Power inverter

[Robert H. Wilkinson]

For coffee I used a SS camp style perc on a butane burner for years but the grounds are a bit of a pain on a boat. Have switched to a single serve Keurig machine which works good on my 750 watt inverter. A bit more expensive per cup but it keeps the grounds contained and you only heat the exact amount of water for your mug. On my boat(not a Cdory) I mounted the inverter up under the gunwale where short of a swamping it never gets wet.

 

[colbysmith]

For coffee I used a SS camp style perc on a butane burner for years but the grounds are a bit of a pain on a boat. Have switched to a single serve Keurig machine which works good on my 750 watt inverter. A bit more expensive per cup but it keeps the grounds contained and you only heat the exact amount of water for your mug. On my boat(not a Cdory) I mounted the inverter up under the gunwale where short of a swamping it never gets wet.

Thanks. That's the kind of info I'm looking for. Colby

 

[smckean (Tosca)]

Colby,

I have a 1000 watt inverter mounted upside down under the splash well. It is handy for many things (computer charging, vacuum, coffee grinder, etc, etc). I would miss it a lot.

The biggest load I place on it is to use a 750 watt microwave to heat up my coffee without having to start the generator. I will say the resulting 60 amp load on my dual house AMG 60 amp-hr batteries used to scare me a bit (pulls about 60 amps out of the battery bank while running). I usually run for 30 seconds, sometimes 60 seconds (note: 60 amps for 1 minute is only 1 amp-hr). I did this every day, multiple times a day, for 2 months on my round Vancouver Island trip in 2022 with no apparent ill effects on my batteries, inverter, or any other electrical component. This allowed me to not run my generator in the peaceful, quiet mornings as I laid on the settee bunk watching the sky and the wildlife while sipping my coffee. BEST TIME OF THE DAY!

 

[colbysmith]

Thanks Sandy. I was almost thinking myself out of starting this project as I did more reading on microwaves and thought about the amperage pull on my battery bank. But I may still go for it. I'm kind of on hold right now until I get the watt meter on the microwave to see what it really pulls. And then I may just get the $160 1200 watt pure sine wave inverter, mount it like you did, hook it up temporarily and then run an extension cord to try stuff out and see how much load is put on the batteries, before installing it more permanently. Colby

 

[smckean (Tosca)]

Colby, frankly I'd be thinking more about wires than battery load. As I mentioned, and as I'm sure you realize, an amp-hr or two out of a battery bank is nothing. Sure it comes out all at once, but I doubt the battery really cares. Even 120 amps for only 1 minute is only 2 amp-hrs (2% of my total amp-hr battery bank capacity of ~100 amp-hrs).

The splashwell location is great because the distance to the batteries is so short, so it's easy to deal with the large gauge wires required. BTW, I've installed a couple of normal 120v outlets in the cabin completely separate from the shore power driven system (fairly easy to do) -- one on each side of the boat so I don't need to run an extension cord across the cabin sole. I find these outlets extremely convenient.

P.S. I have rewired most of the backend of the boat including the inverter hook up, but it was the previous owner (David McKibben) who thought of mounting it under the splashwell.

 

[smckean (Tosca)]

Colby, one last thing.....

"I'd also like to put a switch in the 12 vt wiring from the batteries to the inverter"

You'd probably need a solenoid since a switch to handle 100 amps might be a problem. I have no switch on the 12v side (and have never felt like I need one). My inverter has an on/off switch built in; although I've found on multi-day cruises that I tend to just leave it on 24 hrs a day (the idle draw is very small).

 

[colbysmith]

Thanks Sandy. That's pretty much my plan at this time. I did get out to the boat today. My Microwave spec plate shows it's output of 700 watts output, 1050 watts in. Heating up 16 oz of cold water in a pyrex bowl, I assume it was on high power; my watt meter never went above 1120 watts. Or 10.6 amps. But it did pretty much stay there while the microwave ran. It came up slower than I anticipated. (I thought it would jump right to higher wattage and then come down.) I ran it probably for a good 5 minutes. So, I've gone ahead and ordered that 1200 watt inverter, and will temporarily mount it back in the compartment with the batteries, either under the splash well, or against the compartment's forward bulkhead or side wall. That will keep the positive battery cable to a length of 2 or 3 feet. The negative cable OTOH will need to run about 5 or 6 feet. That's because I want the inverter draw on the batteries to show on my Victron Battery Monitor, so I need to run the negative cable from the other side of the VBM shunt, which is over on the other side of the boat. I'll figure out what size battery cable to get for that. I believe the inverter comes with either 4 or 5AWG cable, 3' long. I'll just run an extension cord into the cabin to see how my items run on the inverter. If it passes that test, then I'll run some 12 or 14 gauge outdoor duplex with the 110vt, into the cabin, along with hooking up the remote on/off switch for the inverter. (I may still put one of those inline battery cutoff switches on the inverters battery cable, to completely shut it off. I don't know yet if the remote switch uses any residual voltage.) I'll either add two more outlets on each side of the boat, or I may use 1/2 of the current outlets in those positions. (One by the back shelf where the microwave sits, and one at the galley counter.) In any case, I'll make sure to mark those outlets as inverter only. Some other thoughts. I can set the microwave on lower power while using, or look into buying a newer, smaller, more efficient microwave. It'll be interesting to see how this pans out.

Now a quick question on batteries. I have no plans to change out my lead acid right now. But what are you guys doing about your outboard alternators when changing to AGM or the other newer batteries? Colby

 

[jkidd]

Outboard will charge an AGM ok but, it will not charge it to 100 percent. You would need to top it off once in a while with the correct charger. Lithium you would need to use a DC to DC charger because the low internal resistance they tend to burn up alternators. For your starting battery I would just use a sealed lead acid battery and for the house your pick AGM for 50 percent capacity or Lithium for say 90 percent capacity. With the AGM and the Lithium you could use the DC to DC charger to get both types to 100 percent.

 

[colbysmith]

Thanks Jody. When I have to replace my house batteries, I'll consider that. The AGM's anyway. I was under the impression that they also needed a different alternator. With my solar panels now, I don't think I'd have any problem bringing them up to 100%. Both my Mastervolt battery charger and Victron solar controller can be set for AGM's. In the mean time, lead acid has been working just fine. Colby

 

[thataway]

The remote switch only uses a small amount of current when it is used, monetary only.

Be sure if you put a 12 V DC switch, be sure it is rated to handle the full current load--up to 130 amps if you are using the 1200 watt inverter. I had used a "500 amp" Chinese switch, and it blew up just with about 200 amps flowing thru it! Fortunately the only damage was to the switch--I changed to an American manufacture and it was fine!

Drawing the 1120 watts continuously will be marginal for a 1200 watt inverter. (Lengthy private message about why I believe a 2000 watt inverter (which was only $20 more when I took first and second looks at the inverter you had chosen-After you posted the higher price, it indeed had been increased to that level-I have seen this before on Amazon.)

There are several reasons to use fine stranded wire for the 120 volt AC side of wiring, instead of using household type of solid type of wiring. A marine surveyor would write that up. I also use terminals on the 15 amp outlets & not the push the solid wire into the back of the outlet clips. (I may have misinterupted your intent as to what type of wiring you would be using??).

I have used group 31 AGM batteries (Sam's Club) on all of my C Dorys. No problem as long as you take them to 100% charge with the battery charger. No different alternator used. In some applications you would set the regulator differently, or as Jody says, use a battery to battery charger which has an AGM profile, such as Sterling.

 

[colbysmith]

Just a follow up on my Inverter project. SO I did get the 1200 watt inverter from Amazon. I temporarily hooked it up, ran a short extension cord to my microwave, and ran the microwave on the beverage setting, I believe is at high power, judging from checking the real wattage it was using earlier. The microwave worked fine, and the inverter showed it was drawing around 950 watts, just a few points above 10 amps. So, I glued some PVC boards in the port aft bilge compartment where my house batteries are. I'm moving my Victron BMV shunt over to that side as well, so I don't have to run longer cables from the inverter over to it. (I still want the Inverter to go through the shunt so I can see it's amp draw on my BMV 712.) I'm putting the shunt on the side of the splash well (underneath) and the Inverter on the port inside hull wall. I just ordered some Marine 12/3 Triplex wire to run from the inverter into the cabin. I also ordered a main battery switch that I can mount inline with the inverter's positive battery cable. Along with that switch, I have the remote on/off switch for the inverter that I'll mount in the cabin, maybe down by my house 110vt electric panel. A couple of separate recepticles for inverter output, and I'm set. I'll post photos later of the setup. But I think this will work fine for my use. Colby

 

[thataway]

Sounds good Colby. Are your batteries under the cockpit floor? If so did you get the Imitra hatches which are supposed to be "waterproof", to keep water out of the aft bilges and replace the hatches in the cockpit floor, which always seem to leak. I had my start and house batteries in the area above the bilge, and under the splash well. The shunts for my batteries all were there also. I would be sure that the 120 V AC 15 Amp outlets should be GRFI protected, even with the inverter, the 120 V can be dangerous. I have put inverter outlets just aft of the helm Binnicalel, on the vertical face of the forward bulkhead by the sink. Also GRFI protected on. the panel just in back of the area where the stove is placed and the cabinet/hanging locker where the microwave resides, plus one under the table, forward of the aft seat's face into the footwell area--and near the 120 V AC panel.

Also for a general comment; the Kill-A-Watt meter and most clamp on volt/amp meters so not measure the inrush current when a Microwave or most AC motors begins to bring the magnetron on line--that is where the spike in amperage is located. AAMES INSTRUMENTS CM610A 600A T-RMS AC/DC Clamp Meter from Harbor Freight for $90 does measure the inrush current. I have no idea how well these last or accuracy. There are similar meters on the Amazon sites, which do give inrush current, for about the same price: Inrush Current Meter 1000A Digital Clamp Meter AC/DC Current Volt Amp Ohm Meter Clamp on Multimeter True RMS 6000 Counts NCV VFD LOZ Measures Current Voltage Temperature Capacitance Resistance, The one I do have some experience with is the Klein CL390. Klein Tools CL390 AC/DC Digital Clamp Meter, Auto-Ranging, 400 Amp, NCVT Tester Clamp Jaw Integration, Hi-Viz LCD Display, Reverse Contrast Display, TRMS and Max/min to measure inrush current for about $77 at both Home Depot and Amazon.

 

[colbysmith]

Sounds good Colby. Are your batteries under the cockpit floor? If so did you get the Imitra hatches which are supposed to be "waterproof", to keep water out of the aft bilges and replace the hatches in the cockpit floor, which always seem to leak.
...
Also for a general comment; the Kill-A-Watt meter and most clamp on volt/amp meters so not measure the inrush current when a Microwave or...

Yes, the batteries are in the aft compartment, but on a raised floor a few inches above the bottom of the bilge. Not directly under the splash well, as that is where the potable water tank is, but off to the sides. No to new hatches. Someday I will replace them.
Good to know that about the kill-a-watt meters.

 

[smckean (Tosca)]

Colby,

My Microwave spec plate shows it's output of 700 watts output, 1050 watts in.

My microwave is rated at 700 watts, and according to my Victron it uses 61 amps when running (12v x 61a = 732 watts), so I don't seem to see the losses you do. BTW, I always run the microwave at 100%, and have never seen any problem with my 1000 watt inverter (for many years now). I figure the inverter will trip itself if it gets overloaded.

I may still put one of those inline battery cutoff switches on the inverters battery cable, to completely shut it off.

I'm curious why you like this idea. Safety I assume. Also, I would probably use a 100 amp fuse instead of a switch (fuse can be removed for switching if necessary).

I'll either add two more outlets on each side of the boat, or I may use 1/2 of the current outlets in those positions. (One by the back shelf where the microwave sits, and one at the galley counter.) In any case, I'll make sure to mark those outlets as inverter only.

Those are exactly the locations I used! Mine are marked too. One thing I decided is to have totally separate outlets for the inverter system and the shore power system; that way I can ignore grounding issues.

I just ordered some Marine 12/3 Triplex wire to run from the inverter into the cabin.

You've ordered the wire, so it mach nichts, but I use 14/3 since it is so much easier to work with. My whole boat uses 15amp protection on the AC side so 14 gauge should be enough.

 

[colbysmith]

Hi Sandy,
I wanted a switch to be able to completely shut power off to the inverter. I have a remote on/off switch, and wasn't sure if it uses power or not. Maybe I'll wait to install that switch, until I install that remote on/off switch to see if any residual power is used when it is turned off. I wasn't going to fuse the inverter cables at all, but after talking with another friend, they convinced me that I should have a fuse at the battery, for any leads coming off the battery. So I ordered a 200 amp MRBF to attach on the battery post. I went back and forth between 14/3 and 12/3. But finally decided on the 12/3 for less voltage drop, and it wasn't much more in expense. I hadn't even considered the grounding lug issue if I used the same outlets, but decided to go with separate single outlets, installed in their own wall mount boxes. Hope to get everything finished up next week. We still have some unseasonably warm weather right now. Forecast 55 on Christmas Day! Then dropping back into the 30's next week, but still 42 on Tuesday. I hope to at least get the cockpit stuff done Tuesday. After that, I can run the Webasto in the cabin, so don't really care what the temperature outside is.

Late note. Actually after rethinking some of this, I'm reducing the fuse to 125 amps, and just protecting the inverter cable. The other cable going to the main battery switch is pretty well protected from any chaffing, and since it's a heavier cable can carry more current than the 5AWG going to the inverter. I could probably get by with a 100 amp fuse for that, but don't want the possibility of the inverter tripping it during a higher power surge. Colby

 

[thataway]

All circuits should be fused. For example where I had 200 amps of LiFePO4 battery and only about 2 feet of 00 cable to the inverter/charger, I fused the 00 within 6" of the battery at 300 amps. Be sure and cover all terminals so there is no possibility of stay tool or wire hitting your live cables.

I also fused the charging circuit (30 amp Sterling B to B charger). I fused at the output of the B to B charger, there was already a fuse on the input of the charger. I also put a 30 amp breaker at the input of the wire from the charger to the battery.

I also fuse the 120V AC out of the inverter. Again, you are protecting the boat. The GRFI is protecting the crew.

Although one might say they are "protecting the cable". You are really protecting the boat from a fire.

 

[colbysmith]

All circuits should be fused. For example where I had 200 amps of LiFePO4 battery and only about 2 feet of 00 cable to the inverter/charger, I fused the 00 within 6" of the battery at 300 amps. Be sure and cover all terminals so there is no possibility of stay tool or wire hitting your live cables.

I also fused the charging circuit (30 amp Sterling B to B charger). I fused at the output of the B to B charger, there was already a fuse on the input of the charger. I also put a 30 amp breaker at the input of the wire from the charger to the battery.

I also fuse the 120V AC out of the inverter. Again, you are protecting the boat. The GRFI is protecting the crew.

Although one might say they are "protecting the cable". You are really protecting the boat from a fire.

I do fuse all my circuits, except for the main battery cables. It's my understanding that the code doesn't require them to be fused between the battery and the starter. In fact, I've never seen any boats, or cars, fuse the main cable off the battery. However, all my other circuits on the other side of the main battery switch, or smaller wires I attach at the battery posts, are fused. I believe as long as the main battery cables are protected from chaffing, and are large enough to handle the starter or combined loads on them, fusing them at the battery isn't necessary.

That being said, after some of your comments, and others, I did decide to get some large amperage MRBF type fuse blocks for the inverter battery cable and for the house battery cable that goes over to the main battery switch. I'm going with 125 amps for the inverter, and 200 amps for the main cable over to the main battery switch. I'm not going to fuse the main cable coming off the starter battery. It's a very short cable going to the main battery switch, and this battery is primary the start battery. My hope is that the very few times I use the house battery to start my main outboard, that the 200 amps will hold the current. IF not, I will likely remove that fuse.

I'm kind of thinking / talking this through as I install the inverter. Another change, rather than putting a main battery switch inline for the inverter, I ordered a heavy duty 200 amp relay. I found out that the remote on/off switch for the inverter doesn't do anything more than shut off the output power. The inverter still must be turned on with it's chasis switch, and the digital window still shows input power. I want to be able to completely shut it down when not in use. And without having to go back into the compartment each time to do so. Having the relay on it, will allow me to switch the power to it off and on from the cabin. I plan to use the Macerator switch at my main helm panel, as I no longer have a macerator, so it's an available switch.
I got the Victron shunt remounted and hooked up today. Had to order a new one, as the "phone line" connection on the old one broke off as I was unhooking it. A new PCB board was only $28 at one of the yacht supplies, so not to expensive. I'll give the install a rest over the next few days while I await my Amazon shipments of wire, relay and fuses. And enjoy Christmas! Colby

 

[Marco Flamingo]

All circuits should be fused. For example where I had 200 amps of LiFePO4 battery and only about 2 feet of 00 cable to the inverter/charger, I fused the 00 within 6" of the battery at 300 amps.

Wouldn't the battery have a BMS to cover this issue? I have a 120Ah lithium that has a 100A BMS and thought this was good to cover 2' of 4 AWG from battry to inverter. Should I have a belt with my suspenders?

 

[colbysmith]

Something else that bothers me. If you have a fuse at the battery post and it blows for whatever reason, what happens to your outboard alternator? This would be the same as turning your battery switch off while your motor is running. I understand what fuses are for. But I believe there are a few reasons why the main battery wire is not fused and why they tend to be heavy gauge.

 

[thataway]

Something else that bothers me. If you have a fuse at the battery post and it blows for whatever reason, what happens to your outboard alternator? This would be the same as turning your battery switch off while your motor is running. I understand what fuses are for. But I believe there are a few reasons why the main battery wire is not fused and why they tend to be heavy gauge.

You are correct that the starting and charging circuit from the primary battery, is hooked directly to the terminal post of what is usually called the "start battery. In some cases, this wire goes to a 1/2/ all/ off switch (which all of those made in the USA do a "Make before break" so there is always resistance to the output of the alternator.

Those of us who use Battery to Battery chargers, mostly for IiFePO4 batteries have the "start" battery as a designated battery. Then the B to B charger is fused from the terminal of the start battery to the input of the B to B charger (usually 30 amps for a 30 amp max charter.

Marco Flamingo:

thataway wrote:
All circuits should be fused. For example where I had 200 amps of LiFePO4 battery and only about 2 feet of 00 cable to the inverter/charger, I fused the 00 within 6" of the battery at 300 amps.


Wouldn't the battery have a BMS to cover this issue? I have a 120Ah lithium that has a 100A BMS and thought this was good to cover 2' of 4 AWG from battry to inverter. Should I have a belt with my suspenders?

The BMS is internal to each battery in the system I put together--using 2 Battle Born 100 amp each battery. Thus the BMS protects the battery, but it might not prevent a wire from over heating lets say that your 2' of 4 AWG all of a sudden has a dead short--there is a chance that that 4 AWG becomes a heating element. (I actually had this happen wth a 8 D battery I was using in a RV that we built 50 some years ago). The BMS protects the battery internally, and the fuse protects the boat. The 4 AWG is not adequate for even the 4 feet (6 feet round trip in my case). For 200 amps (which my Inverter drew) I needed 2/00 wire according to the tables.