Separate Inverter, Charger, or Combo ?

[seapop]

Buying a new used boat, and it only seems to have a trickle charger on the house batteries. I am thinking about upgrading to a more serious charger and also an inverter for the usual reasons. Question is, would it be better to have two separate units or one good combined unit.

Certainly cost is an issue, but more concerned about single-point-of-failure, and better overall management of the power system.

[travellerw]

I would never have a combined unit, ever... Its the number one failure I see out here. One or the other function dies and the unit just goes into error mode and nothing works.

I don't know what your long term plans are (cruising or weekend warrior), but I would recommend 2 separate devices in either cases. If you are planning to cruise (down the the Caribbean) then I would ensure any battery charger you buy can accept a wide range of voltages and frequencies. Then wire the inverter separately and your boat is essentially voltage agnostic. You feed the battery charger the voltage from the dock, and power everything on your boat through the inverter.

[zboss]

Or one combo inverter charger and one “just charger”. The Victrons will talk to each other and make sure they don’t fight each other.

[CarlF]

I think the "separate" argument is not as strong these days as reliability is better (at least a little).

1. An inverter/charger only costs a little more than a good inverter as they share most components. You also save on wiring, breakers, installation etc. over two units.

2.Single point of failure doesn't really apply because inverters and chargers do different things. Most people want both working. I think either an inverter or charger will fail as often as an inverter/charger. Maybe more often as you have two points of failure. And if one breaks, you will want to get it fixed promptly.

3. If you have the budget, look at the smart inverter/chargers such as the Victron's. These have many advantages as they can automatically balance genset/shore power and battery use to handle brief high loads. Their battery charge management is excellent.

4. While I'm a bit of a redundancy nut, I installed two inverter/chargers in the space that would have held separate inverter/chargers. I can use both to charge simultaneously. As two inverters could have phase issues only one inverter can be used at a time. So the backup unit inverter output is not connected - but could be in about 15 minutes if the primary inverter/charger failed (which hasn't happened since installed five years ago).


5. If you are cruising in areas with different voltages/frequencies a charger that accepts both voltages that has its own dedicated shore power inlet paired with an inverter/charger for your primary voltage makes a lot of sense.

[Exile]

What about a separate charger & inverter, but rather than wiring the inverter into the AC system just have the type that has a couple of GFCI plugs built into it?

I rarely feel the need to run AC appliances like a/c, microwave, toaster, etc. when away from the dock, and if I did I also have a generator. A "stand-alone" inverter of sufficient capacity would allow for redundancy should the generator fail or I preferred not to burn the diesel. The only problem is running an extension cord. Even with one of sufficient gauge I'm not sure that's advisable on a boat. Anyone know?

[sainted]

I find that an inverter/charger makes the most sense because of the integrated transfer switch that is incorporated in them.

This feature senses when mains power (shore power or generator) power is available and conducts that power to its a.c. output, which in turn is connected to the vessels a.c. distribution panel. Also, when mains power is available, it's battery charger function runs automatically.

When mains power is NOT available and the inverter is enabled, the inverter/charger will automatically supply 110 v a.c. to the distribution panel.

This feature makes the transition between mains and battery power completely automatic and transparent. No transfer switches to mess with, no plugging and unplugging appliances to move them from one power source to another. Easy.

As a marine electrician, I have seen inverter/chargers fail "half way". That is, the inverter function worked but the battery charger didn't and vice versa. Failures of any kind are rare, however. These things are damn reliable.

If y'all get an inverter/charger, you will need to subdivide your a.c. panel such that only low wattage loads are served by the inverter. That is, you wouldn't want to run your water heater or air conditioning on the inverter. That would flatten your batteries in no time. Generally, the panel is configured such that only the vessels outlets are connected to inverter power and perhaps dedicated circuits for appliances like microwaves and coffee machines.

If you get an inverter/charger, get the remote control for it so you can see what it's doing and turn the inverter function off if you don't need it (to save power).

Modern inverter chargers have a lot of nifty features like supplemental power capabilities, dual inputs and such, but that's too much for this post!

Scott

[Exile]

Originally Posted by sainted

I find that an inverter/charger makes the most sense because of the integrated transfer switch that is incorporated in them.

This feature senses when mains power (shore power or generator) power is available and conducts that power to its a.c. output, which in turn is connected to the vessels a.c. distribution panel. Also, when mains power is available, it's battery charger function runs automatically.

When mains power is NOT available and the inverter is enabled, the inverter/charger will automatically supply 110 v a.c. to the distribution panel.

This feature makes the transition between mains and battery power completely automatic and transparent. No transfer switches to mess with, no plugging and unplugging appliances to move them from one power source to another. Easy.

As a marine electrician, I have seen inverter/chargers fail "half way". That is, the inverter function worked but the battery charger didn't and vice versa. Failures of any kind are rare, however. These things are damn reliable.

If y'all get an inverter/charger, you will need to subdivide your a.c. panel such that only low wattage loads are served by the inverter. That is, you wouldn't want to run your water heater or air conditioning on the inverter. That would flatten your batteries in no time. Generally, the panel is configured such that only the vessels outlets are connected to inverter power and perhaps dedicated circuits for appliances like microwaves and coffee machines.

If you get an inverter/charger, get the remote control for it so you can see what it's doing and turn the inverter function off if you don't need it (to save power).

Modern inverter chargers have a lot of nifty features like supplemental power capabilities, dual inputs and such, but that's too much for this post!

Scott

Very helpful post Scott. As a marine electrician, would you approve of a marine-rated, standalone inverter that has a couple of GFCI outlets built in? My application would be to run a microwave, coffee pot, computer, and not heavy loads like refrig, AC or w/h. My concern is the inverter would have to be mounted close to the batteries, and that translates into a 10-15' extension cord run. Even a cord of sufficient gauge doesn't "feel" quite right to me on a boat, but thought I'd ask a pro. Running such appliances away from the dock certainly isn't worth the risk of potential damage or a fire.

You probably already know this, but I believe there are also standalone inverters which will automatically switch on when there is no AC power coming from shore or a generator. Presumably this would also require subdividing the AC panel to insure that only AC outlets are being supplied by the inverter.

[ranger58sb]

Originally Posted by Exile

My application would be to run a microwave, coffee pot, computer, and not heavy loads like refrig, AC or w/h. My concern is the inverter would have to be mounted close to the batteries, and that translates into a 10-15' extension cord run. Even a cord of sufficient gauge doesn't "feel" quite right to me on a boat, but thought I'd ask a pro.

Can you not connect the inverter's AC OUT to the panel breakers that control the outlets you'd use for microwave, coffee maker, etc.? That kind of run with be using something like 10-3 AC cable, not particularly distance sensitive, etc...

-Chris

[Dockhead]

You haven't told us what kind of loads you have, and how you use your electrical system. I don't think anyone can give a worthwhile answer without that.

A larger cruising boat which uses a lot of AC power benefits enormously from a combined charger/inverter which has valuable functions which separate chargers and inverters don't have, especially power boost. Get redundancy by having two of them in a gang, or just keep a spare simple charger and spare simple inverter (like I do).

A small boat or one with little AC gear doesn't need this. Just buy a good charger, properly sized (about 0.2C, that's important for battery health) and with proper four stage charging profile and voltage and temperature sensors ON THE BATTERIES. Then, buy a small inverter of whatever size needed for whatever AC gear you use occasionally, and wire it up to a separate AC outlet or outlets (that greatly simplifies the installation -- no switching over from the shore power, which is kept separate).

A combined inverter/charger is really the master control system of electrical power on board -- all AC power goes through it, and it controls all AC/DC conversions in both directions. It also controls how you consume AC power from shore power or generator. It is complex to install, besides being expensive, so I wouldn't recommend it for boats which don't use a lot of AC power. But for other boats it's fantastic -- I wouldn't want to be without it.

[Exile]

Originally Posted by ranger42c

Can you not connect the inverter's AC OUT to the panel breakers that control the outlets you'd use for microwave, coffee maker, etc.? That kind of run with be using something like 10-3 AC cable, not particularly distance sensitive, etc...

-Chris

Yes, of course. That's the standard setup, although as 'sainted' mentioned above, it's best to install a sub-panel only for inverter loads so the other high amp loads on the AC side don't get inadvertently turned on when only the inverter is being used. Since my inverter needs will be pretty minimal (I also have an 8Kw generator), I thought it would be simpler and less expensive to install the inverter type with the outlets already built in. Just not sure if running an extension cord is ABYC complaint or otherwise advisable. Other than small inverters running light-duty appliances or charging the computer, my boat has never had the type of large capacity inverter that have become so common these days.

[Exile]

Originally Posted by Dockhead

You haven't told us what kind of loads you have, and how you use your electrical system. I don't think anyone can give a worthwhile answer without that.

A larger cruising boat which uses a lot of AC power benefits enormously from a combined charger/inverter which has valuable functions which separate chargers and inverters don't have, especially power boost. Get redundancy by having two of them in a gang, or just keep a spare simple charger and spare simple inverter (like I do).

A small boat or one with little AC gear doesn't need this. Just buy a good charger, properly sized (about 0.2C, that's important for battery health) and with proper four stage charging profile and voltage and temperature sensors ON THE BATTERIES. Then, buy a small inverter of whatever size needed for whatever AC gear you use occasionally, and wire it up to a separate AC outlet or outlets (that greatly simplifies the installation -- no switching over from the shore power, which is kept separate).

A combined inverter/charger is really the master control system of electrical power on board -- all AC power goes through it, and it controls all AC/DC conversions in both directions. It also controls how you consume AC power from shore power or generator. It is complex to install, besides being expensive, so I wouldn't recommend it for boats which don't use a lot of AC power. But for other boats it's fantastic -- I wouldn't want to be without it.

Good to hear that combo inverter/chargers have become more reliable, and are proving their worth. Certainly something I will consider when my current charger requires replacing. In the meantime, and considering my minimal AC usage, I think a standalone inverter would make more sense for me right now.

My 8kw generator takes care of the few times I may want to run the r/c a/c or heat, and my frig/freezer runs off either 110v (gen or shore power) or an engine driven compressor (very efficient). So all I'd be looking for an inverter to do is power AC outlets when I'm away from the dock and want to run microwave, toaster, TV, coffee pot, or charge the computer, all of which use the AC outlets already on the boat. I'll have a house batt bank of 765ah charged by two alternators and a sufficiently sized charger, so batt capacity shouldn't be a problem. Appliances with a heating element (toaster, coffee) require about 10A @120VAC for brief periods of time. The microwave peaks at ~1000W so approx. 8A. I won't be attempting to run the frig or a/c units off the inverter.

Everything else on my boat, incl. all of what I would call the critical systems, run off DC. The few items listed above are more in the convenience/luxury category, but also not generally worth firing up the diesel generator for. For this reason I haven't thus far been compelled to purchase a more expensive charger/inverter unit, although that thinking might change down the road.

[travellerw]

Originally Posted by Exile

Yes, of course. That's the standard setup, although as 'sainted' mentioned above, it's best to install a sub-panel only for inverter loads so the other high amp loads on the AC side don't get inadvertently turned on when only the inverter is being used. Since my inverter needs will be pretty minimal (I also have an 8Kw generator), I thought it would be simpler and less expensive to install the inverter type with the outlets already built in. Just not sure if running an extension cord is ABYC complaint or otherwise advisable. Other than small inverters running light-duty appliances or charging the computer, my boat has never had the type of large capacity inverter that have become so common these days.

There is no reason an extension cord would not be ABYC compliant. Of course that is if you aren't planning on running it as a permenant solution (i.e. pulling it through compartments or bilges). If you are just planning to pull out an extension cord everytime you want to use the specific device, then there is nothing wrong with that at all. We actually do that for our onboard washing machine. We have another 220V inverter installed on a shelf (with proper 2/0 wire and 12V breaker). We just turn the inverter on, pull out our extension cord, plug it between the washer and inverter, and are good to go. Its a great simple solution.

All the points that were listed for a combined unit still don't sway me. We have run a completely separate electrical AC circuit for our other inverter (120V), vs shorepower loads. We have just a few AC circuits connected to the inverter in the area with the highest use (galley and salon). The outlets are labeled "Inverter" or "Shorepower". No faffing about with auto swtiches. Plus with separate devices, I would only need to replace a relatively low cost component instead of a $1500+ device.. but that is just me.

[Exile]

Originally Posted by travellerw

There is no reason an extension cord would not be ABYC compliant. Of course that is if you aren't planning on running it as a permenant solution (i.e. pulling it through compartments or bilges). If you are just planning to pull out an extension cord everytime you want to use the specific device, then there is nothing wrong with that at all. We actually do that for our onboard washing machine. We have another 220V inverter installed on a shelf (with proper 2/0 wire and 12V breaker). We just turn the inverter on, pull out our extension cord, plug it between the washer and inverter, and are good to go. Its a great simple solution.

All the points that were listed for a combined unit still don't sway me. We have run a completely separate electrical AC circuit for our other inverter (120V), vs shorepower loads. We have just a few AC circuits connected to the inverter in the area with the highest use (galley and salon). The outlets are labeled "Inverter" or "Shorepower". No faffing about with auto swtiches. Plus with separate devices, I would only need to replace a relatively low cost component instead of a $1500+ device.. but that is just me.

It's me as well. I feel like my boat systems are complicated enough, and make do just fine when away from the dock w/o necessarily having what are not actual necessities for running the boat (coffee's a necessity but than can be accomplished on the gas stove ). Of course, everyone defines "necessity" differently, and that's fine too. For this reason, this is the first time I've contemplated a large capacity inverter, and would also be inclined to keep it separate from the charger. But never say never . . . .

My understanding is that such large cap inverters must be installed as close to the batteries as possible. In my case that means the aft cabin, and would be a PITA to run an extension cord down the companionway and into the galley or salon just to run a coffee pot or charge a computer. The only other way is running the cord along existing wire runs through lockers & bulkheads, i.e. more or less permanently installed. Instinct tells me this is a bad idea, and I imagine others with more experienced instincts would tell me the same.

If properly wired into the AC system instead, my thought was to replace my aging Shore-Off-Ship AC selector switch which allows me to toggle between shore power & the generator, with a 4-position Off-Shore-Gen-Inverter switch. Thus far I have found them available from Newmar & Blue Sea. The 'Inverter' position could then be wired to an AC sub-panel which includes only the three circuits for the boat's AC outlets (galley, port, starboard). It seems to me that this might be the simplest & easiest way to differentiate power sources and the circuits they feed, eliminate unhealthy draws on the batts., and have a fully manual system with (hopefully) little to go wrong.

Any thoughts?

[travellerw]

Originally Posted by Exile

If properly wired into the AC system instead, my thought was to replace my aging Shore-Off-Ship AC selector switch which allows me to toggle between shore power & the generator, with a 4-position Off-Shore-Gen-Inverter switch. Thus far I have found them available from Newmar & Blue Sea. The 'Inverter' position could then be wired to an AC sub-panel which includes only the three circuits for the boat's AC outlets (galley, port, starboard). It seems to me that this might be the simplest & easiest way to differentiate power sources and the circuits they feed, eliminate unhealthy draws on the batts., and have a fully manual system with (hopefully) little to go wrong.

Any thoughts?

Hhmmm maybe I'm not undstanding right, but I don't see the need for the AC selector switch change.

Just remove those circuits from the main panel, install a sub panel, then wire the circuits and the inverter to the subpanel. When the inverter is on, those plugs are live (put a label on them saying inverter). Simple as that. (This would be my choice).

Another more complicated option if you still want plugs with both inverter and generator/shore power. You could pull brand new wires to those plugs (I would use 14 guage 3 conductor marine wire). Then break the tabs on the plugs and using the new wires to light up one side of the plug. Then wire the new runs and the inverter to a subpanel. Now you have plugs with one side being Inverter and one side still powered from generator/shore. Label which side is which and boom, have a drink with uncle Bob.

[ranger58sb]

Originally Posted by Exile

Yes, of course. That's the standard setup, although as 'sainted' mentioned above, it's best to install a sub-panel only for inverter loads so the other high amp loads on the AC side don't get inadvertently turned on when only the inverter is being used. Since my inverter needs will be pretty minimal (I also have an 8Kw generator), I thought it would be simpler and less expensive to install the inverter type with the outlets already built in.

Ah, didn't know about those kind of inverters.

FWIW, we didn't have to install a sub-panel; just shuffled around breakers so all those that were to be inverter-powered were on the same buss bar in the main panel.

And since we were doing that, it was an easy choice to inverter-power all the "outlet" circuits in the boat, so there's power wherever, no matter what I might (in the future?) decide to plug in. Within reason, of course.

Which in turn means we don't have to start the genset to make morning coffee or afternoon popcorn.

-Chris