How Long Should it Take to Charge House Batteries?

[filhere]

Can anyone assist? We have a 2007 43 foot Beneteau Cyclades recently purchased from Sunsail, which by the way has been sensational to cruise in here in the Med. We are at anchor and are running little more than the fridge, mooring light, music, some fans and cabin lights but need to run the engine for 10plus hours per day to keep charge in the 4 house batteries.

Is 4 house batteries adequate for our modest energy consumption - I say modest because we rarely use all the other electrical appliances on board.

Are our expectations unrealistic?

Is it the fridge that uses so much energy?

Does idling the engine for that long cause damage to the engine?

Should we instal more batteries?

Any advice or suggestions appreciated.

Thanks, Phil

[carstenb]

Originally Posted by filhere

Can anyone assist? We have a 2007 43 foot Beneteau Cyclades recently purchased from Sunsail, which by the way has been sensational to cruise in here in the Med. We are at anchor and are running little more than the fridge, mooring light, music, some fans and cabin lights but need to run the engine for 10plus hours per day to keep charge in the 4 house batteries.

Is 4 house batteries adequate for our modest energy consumption - I say modest because we rarely use all the other electrical appliances on board.

Are our expectations unrealistic?

Is it the fridge that uses so much energy?

Does idling the engine for that long cause damage to the engine?

Should we instal more batteries?

Any advice or suggestions appreciated.

Thanks, Phil

You don't note how big your house bank is, but I'm guessing it is 4 x 96 AH. This is what I have on my 40 ft Jeanneau. I've never run the bank empty, despite being on the hook for 4 days, meaning no charging at all.

You need to put a meter on the batteries, but from your description, they're shot. Replace them. And do yourself a favor, buy as big batteries as can fit in the battery box.

You should never run your engine at idle for that long. Diesels need to run and get HOT. Idling for that long will burn out the engine.

By the way, you can't just install extra batteries, if the house banks are connected to each other the batteries need to all be replaced and new additions come on at the same time (don't ask how I know this ) If I were you and the space is available, I would drop in something like 4 X 180 AH AGMs. That will give you lots of power. While you are at it, add a couple of solar panels and you'll never need to worry about electricity again.

If you haven't already done so, change out all your light bulbs (including navigation, steaming and anchor) with LED. They are expensive, but after you have changed, you'll use virtually no power

[robert sailor]

Yup the fridge is usually the big draw. See that you have a proper regulator as most of the boats use a simple one designed for an automobile. Idling the diesel is not good for it and if your run it 10 hours a day with no load its really not good for it. Get a proper regulator and maybe look at a higher output alternator, then consider either some solar or wind generated power.
What size are the batteries and how old are they?

[nigel1]

Agree with all of the above. Its very likely the batteries are shot, especially considering that the boat is ex sunsail, it's possible that the batteries have not been well cared for in the past, and most likely abused.
AGM's are good, but expensive. Good quality lead acid if treated properly will seen you fine. Consider using 6V Trojan batteries wired up to make a 12V bank, these will serve better than the so called 12V Leisure batteries.
And, get the charging system checked over.
I have a Bene 473, have recently overhauled the charging system, I thought the stock charging system, especially the wire size, was barely adequate.
I've fitted an external regulator to the alt, fitted new no volt loss battery charge splitter, 2 x 140watt solar panels and a decent wind geny. Had no need over the last year to use the battery charger or the engine for battery charging.
Bit of an expensive outlay, but worth it in the long run.

[edsailing]

You may need to check the charging voltage from the alternator. A common problem is that the voltage is too low so the batteries never get fully charged. It's a problem I have come across on 2 (new) Bennies on delivery.

[nigel1]

I forgot to say, get hold of a multimeter so you can check the voltages across the battery terminals both at rest and when charging, and also a clamp on DC amp meter to check the alternator output.
The fridge most likely draws about 4 amps per hour when running.
Benne's have a lot of interior halogen bulbs, great for heating the deck head, but you will be doing yourself a big favour in replacing them with LED's. If you look around, you can get them at a reasonable price.

Not sure what the alternator rating is on your boat, mine is 60 amps, and with the external reg, cycles between 14.6 and 14.2 volts.
At a later stage, and battery monitor is a worthwhile investment.

[skipmac]

Agree with most all the previous posts.

You need more information:
- Alternator output but understand a 100 amp alternator does not put a constant 100 amps into your batteries. The more charged the batteries are the less charge goes in.
- Measure the power draw on the boat. Yes the frig is probably the biggest draw but a big sound system can draw a good bit and using a lot of inefficient lights is not trivial.
- Both the above can be done by using a battery monitor. If there isn't one already on the boat it's a fairly inexpensive and simple addition. I like the Victron BMV600

You might need new batteries but I don't recommend AGMs. They are expensive and sensitive to proper charging routines and if you mess up you have an expensive mistake. AGMs need to be fully charged on a very regular basis and if you regularly run them down and do not fully recharge you could kill them in a year or so.

If you spend most nights at a marina plugged in or have a really good onboard charging system and are knowledgeable and careful with keeping the batteries up an AGM will offer some advantages but a standard deep cycle, flooded, lead acid battery is very sturdy, simple and easy to keep happy.

The best deal on these in the states is to buy pairs of 6 volt golf cart batteries. They are easier to handle than bigger 12V deep cycle batteries, usually much less expensive (partly because they don't say "marine battery" on the side).

[noelex 77]

Welcome to forum Phil.

Running a fridge and charging with the main engine is frustrating if you want to spend a lot of time at anchor, unless you move twice a day like charterers.
A bigger battery bank helps, but only slightly.

The first step is to make all the systems, particuarly those using a lot of power like the fridge as efficient as possible, but most cruisers relent and fit some solar panels eventually.

You need to do a proper energy budget to work out your running time, but something is wrong if you are doing 10 hours a day.
A battery monitor is the first step to see what is going on.

An hour run, twice a day would be more typical.

[denverd0n]

Agree with the above. Check the actual consumption for the fridge and stereo first--could be a lot more than you expect. Good possibility that you need to replace the batteries.

One other point, though, is you should definitely NOT just idle your diesel when charging. At the very least you want to get it up to a "fast idle" of 1400-1600 rpms. That will be better for your engine and will charge the batteries faster.

[Albro359]

Yup..concur with all of that

Not enough battery power

Put in as many batteries as you can fit

AGMS probably cost/effectiveness...best

Get your alternator mod'd to run a proper 3 stage regulator

Install solar panels with an MPPT regulator

Add a wind generator if you can...

Measure all your loads and work out with engine run time, solar, wind, how to manage it all...there's previous posts here that go into great detail about all of this...

AND..economise on your 12V usage !!!!

[sailr69]

do not add a lot of batteries unless you have the charging power to match. use a 3 step external regulator as well. if you do not have solar or wind chargers you will be using your engine every day to charge. not good to have batteries discharged for a long period of time. BTW, all house batteries should be grouped together with the engine start battery by itself.

[Albro359]

Yup separate the start bat from the house bank...numerous ways to do it..best is probably FET isolator from Vetus or Victron...but make sure your alternator can deliver the current you need...around 25-35% of house capacity...so if you have 400 Ah of house bats, you need an alt that can deliver 100 - 120 Amps...and as the previous poster said...w/o solar and wind, you'll be running the motor every day

Search this forum ... plenty of posts on this subject.

[barnakiel]

Battery size counts little (but you will likely kill the bank sooner if it is 'too small'). Most likely your bank size is fine but your generating capacity is not enough. You must make about 120% of what you consume.

Check out your regulator. If you main charging source is the alternator, you want a quality 3/4 step regulator. To save on engine wear, you may opt for a small genset. You may opt for some sort of diversification too: solar panels (if in a sunny country) or else windmill (if in a windy country), or else a fuel cell. Etc.

And read into Calder's. He explains the whole process very well.

b.

[skipmac]

Originally Posted by filhere

Is 4 house batteries adequate for our modest energy consumption

Depends. Are your batteries like the ones in the back of the photo or the ones in the front. In batteries size matters.

[Vasco]

Just a note to those recommending AGM batteries for cruising. AGM's have to be fully charged often. This is seldom achieved on most cruising boats as the last 15% of charging takes a long time. Most cruisers end up using the band from 50% to 85% and the batteries seldom get fully charged. In this type of charging regimen flooded batteries are preferred. AGM's will last about two years if not fully charged often.