Inverter...

J

JamesTXSD

Active member
With the time for our CD-25 to be built coming, we are trying to plan for what we will want on the boat and have it complete from the factory. We would like to have an inverter (thinking 1000w) installed to be able to use the microwave or a blender when at anchor and not have to fire up the generator. When I visited with the factory today, I was told that they prefer to not install an inverter. I kinda pushed the issue and was told that if I provided the inverter they'd see what they can do.

What have other owners who have an inverter done for install? Any brand that you'd recommend? We have plenty of experience with the use of these (with motorcoaches we've owned) and find them to be a real convenience. Thanks in advance of any guidance you can provide.

Best wishes,
Jim B.
 
Jim, you'll suck a lot of amp hours out of those batteries with an inverter. Not that it can't be done, if you do it, make sure you isolate a battery to get started after you drag all the other ones down. A small genset would be much better to run big stuff. Small stuff, computers, tvs, etc are fine. Microwaves, AC units, etc are too much.

When you're in a motorhome, you're usually near an outlet to recharge. In a boat at anchor, unless you've got a really looooooooooooooooong shore power cable, not so.... :shock:

Chaqrlie
 
I have a small (250w?) inverter on board used only to run the DVD and the knife sharpener (yeah, yeah, yeah, so I can't sharpen a knife. Big deal.) If I was going to replace it or add one, I would get the 1000w that Costco sells for cheap. Those things do pull the amps, but only relative to the load. A microwave for a minute or more would be a lot, but a blender for a few seconds should be fine. To wire it in permanent, you want to oversize the wiring to handle the surges.
 
I installed a 1000W inverter. I have a GFI single outlet in the galley with a indicator light to remind me that it is on. (The inverter is in the battery compartment in the cockpit). I have two house batteries and an isolated engine battery. Also have a Honda 2000 on board plugged into the shore power outlet. I use the inverter for the coffee grinder in the morning mainly (Yes Bill, I grind my own also)
 
JamesTXSD":1fpb5pdb said:
With the time for our CD-25 to be built coming, we are trying to plan for what we will want on the boat and have it complete from the factory. We would like to have an inverter (thinking 1000w) installed to be able to use the microwave or a blender when at anchor and not have to fire up the generator. When I visited with the factory today, I was told that they prefer to not install an inverter. I kinda pushed the issue and was told that if I provided the inverter they'd see what they can do.

What have other owners who have an inverter done for install? Any brand that you'd recommend? We have plenty of experience with the use of these (with motorcoaches we've owned) and find them to be a real convenience. Thanks in advance of any guidance you can provide.

Best wishes,
Jim B.
Click to expand...

Hey Jim,

Well, you're headed down a slippery slope! :shock: There are as many inverters out there as there are vitamin pills!

You really have to define what capability you need (microwave, cell phone charging, latop, etc); that is, how much power and for how long. And then do you want want one that integrates into the onboard shorepower system or a standalone unit? If it integrates into the AC system on the boat does it power one outlet or two? Does it transfer all 30-amps of incoming power when shorepower is plugged in or just 15 amps...or none?

Seriously, I'm not being a smart-aleck here; I do this for a living. I can take you from a "plug it into a 12-volt receptacle model" to a unit where just the 4/0 wire necessary to carry the DC load 10 feet from the inverter to the battery bank and the fittings amount to over $500. It's no wonder the factory doesn't really want to do it and why they want you to choose the inverter; there are just way too many variables.

The answers you'll get here on the Brat site probably won't help you much because different folks do different things with their systems; needing to supply power to a microwave for 15 minutes is a universe away from keeping a knife sharpener going for 2 minutes. Everyone that answers means well and they want to help but it's like asking "what car should I buy?".

So, what do you want to do with your inverter? What does it need to power and for how long? An inverter should have a battery bank that is no smaller (in amp-hours) than 20% of it's output (in watts). That is, a 1000W inverter should have a access to a minimum of 200 amp-hours of battery bank capacity. This lets you run your inverter at full power for one hour. A 200 amp-hour battery bank is the equivalent of two Group 31 deep-cycle batteries (usually about 105 amp-hours each).

In addition, an engine alternator should see no more than 3-times its output (in amps) in battery capacity (in amp-hours). In this example the alternator used to charge a 200 amp-hour battery bank should be no smaller than 66 amps. So if you're choosing the Honda BF135/150 with a 40-amp alternator a 200 amp-hour battery bank is 5 times the capacity of the alternator...not a good situation. The BF135/150 really should be limited to charging about 125 to 160 amp-hours of batterys...about two group 27 batteries. You don't really need to count the starting battery if it isn't being used to supply house power. So you could have one cranking battery and then two Group 27 house batteries (confgured as one bank). Following that recommendation then the inverter should be a max 625 watts to 800 watts depending on battery choice. Not enough to run a lot of microwaves so the choice is usually to go with the bigger inverter and be *very* careful about running the batteries too low; especially if you're not going to run the boat a lot the following day (so the engine alternator really gets the chance to charge).

The easiest way to figure draw on the DC side is just to use a factor of 10 based on AC draw; it's close enough as it also accounts for interanal losses in the inverter. So our 1000-watt inverter draws about 9 amps on the AC side and the inverter has to draw about 90 amps from the batteries. That means #6 wire (at a minumum) feeding the inverter from the batteries; in other words a 1000-watt inverter is a "hard-wired" beast (can't be plugged into a 12-volt socket). The simplest form of a 1000-watt inverter wires to the battery bank and but has its own built-in receptacles and it isn't wired into the boats AC system. As soon as you want to power the boat's existing AC receptacles with the inverter things get complicated. You then have to have a Source Selector (so that the inverter doesn't experiece "backfeed" from shorepower) and you have to decide how to power share; that is, does the inverter transfer shorepower? If so, how much? If not all, which circuits should be carried by the inverter? This often requires a sub-panel to distribute the AC load.

I'm just asking for clarification sake but are you sure you had an inverter in your coach? Or was it a converter?
 
OK, you touched a subject dear to my heart. We had an inverter on the sailboat, and I installed one on journey on. Heres my comments:

1. Get a marinized sinewave inverter. I bought a Xantrec, since I had good luck with their battery charger. 1000 watts is good enough for a SMALL microwave. Squarewave inverters don't work real well with a microwave, because the MW knocks off those sharp corners, and makes a lot of noise doing it.

2. With power, there is the law of supply and demand. You need battery capacity, and the stock ones ain't going to do it. I used 4D's on the sailboat, and it worked. Since space is limited on the 25, I installed 2 ea golph cart batteries on the stbd (right?) battery tray. Made some holddowns, starting with the stock battery tray. 2 golf cart batteries= 1 4D.

3. Electronics doesn't like to get wet. The aft lazerette gets wet, at least in my boat. I installed the inverter above and in back of the water heater, and ran battery cable to/from the batteries, through a switch and breaker. Buy auto battery cable over the internet. Worked for years for me, and it's cheap (compared to WM.)

4. 40 amps is enough to charge the battery. It'll start at 40 amps and then go down quickly to about 20 amps. I installed a 40 amp Xantrex (you're right, stole it off the sailboat when we sold it.) With the charger I can use a Honda 1000 generator (which is good for 800 watts.) The stock battery charger is worthless. When I get rich, I'll get one of those battery monitors, which measure amps, volts, amp-hrs (which is what you're interested in.) Until the just a voltmeter.

5. Wired it up to the 110 outlets (only.) That way it can't be routed to the refridge or hot water heater.

6. Powers the PC when we're cruising and lets us watch TV, Judy doesn't want another microwave (yet.)

Got enough advice yet?

Boris
 
Hi Les,
Thank you so much for taking the time to respond. It is easy to see why you are so highly regarded here. To answer a few of the questions you posed: yes, I am sure we had inverters on our last three coaches. They were Heart 2000 and 2500 inverters. These were all high-end diesel pushers with plenty of battery reserve (7 batteries). The coaches also had 7.5 kw diesel generators. If we were boondocking (without hookups), it was wonderfully convenient to run the microwave or other small appliances on the inverters. I understand the C-Dory will not have the same battery depth, but to use a microwave for a couple minutes (not long cooking times) or a blender would sure be convenient. If we needed the microwave for more time, I would certainly plan on using the generator (we have purchased a Honda 2000w generator just for this usage).

My apologies if I did not convey the experience (many years, 250,000+ miles) we have with inverters on our coaches. We could run everything in the coach except the airconditioners and washer/dryer on the inverter (those were each wired on separate circuits, not through the inverter). When plugged into shore power, an Intellitec unit would take the inverter out of the system. An inverter wired to one outlet would work on our C-Dory. It's my understanding that we will have several 110 outlets, so an inverter wired to all would be fine, too. I truly don't feature using the inverter for any extended time - just a couple minutes (where the generator would barely have time to warm up/cool down), as necessary.

Perhaps I'm expecting too much? I understand that a 25-CD will not be the equivalence of a high-end motorcoach. I'm just thinking that if we want to heat up some soup (1.5-2 minutes with the microwave) or blend some boat drinks (a few seconds with a Magic Bullet), the convenience factor will justify the costs involved in installing an inverter. We plan to do some extended cruising and want this boat to be our way to sight-see the ICW, Keys, and Great Circle Loop. We don't expect it to be a 40' trawler (because trailerability will be important to us), but we're also hoping to not "rough it" too much. We have plenty of experience on the water (I have a USCG captain's license), but it is mostly under sail. I am truly looking forward to the convenience of an enclosed steering station, the ability to pick a course not based on wind direction, and a view out all the windows; I am sure the CD-25 will provide us all that and more.

Again, thank you for the response and the considerations you offered. I have also visited with El and Bill and admire them for their minimalist approach to their traveling. We purchased the 25 so we could have a few more creature comforts along the way. I hope I have clarified our intended usage.

Best wishes,
Jim B.
 
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