Replace Diesel with electric engine

[s/v Jedi]

There, a serious candidate for our next auxiliary motor

https://electrek.co/2021/08/19/cande...r4XHacJuGMd1S0

[Adelie]

Originally Posted by s/v Jedi

There, a serious candidate for our next auxiliary motor

https://electrek.co/2021/08/19/cande...r4XHacJuGMd1S0

Think again, small high speed props, it’s designed for planing speeds, or more accurately for foiling.

[s/v Jedi]

Originally Posted by Adelie

Think again, small high speed props, it’s designed for planing speeds, or more accurately for foiling.

Sounds good to me. No more cavitation, much improved propeller efficiency, less drag. Now design a lift to only lower it when needed

[Adelie]

It’ll take a bit more than 50kW to get your boat up on foils.

[moseriw]

Quote:
Originally Posted by Adelie
I agree that hydro-gen and especially regen has pretty mediocre performance.

You keep overstating how bad it really is. And you seem to be flirting with the idea that regen has poor performance and is not worth it so electric propulsion is not worth it either.


OHH YEAHH

[double u]

Originally Posted by moseriw

Quote:
Originally Posted by Adelie
I agree that hydro-gen and especially regen has pretty mediocre performance.

You keep overstating how bad it really is. And you seem to be flirting with the idea that regen has poor performance and is not worth it so electric propulsion is not worth it either.


OHH YEAHH

....& I think, moserw, you & I are the very last individuals hanging onto stinking oldfashioned thumpers, ALL other boats are running on electric...we'll meet them at the wallbox :-)

[wingssail]

When electronics fail us.

It's going to be a while before we have 70,000 boats with lithium batteries, but the recall of Chevy Bolts because of fires in their batteries is worrisome. Apparently some manufacturing defects cause the cells to go bad, but, quoting Greg Less, technical director of the University of Michigan’s Battery Lab, “Batteries are very hard, when something goes wrong in a cell, the cell goes bad -- but not always right away.” Chevy Bolts have caught fire while parked not while charging and not while driving..

To me this brings up the importance of cell level BMS. If a battery has four cells but only one BMS monitoring all of them wouldn't it be possible for a single cell failure to go un-noticed until a fire starts?

What about a system with 75 cells and one BMS? Should one at least have 75 temperature sensors (also electronic)?

And that is over and above the possibility of a BMS failure. They are electronic devices and as such subject to failure at any future time. Could one not have a bad BMS which is no longer monitoring the battery or the cell and not know it? After all, we'll be expecting these BMS to work 24x7 for years without failures. Do we need a monitoring system to monitor the BMS's, NPPT's, DC-DC chargers, regulators, etc?

What kind of monitoring system can manage all possible "points of failure". There isn't one.

So, to be honest, we should not be surprised some day when electric drive boats start to catch fire.

[Anders]

Originally Posted by wingssail

When electronics fail us.

It's going to be a while before we have 70,000 boats with lithium batteries, but the recall of Chevy Bolts because of fires in their batteries is worrisome. Apparently some manufacturing defects cause the cells to go bad, but, quoting Greg Less, technical director of the University of Michigan’s Battery Lab, “Batteries are very hard, when something goes wrong in a cell, the cell goes bad -- but not always right away.” Chevy Bolts have caught fire while parked not while charging and not while driving..

To me this brings up the importance of cell level BMS. If a battery has four cells but only one BMS monitoring all of them wouldn't it be possible for a single cell failure to go un-noticed until a fire starts?

What about a system with 75 cells and one BMS? Should one at least have 75 temperature sensors (also electronic)?

And that is over and above the possibility of a BMS failure. They are electronic devices and as such subject to failure at any future time. Could one not have a bad BMS which is no longer monitoring the battery or the cell and not know it? After all, we'll be expecting these BMS to work 24x7 for years without failures. Do we need a monitoring system to monitor the BMS's, NPPT's, DC-DC chargers, regulators, etc?

What kind of monitoring system can manage all possible "points of failure". There isn't one.

So, to be honest, we should not be surprised some day when electric drive boats start to catch fire.

Chevy Bolt does not use LifePO4 batteries and any fire in them has no relevance to boats.

[wingssail]

Originally Posted by Anders

Chevy Bolt does not use LifePO4 batteries and any fire in them has no relevance to boats.

Don't be silly. Not all lithium boat batteries are LifePO4, and even LifePO4 batteries have fire potential if mishandled AND cells can have manufacturing defects.

My point, which is generally not acknowledged by lithium battery fans, is that we are building complex systems with lots of potential failure points, which may (or may not) work perfectly when new but will certainly experience failures in the future. Failures which may be hard to diagnose and fix and even have the potential of fire onboard.

[Adelie]

Originally Posted by wingssail

Don't be silly. Not all lithium boat batteries are LifePO4, and even LifePO4 batteries have fire potential if mishandled AND cells can have manufacturing defects.

My point, which is generally not acknowledged by lithium battery fans, is that we are building complex systems with lots of potential failure points, which may (or may not) work perfectly when new but will certainly experience failures in the future. Failures which may be hard to diagnose and fix and even have the potential of fire onboard.

You made a comparison to a specific model of car which uses a specific Lion chemistry, specifically, NMC.

LFP is not the only Lion chemistry used on boats, but it represent by far and away the majority of recreational marine installations.

NMC has a higher likelihood of fire than LFP, so using that as a point of comparison is misleading whether intentional or not.

[mcarthur]

Originally Posted by wingssail

So, to be honest, we should not be surprised some day when electric drive boats start to catch fire.

Hmm, well I haven't read anything in the press about electric boat battery fires around here. On the other hand, there's regular videos about fires and explosions on boats without lithium batteries - gasoline and propane being the most of course, diesel sometimes.

So I have no difficulty agreeing with your statement, but I would lay a few odds that it could well be less than the fires on existing boats!

[PineyWoodsPete]

Greenline has built many hundreds of hybrid yachts over the past 11 years using 11.5kWh 240Ah, 48V LiPo battery modules , beginning with the 33', which I have - a '14 model, already then @ hull# 314, and with 39, 40, 45, 48 and 68' models with as many as 6 of these modules. They all have large solar arrays up to 2.6kW output, and clutched electric motor/generator units in-line with the 220-240 Volvo diesels - from 7/5kW in my little craft with a VW 165TDi diesel to Volvo 220-240HP since '15 with up to 14/10kW. With clutch engaged, you're in electric drive mode; clutch released, in normal diesel drive mode with huge generator output to fill your large banks. In moderate sun, with the 40' twin you can run the two HVAC units all day at anchor in Florida sun and have power to spare for an all-electric kitchen with large upright freezer/fridge - standard even on my 33'er - with full-time 120V..

I'm aware of two fires in early GL 33's (2010 earliest) - one due to an idiot charging straight to batt. terminals, bypassing the BMS w/temp. monitors to each of the 13 cell groups +breaker solenoid. The other unexplained - poss. manufacturing defect. Battery photos below...and the fridge it powers!

[double u]

gotta be seeing more of those, here with high powered electric outboard (only electric motors allowed on this "forest lake" (GPOAT)
Text in Kraut, pics speak for themselves.https://www.meinbezirk.at/eisenstadt...r-see_a4750316

[zloitapok]

Chevy bolt module work for 4 years ok. I built sealed box for it and istalled robust bms. This battery worked at two different boats at river and at sea.
I know there are issues with chevy bolt cars. For 0.00001% am I right?

[PineyWoodsPete]

Originally Posted by zloitapok

Chevy bolt module work for 4 years ok. I built sealed box for it and istalled robust bms. This battery worked at two different boats at river and at sea.
I know there are issues with chevy bolt cars. For 0.00001% am I right?

That's a huge battery, over 60kWh @ 288V in the newer ones, powering a 150kW motor. And weighs nearly 1000lbs! They are listed as only Li-ion, but the specific cell chemistry not given.