diesel to electric motor conversion?

[Stella Maris]

Ahoy,

I’ve read a couple of people saying that they’ve converted their 424s to pure electric propulsion. I’ve generally thought that the tech wasn’t there yet, because the range available simply didn’t compete. But with Lithium iron phosphate batteries starting to become available, the line might be getting close. The Sailing Uma people, for example, have completely electrified their pearson 36 with about 2500 amps of storage, and claim a motoring range of 30 miles or more. I’m curious, if you’ve electrified your 424, what motor did you choose? Where did you find it, and how much did you pay for it?

Thanks – Chris
Stella Maris, hull 200

[Revery]

Hey Chris,
I’ve been meaning to reply all week, but just now had the time to sit down and do it properly.
Revery was converted to hybrid electric in the spring of 2018 and we’ve been very pleased, having put about 5000nm on her since then. This includes two extended trips to the Bahamas and a cruise around the Gulf of Mexico.

We have a 20kw system from Electric Yacht and, while not perfect, it has performed very well. Our good friends have been buddy boating with an electric Pearson 36 (not Uma) that home-brewed (like Uma) and seem to be doing fine. I found value in having a well-engineered and pre-programmed system, so I spent the extra $. There’s nothing wrong with home-brews though, if you’re short on cash and long on time.
The EY system was paired with a 48V 420aH bank made from 8x Northstar 210 Blue+ AGM batteries since, at that time, there were no readily available LiFPO4 batteries that could handle the continuous discharge rate we needed. They exist now and we’ll put them in when its time to replace the AGMs (5-7 years from now).
The motors fit perfectly where the v-drive was and we remoted the motor controllers to the old engine pan. The batteries reside where the fuel tank was, in a custom tray that I glassed in. Electric Yacht has experience with at least three 424 conversions and will work closely with you to customize the shaft that couples to your existing prop shaft.
To charge the batteries, we installed 1200 watts of solar over the cockpit and davits on a t-top like canopy stick built at the boat. Revery is a factory cutter so there’s no mizzen in the way. We’re adding another 400 watts this fall before we head to the Caribbean. Now, if you don’t want to motor far or for long, solar does really well, but we weren’t comfortable trusting our safety to a purely electric system. That’s where HYBRID comes into play.
We installed a Next Gen 5.5kw generator with enclosure transversely on the old motor stringers. This is paired with a 48V/80a charger custom made for us in China. We started with a pair of US-made 40a chargers which were “supposed” to play well together, but never did, so we replaced them and kept one for backup. After 5000nm, it’s apparent to me that the chargers are the critical link in the system. We did fine with the old ones (learned how to adapt our cruising to their limitations), but having the ability to put 75+ amps into the batteries as we motor will be a game changer. I can go into much more detail as to the how/why later if you decide you’re interested in going down this path.

All in all, it cost us about the same as putting in a new Beta 50 and gives us about the same power/speed. And even when we’re loading the generator, we burn no more than 1/3 gallon/hr or diesel. We carry 20g in a small tank in the starboard lazarette where the original battery boxes were so no loss of space. We also carry 15g in jerries on deck. Weight for the system without solar, even with the ridiculously heavy AGMS, came out to within ~65 lbs of the original setup with a full fuel tank. And we don’t have a smelly ancient diesel engine in our bedroom!

A side benefit that we didn’t even think about was, when we’re at anchor, we have an obscene amount of energy in reserves…think 1640aH @ 12V. Enough that we could run the AC (we don’t) and our CruiseRO 20gph watermaker through our 3000w inverter. We’re even converting to electric cooking with a June Oven and a small induction cooktop. We wouldn’t have bothered with that, but our beloved Seaward Princess oven finally gave up the ghost (but might be repairable). It’ll stay in storage in case the all-electric experiment doesn’t work out.

Anyway, long-winded I know. But I wanted to give you a good run-down of what we did. I worked with Keith on S/V Vagari when he was installing his system and, between my experience and his great mind, he put in a solid system using LiFPO4s. Hopefully, he’ll chime in here as well. If you’ve got any questions, feel free to ask on here for everyone’s benefit. We can sideline for the nitty gritty details if you end up thinking you want to do this.
Converting definitely is NOT right for everyone, but we believe it pairs up with island hopping the Bahamas and Caribbean very well.

Cheers,
Evan
S/V Revery #219

• This reply was modified 3 years, 10 months ago by Revery. Reason: edited tags
• This reply was modified 3 years, 10 months ago by Revery.

3 users thanked author for this post.

Stella Maris, Discoverie, robshookphoto

[robshookphoto]

Thanks for the incredibly detailed reply. Do you mind sharing the ballpark prices for the generator and batteries?

And in practice, how often do you use the generator?

Pearson 424 cutter - "Effie"

[Revery]

Hey Rob,

The batteries ran me about $4400 shipped (I’ve got a guy) and the generator/enclosure was another $6500 or so (can’t find the invoice). Keith on Vagari has a source for LiFPO4s that aren’t much more than my AGMs were.

Total generator run-time was ~900 hours over 5000nm+ and 9 months. It gets turned on any time we plan on running the motors for more than 1/2 hour or so, just in case. I also attribute a lot of that to my old chargers only putting out about 55% of spec. It’ll be interesting to see how much I can reduce the hours with the new chargers.

Evan
Revery #219

[Bryan Bywalec]

I am very interested in Beta’s new Hybrid offering. Sort of like going electric with a generator but all in one package. Only drawback is the lack of flexibility in mounting the engine remotely

Keel Cooled Hybrid Propulsion

-----
Bryan Bywalec
S/V Pelican, Hull 209
Siren Engineering, LLC

[Author]

Posts