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[arthur]

What do you cruisers recommend for keeping batteries charged?

My wife and I did some anchoring for the first time last summer on our cruise and found to keep the frig cold and not worry about running down batteries, we needed to run our engine an hour 2-3 times per 24 hours.   

I'm considering a Honda generator or some solar panels.  If solar panels are suggested, how many amp/amp hours do I need?

[Craig Illman]

Arthur - There are a lot of existing discussions here about battery management. I'd suggest doing a lot of searching and reading. Batteries don't accept a lot of amp hours when they're almost fully charged, so topping them off with the enigne isn't efficient. I wouldn't waste diesel bringing them up above 80%. You don't mention your bank capacity, but with a refer, you should have a minimum of a pair of group 27 deep-cycle batteries in parallel. Go down the the auto parts store and buy a hydrometer and test them fully charged to see what their state is. If you're charging 2-3 times a day, either your batteries are on their last legs, your compressor is on it's last legs or you're digging in for beer too often.

Search the forum and review other's electrical upgrade examples.

Craig

[Jon Schneider]

What's too often? ;)

SNIP: If you're charging 2-3 times a day, either your batteries are on their last legs, your compressor is on it's last legs or you're digging in for beer too often.

[Craig Illman]

Jon - If you have a 200AH bank and only take it to 50%, then you would have 100AH from fully charged to work with, 60AH if you only charged back to 80%. The refer should pull less than 50AH/day, I'll admit that doesn't leave much for everything else. I guess I'd prefer to have enough battery to only need to run the engine once a day and have an alternator/regulator that would bulk charge at 60A or better. I just put the four T-105's in this fall. I'm looking forward to 48 hours on the hook without firing up the engine.

Craig

[Stu Jackson]

Arthur, here's one of hundreds of places to start:  http://c34.org/bbs/index.php?topic=1563.0

Please also check the first thread on the message board and update your profile, thanks.

Searches on the following words will get you lots of information:  chargers, batteries, alternator, regulator, solar, Honda and generator

An "energy budget" is the first place to start.  Nigel Calder's Boatowner's Manual and West Marine Advisors (printed catalogs and online) have lots of information on that subject.

The basic issue:  how much do you use daily compared to how much you can store and how you choose to replenish the amps back into your battery bank (i.e., shorepower, alternator via engine run time, solar, etc.)

[Ron Hill]

Craig : I believe that Jon was referring to "how often you dig for a beer" 

Arthur : I'm guessing from your hull # that you are a MKII with 2 4D batteries that have 400 total Amp Hrs!  If that's correct I'll guess that you really don't have to recharge until you've stayed at anchor for 24hrs (with the fridge running). 
What you do need is a battery monitor so you know how many amp hours you've used.  I have both a Honda and 2 solar panels and I use both.  When I get down about 50 amp hours I recharge with the Honda, but your living style may be differant than mine.  The two (flexable) solar panels will hold the fridge "at bay", but won't really recharge the batteries back up - the Honda will! 
Our site is full of info on this very topic.  You just need to take the time to read about it!!   

[Stu Jackson]

In addition to my earlier suggestion about searching on this message board, please become familiar with the electrical material available in our Projects section, here's an example: http://www.c34.org/projects/projects-electrical-system-upgrade-2.html

The link to the Technical Resources available to you is: http://c34.org/bbs/index.php?topic=2629.msg13752#msg13752

Anything else you need, please let us know.

[reneestargazer2]

Determine your consumption to be able to make a valued judgment . Adler Barbour in a four foot refrigerator on my boat is fueled by a 120watt Kyocera hard panel mounted on top of the dinghy davits. I use the motor to come into and leave the anchorage only. (I don't care about looking kewl as much as I do about safety). In the past two years of sailing in the Bahamas I have yet to deplete the batteries. Out of one month we may dock overnight once in a marina but seldom plug in electric.  All my lights are the LEDs, go to bed when it's dark and get up when it's light. Wouldn't do it without the battery monitor! Each boat is different and our lifestyle vary so you will have to pick up from comparing notes with all of us, what will work for you.

[DougP]

Short answer for me was the small generator. I have a little Yamaha that I run for about an hour or so to top off the batteries. Just plug it in to the normal shore power inlet and it works fine. Of course, it's only a 1,0000 watt so I can't pile on things like the water heater, space heater, and other items when I'm charging, but when I'm on the hook I don't use any of those things anyway. Worked great on three weeks in the Gulf Islands last Summer. Also has the added benefit of running my lights at home during the inevitable Winter power outages.

[arthur]

Thank you: Craig, Jon, Stu, Ron, reneestargazer2. and Doug P for taking the time to comment on my "keeping batteries charged".   I will be checking out the web sites and other recommendations.

Added information;  While on the anchor I only ran the frig when I ran the engine.  That is, if the frig felt like it was cooling down, I started the engine and flicked on the frig breaker until the frig felt cold again.  I guess I was worried about running down a battery with the frig running.  I use only one battery when anchored. 

Is the amp gage on my battery switch panel accurate enough to show when battery is in need of recharging?

[Stu Jackson]

arthur, the ammeter on your instrument panel is most likely a 0-25 amp meter.  As such, it has a built in shunt and is wired in series to the common terminal of your 1-2-B switch.  When current is being drawn, it shows how much at that point in time.  It is NOT a "battery fuel gage" because it only shows momentary consumption, not how much "fuel" (amp hours) is left.

For instance, when my fridge turns on, it use about 5 amps, so when the ammeter shows 5 and I have no lights or anything else running, I know the fridge is working.  The fridge works about 50% of the time, cycling on and off.  So, 5 amps X 24 hours X 50% = 60 amp hours a day.  See my Energy Budget post (http://c34.org/bbs/index.php?topic=3976.0).

Battery "Capacity" -- and need for recharging - only an amp hour meter, like a Link 10, will tell you that, unless you can do the math in your head about consumption compared to capacity.  If you have a 100 ah house battery (you did say you have a single battery) then you only have 50 amp hours available to use, which is one day use or less of the fridge turned on all the time without using any other 12V loads.  That assumes that your battery is fully charged.  It's capacity of battery (bank) times one half less amp hours taken out.

Battery Condition:  The ammeter then does NOT tell you ANYTHING about the condition of your batteries.  The ONLY way to know that is to have a multimeter voltage measurement device and a hydrometer which reads specific gravity of the acid in the battery cells (assuming you have wet cells).

If you haven't yet, I highly recommend that you purchase, beg, borrow or lend from a library Nigel Calder's Boatowner's Manual for Mechanical and Electrical Systems.  It's on its 3rd edition, but if you find a 2nd edition it'll most likely be less expensive and cover all you need to know.

If you are anchoring out a lot, and like to do that, you NEED to add more batteries to increase your house bank.  Others will say you need a generator, a higher output alternator and a regulator to run it, or solar panels.  Many different ways to skin the cat. 

[Jack Hutteball]

Arthur,
I am not sure what batteries you have or their age, but I thought I would give you the results of our practical experience.  I have 2 - 4D batteries that are now almost 7 years old.  When we are cruising, I alternate running on one or the other so that one is always charged for engine starting.  For the first 4 years we ran the refer continuously and were on the hook for generally up to a week.  We generally move at least every other day and run the engine about an hour a day, sometimes more if the wind is light.  I never sit at anchor and run the engine to charge the batteries.  Here in the Northwest it's about 50/50 sail/motor in the summers around the islands.  We have never run out of battery power.  I have only had to switch to the second battery to start if we have been anchored for 3 days continuously.

At 4 years I noticed that the batteries were not keeping up as well as when new.  When we headed to desolation sound for 4 weeks I bought a Honda 1000 "just in case" we needed it.  During that 4 weeks, never on shore power, I ran the generator 2 times for a total of about 3 hours.  Most days we ran the engine just getting in and out of anchorages, generally less than an hour.

During the last two years I have done what Stu does and turn the refer off at night after dinner and on again at breakfast.  It stays cool enough as no one is in it.  The refer is our big power draw.  We don't run a lot of stereo or other electronic equipment, except for nav equipment which is speed, depth, and a chart plotter.  Most of the time our VHF is even off.

With 7 year old battery's, we were out for 7 days in September and put a total of 6 hours on the engine (sailing was great) and never connected to shore power.  With 4 on board we ran the refer as described, used cabin lights in the evening, and were on the same battery all week.

That said, I am probably getting close to the end of the life of these battery's.  When I replace them I am going to do what others have done and install 4 - 6 volt golf cart batteries in a single house bank and install a separate starting battery.  I expect to do even better with that system.

[Ron Hill]

Arthur : Are you sure that you have an "amp gage" or do you have a Volt meter? 
As Stu said an ammeter will only show amps - flowing into or maybe out of the batteries (depending how the shunt is wired).
You cannot calculate the number of amp hours consumed by youself - only a microprocessor like a Link 10/20 Battery Monitor can.  Install a seperate staring battery.
Don't know what else to tell you .  OUT !!