Starside's Electric Conversion

Starside said:

I was also told that a portable generator will only give her a 20% additional range which means that's basically useless.

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How many amps do the motors draw and what is the size of the genny?

Starside said:

I'm being selfish mostly bc I wanted to cross the Bay for the classic boat show at St. Mikes to show her off! but I'm truly excited about having Starside back in the water & look forward to exploring her new engine.

Next year, I'll dock her on the other side of the Bay so I can get to the show(s).

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A guy in our marina shows a restored Hackercraft runabout over there... and he trailers it over and back. Depending on Starside's beam, that might not be difficult to organize...

Mears Point Marina and Piney Narrows Marina -- both in Kent Narrows -- both have some covered slips. I don't know much about Piney Narrows, but we've stayed at Mears several times and we like being on that side of the Narrows. That area would give you closer access to the Miles/St. Michaels, and also to the parts of the Wye systems and the Chester that would be within your range.


Once you recover from restoration/conversion costs, as Ski says, the engineering can be sorted to increase your range. That could include solar (BruceK's note), wind generators, gas or diesel generators, "better" batteries, more batteries, etc... and much of that can be incorporated a bit at a time.

-Chris

fryedaze said:

How many amps do the motors draw and what is the size of the genny?

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I'll get this to you on Friday. I left my notes on the boat!

Chris, I'm trying to avoid extra costs like trailering or towing - the latter being my electrician's idea for the show. I haven't ruled it out completely but hate to put that strain on her. Will probably forego the show this year. Sad...

I had my eye on Piney Narrows cuz they offer covered slips for sale. Figured w a woodie, that cost may make sense.

This year, I'm on the West River. Supposed to be a beautiful River area so can enjoy that this season, then explore the other side next year. It's not a bad plan...

I didnt go back and re-read all the posts but if Im not mistaken, all of those shortcomings were touched upon, some hashed and rehashed. Surprise should have been the least possible outcome. I had a good friend that had convinced himself that cruising on batts was the perfect idea. He was planning/designing an inshore cruiser on a carrycraft hull. It took awhile for him to grasp the concept that it just was not pheasible with currently available tech. Cool to think about, and done in the past (with poor results) but just not practical,,,yet. That is a beautiful boat. I would think that a new, old style retro, hit and miss engine would be period correct and really cool, not so quiet tho

Starside said:

Chris, I'm trying to avoid extra costs like trailering or towing - the latter being my electrician's idea for the show. I haven't ruled it out completely but hate to put that strain on her. Will probably forego the show this year. Sad...

I had my eye on Piney Narrows cuz they offer covered slips for sale. Figured w a woodie, that cost may make sense.

This year, I'm on the West River. Supposed to be a beautiful River area so can enjoy that this season, then explore the other side next year. It's not a bad plan...

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Yep, gotcha ref additional expenses.

Didn't know Piney Narrows was a dockominium; good to learn. Also, we sub-letted from an owner at the marina in Galeseville when we were there, and that worked out well. (IOW, didn't have to buy.) Mears is just a straightforward marina, and we've enjoyed our stays there.

And yep, you've got lots of places in the West and Rhode Rivers. You might have range enough to get to Deale, too, and maybe up here into the South. Enjoy it!

-Chris

I once had a 4 wheel drive buggy that also had the 72 volt motor. I could adjust all the parameters of the CPU with my laptop. Anything from about 40 mph for an hour to about 10 mph for 5 hours. I assume you have a controller of some sort?

dimer2 said:

I once had a 4 wheel drive buggy that also had the 72 volt motor. I could adjust all the parameters of the CPU with my laptop. Anything from about 40 mph for an hour to about 10 mph for 5 hours. I assume you have a controller of some sort?

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Yes, I have this flatscreen that shows amps and speed, etc., and I was instructed that by doing some math, I can figure it all out and get the best range.

The real issue is conditions...for example, I can easily go 5.5 knots in perfect conditions to stay at the recommended amps for longer range, but if it's windy or the swells are high, that's when it gets tricky -- you basically have to do the math equation to figure out your range on any given day depending on weather conditions.

In other words, you can cruise in good weather and get a good range of 3+ hours, but as we all know, sometimes a nice day turns bad, and that's when you have to be mindful.

I suspect once I get used to it, it will be second nature, but until then, I have to do the calculations. The batteries are expensive enough to consider ampage vs. range to avoid using them up too quickly...

I'll post this weekend what the amps are for maximum range. I left the equations on my boat...

I think as a cruiser, the real issue is...PLANNING. It's rare to have perfect conditions, so what if you make it to Annapolis, but you're stuck there for days b/c there's a storm or something? That's the real set-back and something I'll have to adjust to.

Rambling...will know much more once I get actual experience...bear with me...

Have you had the chance to go for a run yet? I gather not quite yet. That run with some data collection will be key. Post it here when you get it and us engineer types can help crunch numbers.

I do think a Honda 2000w and a five gal can stowed will solve the range problems. 90% of your trips it can stay stowed, but it's there if needed.

my boating lesson is scheduled for Tuesday. I'll have the numbers next week.

Your boat is very similar to mine when it comes to hull form and size. So I think your power requirements will be about the same as mine. The graph below shows the power requirements for my boat versus boat speed. If that assumption is correct your boat needs about 10 hp to go 5.5 knots. 10 hp is 7460 watts or 104 amps for a 72 volt system. However, if you drop your speed to 5 knots the power requirement goes down to 7 hp (72 apm draw). If your cruising range at 5.5 knots is two hours (11 nautical miles), then you should be able to run almost three hours at 5 knots (15 nautical miles). Similarly dropping your speed to 4.5 knots cuts your power requirement to 5.2 hp (55 amps or a range of 16.4 nautical miles).

One very expensive solution would be to replace your 6 8D batteries one of the new Tesla lithium ion batteries. They come in 10 kilowatt capacity and would significantly increase your range.

TD thank you!
My concern is crossing the Bay. At 5 knots, that's perfect conditions. Not always possible. That's my concern. I understand the math & range but it's the reality of cruising on the Bay that has me concerned.

On a happy note, imagine my thrill to see my boat featured in the Chesapeake Bay magazine! That's me last year! & why I want to make it this year, too!

Im very happy to see her featured!

Here's the whole article.

Congratulations on getting your electric drive installed!

You will gain lots of practical experience running Starside and sort out exactly your power needs doing so. Meanwhile research newer batteries such as lifepo4 and others that pack way more wallop per pound. I think in the very near future you will reasonably afford a much larger fuel tank (more battery power). The newer batteries can be discharged more deeply so you will not be carrying around 50 to 60% unusable capacity.

Thanks for taking the time to share your project!

Starside - Great job. I love the mic of traditional and hi-tech.

I'm sure the way batteries are developing, you'll be crossing the bay before long.

I too was seriously considering going electric, while I was waiting for the old volvo to die. I had a year or so to price things out fairly accurately, and in the end, it just didn't add up. But I still admire those who break new ground.
It we only did things that made good financial sense, none of us would have boats.

AusCan said:

Starside - Great job. I love the mic of traditional and hi-tech.

I'm sure the way batteries are developing, you'll be crossing the bay before long.

I too was seriously considering going electric, while I was waiting for the old volvo to die. I had a year or so to price things out fairly accurately, and in the end, it just didn't add up. But I still admire those who break new ground.
It we only did things that made good financial sense, none of us would have boats.

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Oh that last line cracked me up!

Okay, sorry for the delay. I had my first lesson that was cut short cuz of bad weather, but I finally got the numbers.

I'm going to type my notes as I wrote them down w the electrician. This will make more sense to those of you who are familiar w this stuff. As a novice, I apologize in advance!

Here we go...

I have 3 electrical systems - 12 volt, 72 & 120.

12 volt is house.
72 is propulsion/engine.
120 is charging system.

245 amp hours.

Battery life depends on depletion. Below a 50% charge harms my battery life.

Full throttle is 107 Amps per hour.

Best cruising speed is 1100 RPMs using 58 Amps. That averages 5 knots in calm seas.

122 hours to usable amp hours (50% of battery).
122.5 amps available divided by amps being used = hours available

That's the tech stuff.

My experience so far is this: she cruises well at 5.5 knots in calm seas. I have to slow her down to 4 knots in rougher weather.

She handles well. What's weird is that under 600 RPMs, she doesn't move! At first I thought it was broken but learned that she needs some power just to move her along. I have to get used to her throttle but it's smooth & a matter of practice.

She's very quiet & responds well once she's underway.

My next lesson is next week & I'll take pics! Until then, I hope this answers questions.

Oh, as an aside, there isn't a midway point to St. Michaels from Galesville (who knew?) so Starside won't make it to the classic boat show this year. It will just be me & my dog, Smiley, but next year, I plan to dock on the other side of the Bay so I can cruise her to the boat shows. This year, I'm concentrating on learning how to dock & maneuver. The West River is a good place to practice. ?

One more thing...

Re the portable generator, here are the numbers if operating while cruising to get a further range -

122 divided by 20 = 6 hours to recharge.

That's why it wouldn't work. Id need a larger generator or would have to stop for 6 hours to recharge.

So as a simple summary, you have 2hrs of run time available between recharges, and it takes 6 hrs to recharge. So you basically get 2hrs a day of run time.

I'd guess the recharge will actually take longer than that due to the tapered charge rate as the batteries get full. It will probably be more like 8-9 hrs.

All this pretty clearly demonstrates why battery-electric boats have very limited application. To get more run time, you start looking at a generator. And pretty soon that generator has the same power as required to drive the boat. So why not just connect the engine directly to the propeller....

But for local puttering around in the silent serenity of your classic boat, it can work.

Nicely done, enjoy your boat Starside!

twistedtree said:

So as a simple summary, you have 2hrs of run time available between recharges, and it takes 6 hrs to recharge. So you basically get 2hrs a day of run time.

I'd guess the recharge will actually take longer than that due to the tapered charge rate as the batteries get full. It will probably be more like 8-9 hrs.

All this pretty clearly demonstrates why battery-electric boats have very limited application. To get more run time, you start looking at a generator. And pretty soon that generator has the same power as required to drive the boat. So why not just connect the engine directly to the propeller....

But for local puttering around in the silent serenity of your classic boat, it can work.

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No, that was for the portable generator recharge.

I have onboard the Quick Charge. That charges from shore power at a much faster rate. General rule is that if I cruise for 2 hours, my Quick Charge will take 2 hours to fully charge the batteries.

In other words, it's even cruising/charge time. The issue is that I need shore power to utilize the Quick Charging system. The generator would just be a portable option & that's not worth it.

I can cruise longer distances if there are marinas to stop at. So cruising the Bay is possible - say, a morning cruise to Annapolis, have a long lunch, then cruise to Piney Narrows in the afternoon. You just need to plan to marina hop.

congratulations on the success of your project.

I would never consider trailering a wood boat. A recipe for disaster IMO

My calculator died so I have to toggle screens- PITA!!

I think the key to this is gennie size.

72v at 20a is 1.4kw, about the limit for a Honda 2kw

Running at 58a at 72v is a touch over 4kw.

2hr run time at 5kts is 10nm. 10nm of silent running.

If you need to cover more than that, run the gen the whole time. That will nearly double your range.

Or get a larger gen, say 4kw. With that running you can run almost indefinitely, limited by fuel.

Now running a gen does take away from the magic of silent travel, but this is probably only necessary when doing long hauls like crossing the bay. 90% of travel can still be in silent mode.

Starside, are you saying it's not possible for you to power your shore charger with the Honda generator while underway? I have my shore power cord plugged into my generator and can power the charger or other 110V systems as needed with the Honda eu2000i. Have you tried this?

I think it's that the fast charger is about 4kW, about the limit of a 30a shore cord. That draw would stomp on a 2000i.

I might have missed Starside's charger output. I run my 55A charger at about half-throttle on my Honda. It could probably handle a 75-100A charger if the Honda load is limited to 13.3A.

It's 72vdc, so 20a is a bigger deal than at 12v.