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Hi Captain Canuck,

You are headed in the right direction with your plans. If you are planning to use lithium it's probably a good idea to use a BMS (battery management system) so you don't run the batteries down too low or charge them too high. When I repowered my 1976 Ericson 27 with electric I hoped the AGM batteries that I used would last 5 or 6 years. At that point I thought I would replace to batteries with lithium. I have yet to make the change (6 + years) but I'm in the process. I didn't see any mention of instruments (I may have missed it). A voltage reading for each battery (down below) and an ammeter/voltmeter at the helm are pretty much must-haves. It's amazing how a very small adjustment in throttle position can lower your current consumption and keep you moving at the same speed. Also the ammeter at the helm is critical for regeneration. I started a description of my system on the Ericson Yachts web site, I need to update it but it may be helpful Ep - Blogs - EY.o Information Exchange
 

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mark you were one of the first conversions I read about

congrats on such a great system

and thanks

christian

ps what lithiums are you thinking about and what mods to your system would that entail?

how much % battery loss do you think you have endured over 6 plus years?
 

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I'm posting up on this thread because of very little activity in the classified section. I have a complete 5 Kw Electric Yacht motor set up. Would be a good option for a 27 Catalina or smaller sailboat, replacing the Atomic 4.

Set up comes with everything you need to do the conversion. I'm selling the unit because I bought the boat with the electric already installed and an outboard too. I don't need both, and I do long trips vs short day sailing that require many hours of motoring. I do sail when I can, have enjoyed the electric for maneuvering in the harbor, zero maintenance, or just out for a day sail.
The Electric Yacht complete unit with 4 (100amp)batteries and charger would be $6000, asking 1/2 price, $3000 OBO. Unit is still operational in my sailboat.
I have complete description and pics here:
5.0 KW Inboard Electric Motor For Sailboat For Sale

Any help getting my set up to someone looking at doing a conversion would be appreciated.

Thanks
 

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I'm following this thread because I need to do the same thing and I need all the help I can get. Lilliput is a 20' pocket cruiser with a dead MD1 engine. Displaces 3000 lbs. or so. Her prop is in an apperture between keel and rudder so regeneration may not work, I'm told.
 

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Discussion Starter · #46 ·
Hi Guys. I'm purchasing a hunter 29.5, so I'm going to have to rethink my repowering strategy. The good news is the Yanmar diesel in the boat is in pristine condition, so I should be able to sell it for more than enough to do the conversion. Once I have the boat in hand I can start planning out the conversion. I'll probably start once the season ends, I don't want to take away my family's time on our boat during good weather.
 

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Discussion Starter · #48 ·
So why replace it? Electric will both reduce range and resale value. A diesel in good condition will have lower long term running costs than electric's periodic battery replacement I would think as well.
I'm not going to be using lead acid batteries, I'm going to be using LiFePo4 cells. Their lifespan should be at least 10 years, vs 5ish for lead acids. They're also considerably lighter (60lbs for 2kWh vs 400lbs). I'll no longer need a starter battery. I'll have a little honda generator for backup if I need it.

The electric motor will be about 60-70lbs, vs the 250+ for the diesel itself. It doesn't need any cooling, provided you run the motor at or under it's rated power. When under sail, I can regen some power back into the batteries.

So, the benefits are:

Less weight
No maintenance
Instant power (no warm up)
Quiet
No diesel smell
Amortized cost of batteries is low
More batteries can be added later
Power is cheaper than diesel
Regen when under sail
No house batteries, just a DC to DC converter

The downsides:
Up front costs are higher
Lower range (can be mitigated with more batteries later)
Requires an understanding of electricity to build a system, but not to run it.

The way I look at it, battery costs drop about 7% per year. If, at the next of next season, I feel that I need more range, I can drop in another set of batteries and add to the stack. I don't need huge range, I just need to get out of the marina and back. A friend of mine converts boats, and he says a typical monohull of my size runs about 750W of draw to go 3kts, which is about as fast as the marina lets me go anyway.
 

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LiFePo4 batteries have not gone down in price recently - gone up as a matter of fact.

I can understand switching if the diesel is shot but to replace a good diesel with electric and get less range and resale makes no sense.

A well maintained diesel doesn't smell.
 

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Discussion Starter · #50 ·
RE; #2 Fix the diesel leak? I never smell in on my old tub with it's new fuel system.
RE; #3 Do you row the boat in July and August?
RE; #7 fire danger with Lithium Ion batteries?

add; #8 we have unlimited funds
add; #9 how much and how large copper cables, terminals, etc
I think you're assuming that I'll be running a 12V system. It will be 48V most likely, or 72V if I go with a bigger motor. That changes the cable calculus quite a bit. As a rule, I generally go with one step higher than I think I'll need.

Also, LiFePo4 batteries, amortized over their lifetime, are cheaper than lead acids are now for the same usable charge. Here's the math:

LiFePo4: $500 per kWh x 80% useable = $600 per useable kWh, /10 year lifetime = $60 per kWh/year
Lead Acid: $266 per kWh x 50% useable = $532 per useable kWh, /5 year lifetime = $106 per kWh/year

LiFePo4 batteries don't explode, even under the most extreme conditions. You're thinking of Lithium Ion batteries, which is an entirely different chemistry.

Since I can do the work myself, and sell my existing Yanmar, I can probably do the entire conversion for the value of the diesel on the open market, possibly a bit more.

Plus, I can always add capacity later on if I find I don't have enough battery for my propulsion needs.
 

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Discussion Starter · #51 ·
LiFePo4 batteries have not gone down in price recently - gone up as a matter of fact.

I can understand switching if the diesel is shot but to replace a good diesel with electric and get less range and resale makes no sense.

A well maintained diesel doesn't smell.
Funny, I haven't seen prices go up, and I monitor them pretty closely. Where are you sourcing your batteries? I'm generally seeing them for around $450-$500/kWh for the CALB Prismatics.
 
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