ANOTHER LOOK AT REGEN

I installed electric propulsion in BIANKA for several reasons. One was because my diesel engine died. Two because I spent a good amount trying to get it running again. I began looking at alternatives to having a diesel. Diesel works well where it is worked hard. On a sailboat where most people use the engine to primarily get into or out of the harbor is not the best way to use it. Installed on a trawler is a much better match. So diesels tend to rust out before they wear out or fail at some point when you least expect it. Hopefully in some location  where you can get help and parts.  Another thing about electric propulsion is the ability of it to regen i.e. recharge the battery bank when the boat reaches a certain speed under sail. I thought for the first few years  that my system was not capable of regen but, then one day I discovered that it did. Hybrid Marine has a nice video of how regen works.  The boat in question is a hybrid design and still has a diesel engine. Which would mean the engine might be used even less than in a normal engine setup. But, you still have all the maintenance issues involved with having a diesel installed. But, for those not quite ready to make the leap to a pure electric propulsion system it is an option. Anyway this video is a good primer on the regen aspects of electric propulsion. Hat tip Elektra Yachts:

END OF THE SEASON THOUGHTS OF AN ELECTRIC SAILOR: 2011

It's that time of year when I look back on how my electric propulsion system did during the past season. Once again I was surprised by it. When I decided in 2007 to repower with an ASMO MARINE Thoosa 9000 system. There were no boats that I knew that had done this and I thought long and hard about it before making the leap. But, after four years of operational experience I'm still very glad I did. The fourth season will stand out because of two firsts that occurred. One was an extended day of motoring. About ten hours to be exact. A rare day here around the Isle of Long when hardly even a whisper of a breeze filled the sail. So after starting out early and motoring under battery power for a few hours I carried the Honda away from the cockpit and fired it up. I could never do that with the old diesel. The noisy diesel was always right below the cockpit vibrating away making for a noisy afternoon of motoring. Fatiguing too! My day of extended motoring was much more pleasant experience with electric propulsion.

Another first I discovered quite by accident was that BIANKA can actually regen power back to the battery bank. I discovered this while electro sailing moving along at about 6 knots. I had earlier in the season decided  that the best way to operate  under sail was to slightly turn the prop under power. This will negate any prop drag when sailing and therefore increase boat speed. Sounded like a good plan and it uses minimal power from the battery bank and no need to buy a folding prop. But, as I found out that if the boat speed under sail starts touch around 6 knots it also starts recharging the battery bank.


 This is known as "regen" where the prop starts to turn the motor backward and it starts operating as a generator. It's not a lot at the low end but, you really don't want a lot charging because you don't want to take a chance on overcharging the battery bank.  I'm looking forward to next season and hope to experience more days where I can see the regen in action. So even after four years my boats electric propulsion system still had some pleasant surprises left to show me.

MORE REGEN!

A reader of this blog reminded me of another video I had seen recently regarding regen. Though it's not often that BIANKA will hit 7 knots under sail but, I'm happy when it does. But, this video of a test by ASMO MARINE shows what can be achieved by regen in the right conditions:



Interesting that they achieved this with a two blade folding prop too!

ANOTHER ADVANTAGE OF ELECTRIC PROPULSION: REGEN

It seems every year I discover something new that my electric propulsion system can do. Last year there was the joy of sailing along  double reefed at 7 knots SOG while my solar and wind generator were at the same time pumping energy back into the battery banks. Earlier this season I had another epiphany while electro sailing on a pretty windless day.  I thought I should probably always electro sail when I sail the boat. Since the prop is going to be turning no matter what unless I install some type of shaft lock but, that would also increase drag and slow the boat down.  So I might as well electro sail by turning the prop just enough to negate the prop drag. My boat would move faster through the water and I could also point up more since the motor was helping to push the boat slightly when the wind dies. Adopting this routine has led to another surprise. Something that I have not been able to see until now and that is to see my electric propulsion system actually regen. Regen is the concept of spinning and electric motor by it's shaft so that it becomes and generator and "regenerates" power back into the motor's  power source. In the case of BIANKA the 48 volt electric propulsion battery bank. For example on a sailboat with electric propulsion in regen mode you are recharging the batteries while you are enjoying a nice sail. I had just about given up on this on board BIANKA since a lot of factors can influence the ability of a sailboat to actually regen. Things like the keel shape that might cast a "shadow" around the prop so that it never sees enough water flowing past the blades to turn the prop enough for regen to occur. Then there is the prop its self. It might not be big enough or have the right pitch to rotate enough for regen. Changing the prop and/or some of it's specs might help but, that will cost $$$. Since I was already very happy with my electric propulsion system as is I did not feel an urgent need to try and experiment with a new prop. I had the same three bladed prop that had propelled BIANKA when she had a Westerbeke diesel installed. But, a few weeks ago I was electro sailing BIANKA and took a look at the amp meter and was pleased to see that there was a positive indication on the amp meter. Which meant that the boat was moving fast enough so that it was spinning the motor backward enough and had actually achieved regen!  It was only about about a quarter  to a little over one amp but, that was enough to make me very happy. When the motor is in regen mode unlike a sophisticated battery charger there is no regulation. So you  have the potential of over charging the battery bank if too much current flows back into the battery bank.  You don't want too many amps flowing into an already charged battery bank. But, an amp or two over a few hours of sailing may be enough to bring the battery bank back to the same level as when you left the dock. In essence you would have the same amount of fuel when you come back as when you left. That's the beauty of regen. Here is some video of my electric propulsion system operating in the regen mode:

On another sail I also got some indication that regen may be occurring earlier than the speed of 6 knots. But, until I can get some type of current meter installed that I can view in the cockpit without opening a hatch and bending down to get the readings I'll have to wait to do more precise observations. But, at least I can now say that regen works and it is just another added benefit of having electric propulsion on board.