I am looking at making my Ericson... A hybrid. (Electric/Diesel)

[willo]

So I have a couple things to sort on my E46. the Beta 50 needs some love. As a contingency I started looking into converting to electric... And then I got to pondering, what about a hybrid Diesel Electric?

I've been picking up some parts with this idea in mind.
I have a water cooled Electric motor that two different conversion companies suggested. (ME-1616 for the nerds)
I've picked up a few Tesla modules for this. It was a decent deal and I can always just build an ATV of doom or something.

Anyhow, as I investigate this it gets interesting as I look at options.

• Fix the diesel - then I have a 100ft/lb motor going out a 2:1 trans for 200ft/lb.
• Connect the electric motor to the prop shaft at the transmission output.
• Can do hydro regen to be super green, diesel regen (for lots of power while running the motor)
• Can use instant electric power for docking/anchoring/etc.
• Could use the combo to save fuel on passages\
• Can charge from my huge lithium house battery or the reverse and charge house from the traction pack.
• Could add a generator as a backup power source (My e46 had one but it was left behind at one point to drop weight)

The more I look at it the more I really like this idea. It's not trivial to make a road vehicle a hybrid, but on a sailboat? It becomes very, very interesting!

 

[Loren Beach]

For a major adventure in large Ericson restoration, albeit with a different auxiliary engine scheme than yours, here is a long thread to ponder--

Ericson 41 Florida - Norway

Hi Gareth Harris, Your survey from 2004 is very informative. I have decided to lift her out of the water and have the hull inspected for any damage. Then I think I will keep her on dry land until she is in prime condition. If you have any recommendation on how to repair this micro cracks you...

ericsonyachts.org

Major work and time was invested. And it was still simpler than a hybrid diesel/electric/regen drive setup. Well, sort of.

 

[Jerry VB]

There is a famous quote in the software world:
Some people, when confronted with a problem, think “I know, I'll use regular expressions.” Now they have two problems.

IMHO, the same thing applies to a hybrid solution except it is four problems because it is 2 motors x 2 energy sources (battery, diesel). Five problems if you factor in the transmission problem. Six when you try to figure out where to fit all the extra pieces.

OTOH, it is a fun engineering problem and, if you are into fabrication, a fun fabrication problem.

• Fix the diesel - then I have a 100ft/lb motor going out a 2:1 trans for 200ft/lb.

Good.

• Connect the electric motor to the prop shaft at the transmission output.

It will be a bigger challenge than you expect. It always is.

• Can do hydro regen to be super green, diesel regen (for lots of power while running the motor)

There won't be as much regen energy as you anticipate. (a) It is remarkable how little energy it takes to push a sailboat through the water. (b) If you have enough wind for useful regen, you probably will be overcanvassed in order to get good regen. (c) For the (YouTube) sailboats that have had an electric conversion and can do regen (e.g. Sailing Uma), they test the regen and then don't talk about it again. My guess is that it isn't very useful (solar panels are more practical than regen).

• Can use instant electric power for docking/anchoring/etc.

Good.

• Could use the combo to save fuel on passages

Strictly speaking, you are not saving fuel, you are increasing your range (trading battery electric for diesel in the tank). Since the electric is "free", you will be saving costs over time, but at a huge up-front expense. It is really hard to beat the economics of diesel and batteries will never beat the energy density of diesel.

• Can charge from my huge lithium house battery or the reverse and charge house from the traction pack.

That is just rearranging the deck chairs.

• Could add a generator as a backup power source (My e46 had one but it was left behind at one point to drop weight)

Solar panels are much quieter.

 

[Parrothead]

Could add a generator as a backup power source (My e46 had one but it was left behind at one point to drop weight)

This is the line in your opening post that caught my attention. Considering the highlighted part, the current plan suggests added weight is no longer a concern.

 

[Christian Williams]

Isn't a hybrid system the worst of both worlds? Talk about complication and expense for unknown return....

 

[toddster]

IIRC, those regen tests revealed that energy only started to be produced when the speed was greater than six knots. Seems like a lot of moderate-sized boats will get left out. Someone (E Starzinger?) once published an article on crunching data from a lot of trans-oceanic cruising rallies and came up with an average speed for just about all boats of something like 5.4 knots (without, you know, actually putting any effort into finding the original article.) I’d think that coastal cruising speeds would be somewhat less.

 

[willo]

Some fun facts on my boat/build so far:
It's getting 3x 530w solar panels, which all feed to dedicated controllers and into my house battery.
I have to repair/rebuild part of my bimini to support them but that's a decent solar install base.
The house battery is around 24kwh on it's own and runs at 24v.

Ultimately I'm not very worried about regen on hydro. I think that will be better done with smaller motors and reverse flow optimized blades.
Which... just so happens to match up with diy efoil hardware. I'm going to experiment a bit with that idea at some point.
Rigging Doctor made a nice vid talking about hydro - their take was that it is useful just not highly effective as a charging source.

I have determined not to be in a rush on this build. I have some parts for it, but I'm going to get my diesel sorted or at least fully troubleshot on my next boat work trip. My parts are low risk purchases to me - I can always build an electric ATV or something if I decide not to do the boat install.

 

[willo]

Isn't a hybrid system the worse of both worlds? Talk about complication and expense for unknown return....

Not really. On a sailboat with a shaft drive, adding it as a secondary feed the the propshaft shouldn't be all that bad. The rest of the hardware isn't complicated (to me at least). Electric motor to a reduction drive to the propshaft.

Calling it an unknown return is a bit much. The return is clear - the ability to motor without burning diesel for an hour or two with my battery pack size. Ultimate efficiency won't be known until I can measure the drive loss. In addition, the ability to still use the diesel when longer range is required.

Let's not forget the free fuel source coming from the sky and the reduction in emissions.

 

[Christian Williams]

Check out Sailing Uma. They are the test bed for many of these ideas, for better or worse. They've dealt with batteries, regen, and several motors--and they're sponsored. Not easy to find each segment, but you can start here--

Not harshing your mellow. But what you describe, I think you will find, is extremely complicated and expensive.

 

[Mblace]

Why not go with a diesel-electric setup where the electric motor is the only motive drive, and a Diesel engine/generator provides the power to 1) charge batteries and 2) provide power directly thru the controller to the motor. This eliminates a dual-drive clutching and transmission setup, and allows infinite speed control. It also allows sourcing of the “perfect” diesel to maximize efficiency (always runs at optimal rpm) and reduces the HP requirement. The biggest challenge then becomes the design of the system and determining battery capacity (I’d go for at least 20 KwH). Torqueedo has a pod drive setup that would be a possible consideration, and has recently developed a hybrid drive system. If they are marketing it, it’s definitely viable. Check out their website (they are mega expensive, so a home built system is a worthwhile alternative…).

 

[Teranodon]

Why not go with a diesel-electric setup where the electric motor is the only motive drive, and a Diesel engine/generator provides the power to 1) charge batteries and 2) provide power directly thru the controller to the motor.…)

This is used to great advantage in standard diesel locomotives. It allows them to generate hugely variable amounts of torque at hugely variable speeds (for example, getting a giant train moving). Takes the place of a transmission. I see no advantage in a sailboat, except if someone would rather be working on their boat instead of sailing. And there are people like that, so - why not?

 

[steven]

I have been researching hybrid for awhile but still have two open questions.

Can a diesel gen "provide power directly thru the controller to the motor." ?
I've told by vendors that "modern" controllers might sense voltage fluctuations and do weird stuff.
Recommendation has been to use a small capacity battery or an "ultracapacitor" (whatever that is) to buffer.
Is there a controller on the market that can power the motor direct ?

What about using a more substantial battery banks but when needed use the genset to charge the batteries while they are also discharging.
Seems simplest if it will charge at the same rate the battery is discharging.
Will this work ?

--Steve

 

[Jerry VB]

Can a diesel gen "provide power directly thru the controller to the motor." ?

Yes but no. "Generator" implies DC power generation. DC generators produce a voltage proportional to the speed at which they are turned. They provide the current required to achieve the voltage that the generator "wants" to produce based on the rotational speed. Power is current times voltage (P = I * E) - for a generator voltage (E) is (mostly) fixed and current (I) is the variable. To the best of my knowledge, train locomotives use generators, not alternators.

Gensets tend to be alternators. Alternators generate AC power which is then fed through diodes to produce "DC" (it is actually two halves of a sine wave). The alternator generates a voltage and current that are proportional to the current fed through the alternator field windings (the job of the "regulator" box). With an alternator, both the output voltage and the output current are controlled by the current fed through the field windings - both "I" and "E" are variable.

If there is no load on the alternator (no current drawn), the voltage tends to go to infinity (well over 100 volts) and the diodes tend to blow up.

The battery is required for two reasons:

1. To "smooth out" the valleys between the peaks of the rectified sine wave.
2. To limit the maximum voltage across the diodes in the case where there is insufficient current (load) to do so.

That is why you should never switch the A-B-Both switch to "off" while the diesel is running - your alternator diodes likely will blow.

I've told by vendors that "modern" controllers might sense voltage fluctuations and do weird stuff.
Recommendation has been to use a small capacity battery or an "ultracapacitor" (whatever that is) to buffer.
Is there a controller on the market that can power the motor direct ?

Ultracapacitors are simply capacitors that have a huge amount of capacitance for their size. The limitation of ultracapacitors is that they have maximum voltage limitations, typically much less than 10 volts, and blow up if you overvoltage them. By the time you build a capacitor that can handle the maximum potential alternator output (many 10s of volts) and have sufficient capacitance to smooth out the alternator output, it will be physically very large. Also, capacitors tend to charge to infinity if given a chance, causing both the diodes and the capacitor to blow up.

Batteries store the excess power in a chemical reaction and, once the battery is full, slowly get warmer. They get warmer slowly enough for the charge controller to ramp back the power generated before the battery boils dry.

What about using a more substantial battery banks but when needed use the genset to charge the batteries while they are also discharging.
Seems simplest if it will charge at the same rate the battery is discharging.
Will this work ?

Yes, that is actually the way it works. If the batteries are full and there is no load, the alternator regulator (charge controller) dials back the alternator field so it produces the same voltage (on average) as the battery which causes the current (on average) into the batteries to be zero. When you engage your electric motor, it will pull current out of the batteries, the regulator (charge controller) will sense the voltage drop and ramp up the current (increase the alternator's field current) to balance the equation again.

 

[steven]

Can a conventional battery be charged at or about 1C ? If yes then I think his is a good solution (for my usage pattern - losts of short in and out of the harbor, with occasional 40 miles trips)

Use a modest battery bank for local in and out of the dock.
Have a generator (carbon fuel in - AC out) to a suitable a charger (AC in - DC out) to alleviate range anxiety .

Are there suitable chargers on the market ?

I've checked with multiple vendors of boat electric and chargers and such, but as yet have not been able to get a clear answer.

 

[Teranodon]

What about first principles?

Without a big battery bank, all of the energy comes from the diesel fuel, so all of it must be generated by the internal combustion engine. Introducing a generator and an electric motor can only reduce the efficiency of the drive system, by the First Law of Thermodynamics. It's true that you can eliminate the transmission, but in our boats it's a very small, simple mechanism that doesn't consume much energy. So there is no point.

Now add hundreds of Ah of batteries. For cars, this results in better mileage because of the ingenious technique of regenerative breaking. Can that work on a sailboat? I don't really know, but I rather doubt it. First of all, friction with water (as in boats) is much higher that friction with air (as in cars) so it will dominate, and that's where the stored motion energy will go, not back into the batteries. Think about how quickly a boat stops when you stop the engine or the wind dies, compared with a car that keeps rolling. Secondly, a propellor, even properly feathered, is not a very efficient break (energy absorber) compared to the hull which will do most of the breaking, and for a short time only. So I don't think that this is worth doing, but I'm ready to stand corrected.

 

[Jerry VB]

Can a conventional battery be charged at or about 1C ? If yes then I think his is a good solution (for my usage pattern - losts of short in and out of the harbor, with occasional 40 miles trips)

Use a modest battery bank for local in and out of the dock.
Have a generator (carbon fuel in - AC out) to a suitable a charger (AC in - DC out) to alleviate range anxiety .

The answer is yes, but the math says ummm, nevermind.

1HP = 746 watts.
1 watt = 1 amp x 1 volt or 12 volts x 0.083 amps.

For boats our size, it takes ~10HP to move at ~6kts.

10HP = 7460 watts.

If you are running your electric motor at 48v (common)...
7460 watts = 48 volts x 155.4 amps.

If you want to motor for an hour, you will need a 155.4 amp hour (@48v) battery bank. Minimum, just to make the math work. Actually quite a bit bigger because batteries don't like to be fully discharged and prefer to be discharged at less than 1C. And the system is less than 100% efficient.

Assuming your battery can be discharged to 20%, your battery is 98% efficient, your motor controller is 98% efficient, and your electric motor is 98% efficient, the math says your total system is 0.8 x 0.98 x 0.98 x 0.98 = 75% efficient so your battery actually needs to be around 207AH.

If you want to motor more than ~6nm, you will need several times 200AH (times 48v => 7.46kWh). That is why electric boats (and cars) have tens of thousands of kWh batteries (10,000kWh - 100kWh).

If you want to motor beyond battery range, you need a (diesel) genset that is roughly half the size of your current diesel plus a really big alternator (much bigger than 155A @ 48v). Basically, one of those 10KW gensets that you can buy at Home Depot, but with a diesel instead. Big and remarkably heavy.

Example: DUROMAX 10000-Watt/8,000-Watt Electric Start Gasoline Powered Portable Generator
Assembled weight 221 lbs (a diesel genset is going to be quite a bit heavier)
Note that this is 8KW continuous, so it will be going full tilt all the time to push your boat at ~6kts (7.46KW)

P.S. A bare generator is going to be around 100lbs. This 7.2kW generator (pdf) is listed at 78lbs.

 

[Mblace]

So at the end of the day, this is an interesting mental exercise, but… I’m an airplane guy (both power and sailplanes) and have seen practical adaptations of electric sustainers for gliders (to get you home when the lift quits) but not as a main propulsion alternative for power planes. Pound-for-pound, IC propulsion is the best choice right now, owing to battery limitations, primarily. For a glider a sustainer might need to run (producing maybe 6-10hp equivalent) for 30 minutes. But for a 4-seat Piper, 50 gallons of gas gets you maybe 600 miles, where the current state of electric might get you 100 miles without exceeding max weight. By comparison, an EV like a Tesla model 3 weighs a good half ton more that a similarly-sized gas only sedan, so the tradeoff between gas and stored electric of equivalent energy yield is 10-1 (120# of gasoline vs. 1200# of lithium batteries).

I’d also venture that regen on a sailboat is pointless - you’re converting drag to power so any regen will (inefficiently) be making a few watts but be like dragging a sea anchor.

I’m about to add solar to my house - there have been some amazing new technologies recently brought to market such that I can grid-tie, with batteries, with a plug-in port for a propane portable generator - all controlled by a relatively compact inverter/charger/controller that is able to automatically manage the whole setup to get max efficiency and provide whole-house backup when we lose grid power (annoyingly often). It’s not cheap, but the numbers make sense. I assume the same components are or soon will be available for EV retro-conversions, or for a boat. Still, until batteries get a LOT better, I agree with Teranodon and Jerry VB - why bother…

 

[Teranodon]

There's another issue that rarely gets mentioned: resale value. Those of us who keep their boats in good condition expect to get some money out of them for whatever the next phase is (unless it's passing through the eye of a needle). A boat with a novelty drive system will not attract buyers, especially if the technology has become obsolete quickly. Not long ago, one of the bigger Ericsons was listed with an all-electric drive. The asking price was shockingly low. So converting has a hidden cost of many, many thousands of dollars.

 

[steven]

So what about leaving the internal combustion enginer (ICE) in place and connecting an electric motor to the engine shaft behind the ICE-shaft coupling, with a belt.

Just for short range. (a couple hundred AH would be fine).
Put the engine in neutral and run the electric motor.

For longer range use the conventional engine.
(would the motor need to be mechanically disengaged when using the engine ?).

 

[Christian Williams]

But...why?