would be more germane in a system with multiple charge sources?

-Chris
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Old 10-04-2018, 04:55   #47
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Re: Inverter/Charger Recommends

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Barring an internal failure of some sort, can an inverter/charger with its own internal automatic transfer switch ever be a load and a charge source simultaneously?

And/or perhaps the issue would be more germane in a system with multiple charge sources?

-Chris
I'm going to have to be careful here because as soon as I'm done, somebody will find some obscure unit that proves me wrong.

But to the best of my knowledge, no.

Think about it. An inv/chg needs AC to make DC. And DC to make AC.
So if you need to make AC, it draws power from the batt. But you also want to charge the battery, so now you need AC to power the charger. But if you have AC available, why would you need to use the inverter.

The transfer switch circuitry is basically doing the same thing. If it senses AC on the shore side, then it passes through the power. Without an AC voltage on the input side, It switches over to inverter mode.

I Know that most of the older inv/chg had relays for the transfer switch. Which were either in one position or another.
I think that most have now gone to solid state, which technically can only be in one state at a time, barring any failures.
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Old 10-04-2018, 04:57   #48
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Re: Inverter/Charger Recommends

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Would love to find a good source for numinous wires.

Sorry, just couldn't resist, lovely idea that.
Yeah, I hate spell check!
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Old 10-04-2018, 05:21   #49
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Re: Inverter/Charger Recommends

There is the power boost feature of Victron, maybe others, where mains power and batt+inverter power are combined to service AC loads so high the upstream mains can't handle the current alone, e.g. without tripping a breaker.

Then when the need passes, automatically returns to simultaneously servicing loads and recharging the bank.
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Old 10-04-2018, 06:17   #50
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Re: Inverter/Charger Recommends

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There is the power boost feature of Victron, maybe others, where mains power and batt+inverter power are combined to service AC loads so high the upstream mains can't handle the current alone, e.g. without tripping a breaker.

Then when the need passes, automatically returns to simultaneously servicing loads and recharging the bank.
Quite a few can power share.
But I don't think that they can invert and charge at the same time. Infact I can't electrically figure out a way for it to happen.
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Old 10-04-2018, 07:07   #51
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Re: Inverter/Charger Recommends

Well, it is possible with power assist function enabled.

You set a treshold for the ac-input current. there is a soft start for the inverter when the load is near the treshold, so the inverter kicks in, when the power consumption goes down, the power assist function reduces the output, finaly the charger kicks in slowly and consumes part of the incomming power to re-charge the battery.

During all this time the ac-input and ac-output is active, and also power is transferred through the synchronized transfer swich.

Internaly the device prevents a loop from inverter and charger to prevent perpetuum mobile effects
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Old 10-04-2018, 07:20   #52
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Re: Inverter/Charger Recommends

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Quite a few can power share.
But I don't think that they can invert and charge at the same time. Infact I can't electrically figure out a way for it to happen.
Why not? Not talking just Victron here, but generically.

Just two separate functions in one box with some coordinating oversight modules, transfer switches etc.

An inverter and charger as separate units have no problem running at the same time.
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Old 10-04-2018, 07:48   #53
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Re: Inverter/Charger Recommends

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Well, it is possible with power assist function enabled.

You set a treshold for the ac-input current. there is a soft start for the inverter when the load is near the treshold, so the inverter kicks in, when the power consumption goes down, the power assist function reduces the output, finaly the charger kicks in slowly and consumes part of the incomming power to re-charge the battery.

During all this time the ac-input and ac-output is active, and also power is transferred through the synchronized transfer swich.

Internaly the device prevents a loop from inverter and charger to prevent perpetuum mobile effects

Interesting..

I would think that there would be some kind of feed back inhibitor to prevent a run away. But maybe not an issue with lower voltages.
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Old 10-04-2018, 07:53   #54
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Re: Inverter/Charger Recommends

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Why not? Not talking just Victron here, but generically.

Just two separate functions in one box with some coordinating oversight modules, transfer switches etc.

An inverter and charger as separate units have no problem running at the same time.
Two units acting separately is a bit different than one unit with two functions.

Simply, some parts don't like to be pulled and pushed at the same time.
But as Cat pointed out, at these low voltages, maybe I'm looking at this wrong.
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Old 10-04-2018, 11:07   #55
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Re: Inverter/Charger Recommends

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Well, it is possible with power assist function enabled.

You set a treshold for the ac-input current. there is a soft start for the inverter when the load is near the treshold, so the inverter kicks in, when the power consumption goes down, the power assist function reduces the output, finaly the charger kicks in slowly and consumes part of the incomming power to re-charge the battery.

During all this time the ac-input and ac-output is active, and also power is transferred through the synchronized transfer swich.

Internaly the device prevents a loop from inverter and charger to prevent perpetuum mobile effects

I think you may be confused between different features. Power assist is when the inverter contributes AC current because the generator or shore power available is not enough. But when that is happening the batteries are being discharged. In all cases the inverter is either producing AC and discharging batteries or it is not producing AC and is charging batteries but never producing AC and charging at the same time. There would be no point in doing that.
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Old 10-04-2018, 11:46   #56
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Re: Inverter/Charger Recommends

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I think you may be confused between different features. Power assist is when the inverter contributes AC current because the generator or shore power available is not enough. But when that is happening the batteries are being discharged. In all cases the inverter is either producing AC and discharging batteries or it is not producing AC and is charging batteries but never producing AC and charging at the same time. There would be no point in doing that.
Of course there is, are you saying can't use the toaster just beacause the bank is depleted 30%?

It's super common for shore power or genny output to be passed through the inverter for auto-transfer, not just power assist.

And before or after the power assist is required, the bank could require ongoing charging for any number of reasons.

Anything two separate different brand units not communicating with each other can do, any Combi unit should be able to do and more.

I still say separates are better for most use cases, a good Combi rarely saves money anyway.
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Old 10-04-2018, 13:41   #57
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Re: Inverter/Charger Recommends

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I still say separates are better for most use cases, a good Combi rarely saves money anyway.
That idea surprised me, so I did a quick check of sorts. Looks like maybe true, at least in this quick check, and not counting installation costs.

FWIW, Hodges Marine (for example) lists a ProMariner ProNautic 1260P (60A charger) for $700 and the ProMariner TruePower Plus pure sine wave 2000W inverter for $590. They list the ProMariner TruePower 2000PS Combi (70A charger) for $1300. Those all "MAP" prices.

Their real price for the Combi was significantly lower, but presumably those real prices would flow across all three products.

Anyway, interesting...

Other factors influenced my own decision to get the Combi; that was very much about how close I could get the inverter to the battery bank, and then about adding more overall charging capability to the boat at the same time.

-Chris
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Old 10-04-2018, 13:59   #58
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Re: Inverter/Charger Recommends

John,

You can argue whatever you think is best. But you canít have mains power assist using separate devices. At least I have never seen a simple inverter that does it. I doubt there is any demand for such a thing.

A combi is the ideal KISS device. Nearly all boats have multiple means of charging batteries besides the inverter/charger. So reliability is not enhanced by separating the two. In fact, on a parts count basis reliability should be lower with separates.
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Old 10-04-2018, 15:39   #59
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Re: Inverter/Charger Recommends

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Anything two separate different brand units not communicating with each other can do, any Combi unit should be able to do and more.
.
Yeah, Iím not getting it either.
I donít see how two separate devices can provide power, to each other, at the same time
Even with a two unit system, the inverter will not began to operate until:
1) Shore power is removed, meaning that the battery charger is no longer charging.\
2) The demand for AC power is greater than the shore power can handle. Which also means if the current demand is larger than what shore power can carry, there is nothing left for the charger to use. So it is once again not charging.
Now they may both operate for a few milliseconds while things like cap's drain. But I would not call it operating.
What do you know that you are not telling us?
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Old 10-04-2018, 17:18   #60
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Re: Inverter/Charger Recommends

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That idea surprised me, so I did a quick check of sorts. Looks like maybe true, at least in this quick check, and not counting installation costs.

FWIW, Hodges Marine (for example) lists a ProMariner ProNautic 1260P (60A charger) for $700 and the ProMariner TruePower Plus pure sine wave 2000W inverter for $590. They list the ProMariner TruePower 2000PS Combi (70A charger) for $1300. Those all "MAP" prices.

Their real price for the Combi was significantly lower, but presumably those real prices would flow across all three products.

Anyway, interesting...

Other factors influenced my own decision to get the Combi; that was very much about how close I could get the inverter to the battery bank, and then about adding more overall charging capability to the boat at the same time.

-Chris
Ranger42c,
Iím also in the same camp as John. As far as separate components.

On my current project, Iím removing a fully functioning Freedom 1000 inv/charger and replacing it with a Sterling ProCharge 50 and a Xantrex Freedom x 2000.

Several reasons:
1) The Sterling charger is more programmable than most. Important for FireFly batteries and more important for a future LiFePo bank.
2) As mentioned above, the master plan is to go to LiFePo, which the main ships wiring is being converted to a dual buss system. Meaning two units are needed for connection to both the charge and load bussís.
3) The most important consideration right now is space. Two units fit better than one.

FYI, the current location of the Inv/chg is where the start battery is being relocated to. So this location is no longer available for a single unit.

Another consideration is that if one part of a combo unit goes bad, then the whole thing has to be replaced. With separate units, only the malfunctioning unit needs to be replaced.

But a valid point was made about the more stuff you have the greater the chance of Murphy getting involved.

As far as price goes, you are correct that most often, two are around the same price as one. But a hidden cost is the extra heavy gauge wiring that is needed to connect two units instead of one.
Not a real concern for me, but to others it can be a significant added cost.

So it really boils down to your exact needs. And for most, a combo unit fits the bill best.
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