Re: [electricboats] Recommendation for 48 v inboard motor + generator.

Hi Dan,

Thanks very much for replying and once again thanks for your 10M page – a superb reference that I'm using all the time now!

So it looks like I have a decent line on a Westinghouse iGEN2500 which is 2,200 W output for $600. https://westinghouse.com/products/igen2500-inverter-generator

 

I do need to get a generator in the next few months because, though I don't want to be using it much, my boat will come out of storage in April or early May and the marina it is presently at will only give me about 2 weeks of slip time since they are full and I won't be there for the summer. I did find a marina in Saket's Harbor and it is about a 2-3 day trip from Sodus Bay to Saket's Harbor. Due to these considerations and unpredictability of the weather and crew availability around then, I plan to go via Oswego where there is a town dock with overnight slips that have power and I can recharge fully there as needed. Still I want to have backup onboard even though we will sail as much as possible and the trip is a favorable one for travel by sail.

 

I don't plan to use this very much but want to have it at the ready just in case I get stuck really needing it.

Down the road there will be a few passages where it will be needed – St. Lawrence Seaway, Detroit River – for all these I am hoping that it may be possible to split the trip in half, thirds or quarters for the power intensive section and just plan to recharge whenever possible. One of the folks at the marina my boat is at went on and on and on about the Georgian Islands – looks super for when I am retired in a few years and have the time to get my boat up there and back in a season or so –

 

I am sure I'll have some more questions about the 10M. I have to reconnect the water system in mine so that is my main item aside from fixing the anchor light. Very much looking forward to spring!

 

Thanks again,

Scott

 

 

From: electricboats@groups.io <electricboats@groups.io> On Behalf Of Dan Pfeiffer
Sent: Tuesday, December 26, 2023 9:37 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Recommendation for 48 v inboard motor + generator.

 

The answer to your question is (of course), it depends.    What is the output capacity of your AC charging system?  The gas generators you are considering are 120VAC output?  (The 5,000 watt may have a 220VAC output?)  You will be delivering the power to the batteries or the motor through the battery charger that you would plug in to shore power.  That means you have a max power limit that is set by the charger output.  If your charger output is 1500 watts max that's your limit.  You can't get more through the charger.  So you can't use any generator capacity beyond what the charger can put through to the battteries/motor.  

You have  speed limit on generator of whatever the max output of the charger is.  If it's 1500 watts that's all you can deliver from the genset through the charger regardless of the genset output capacity.  For your boat (assuming a well matched prop) that going to be about 4 knots.  Probably a bit less but I don't know the details of the installation (reduction, prop specs).   You can go faster but you'll be drawing the additional required power from the batteries. 

You can increase the charger capacity but there is no point in having a generator that has capacity several times what you can actually use?  My charger (Thunderstruck EV TSM2500) puts out 1500 watts with 120VAC input.  If I had 220VAC it could put out 2500 watts.  So a 220 VAC generator of 2500 watts could in theory get me motoring at about 5kts.  These chargers can be paralleled and two of them would get me to 5000 watts and 6kts continuous with a 220VAC generator. 

But there are some other limits as you start to try to motor at higher speeds.  Mainly heat.  Can your motor run at that output level continuously?  That's why I went with the 12kW liquid cooled motor.  It can.  The 10kW?  Not sure what it's limits are but its quite a bit lower for continuous operation. 

My project (same boat) is still developing and I thought I would want about 10kW of generator capacity to get continuous motoring speeds of 6+ knots (need that to transit Detroit river in reasonable time) but after running the electric drive for a few seasons I think I would be fine with 5 or 6kW.

As to the generator, I would rather NOT have a gas powered generator on board.  Refueling underway from a gas can sounds like a sloppy process.  Gas fumes can accumulate in the bilge though that can be mitigated with careful handling.   I would consider a propane powered unit.  Same fume issues but swapping out a new propane tank seems a lot easier at sea than re-filling the gas tank on the generator.  A little less output on propane Vs gas but the handling advantages seem worth it to me.  And these generators are strictly for above deck use.  Same for the fuel storage. 


Dan Pfeiffer


More on limits here:
http://dan.pfeiffer.net/10m/electric_drive_limits.htm

More on gensets:
http://dan.pfeiffer.net/10m/diesel_genset.htm

On 2023-12-26 1:46 pm, Scott E Erdman via groups.io wrote:

Hey Folks - I apologize for not maybe having all the specifics needed for this but related to this thread and a somewhat more simple question:

I did buy the Pearson 10M that had been converted to 10 kW Thunderstruck with 2x24 x 2 48V bank w/ 196 AH. 
Presently there is no other way on the boat to recharge other than plugged in on a slip. 
Looking at everything, I figure that purchasing a gas generator is the best insurance on expanding range and dealing with extended draw conditions (currents, etc)
So my question is this - does it make a big difference whether the generator I get is 2,000 vs. 5000 W ? 
I am looking on Craigslist and I can find quite a few used 5,000 W generators for good prices - I expect space is a consideration as well. I guess my main question is what would I gain from getting a 5,000 W generator vs. the smaller, more portable and perhaps more quiet 2,000W ones?

Trying to take care of some of these purchases this winter -

Thanks,