Adding an Inverter

[brimanst]

I am about to start spec'ing out an inverter system for my new-to-me 480DB. I am here soliciting help as to how much power I need, where to install it, how to put into the A/C system and any possible brand recommendations for the equipment and/or batteries.

I want to be able to run:
- Refridgerator
- Freezer
- Icemaker
- Wine Cooler
- Stereo/TV equipment
- Microwave
- Computer/network system

I would like to be able to go for about 6-8 hours with no genny.

I know that most inverters are not approved for the bilge, but does that matter in a diesel boat?
I am thinking about using the AGM batteries. If I do, can I install them inside the cabin somewhere in the lower bilge spaces (or under a bunk)?
What size/how many batteries do I need?
Do you put the transfer switch on the genset or shore power side of the A/C system?
Do I have to rearrange my A/C panel to only power one side of the 220 bus? Or do I just make sure I keep all the other items off?
Is it easier to just use an inverter/converter?

Is this a factory option? If so, where does Searay put the inverter system and batteries on the 480DB?

Once I get the answers, I will generate a drawing and post it back. Thanks in advance.

 

[Asureyez]

First thngs first

Having determined what you want to run simultaneosuly you'll need to make a calculation of the power consumption of each item As follows:

Applicance / Statup Watts / Volts / Running Watts

Refrig.
Wine Cooler
And so on

Then total the wats for 120 and separately for 220. Total the watts at 120 and 220 and the total with peak demands.

This will give you a profile of total continous demand and the peak demand in watts. Convert the 220v draw to 120v/watts and total the entire demand as 120.

Lets assum that your profile is total demand is 2500 watts per hour at 120 volts Peak (if all motors kicked at once) 7,500 watts. The Big Heart Interface Inverter/Charger will give you 3000 watts continous, 7500 peak for motor starting at 120v.

Convert the watts draw to amps at the desired voltage.

Watts divided by volts to get the amps needed per hour.

Then determine what the outside number of hours will be that you will want the batteries to run everything and multiply the Amps per hour by the clock hours. This number represents approximatley half the total amps you'll need to store in deep cycle batteries.

2500 watts / 120 volts = 20.85 amps continous draw and 63 Amps peak.

Thus lets say 6 Hours is the max period, then you'll need 20.3 X 6 hrs = 122 amps X 2 for total battery capacity

245 Amps in deep cycle batteries.

This is the general set of considerations you'll need to evaluate to determine if you can accomplish your goals and then if you shoud attempt to do it as planned or to take items off the system during this period.

Once that is determined then you'll need to find an inverter that can deliver the power load you want and the place to put it.

Then the size and configuration of the house bank you'll need to supply the inverter and where to put the new batteries.

And then if you do not get a charger/inverter you'll need additional battery charger capacity in order to get the amps back in within a reasonable time before the next draw down. Or upgrade the alternators on the mains.

And then how this system will be cabled, small gage wires won't do ( think 2/0 cable), fused and breakered. Yes, you'll need a big honking fused buss in line to prevent fires with the huge peak DC draws on nearly empty batteries.

By way of referance, a womans hair dryer will draw up to 1500 watts during the 8-10 minutes its used, a Microwave will draw 450 to 750 watts while in use, a convection microwave perhaps 1500 at times, the compressors in the airconditioning and raw water pumps ... the list will go on so be very complete in analyzing these systems involved and other systems that will kick as well.

Once you get the book work finished I'm sure we can help you think through your project even more.

Good luck, sounds like a interesting project.

 

[boatmailster]

Like said above, you will need extra boat just to put spare batteries
If you really think to go for inverter system better contact professionals who can design system to fit your boat and your needs (if possible) and check for space on boat because those golf cart batteries are not small. Plus you have to remember about safety - automatic switch over or disabling inverter when shore power or generator is presented and etc.

 

[Asureyez]

Batteries

I'm gusessing this system will take 6 - 6 volt bats two each in series and then all three in one big 12 volt bank, that would deliver perhaps 450 amps for six hours which is where this will probably fall out once heat loss, voltage drop in cable runs and diods come into play.

One nice thing about the Heart's is they can be set to automatically drop off line when another sourc eof AC comes on line and if its the Inverter charger, it will begin charing as well. If the Alternators and sharger are to a series of diod blocks the strongest voltage souce will get through the gates and the other source(s) will back down and thus the batteries will get the most volts.

I had a similar system on a 42 ft sailboat soem years back and it was a massive rig that would pump out 3000 watts for my dmanad for 24 hours, but I never tried to run 120 volt motors, but the holding plat freezer refrig. was 12 volt and its draw was a lot.

I see to remember that the whole rign with new Rolls bats, catalytic caps for the Rolls, the Heart, the new diods for the whole ships power system, a Balmar 120 AMP Alternator and install of cables and buss and fusees to the main panel plus and jury rigging which there alwasy is in moving other stuff to get room to install new I spent about 12,000 in 1998. All so the wifey of the day didn't have to listen to a Kohler sound proofed genny banging away.

Its a big job and with the added room on a 480 I'm sure it can be done, just some existing things will have to be moved or valuable storage space sacrificed to new uses. The Bats will be the issue at the end of the day.

 

[Sorrento 25]

I run a Pro-Sine 2.0 2000W Inverter/Charger on two Trojan L16HCs - 420 Ah - 250 lbs. - reduce your boat capacity accordingly! The Pro-Sine is nice because it includes a full function remote panel, automatically switches to/from shore power, has standby mode, off mode, etc. 2 of these will give you 220V. Sun Electric has some good deals on refurbed Xantrex stuff.

 

[Dave M.]

I would like to be able to go for about 6-8 hours with no genny.

You might want to make this requirement flexible. It will affect the total battery size, so you may need to bend a bit when you come up with the numbers.

I am thinking about using the AGM batteries. If I do, can I install them inside the cabin somewhere in the lower bilge spaces (or under a bunk)?

I am not a big fan of AGM batteries, but one of the advantages of them is that you can put them in places you could not put normal wet cells, and you can lay them on their side. So they may work well for your application. You will need at least part of the battery plant within a few feet of the charger/inverter. But if you end up with three sets of parallel batteries, you might consider that at least one set does not have to be this close. They will equalize when not under high current load.

What size/how many batteries do I need?

You have to determine that by calculations as described above. Asureyez built in a factor of two in the battery capacity, so you don't discharge them more than half way for maximum battery life. This is a rule of thumb "everyone" uses. I am not convinced it always makes sense in a boat. Suppose you get a nice set of AGM batteries that come in the cylindrical cases (I forget their name). If you look at the ratings, they may be good for 500 discharges at 100% of rating, or 1200 discharges at 50% of rating. So you are paying twice as much to get 2.4 times as much potential life. But you are hauling around twice as many pounds of batteries to do it, using twice as much valuable boat space, and you are investing your money up front, as though it has no time value. You are also assuming that the reason for replacement is that you have used up all the discharge cycles. I suspect that most boat batteries fail for some other reason before that happens, so you really may not get the extra life anyway. Just my opinion.

Do you put the transfer switch on the genset or shore power side of the A/C system?

I would expect that a professional would put them after the bus that combines the two items. That way you could charge the batteries from either the genny or shore power.

Do I have to rearrange my A/C panel to only power one side of the 220 bus? Or do I just make sure I keep all the other items off?
Is it easier to just use an inverter/converter?

I think you would need your main AC panel rewired, so that only the items that you intend to be fed from the inverter are actually connected to it. And I think the inverter should have an automatic transfer switch built in, so you no one on the boat has to worry about getting the switch positions right under differing conditions. You want it to "just work".

 

[brimanst]

Thanks for all the advice. My homework list just got bigger. I will do some research and post my proposed solution.

 

[Sea Gull]

We installed an inverter this year. We have a 24volt bow thruster that is powered by 2 x 8D batteries. We opted to run the inverter off these batteries rather than a dedicated bank. The primarey advantage is the weight and space savings of the batteries. Also, since the thruster bank already had a charger we needed only an inverter instead of a combo inverter/charger unit. Operating at 24v is more efficient, but the equipment is slightly more expensive. The other slight disadvantage is that I cannot run the inverter and the bow thruster at the same time - it would draw too much current. But the thruster gets used once in a while, usually around the dock. The inverter gets used only when we are on the hook.

Our goal is to run the Sub-Zero refridgerators and freezer overnight and so far the 2 x8Ds seem to do the trick. Of course they are brand new and over time I may need to suppliment the storage capacity. In this case I may opt for 3 8 volt batteries that would take more or less the same footprint as the 2 8Ds but have significantly more capacity. (for me height is not a major issue).

On battery location: they need to be as close as possible to the inverter.

 

[Asureyez]

THe issue with huge demands from DC

The issue that concerns me with the inverter scenario is the huge draws being planned or are in use.

DC current from the battery to the inverter will have to have huge 0/0 cables and a giant fuse in line to prevent serious fire or the ruin of the items drawing current. And then with a massive fuse the run will need to be short thinking a in feet 10- 12 and not much more.

Sure things go well with DC when the batteries are at peak, but as they draw down and the demand for amps continues the resistance builds rapidly. When the batteries are at half discharge the situation becomes much more risky and if starting electric motors gets thrown on to the load at this state of discharge Whew! The heat generated can melt lead terminals, ignite surrounding flamable materials.

If a system is designed with battery capacity, that by design, contemplates drawing batteries down to zero, it is a design that could have disaster built in. In such design those circuits in the supplied by inverter should be put on a separate buss from anything critical for safe boat operation that is for sure and the batteries totally separate from engine starting and navigation needs.

Perhaps multiple inverters might be considered and break the loads down to more manageble sized separate batt banks? I'd sure consider it when looking at whole ship type loads as we are.

 

[Steve36]

Just had an inverter installed last week. Wanted to run the same stuff as you did but I wanted to run for 48 hours at a time.
Your Fridge and Freezer already run of DC. So you only need to run all your other stuff.
I went with a 2800 Watt Magnum Energy inverter (pure Sine) as well as two Trojan L16H batteries.
Everything runs great. The inverter powers the TV's and the satellite receivers.
I would say that you should get it professionaly installed.
There is just too much that can go wrong.
You will be looking at a total cost (including batteries, inverter, installation and misc items) of roughly 5000.00
If you hate running the genny (like I do) than this is your ticket.
Please remeber that you can readily recharge your inverter batteries within 2 hours.
Good Luck

 

[MadDog]

I also used the bow thruster batteries

I used the same approach mentioned above and used the bow thruster batteries. I however replaced the charger with a Xantrex 24v/3000W charger/inverter. I had the same reason - i wanted to run the fridge and freezer overnight.

I installed a 24V unit myself, then had it professionally inspected. So far, so good.

mark

 

[Warren]

Brimanst: As you have heard already on this thread - anything is possible if you are prepared to pay the price. In this instance there are more than $ involved. There may be a price to pay in terms of weight + boat handling and performance. The boat will be lower on her lines. In our last sail boat I had a house bank of 6 golf cart batteries plus a 12 V starting battery. The requirements will obviously be different on a power boat but use the calculations given, to calculate your amp/hr requirements per day and at the end of the day it will mean a substantial amount of extra weight.

On our last 2 sailboats I consulted with Jack Rabbit Marine and purchased inverter kits from them which included all of the components including a smart voltage regulator (not needed by you), a 2kw inverter/charger, solenoid, fuse, bus, etc., and an Emon II amp hour meter. I would highly recommend that you purchase a good amp hour meter to tell you how many amps you are consuming, voltages, battery temp, and how much power you have left in the bank. Many will allow you to set alarms to alert you when the bank is say, 40% depleted. A good investment if you are purchasing expensive new batteries.

You are on the right track. Speak with an expert like Jack Rabbit. Plan the installation carefully and do find an experienced installer - it's a must in my book.

Good luck!
Warren