Electrical Musings

[Maine Sail]

Originally Posted by donradcliffe

Using small inverters that match the loads is by far the cheapest solution, for laptops, cell phones, Ipads, and such. It is much more efficient than running a big inverter. We carry three 150 watt inverters for a total cost of $75.

Our 12V iPad dual USB adapter cost us $5.50 on-line (even cheaper now days), 12V cell phone charger is the free USB cable that came with the phone and plugs into the unused USB port for the 12V iPad charger, 12V laptop adapter for our HP laptop $19.00 on Amazon.. We have just $24.50 invested in DC adapters for iPad, phone and computer and they are also more efficient so those savings add up too....

Even my small 150W inverter has about a 30% inefficiency as the net result when charging my laptop.. DC to AC and back to DC again...... The $19.00 was worth it..

I have also run our TV both ways, inverter and 12V, and it looks like this:

Same LCD TV 12V vs. Inverter:

12V = 3.9A
400W Inverter = 5.2A
1200W Inverter = 5.8A

[FlyingCloud1937]

Originally Posted by donradcliffe

Using small inverters that match the loads is by far the cheapest solution, for laptops, cell phones, Ipads, and such. It is much more efficient than running a big inverter. We carry three 150 watt inverters for a total cost of $75.

Point of Note:

If you already have an inverter running then multiple inverters won't add up to the same efficiency.

If they were only to run one by one then an inverter sized to the load for max-eff...y might make cents. But as soon as you turn 2 on at the same time it becomes Q...able

Most large inverters have 2 modes On/Standby and =draws x amount of power no matter the load, and Search which only wakes up when the search watt load above X is reached.

So in essence if you set your search load properly the inverter sleeps, until its called to do real duty. All of the AC chargers then become opportunity chargers.

It doesn't seem like much but can be a real advantage.

[Dockhead]

I'm just back from a month of cruising, during which we had shore power only six or seven nights.

I agree with Nick that fine tuning the inverter size to suit individual loads is really gilding the lily. I have 12v chargers for mobile phones and at least my laptop (but there were at times five laptops or more on board), but rarely used them. My Victron inverter/charger seems use something like 0.2 amps with no load which seems to me really not even worth thinking about if you have 420 a/h of batteries as I do. Someone always needed to plug in and charge something so I just left the inverter on and it worked fine.

I think the main thing for electrical happiness is to have enough battery capacity and to have a way to get power into them efficiently every day. We generally got 24 hours of life on board with a full charge, and by the end of 24 hours I needed 230v power for something else anyway, so it worked out fine. I rarely let the batts get below 60% -- 65%. If I left all the electronics on all night while at anchor (in case of needing to make a quick getaway) together with the anchor light, and if people were using toaster or nespresso machine or microwave on inverter power, then sometimes I would need to run the genset after less than 24 hours.

We were really lucky with the wind and had no long passages under power. Nevertheless, even a little motoring out of or into a harbor seemed to always get the batts back up and the domestic hot water hot.

So in sum, we really didn't worry about electrical power this year at all. The key, I think, was the new Trojan batteries, with adequate capacity.

I used the small Honda generator I bought as a backup only once. There was in fact no need for it while cruising. I will use it tomorrow to put a finishing charge on the batts before leaving the boat to fly back home.

One thing I did wish I had was a calorifier loop from the genset cooling circuit. Making hot water was a fairly tedious daily task when there were a lot of people on board. I have a 1500 watt immersion heater, and I would run that off the genset, but that's very inefficient compared to just taking the heat out of the cooling circuit.

[noelex 77]

There are really two styles of running a larger crusing boat. With a generator or with sufficient solar and wind to meet your power requirments

With a generator there is much less need to reduce power consumption. The drawback is the heat and noise (which can be minimised by good installation) and, to my mind the biggest problem , a dependency on on a reasonably unreliable piece of gear.

If you want to generate all the boat Power from wind and solar and still enjoy all the luxuries it's important when selecting and installing equipment to chase down the most effient system possible.

In many ways these two styles of running a boat are very different and owners do not fully understand the philosophy behind the alternative. People running generators, just cannot undersand anyone who is concerned about wasting 10AHrs a day and owners of solar/wind powered boats cannot understand why anyone is not horified by the prospect..

[donradcliffe]

The big inverter has a standby draw of only 0.1 amp, but plug in a cell phone charger and it jumps to 3 amps, vs 0.3 amps for the same charger on a small inverter. My netbook draws 1 amp dc through the small inverter, which is low enough for me to stop chasing alternatives.

[Dockhead]

Originally Posted by noelex 77

There are really two styles of running a larger crusing boat. With a generator or with sufficient solar and wind to meet your power requirments

With a generator there is much less need to reduce power consumption. The drawback is the heat and noise (which can be minimised by good installation) and, to my mind the biggest problem , a dependency on on a reasonably unreliable piece of gear.

If you want to generate all the boat Power from wind and solar and still enjoy all the luxuries it's important when selecting and installing equipment to chase down the most effient system possible.

In many ways these two styles of running a boat are very different and owners do not fully understand the philosophy behind the alternative. People running generators, just cannot undersand anyone who is concerned about wasting 10AHrs a day and owners of solar/wind powered boats cannot understand why anyone is not horified by the prospect..

I hear you -- that is elegantly explained. But not being horrified about wasting 10 amp/hours a day seems to me a pretty strong argument for the generator. I would hate to be distracted from the joys of cruising with that kind of micromanagement of amperes. On the other hand, I have recently been distracted from the joys of cruising with generator problems, so . . . as usual, everything is a tradeoff, isn't it?

We don't have heat or noise problems with our generator. It was installed as part of the original build, and is inside a sound enclosure which is inside a heavily soundproofed engine room. It is almost inaudible. Now if I can just make it totally reliable . . .

[Fuss]

Originally Posted by Dockhead

We don't have heat or noise problems with our generator. It was installed as part of the original build, and is inside a sound enclosure which is inside a heavily soundproofed engine room. It is almost inaudible. Now if I can just make it totally reliable . . .

Make the generator totally reliable.....

Its a common problem that most generators have. If you have a top quality generator and a top installation then most of the things below will have been addressed
If the generator is made of good components then there is no reason why this can not be done. However my generator from brand new is only good for 50 hours before the first breakdown, even though it has good basic components - Perkins 100 series based.

The reason for this is the add on components and the sound enclosure and maybe the installation.

So ...
1 - replace every rubber hose in the enclosure with high grade industrial quality.
2 - ensure that the water pump is easily got to and maintainable
3 - ensure that the diesel fuel source and filter installation are of a high engineering standard. That goes for the raw water supply and exhaust as well.
4 - ensure the raw water pump does not have to suck air first until water comes. Combine this with a Vetus type raw water filter.
5 - make sure the siphon is engineered properly.
6 - do not use the exhaust temp shutoff as your only guide that no raw water is flowing. This is very important that the moment the raw water stops flowing the generator must switch off immediately.
7 - put an electric pump in the diesel line to simplify bleeding. It should not always be used so diesel should be able to be sucked through. Good also for problem solving.

[FlyingCloud1937]

Originally Posted by donradcliffe

The big inverter has a standby draw of only 0.1 amp, but plug in a cell phone charger and it jumps to 3 amps, vs 0.3 amps for the same charger on a small inverter. My netbook draws 1 amp dc through the small inverter, which is low enough for me to stop chasing alternatives.

That means you don't have the search watt set properly.

Lloyd

[mbianka]

Originally Posted by donradcliffe

The big inverter has a standby draw of only 0.1 amp, but plug in a cell phone charger and it jumps to 3 amps, vs 0.3 amps for the same charger on a small inverter. My netbook draws 1 amp dc through the small inverter, which is low enough for me to stop chasing alternatives.

A good point. The more voltage conversions you do the more inefficiency (amp draw) you introduce into the system. I have two battery banks on board one for 12 volts (2 Group 27 batteries) and the other 48 volts (electric propulsion). The 12 volt bank has 150 watts of 12 volt solar panels (thats optimum) which provides enough power to keep my Engel freezer and other electronics operating most days. Like wise my 48 volt solar panels and 48 volt wind generator keep my 48 volt propulsion bank topped up when at anchor. Because they both operate at 48 volts there are no conversion losses. I can also tap into the ten kilowatts of power of the 48 volt bank by using a 48 volt to 12 volt converter which I sometimes do for using the laptop just because I have it available. Though it is not as efficient as plugging it into the house 12 volts directly with the proper 12 volt DC power supply. But, if I am at anchor the 48 volt bank is not doing anything but, just sitting there my feeling is why not tap into it rather than draw down the 12 house bank. The solar and wind generator quickly replace what ever I used. My Honda 2000 provides another back up option for charging or operating and those rare times I need to use 120 volts for running power tools for example. But, often it is not needed as the solar and wind keep things topped up rather nicely on both systems. Also as you have mentioned I'm not depending on a single inverter to keep everything charged. I think individual adapters for those electronics allow for more efficiency and reliability on board.
I also find the "portable" 47 lb Honda generator will be much easier to maintain and repair when needed. I'm done trying squeeze down below to work on anymore engines.

[donradcliffe]

Originally Posted by FlyingCloud1937

That means you don't have the search watt set properly.

Lloyd

No, using a big inverter to charge a cell phone is like swatting mosquitos with a 45 automatic. If you set the turn-on load too high, it won't charge the phone.

[FlyingCloud1937]

Originally Posted by donradcliffe

No, using a big inverter to charge a cell phone is like swatting mosquitos with a 45 automatic. If you set the turn-on load too high, it won't charge the phone.

Bingo, that's why it's called opportunity charging. It only charges while running other larger loads.

Lloyd