Generator or more batteries?

[gmowbray]

My boat has a generator - but to be honest I seldom use it. I usually just turn it on to see if it works but last time I tried that it didn't work.

The previous owner of my boat had a detailed service log and featured often in that log is the generator - one of those items you don't like to see on the list a lot.

I have put 560W of solar on the boat (she's in the WI's) and new batteries - as large capacity as I could fit - and I don't have issues of power for normal day-to-day use but I am probably red-lining it every now and then - but I don't use the generator to charge batteries.

Why wouldnt I just de-commission the generator and replace that weight, in that location, with batteries? I might also possibly install another panel.

I know the generator is another good backup for electricity onboard but it does strike me as too failure-prone or at least "service-needy".

[ohthetrees]

Only you can answer these questions really. But a couple of thoughts....

If I was starting from scratch, I'd always see if more panels and more Lithium batteries could be selected instead of a generator. So much less maintenance, and you can get a lot of batteries and panels for the cost of a generator.

But you already have one, so that really changes the math. Personally, I'd maintain it, but when the first major repair comes up, ask yourselves this questions again. If you really never use it over a period of years, and are facing an expensive repair, why keep it?

[Lucid]

I had solar on my last boat and added extra batteries adding batteries and more panels adds more complexity, no free lunch.

When I purchased my latest boat I did add the generator mostly to support the AC but I do use it to top off the batteries earlier and later in the season or if the weather has not been able to support my solar panels. I have two semi flexible panels on the Bimini that handle the house load a refrigerator and separate freezer and nav gear most days.

Things to consider, we work from the boat and my son took on line classes and the computers out a strong on the batteries. My wife’s hair dryer can suck up some amps too. So depending on how you are going to use it helps.

A happy medium might be to put a high output alternator coupled with the solar That’s what I did with my first boat with solar and it was manageable.

[smac999]

more batteries is the answer if you are getting back to a dock often to charge back up. IE weekend trips. a bigger bank can last a whole weekend without charge.

with no dock access. if you are currently not producing enough charge to keep up with day to day use. more batteries does not help.

[Bill O]

Originally Posted by gmowbray

My boat has a generator - but to be honest I seldom use it. I usually just turn it on to see if it works but last time I tried that it didn't work.

I have put 560W of solar on the boat (she's in the WI's) and new batteries - as large capacity as I could fit - and I don't have issues of power for normal day-to-day use but I am probably red-lining it every now and then - but I don't use the generator to charge batteries.

Why wouldnt I just de-commission the generator and replace that weight, in that location, with batteries? I might also possibly install another panel.

I know the generator is another good backup for electricity onboard but it does strike me as too failure-prone or at least "service-needy".

We need more info. What is your current house bank size, type (FLA, etc.)and your average ah daily usage?

[gmowbray]

I would be interested in those things that turned into "no free lunch" - I found installing panels, controller etc. to be pretty straightforward. No?

[gmowbray]

Originally Posted by Bill O

We need more info. What is your current house bank size, type (FLA, etc.)and your average ah daily usage?

My question was more theoretical or "what are the issues" I did the math on sizing the panels/batteries/Controller and consumption and, at least in the Caribbean, the panels provide me liveaboard power.

I guess I am going to take the generator out because it seems an ever-present threat of failure - I just am hoping here to find out how badly I will regret that decision!

[mvweebles]

To me, the calculus comes down to Air Conditioning. I have 800w solar and 700ah lithium. I still replaced my generator to assure I have ample AC in humid tropic weather. It was a close call though. Definitely not a slam-dunk decision. Threat of making a wrong decision by not having a generator haunted me too - I remember being on a boat at West End Bahamas where choice was open hatches and get devoured by no-see-ums, or closing hatches snd slowly roasting. I would have given a lot of money for AC that night.

Peter

[rslifkin]

Since adding solar, my generator doesn't get a ton of use. When we're away from shore power, it gets run for about an hour in the evening most days. This is just to power the high-demand electrical stuff that solar can't keep up with like the electric stove to cook dinner. And while we're cooking, the water heater gets warmed up for showers.



But as much as I don't use the generator a lot, I wouldn't give it up. I could easily replace it with more batteries, but the big limitation would be in finding space for more solar (I don't think I could add enough to keep up with cooking and hot water, let alone catch up after a cloudy day).

[EngineerRetired]

Question... Assume depleted batteries in the morning. At what time of day do the solar cells have them recharged? If the answer is a few hours before sun set them more batteries makes sense. If they are not fully recharged adding more won't help a bit.

[Bill O]

Originally Posted by gmowbray

My question was more theoretical or "what are the issues" I did the math on sizing the panels/batteries/Controller and consumption and, at least in the Caribbean, the panels provide me liveaboard power.

I guess I am going to take the generator out because it seems an ever-present threat of failure - I just am hoping here to find out how badly I will regret that decision!

Personally I would not take out/remove the gen. just from the idea that it may fail. Your engine may fail or have a mechanical issue, but you're not going to take that out are you?
Depending on why it won't start at the moment, would keep it it it's just a minor maintenance issue. Depending if your have a water maker (AC motor driven), it could be useful.

Originally Posted by EngineerRetired

Question... Assume depleted batteries in the morning. At what time of day do the solar cells have them recharged? If the answer is a few hours before sun set them more batteries makes sense. If they are not fully recharged adding more won't help a bit.

Going further down this path, how deep of a discharge/what is the SOC when you wake up? With a larger bank, your depth of discharge will be less and you will get more cycles/longer life out of your batteries.

[C420sailor]

I don’t like the idea of putting all my eggs in one basket. Options are always good.

I’d keep the generator.

[gmowbray]

There are days when I might view the engine as disposable - but I get your point.

I think there are "Must have's" i.e. engine and "Nice to have's" i.e. Generator. We dont have A/C, Water Maker, electric stove or even a wife that uses a hair dryer so overall consumption seems less than some of you others.

THanks for the ideas/discussion - When I get back down there I will sternly look at the Generator and ask it to justify itself.

Graham

[moseriw]

Title? What the f. are you mixing?

A generator produces energy
A battery stores energy

There is nothing that enables an if then else question.

[MJH]

Originally Posted by gmowbray

My boat has a generator - but to be honest I seldom use it. I usually just turn it on to see if it works but last time I tried that it didn't work.

The previous owner of my boat had a detailed service log and featured often in that log is the generator - one of those items you don't like to see on the list a lot.

I have put 560W of solar on the boat (she's in the WI's) and new batteries - as large capacity as I could fit - and I don't have issues of power for normal day-to-day use but I am probably red-lining it every now and then - but I don't use the generator to charge batteries.

Why wouldnt I just de-commission the generator and replace that weight, in that location, with batteries? I might also possibly install another panel.

I know the generator is another good backup for electricity onboard but it does strike me as too failure-prone or at least "service-needy".

My new-to-me sailboat came with a Onan GenSet 8.0Kw and air conditioning. I quickly got rid of that ugly 500 lb. monster but the ac unit is still installed but don't need/use it here in the NW.

I have since installed 4x140W (560W) solar panels to feed my two 8D Gel house batteries that also came with the boat (replaced after 15 years service) finally replacing them two years ago with new 8D Gels...they will outlive me. My round trip to Hawaii never saw the power get below 85%.

It sounds like you have REASONABLE power needs as you don't have air conditioning or water maker, so there is no reason to keep the generator unless you think it might be a selling point when that time comes.

It would be interesting for you to complete an energy use budget. There is a sample on the Pacific Cup web site that I used. Try Googling...Pacific Cup 2012 Sample Energy Budget (a spreadsheet) and modify it to your needs.

Good Luck.

~ ~ _/) ~ ~ MJH