Best inverter for the buck

[Stu Jackson]

Woody, why bother?

the reason i ask is ...i am planning to do the inverter and also install the second shore power inlet in order to be able to hook up the honda gen set via a spare shore power cable and inlet.....

You'll never have the generator AND shorepower on at the same time, right? Just plug the generator into your existing sp inlet. So why go to the expense of adding another sp inlet when you can use the one you have for the generator when away from sp? Makes the inverter and manual transfer switch a way lot easier, too, since you'll only need the one transfer switch.

Am I missing something here?

 

[prroots]

I just received this note from Yandina. I had asked for help running a test. I thought it might be worth sharing. Comments?
Pete

There is no such thing as fail safe, the fail safe process itself can be destroyed by sufficient overload. We have sold thousands of isolators over just under 15 years and all have UNCONDITIONAL warranty. To date there has only been one warranty return and it had been destroyed by lightning. They are extremely reliable. We don't rely on type testing of a sample or two, EVERY one we make is tested to ABYC electrical specifications on 130% full load until the temperature stabilizes.

There are a number of ways to test it.

The simplest but less thorough way is to measure the voltage across it while in use with normal loads, preferably including battery chargers. If it measures zero or more than 1.5 volts on DC and AC it is faulty. A "normal" reading should be less than 1/2 volt but not zero. You can then mis wire a lamp so it is using ground instead of neutral and turn it on. If it lights, or pops the Ground Fault Interrupter then the isolator is OK.

A more thorough way is your digital meter but unfortunately the diode tester function on some meters does not have enough voltage to test them.
To get to both sides of it electrically you unplug the shore end of the shore power cable from the dock and bring that end aboard. The ground terminal in that plug is one side of the isolator. Take the end close to an electrical outlet on board, the ground pin on that is the other side of the isolator. Use your meter on diode setting in both directions and each one should read about 1.2 volts.

If it does the isolator is OK, if it doesn't it usually means the meter doesn't have enough capacity to measure that much diode drop.
In this case you need to find a way to pass a current through it so you can measure the voltage.

One way is to mis-wire a table lamp so the return circuit goes through the ground when turned on. This AC current has to flow through the isolator and an AC voltage measurement across it should not be zero and not more than 25 volts. The actual reading will vary from meter to meter it is just the limits that are significant. Unfortunately this method won't work in many cases due to Ground Fault Interrupters that will cut the power off that you are using for the test.

Finally a battery and a lamp passing current through it in either direction should have DC voltages in the above ranges. Unfortunately you will need to use a portable battery because you can't use the on-board 12 volt battery to do this since one side is (OR SHOULD BE) grounded to the AC ground so you can only measure in one direction.

 

[woodster]

You'll never have the generator AND shorepower on at the same time, right? Just plug the generator into your existing sp inlet. So why go to the expense of adding another sp inlet when you can use the one you have for the generator when away from sp? Makes the inverter and manual transfer switch a way lot easier, too, since you'll only need the one transfer switch.

Am I missing something here?

ya know after i posted that.... i left a drove to Atlanta.....on the way i got to thinking it woild be redundent to do that...you are correct and did not miss a thing......but i do have a spare inlet that used to be for phone and cable tv all i needed to do was change the internal parts to have another inlet....but as you pointed out why....dont know of a need for the second one at this time....guess i will just keep the lid on it screwed thight and for get it .....thanks for pointing that out.....oh btw i didnt mean to hijack this thread ....hope i havent done that as this has been most inlighting to read....

regards

woody

 

[prroots]

Last night I purchased the Xantrex Prowatt SW2000 for $312 at West Marine using online price matching. That's the best of both worlds: great online price and convenience of local store with returns, etc. Yes, I know there were several negative comments about Xantrex (and I appreciate them all), but I've also read numerous positive reviews too. The bottom line is that it seemed the best product in it's price range and this way I get to use it now as opposed to waiting until the budget recovers which could be a long time.

I now plan to do the install in two phases:

1. Mount inverter and install DC side; use as standalone with extension cord
2. Install AC wiring and AC transfer switch

Pete

 

[Bill Roosa]

don't froget to post some pictures of the final install
Please

 

[joker460]

@prroots

Don't know if you saw this video testing the sw2000.

http://www.youtube.com/watch?v=mwuiQYZhGRc

What I found interesting is the current draw on the DC side. Shows how High it will get and how important wiring will be.

 

[prroots]

@prroots

Don't know if you saw this video testing the sw2000.

http://www.youtube.com/watch?v=mwuiQYZhGRc

What I found interesting is the current draw on the DC side. Shows how High it will get and how important wiring will be.

Thanks. Yes, I saw it and it was one of the reasons that I chose not to believe the reports that stated they didn't meet their load ratings. Chances are the reviewers simply installed undersized wire.

I'm installing 5 feet (round trip) of 2/0 marine cable plus a 250 amp class ANL fuse in line with the positive side.
Pete

 

[Maine Sail]

Thanks. Yes, I saw it and it was one of the reasons that I chose not to believe the reports that stated they didn't meet their load ratings. Chances are the reviewers simply installed undersized wire.

I'm installing 5 feet (round trip) of 2/0 marine cable plus a 250 amp class ANL fuse in line with the positive side.
Pete

We have the ProWatt 1000 and I regularly run my Milwaukee heat gun for long enough to shrink connectors...... Incorrect installation does not make the inverter bad it only means they are installed it incorrectly. Ours regularly exceeds its rating for long enough to heat shrink stuff.... they can handle surge loads pretty well.

 

[prroots]

We have the ProWatt 1000 and I regularly run my Milwaukee heat gun for long enough to shrink connectors...... Incorrect installation does not make the inverter bad it only means they are installed it incorrectly. Ours regularly exceeds its rating for long enough to heat shrink stuff.... they can handle surge loads pretty well.

Thanks; very true. I had noted you had one on your boat I hope to get it hooked up today once I figure out the exact cable lengths and get the terminals crimped on. The big test will be running our microwave.
Pete

 

[Benny17441]

Pete as far as the inverter size, wiring gauge, and fuse load handling and protection I think you have made a very well informed decision within the budget. If it were me I would just add one more thing. A small On/Off battery switch between the (+) battery terminal and the Fuse. I know it is redudant but I do feel more confident relying on the battery interrupt than only on the Xantrex switch when the boat is unattended. You now have me thinking of connecting my stand alone to the boat's AC circuits.

 

[prroots]

Pete as far as the inverter size, wiring gauge, and fuse load handling and protection I think you have made a very well informed decision within the budget. If it were me I would just add one more thing. A small On/Off battery switch between the (+) battery terminal and the Fuse. I know it is redudant but I do feel more confident relying on the battery interrupt than only on the Xantrex switch when the boat is unattended. You now have me thinking of connecting my stand alone to the boat's AC circuits.

Thanks. Actually the Beneteau came with a SPST battery switch on the positive and another on the negative lead from battery bank (not shown in my schematic). The switches isolate all loads not just the inverter.

Update: we just finished connecting up the DC side of inverter and ran the microwave. During a 4 minute test the Voltage and power stabilized at 12.0 Volts and 1240 watts, respectively. The microwave is rated at 1260 watts. We are very pleased with these results. We'll do more testing later.
Pete

 

[Stu Jackson]

Pete, congratulations, glad to hear it's working out. Stu

 

[prroots]

As an update, this morning I did a more accurate load test and remembered to turn off the battery charger and all DC loads (so that my Victron BMV-600 battery monitor could be used accurately). During a 4 minute test of microwave (just long enough to bake a medium sized potato), the Voltage and power (as read at inverter) stabilized at:

11.8 Volts
1270 watts
​

While the above readings were being made, the battery monitor read:

11.93 Volts
120.6 amps
​

which yields 1438.8 watts. The efficiency would then seem to be 88% (ie, 1270/1438.8). The voltage drop was approximately 0.13 Volts (ie, 11.93-11.8) between batteries and inverter. Assuming the stabilized readings over the full 4 minutes that represents approximately 8 Ah of battery consumption. All in all, I'm still very pleased with the result. BTW, if it couldn't pass this important test I was prepared to take advantage of West's liberal return policy
Pete

 

[prroots]

Here's a picture of the Xantrex Prowatt SW2000 mounted next to the battery switches and fuel shutoff in the quarter berth. The positive and negative battery terminals are on the opposite side of this bulkhead so it's a very short run (~ 4 feet round trip)

Edit: the DC cables are attached at the rear and in this type of mounting the holes in bulkhead must be drilled precisely given the stiffness of the 2/0 cables and proximity of terminal studs to bulkhead. We measured twice and drilled once
Pete

 

[mitiempo]

Pete

The run is measured from the inverter to the batteries and back, not the switches.

 

[prroots]

Pete

The run is measured from the inverter to the batteries and back, not the switches.

Thanks. That's right, but it was more convenient to measure to the positive and negative terminals Also, the wire gauge is larger from positive and negative terminals to batteries and also the two pair of golf cart batteries are located at two different distances so things get complicated. I would say there is an additional 8 feet (round trip) from terminals to closer golf cart pair. Of course, the important thing is that Voltage drop is quite minor which was the goal. Today, I'll run a test with a 1500 watt space heater even though we don't expect to be using loads that heavy.
Pete

 

[prroots]

I just tested a space heater rated at 1500 watts with the Xantrex Prowatt SW2000. The Xantrex readings stabilized at 11.7 Volts and 1400 watts. The Victron BMV-600 battery monitor read 11.98 Volts and 127.3 amps. I calculate DC power draw as 1525 watts which would then give an efficiency of 92%. The Voltage drop was 0.28 Volts. It certainly appears that this inverter has little difficulty meeting its rated power output (its rated for 1800 watts continuous).

The other good news is that I didn't blow my 250 Amp fuse which is based I suspect is based upon the 3000 watt surge power rating (ie, 3000/12 = 250A). I believe inductive loads such as motors would create the largest surge currents.
Pete

 

[Bill Roosa]

Please tell me you did not size the fuse for the equipment, please.
the fuse is intended to protect the wires so they don't catch on fire. The equipment should have a CB / fuse of it's own for its protection.

 

[mitiempo]

Pete said he was using 2/0 and a 250 amp ANL fuse.

 

[Bill Roosa]

And depending on the type I get the max current for 2/O as;
TW UF ---145 amps
RHW/THW ---175 amps
TBS/SA/SIS ---195 amps

so the wires melt first and then the fuse blows..... It is just a matter of time

http://www.armstrongssupply.com/wire_chart.htm


From Doctrine Man on Clausewitz
Experience is something you don't get until just after you need it most.
and
No plan is fool proof when executed by a sufficiently demented fool.