Let's Talk Electric Propulsion Part 2 - Installation Tour
18 12 2011 Posted by Daniel
Let’s take a break from the theory of electric propulsion (in Part 1 of this mini-series) for a bit and get down to brass silicon bronze tacks with a guided tour of my particular installation.
If you refer back to the description of an installation in Part 1 of this article, you’ll see that we described the electrical system with fairly few words: batteries, some control cables, and the motor. That’s pretty much it, and as Bob at Boat Bits recently pointed out: its pretty boring! But I think its illustrative to highlight one of the biggest practical advantages of the electric install: MORE SPACE available for other uses (not to mention more space that is now usable because high heat is not a major factor anymore). So, here is a general photograph of the engine compartment as it is with the electric motor in it:
Where’s the motor you ask? Good question, its hard to see, even though that entire white-painted frame used to be chock-full of my diesel engine.
The Electric Yacht 180ibl is not much bigger than the transmission on my old diesel and is the black box with the blue label on it, sitting low and aft in the engine well. Here’s a closer look, and I took the cover off the box so you can see more detail:
The mass of cables surrounding the control box comes pre-wired for you, so the only two cables you really need to hook up are the positive and negative wires running up from the lower right hand corner of the photograph - which come from the master battery switch and a relay controller. A few smaller cables for the intelligent control module make up the remainder of the pretty straightforward install. In fact, the part that took the longest was just ensuring that my old motor mounts would fit the new motor - which is something one has to do for nearly every repower anyway and took just a couple hours over a few days to get right. The motor unit weighs less than 50 lbs by itself so its not difficult to put into position by yourself - I installed it without any assistance (unlike the removal of the diesel which took a team of people and a power crane to get out). The electric motor mounts are lightweight yet rigid aluminum. Here are a few more views of the installation as I approached final placement of cables and stuff:
Next, let’s take a look at the power control circuitry, before we get to the battery installation.
Here is a view to the port side of the engine compartment. This used to hold the fuel filter and routing system, along with spare water pumps and impellers, among other odds and ends. Now it is dominated by the 48V charging system (25A at 48V programmable charge controller), with the massive sealed relay visible on the right hand side of the photo. Behind the relay and to the top right of the picture is the main battery cutoff switch which runs through the bulkhead and is accessible outside the engine compartment. Not shown in this photo is the wiring for the DC-DC converter which allows me to use the 48V battery bank to power or maintain charge on my 12V DC system, which has its own bank of batteries (though, in all honesty, with a redundant DC-DC converter in the event one failed, I could absorb those batteries into my 48V system and not really need two banks - many electric boaters do precisely this, feeding the house 12V loads off the converter).
This brings us to the battery installation. Those of you who have been following the blog for some time have seen the periodic posts on battery installs and already know what the system looks like and how I securely attached them to the boat. Here is a recap photo of the battery bank, nearing completion and ready for final cabling:
After cabling, I rebuild the cabin sole decking over the battery compartment. Instead of sealing the decking down, though, since I had designed the battery tray for drainage I simply screwed the decking in place, making it fairly simple to later access the batteries for replacement. Since they are sealed AGM batteries, no maintenance is possible or necessary and therefore complete ease of access was not needed. A quick spray of CorrosionX HD on the battery terminals to help guard against the inevitable corrosion was the final touch.
The batteries terminate into a huge T fuse, capable of handling and interrupting the entire current output of a string of 8 high-amperage 6-volt batteries. The current capability of this bank is enormous, so it pays to treat the system with RESPECT. As a result, the fuse is located less than a 7” cable run from the primary positive power terminal on the bank. In addition, I cross-connected the series string, which helps to reduce the EMI (electromagnetic interference) produced when the system is operating at higher amperages. This reduces compass flux and other unwanted interference and is a simple thing to do when installing the system that can have a very significant effect on the final result.
Another simple thing to do that pays off is to twist your cable pairs whenever possible. With these heavy gauge (2/0) cables its difficult for short runs but with the longer runs such as to and from the fuse to the battery switch and to/from the relay to the motor, the runs are easily twisted together. Again, this reduces interference and helps prevent things like radio noise, compass deviation, and other unwanted side effects of high current conductors in close proximity to other systems.
Notable Differences
So, there aren’t many comparison notes I can make that I haven’t already illustrated. We’ll do a full on-the-water review later in the month or early next month as I have a rigging pull scheduled for early next week and am frantically preparing for that. To give you a pretty good summary of the differences so far, I’ll leave you with a diptych or two for thought:
Stay tuned. The next article in this series will deal with recharging strategies and power management.
__________ /) _____________
Categories : Ship EquipmentIf you refer back to the description of an installation in Part 1 of this article, you’ll see that we described the electrical system with fairly few words: batteries, some control cables, and the motor. That’s pretty much it, and as Bob at Boat Bits recently pointed out: its pretty boring! But I think its illustrative to highlight one of the biggest practical advantages of the electric install: MORE SPACE available for other uses (not to mention more space that is now usable because high heat is not a major factor anymore). So, here is a general photograph of the engine compartment as it is with the electric motor in it:
Where’s the motor you ask? Good question, its hard to see, even though that entire white-painted frame used to be chock-full of my diesel engine.
The Electric Yacht 180ibl is not much bigger than the transmission on my old diesel and is the black box with the blue label on it, sitting low and aft in the engine well. Here’s a closer look, and I took the cover off the box so you can see more detail:
The mass of cables surrounding the control box comes pre-wired for you, so the only two cables you really need to hook up are the positive and negative wires running up from the lower right hand corner of the photograph - which come from the master battery switch and a relay controller. A few smaller cables for the intelligent control module make up the remainder of the pretty straightforward install. In fact, the part that took the longest was just ensuring that my old motor mounts would fit the new motor - which is something one has to do for nearly every repower anyway and took just a couple hours over a few days to get right. The motor unit weighs less than 50 lbs by itself so its not difficult to put into position by yourself - I installed it without any assistance (unlike the removal of the diesel which took a team of people and a power crane to get out). The electric motor mounts are lightweight yet rigid aluminum. Here are a few more views of the installation as I approached final placement of cables and stuff:
Next, let’s take a look at the power control circuitry, before we get to the battery installation.
Here is a view to the port side of the engine compartment. This used to hold the fuel filter and routing system, along with spare water pumps and impellers, among other odds and ends. Now it is dominated by the 48V charging system (25A at 48V programmable charge controller), with the massive sealed relay visible on the right hand side of the photo. Behind the relay and to the top right of the picture is the main battery cutoff switch which runs through the bulkhead and is accessible outside the engine compartment. Not shown in this photo is the wiring for the DC-DC converter which allows me to use the 48V battery bank to power or maintain charge on my 12V DC system, which has its own bank of batteries (though, in all honesty, with a redundant DC-DC converter in the event one failed, I could absorb those batteries into my 48V system and not really need two banks - many electric boaters do precisely this, feeding the house 12V loads off the converter).
This brings us to the battery installation. Those of you who have been following the blog for some time have seen the periodic posts on battery installs and already know what the system looks like and how I securely attached them to the boat. Here is a recap photo of the battery bank, nearing completion and ready for final cabling:
After cabling, I rebuild the cabin sole decking over the battery compartment. Instead of sealing the decking down, though, since I had designed the battery tray for drainage I simply screwed the decking in place, making it fairly simple to later access the batteries for replacement. Since they are sealed AGM batteries, no maintenance is possible or necessary and therefore complete ease of access was not needed. A quick spray of CorrosionX HD on the battery terminals to help guard against the inevitable corrosion was the final touch.
The batteries terminate into a huge T fuse, capable of handling and interrupting the entire current output of a string of 8 high-amperage 6-volt batteries. The current capability of this bank is enormous, so it pays to treat the system with RESPECT. As a result, the fuse is located less than a 7” cable run from the primary positive power terminal on the bank. In addition, I cross-connected the series string, which helps to reduce the EMI (electromagnetic interference) produced when the system is operating at higher amperages. This reduces compass flux and other unwanted interference and is a simple thing to do when installing the system that can have a very significant effect on the final result.
Another simple thing to do that pays off is to twist your cable pairs whenever possible. With these heavy gauge (2/0) cables its difficult for short runs but with the longer runs such as to and from the fuse to the battery switch and to/from the relay to the motor, the runs are easily twisted together. Again, this reduces interference and helps prevent things like radio noise, compass deviation, and other unwanted side effects of high current conductors in close proximity to other systems.
Notable Differences
So, there aren’t many comparison notes I can make that I haven’t already illustrated. We’ll do a full on-the-water review later in the month or early next month as I have a rigging pull scheduled for early next week and am frantically preparing for that. To give you a pretty good summary of the differences so far, I’ll leave you with a diptych or two for thought:
Stay tuned. The next article in this series will deal with recharging strategies and power management.
__________ /) _____________
