Charging Batteries

[Gazelle Family]

I have 225 amp hours of battery bank on my schooner.
to avoid running the Yanmar 77 hp Diesel, and not having solar yet,
what combination of Battery charger and small portable Generator is most efficient?
I like the little 2k honda generators... whats that? 15 amps?
or is it more efficient to fire up the beast daily on a crossing??

[jdoe71]

Do you know how many amps you use per day? That's kind of a starting point. 225 amps hours is nothing these days for most cruising boats.

[cfarrar]

There are a few recent threads on this topic. For example:

Here.

And here.

Colin

[onestepcsy37]

i have a honda 1000 generator. exceptionally reliable and quiet. the problem is that it only puts out 8 amps on the dc circuit. so i bought a 35 amp automobile battery charger that easily runs off the honda 1000 and use that to charge the bank. if your boat already has a large battery charger on board you can just plug that into the honda by uising the shore power connector.

i've since installed a 135 watt solar panel and that makes a big difference. don't have to run the honda as much when at anchor.

and as jdoe71 said, 225 amp hours is not much on a boat your size. if you're going to do any serious cruising/liveaboard, i would think that four golf cart batteries (450 amp hours) would be easier to live with.

[skipmac]

Do you already have a battery charger installed? If so, you need to match the power of the generator with the power demand of the charger.

Then, as already noted, you need to estimate how many amp hours you pull out of your batteries every day and size the system to replace that amount.

[btrayfors]

I agree with the comments re: the 225AH house battery bank being insufficient for most cruising boats these days.

Why?

1. You never want to cycle the batteries below about 50% state-of-charge (SOC). That gives you 112.5AH available from a fully charged battery bank.

2. Your batteries will almost never be fully charged, except immediately after you leave the dock having been plugged in for a couple of days.

3. On a cruising boat, most batteries cycle between 50% and 80% SOC. So, you're really only using about 30% of the rated capacity of the batteries. That gives you a realistic 67.5AH to use between charges.

Your daily consumption will very likely be more than that.

To replace 67.5AH into your batteries starting from a 50% SOC will take about 80AH from your generator/battery charger, allowing for approx. 20% loss in charging efficiency.

That's why you want the largest charger you can power from a small portable generator. The Honda EU2000i is an excellent and popular choice, but it can't power a charger much larger than about 70-75 amps output. If you had this setup, you'd need to charge the batteries for about an hour and a half to go from 50% SOC to 80% SOC.

And this is just for the 225AH battery setup you now have.

Bill

[Gazelle Family]

I must have hit my head on something
I have 600 amps of batteries ( not 225 )
We are electrically pretty frugal but the autopilot is a luxury i enjoy.

[cfarrar]

The Honda EU2000i is an excellent and popular choice, but it can't power a charger much larger than about 70-75 amps output.

I think if you have a big charger you can de-rate it to avoid overloading the generator. For example, on the Xantrex units you should be able to do this with the Powershare function. I've not done this, myself.

[Andina Marie]

While cruising we used a 1KW Honda generator for power in the evenings to minimize the battery capacity needed. Our boat was large enough that the quiet generator was not a noise problem with it way forward and it worked fine.

BUT

Small gasoline generators like that are designed for intermittent and emergency use, not daily power supply and after about 3 months it became a maintenance nightmare.

[Cotemar]

Honda 2000 will do the trick with you acting as the baby sitter.

Solar would be the best. No sound, No noise, No maintenance, No baby sitting