What would it take - inverter

[Matty]

I have a 2018 R27 luxury (a/c). What would it take to convert to battery/ inverter for 3-4 hours of a/c and eliminate the generator. Generator is too noisy and too many issues. At night I usually am at a marina. So just need a few hours of a/c during the day in FL HOT sun.

 

[CruisingElvinRay]

The A/C on my R-23 pulls 61 Amps with the engine running at idle. (I tested this at night). No engine is 92 Amps. Underway, on a sunny day at cruise, it pulls about 43 amps. On my factory 3 battery house bank, I can run for about 2.5 hours (give or take) before I'm about down to about 50% SoC.

I'm looking at upgrading my solar (factory 90W) to 300-400W, and will switch to newer technology when my batteries age out to allow me to go to a deeper discharge. This should at least double my run time.

Hope this helps.

 

[Brian 27 OB]

The AC and seawater pump on my 27 pulls 108amps together. After running two hours or so it jumps up to 120. I have a kisae 3000 watt inverter powered by 6 one hundred amp hour battleborn lifepoe4 batteries. No engine running, while anchored and the factory solar providing almost no assistance, I can do 3 hours comfortably. Math would tell me I should be able to make it close to 5 hours but the draw down happens faster than that and you will have other stuff running too.

In addition to the inverter, you will need a dc to dc charger and a good sized ac charger for the lithium bank. I used kisae for both. 60amp shore charger and a 50 amp dc to dc charger that the outboard stator powers and can also be fed from solar. The F300 sometimes shows up to 48 amps available for the house bank, but typically it is in the low 40’s.

 

[Submariner]

With such a large draw of amps, a significant voltage drop occurs. This voltage drop will prevent you from being able to use all the amp hours of the batteries. The amp hour rating is based on a 20 hour period. 5.5 amps an hour for 20 hours equals 110ah, for example.

Air conditioning will pull 65-75 amps, maybe more depending on the ac unit.
While I don't have air conditioning, I do have an electric bbq grill and hot water heater. I also have 3 Firefly Oasis G31 batteries which I can run down to zero percent state of charge (SOC). I have 348 amp hours total.

The hot water heater pulls about 65 amps. I can run it only if my batteries are at least 55pct SOC or better.
The kenyan bbq grill will pull over 100 amps. I have to be at 80pct SOC or better.

I am able to improve these numbers when my 400 watt solar array is putting in 15-28 amps. Or by running the Yamaha F300 for another 20-40 amps. I can leverage both solar and engine charging simultaneously for even better results.

To leverage the engine alternator amps I need to parallel the engine and house batteries to bypass the ACR (automatic charge relay) which would otherwise isolate the engine charging from the house bank. I must exercise caution here as I don't want my engine battery to be used as a deep cycle else damage could occur. I monitor the engine battery voltage directly on my phone with a Victron battery Smartsense voltage and temp sensor.

The discharge rates for firefly batteries are as follows.
These rates are similar to other AGM batteries.

Time - amp draw - total amp hours available
15 minutes - 180 amps - 45 ah
60 minutes - 68 amps - 68 ah
3 hours - 29.3 amps - 87.9 ah
5 hours - 19.2 amps - 96 ah
10 hours - 11 amps - 110 ah
20 hours - 5.8 amps - 116 ah

If I needed air conditioning, I would go as big as I could on a solar array and would leverage engine charging while cruising.

I get a lot of free hot water underway leveraging engine and solar simultaneously as described above.
(Outboard motors don't have engine coolant to leverage like an inboard)


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[knotflying]

What issues are you having with the generator? I think for my money I would try to make things work with the current setup. My understanding is that the major issue is losing prime on the A/C pump if you go too fast.

 

[Matty]

Last year the generator would cut out after 20 minutes of running. I removed the electric solenoid that actuated the seawater flow. Seemed to be restricted. This summer it would run but shut off under load. I found water in fuel cell. Drained and it worked OK for awhile. Now it will not start. Does not fire at all. Seems to be either water or fuel pump issue. I hear the westerbeke generators are more sensitive to water in the fuel. The outboard runs great btw.
Biggest issue is finding anyone to work on it. I do most repairs myself but due the tight working conditions and complicated design I have resolved my self to seeking hBTW.

Just trying to understand the available options.

Thanks

 

[CruisingElvinRay]

What issues are you having with the generator? I think for my money I would try to make things work with the current setup. My understanding is that the major issue is losing prime on the A/C pump if you go too fast.

My 2021 R-23 has a scoop style through hull fitting, which seems to do well underway at our 26-30 MPH cruise speed.


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[Brian 27 OB]

I’m at the boat now and just really looked at the system I had installed and realized I actually have 7 battle born batteries. There are 5 in the port lazarette and 2 in the center one behind my seakeeper. So my calculations are off by a bit. As other stated, get as much battery as possible. I’m like the OP in that I just need juice from one marina to the next. The only time we over night is on lakes and it’s only for a couple days time when the weather is not blazing hot. We run the ac at night to get the humidity out and swim all day so the solar keeps up with the fridge and stereo. But whatever the AC uses never gets replenished until I can plug in.

My last boat had the westerbeke 3.5 gen set. The Regal dealer told me that if I didn’t want problems with it, it should be the first thing turned on and the last thing turned off when we were on the boat. We had that boat for two years. The engine had 80 hours on it and then generator had 210. Once it ran for 4 days straight. I never had an issue, but I know plenty of guys that did. My biggest concern with it was dying from the fumes or it deciding to catch fire while we were sleeping.

Also have zero issues with the seawater inlet at speed. It is the scoop style. Had more problems with sea weed in shallow water than running on plane.