Inverter for when main engines are running

[TBill36]

I have a relatively power consuming sportfish that I run the generator whenever I'm on the boat when not plugged in. There is currently no inverter or means to run anything 110v without the gen running.

I'd like to have the capability to run the 2 refrigerators, 2 freezers, 2 icemakers, and the fresh water pump if the generator quits. Probably somewhere around 800 watts when everything is running which does not account for motor start up. As they cycle on and off the 800 will be less, but I'll need to account for some of them starting at the same time. I'm thinking a 3000 watt pure sine wave transformer type inverter. I had good luck with Magnums in the past, but heard they have been bought out so maybe concerned.

I'm not interested in a large battery bank size and would think the two 90 amp main engine alternators would be sufficient to power everything in case the gen quits. I have no intention of running the appliances without the main engines running.

The current set up has 2 group 31 batteries per engine and one of the sets is used for the house also. On a previous boat, I had a small bank and believe it contibuted to electric motor start up problems. I'd like to avoid that, so maybe I need to up the house bank size.

This is a new boat to me and I intend to have one set of batteries for starting both motors, one bank for house, and one dedicated to the gen.

I think external voltage regulators on the alternators and an acr to combine them to maintain the house when running off the inverter is what I need. The gen will be totally separate.

Any suggestions and area of concers is greatly appreciated.

 

[rslifkin]

If you're staying with lead-acid (flooded or AGM) batteries and don't care about getting the fastest recharge possible from the alternators, you can just add ACRs and skip the external regulators. You won't cook the batteries and they'll still power your loads fine.

 

[jgwinks]

I have a 3000w inverter and it runs my 2 refrigerators, lights, and various small loads for phone chargers etc just fine. The engines stay ahead of the load with the stock 55 amp alternators. I do have a large battery bank and some solar, I can run off the inverter at anchor (engines off) for about 2 days before I get down to 50% on the batts. I refuse to be one of those guys who runs the genset all night. But that's a different use profile altogether.

 

[Greg QS]

I really like the Victron gear. they have a multiplus 3k inverter /charger

 

[SteveK]

Tbill. Your genny is able to run what you want. What is the GEN output in amps per hour.
The battery bank will need to support the inverter with the same amps per hour for a needed number of hours before recharge.

 

[Mambo42]

31 batteries ? What Ah do they have ?
Perhaps it is easier to switch to less batteries, but with a larger capacity ?
As for the inverter, my boat has a complete Victron installation and I am happy with it. We are running the 2 fridges, freezer and all our other equipment through the inverter. Perhaps you don't have that equipment on board now, but will you have it in a later stage ? We have a washing machine, dishwasher, TV, stereo, microwave, induction plate, water maker, air conditioners, stablizers, which we are not running all at the same time, but e.g. if you run the washing machine, the water pump will switch on as well and that is a 220 V pump, which means through the inverter. The boiler is also 220 V and also that switches on when the dishwasher switches on. So even though the dishwasher is only 1000 W, the waterpump will add 1500 W and the boiler an additional 1400 W. Add that to the standard load and I am up to 4500 - 5000 W real quick. So based on that I installed a Victron Quattro 24 V / 8000 / 200 inverter charger.
Since I also don't want to run the generator all the time I have 3.2 kwp of Solar and now in summertime I often get 2.5 Kw per hour out of them.
All my solar panel controllers are Victron, the chargers are Victron, the control panel is Victron and in about 2 weeks time I will have Victron batteries as well. It makes my life very easy, since I can see everything on the phone via blue tooth.

Perhaps not necessary for your boat, but if you are thinking about changing some parts you may want to think about changing a bit more. It is just an idea.

 

[O C Diver]

I have a relatively power consuming sportfish that I run the generator whenever I'm on the boat when not plugged in. There is currently no inverter or means to run anything 110v without the gen running.

I'd like to have the capability to run the 2 refrigerators, 2 freezers, 2 icemakers, and the fresh water pump if the generator quits. Probably somewhere around 800 watts when everything is running which does not account for motor start up. As they cycle on and off the 800 will be less, but I'll need to account for some of them starting at the same time. I'm thinking a 3000 watt pure sine wave transformer type inverter. I had good luck with Magnums in the past, but heard they have been bought out so maybe concerned.

I'm not interested in a large battery bank size and would think the two 90 amp main engine alternators would be sufficient to power everything in case the gen quits. I have no intention of running the appliances without the main engines running.

The current set up has 2 group 31 batteries per engine and one of the sets is used for the house also. On a previous boat, I had a small bank and believe it contibuted to electric motor start up problems. I'd like to avoid that, so maybe I need to up the house bank size.

This is a new boat to me and I intend to have one set of batteries for starting both motors, one bank for house, and one dedicated to the gen.

I think external voltage regulators on the alternators and an acr to combine them to maintain the house when running off the inverter is what I need. The gen will be totally separate.

Any suggestions and area of concers is greatly appreciated.

2 refrigerators
2 freezers
2 ice makes
1 freshwater pump

Sounds more like 1,000 to 1,500 combined watts depending on what the ice makers draw. 1,500 watts will require roughly 165 amps at 12VDC.

I think you're good with the 3,000 watt inverter and two 90 amp alternators, while running. You didn't mention the type of sport fishing you're doing. This isn’t going to work trolling as the alternator output is way down at low RPM. Also, this will eat a battery bank in no time if engines are idle or off at anchor..

For reference, I ran an air conditioner off my charter boat engine while going out and back on scuba charter. So, it can be done, but total amp draw is critical as is the type of charter fishing.

Ted

 

[SteveK]

31 batteries ? What Ah do they have ?
Perhaps it is easier to switch to less batteries, but with a larger capacity ?
As for the inverter, my boat has a complete Victron installation and I am happy with it. We are running the 2 fridges, freezer and all our other equipment through the inverter. Perhaps you don't have that equipment on board now, but will you have it in a later stage ? We have a washing machine, dishwasher, TV, stereo, microwave, induction plate, water maker, air conditioners, stablizers, which we are not running all at the same time, but e.g. if you run the washing machine, the water pump will switch on as well and that is a 220 V pump, which means through the inverter. The boiler is also 220 V and also that switches on when the dishwasher switches on. So even though the dishwasher is only 1000 W, the waterpump will add 1500 W and the boiler an additional 1400 W. Add that to the standard load and I am up to 4500 - 5000 W real quick. So based on that I installed a Victron Quattro 24 V / 8000 / 200 inverter charger.
Since I also don't want to run the generator all the time I have 3.2 kwp of Solar and now in summertime I often get 2.5 Kw per hour out of them.
All my solar panel controllers are Victron, the chargers are Victron, the control panel is Victron and in about 2 weeks time I will have Victron batteries as well. It makes my life very easy, since I can see everything on the phone via blue tooth.

Perhaps not necessary for your boat, but if you are thinking about changing some parts you may want to think about changing a bit more. It is just an idea.

The current set up has 2 group 31 batteries per engine
He does not have 31 batteries

 

[mvweebles]

....Sounds more like 1,000 to 1,500 combined watts depending on what the ice makers draw. 1,500 watts will require roughly 165 amps at 12VDC.

I think you're good with the 3,000 watt inverter and two 90 amp alternators, while running. You didn't mention the type of sport fishing you're doing. This isn’t going to work trolling as the alternator output is way down at low RPM. Also, this will eat a battery bank in no time if engines are idle or off at anchor..

Ted notes a number of cautions I'd agree with. I'd add that voltage sag across a pair of G31 FLAs is meaningful.....even if cabling is beefy.

In short, I think you're nearing the max charge/concumption capacity of the system. Stock alternators are not known for producing anywhere close to their stated rating. Plus you have other running loads such as instruments, autopilot, navigation, lighting, etc. 3000W inverter should be fine, but I suspect you'll eventually need improved alternators and a larger house battery bank.

Peter

 

[TBill36]

I think Ted hit the nail on the head. I would be trolling most of the time and therefore alternators not putting out much. Need to rethink that one.

A lot of my trips are to the Bahamas and I don't want to be forced to come home because of loss of refrigeration. I can stay in marinas and plug in at night, but during the day need to be able to run the refrigerators and freezers at a minumum. The ice makers can stay off.

I intend to run the gen. It a relatively new Northern Lights 12 kw with about 600 hrs. Just want a prevision in case it goes out so I don't have to come home. A back-up small gen would also work, but don't know where to put it and don't want the added maintenance.

Sounds like more batteries and throw in some high speed trolling.

 

[OldDan1943]

Ted notes a number of cautions I'd agree with. I'd add that voltage sag across a pair of G31 FLAs is meaningful.....even if cabling is beefy.

In short, I think you're nearing the max charge/concumption capacity of the system. Stock alternators are not known for producing anywhere close to their stated rating. Plus you have other running loads such as instruments, autopilot, navigation, lighting, etc. 3000W inverter should be fine, but I suspect you'll eventually need improved alternators and a larger house battery bank.

Peter

You need to remember, larger inverter, larger healthy batteries.
Larger batteries need a way to charge them
Larger battery charger and or larger alternator.
Sort of never ending circle of alternatives
If the alternator craps out, you rely on generator and the battery charger etc. The circle continues …
If everything craps out and the boat goes dark, you are sort of screwed unless solar cells….. Recharging via solar cells may take a while. My solar cells are not larger enough to quickly charge the batteries and that gives me time to investigate and replace parts or call for help.
I think I got all that right. Correct me if I am wrong or left something out.
Basically the marine electrically is made up of over lapping circles. If one part craps out, if the system is designed and implement properly, the remaining circles will pick up. Two circles crap out, the 3rd should be able to support the necessary equipment on the boat to get you home. If 3 circles crap out, I hope you are tied to the dock and shore power is available.
So carry a spare alternator and belts as required. Remember the battery parallel switch too.

Now we can play the “if, if, if” game if you wish. SMILE

 

[twistedtree]

I would add the inverter. It’s a perfect fit for this application. If you are trolling extensively, the alternators aren’t keeping up, and the batteries start to get low, you can always start the generator then and run it for a while to recharge. But I expect your alternators will keep up just fine.

 

[CaptTom]

... A back-up small gen would also work, but don't know where to put it and don't want the added maintenance...

A 2000W Honda portable doesn't take up much space, and the cost isn't that far off a comparable inverter. Maintenance is minimal. Only problem is keeping a few gallons of gasoline aboard. Not an issue if you already have a gas motor on your dinghy.

I've come to just accept that some boats are designed to always have AC power. Start the genset before unplugging, and shut it off after plugging back in.

 

[sunchaser]

TB
No matter what brand of inverter or number of batteries there is one thing you can do to solve many of your concerns. - spare parts for your NL. To name a few:
- alternator
- starter
- exhaust elbow
- raw water pump
- belts and hoses
- oil and fuel filters
- zincs
- impellers

Armed with some basic knowledge on how to maintain and service that unit you should be good for several years. Go by the book and that genset will be less trouble and outlast the main engines.

 

[Jeff F]

A 2000W Honda portable doesn't take up much space, and the cost isn't that far off a comparable inverter. Maintenance is minimal. Only problem is keeping a few gallons of gasoline aboard. Not an issue if you already have a gas motor on your dinghy.

For emergency backup this seems like a simple cheap solution. I'd want to configure a plug to use the shore power cord to connect to the portable generator.

 

[jgwinks]

That's what I did on the sailboat. 15 amp male plug for the gen end and a 30 amp female twist lock for the boat end. Big box stores sell the 10 gauge 3 conductor wire by the foot so you don't have to butcher a good cord.
The are other brands of generator that have the 30 amp outlet built in but they're probably not as good as the Honda.

 

[OldDan1943]

For emergency backup this seems like a simple cheap solution. I'd want to configure a plug to use the shore power cord to connect to the portable generator.

Call a local electrican, he can make up a pigtail for you. I have 2 Honda generators at home, in case of power outages. I have yet to find a need. I had an electrician out for another problem, mentioned it to him and within an hour, he had drilled 2 holes, mounted the plugs. Now I can run the generators without propping the door open.
I use a locking socket heavy duty extension cords. They wont support the entire condo but enough to maintain creature comforts ie fridge, coffee pot and heat lamps or a heater and TV in a bathroom.

 

[CaptTom]

Most of us carry a 15A and/or 20A adapter anyway, so we can plug into shore power at those odd places which only offer "regular" outlets. Even if you don't, they're not that expensive to buy.

 

[Nick F]

I would add the inverter. It’s a perfect fit for this application. If you are trolling extensively, the alternators aren’t keeping up, and the batteries start to get low, you can always start the generator then and run it for a while to recharge. But I expect your alternators will keep up just fine.

+1 !

But you may have to beef up at least one alternator.

 

[TBill36]

There is no way a gasoline powered generator is going on my boat. I don't want this to turn into a discussion on why, but just not going to happen.

I'm pretty good with maintenance and knowledgable with NL generators, so maybe I'm worrying about something unlikely to happen.

Reading through the responses and rethinking this a little, I think a 600 amp hr battery bank would work if I only run the referigrators and freezers. Again, this is only in the event the gen goes out and I don't have to cancel a trip, Sometimes I'm 400 miles from home which equates to a long return and disappointing trip. The cost of one incident would almost pay for the inverter and batteries.

 

[Greg QS]

Just yelled at my buddy about this the other day. Uses a Honda gen set. ( no gen on board) and stores it in the v birth.

Diesel boats are not designed ignition protected. They are bombs when it comes to gasoline fumes!!!!!!!!!!!!!!!!!!!!!!!!!

 

[jgwinks]

Just yelled at my buddy about this the other day. Uses a Honda gen set. ( no gen on board) and stores it in the v birth.

Diesel boats are not designed ignition protected. They are bombs when it comes to gasoline fumes!!!!!!!!!!!!!!!!!!!!!!!!!

Yep. I used one on the sailboats, but it stayed out on the back deck all the time, padlocked down with a cable. Exhaust and any spills went directly overboard. I made a canvas cover for it to keep the rain off.
As far as I know the only really ignition protected things on a gas boat are the starter and alternator. At least they're supposed to be, I'm sure not all are.

 

[mvweebles]

There is no way a gasoline powered generator is going on my boat. I don't want this to turn into a discussion on why, but just not going to happen.

I'm pretty good with maintenance and knowledgable with NL generators, so maybe I'm worrying about something unlikely to happen.

Reading through the responses and rethinking this a little, I think a 600 amp hr battery bank would work if I only run the referigrators and freezers. Again, this is only in the event the gen goes out and I don't have to cancel a trip, Sometimes I'm 400 miles from home which equates to a long return and disappointing trip. The cost of one incident would almost pay for the inverter and batteries.

600ah is a good size - I ran that for many years, though with just one fridge. Not sure how big your fridges are, but you could probably run overnight at anchor if desired.

 

[mahal]

https://www.jackery.com/products/ex...Xc9JLq_bITIHpSaH1WGHFxqxVGEog-jRoCTl4QAvD_BwE

Since it's just for a back-up and peace of mind and there's a chance that it may not be used at all, I would consider a portable unit like the one linked. One advantage to it is its usefulness for other purposes shore side.

 

[sunchaser]

TB
When you’re cruising and all power draws functioning what is amperage draw on the NL? Then turn off the don’t need it draws like AC etc and what is amperage draw? Your two 90 amp 12 volt alternators may only average 60 amps.

A good battery monitor in addition to the inverter will be required. The inverter/charger should be located in a cooler spot for optimum efficiency.

What size of boat do you have? If engines are electronic be wary of hooking inverter up as sporadic loads could affect the voltage the on engine’s electronics see.

 

[mickand]

I'm glad TBill won't go for the Honda generator - a poor solution to his issue.
As regards inverters, consider an AIMS 3000 full sine wave unit. I live aboard and mine has served me well for over 4 years.

 

[OldDan1943]

Maybe a one or 2 cylinder diesel generator?
Assuming it is used to charge the batteries and not tie directly into the AC bus.

 

[Cargile]

If you're staying with lead-acid (flooded or AGM) batteries and don't care about getting the fastest recharge possible from the alternators, you can just add ACRs and skip the external regulators. You won't cook the batteries and they'll still power your loads fine.

Please explain the idea of an ACR precluding an external regulator. I have LA starter and house batteries with an ACR. Thinking of switching the House to LFP.

 

[rslifkin]

Please explain the idea of an ACR precluding an external regulator. I have LA starter and house batteries with an ACR. Thinking of switching the House to LFP.

If the voltage set-point of the alternators isn't too far above the float voltage spec-ed for the batteries, then the internally regulated alternator won't hurt a lead acid battery. It just won't get it to the full absorb voltage, so it will take longer to charge.



With LFP, you either need a DC-DC charger or an externally regulated alternator. I wouldn't use an internally regulated one with an ACR in that situation.

 

[PM]

You don't mention the size of your boat. It must be a "Big un". Maybe I didn't understand the post, but whats wrong with running the genny?

pete