Battery & etc opinions...

[stargazer ltd]

New to the forum. I've read countless posts about batteries, etc, but was hoping for a little help with my situation.

So, the back story: 1982 Catalina-30, no auto-pilot, weekend sail 95% sleeping at the marina w/ shore power. No refrigerator, no inverter, no TV. Really only loads are depth/speed/stereo, VHF and occasional running lights. Cabin light or two if at anchor (but again rare).

Currently, I have two "dual-purpose" interstate batteries (Previous Owner) and a portable charger (westmarine again P.O.). One battery has gone south, but the other holds a charge and is fine.

MY PLAN: Make the single "dual-purpose" battery a back-up or auxillary (start) battery - Bank 1 on the connection. BUY A NEW CHARGER and then do one of the following for Bank 2 (House): Option 1: two "dual-purpose" batteries in parallel. or option 2: two 6v golf cart batteries in series.

HELP#1: Would a 12amp charger be sufficient (looking at Promarine) or would I be better served with 20amp? I cannot afford to buy an echo charger for the "auxiliary" bank at this time, so the charger would be set for both banks.

HELP#2: Should I go with two dual purpose batteries (Costco) or two 6v batteries (Costco). I understand my limitations with 6v (ie if one cell goes, then the entire 12v is out), but if I have the auxillary bank, I can at least start the boat and get home. I cannot afford to buy two additional 6v golf cart batteries at this juncture... but that might be the plan down the road...unless that is a bad idea since that new "group of two" batteries would be then wired in parallel with the older golf carts...

FINALLY: without getting too deep into it now (I really need to finalize Help 1 and 2 soon), would the theory be use the Auxiliary for start purposes (or)... use that for "emergency purposes only"? Should I have the alternator charging both banks or just Bank 2 (house) (I have a feeling an echo might be the way... but that might be several months from now).

Thanks!
... Line

[S/V Illusion]

Any battery will start your engine. So-called dual purpose batteries are unnecessary and a compromise for either purpose.
The only other comment I have is to ignore the nonsense about the one cell going bad concern when using two 6v batteries as that is true for a 12v battery as well. The reality is that 6v batteries are generally more robust thereby lessening the chance of a bad cell.

As to the other issues, they are largely a personal preference. There is no right and wrong here.

[Stu Jackson]

Don't leave your boat plugged in when you're not there, just charge the batteries fully and turn it off.

Use the B on the switch instead of an echo charger.

Move your alternator output to the house bank.

Dual purpose batteries are junk, as mentioned above. 12V or 6V wet cells deep cycle are what you need.

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

[stargazer ltd]

Stu,

I don't think "turning off power" is an option. Often, we will get back to the marina and not have time to charge the batteries before we leave. There are times when it can be a month before we are back at the boat.

Thanks for the links, I'll read them over now.

... Line

[djmarchand]

Without considering your plan in detail, this is what I would do:

Have one Group 27 starting battery and 2/4/6/8 golf cart house batteries. Dual purpose batteries are BS. They won't last near as long as real, deep cycle batteries. Golf cart batteries are the best deep cycle and Trojan is one of the best (but may not be cost effective). Costco golf cart batteries are ok.

Make sure that your new charger has two outputs: one for the starting battery and one for the house. Unless you want to recharge your batteries at the dock overnight, 12 amps is fine. It will recharge them before the next weekend for sure.

Until more money and time is available, use your 1,2,all switch to islolate your starting battery while anchored out. Later add a combiner, ACR, Echo Charger, etc to automate it.

[ranger58sb]

Bank 1, starting battery. I assume small diesel? Shouldn't take a bazillion CCAs...

Bank 2, two 6v golf cart batteries.

Engine alternator charges both. The second bank may be overkill if you seldom anchor, but OTOH, if you increase your battery capacity that might lead you to anchor more often.

Two deep cycle (not necessarily dual purpose) Group 31 12v batteries instead for the second bank could work equally well, given you're not anchoring often. Even a single Group 31 deep cycle 12v might work, depending on how often/long an anchoring period might be... but more often, more amp-hours is better.

Two- or three-bank "smart" charger, installed for two battery banks. Nice to have a battery monitor. You could consider an inverter/charger, but perhaps only useful if you want to run lightweight AC (alternating current, not air cond.) stuff underway or at anchor. Can't speak to 12 vs. 20 amp.

-Chris

[jeepbluetj]

As mentioned, there's a lot of ways you can go.

I just re-batteried (is that a word?) my Catalina 30. I _do_ have autopilot, fridge, etc. But still had no more room than you probably do to stick batteries in there.

I kept it pretty simple:
Bank 1: "Main" bank - 2 220AH 6v golf cart batteries under the chart table (stock location in my boat)
Bank 2: "Reserve/Emergency" bank - A single G24 deepcycle in the starboard bunk (right in front of the chart table)

Stock 1/2/all switch, charging source(s) comes into common point.

Run in 1 all the time. If it ever drops low, switch to 2. Goal is to never use 2. Switch to 2 sometimes to charge the reserve battery.

My C30 has the A4, so starting could be done with 6 D cell flashlight batteries, no need for a "start" battery - more useful to have a "reserve" - If I killed bank 1, I could start the boat on 2, and switch back to 1 to have the alt charge 1.

Easy, simple. Works fine.

Do get a good 3-stage charger that won't boil your batteries. You can leave the good ones plugged in all the time.

[Stu Jackson]

Originally Posted by stargazer ltd

Stu,

I don't think "turning off power" is an option. Often, we will get back to the marina and not have time to charge the batteries before we leave. There are times when it can be a month before we are back at the boat.

Thanks for the links, I'll read them over now.

... Line

Happy reading. Please let me know if U have any ?s.

With no fridge, and your use, I suggest you do an energy budget. What I'll bet you'll find is you almost put as much back motoring for an hour as you use during a day. Give it a try and see what happens. You can also modify your "operations" to get back to your slip a tad earlier, or stick around for another hour (I know, your life, your choice ). But a full bank is when you reach 2% less than the bank. If you had a fridge, I'd say no or just turn it off a hour before you get back to your slip. Just read a story on this or another board about some poor skipper whose boat burned down because he left it plugged all week while he was away and one of the batteries failed.

Your best bet? Get a small solar panel, and unplug, it's dangerous for your boat's health and isn't doing your batteries any good sitting on float for that long - sulfation builds.

Good luck.

[foggysail]

I have left our boats plugged in now for over 30 years. My guess is most boats at slips are connected to dock power 24/7

[Stu Jackson]

Sure, doesn't mean it's good for the batteries though.

[foggysail]

Originally Posted by Stu Jackson

Happy reading. Please let me know if U have any ?s.


Your best bet? Get a small solar panel, and unplug, it's dangerous for your boat's health and isn't doing your batteries any good sitting on float for that long - sulfation builds.

Good luck.

I read and personally found lead acid batteries not fully charged have the greatest risk for sulfation, not those on float between 13.8 and 14vdc. I have 580 watts of solar that is also left on 24/7 in parallel with my Xantrex 50 amp 3 stage charger. The float voltage for the Xantrex is around 13.8 whereas the solar regulator floats at 14.2. So your recommendation for solar which I think is great, does result in high float and of course, this depends on teh regulator.

If you float much higher than 14.2 there is a risk of boiling the electrolyte.

[Sailor Doug]

How long will your bilge pump run on battery power? I leave my boat plugged in all the time. If boat develops a leak as soon as I leave charger will keep pump running till I come back. If everything is UL ABC approved no problem. If you have a house and leave for a week you don't disconnect the power.

[Dockhead]

Originally Posted by ranger42c

Bank 1, starting battery. I assume small diesel? Shouldn't take a bazillion CCAs...

Bank 2, two 6v golf cart batteries.

Engine alternator charges both. The second bank may be overkill if you seldom anchor, but OTOH, if you increase your battery capacity that might lead you to anchor more often.

Two deep cycle (not necessarily dual purpose) Group 31 12v batteries instead for the second bank could work equally well, given you're not anchoring often. Even a single Group 31 deep cycle 12v might work, depending on how often/long an anchoring period might be... but more often, more amp-hours is better.

Two- or three-bank "smart" charger, installed for two battery banks. Nice to have a battery monitor. You could consider an inverter/charger, but perhaps only useful if you want to run lightweight AC (alternating current, not air cond.) stuff underway or at anchor. Can't speak to 12 vs. 20 amp.

-Chris

Ask 10 sailors and you'll get 10 different opinions on something like this.

I'm going to second Chris' advice, and add a couple of points.

1. Your pattern of use is extremely undemanding, so don't overengineer the solution, or waste money on something excessively elaborate. Almost anything will work for this type of use.

2. It's really good and correct practice to completely separate start from service banks. The less connections between them the better.

3. Hence it is better to have two separate battery chargers. Since you are not rapid charging from a generator, you will want to avoid excessive charger size which will tend to cook your batteries. I would not exceed 15% of their capacity (that is, for a 200 amp/hour bank, a 30 amp charger). Chargers should be good quality multistage type. Don't buy Xantrex, or any no-name Chinese carp. Stick to Sterling, Newmar, Victron, Mastervolt, etc. In these small sizes, they are cheap enough anyway. The start battery will need only a small, inexpensive maintenance charger, like this one: Victron Blue Power Battery Chargers, or even this one: 12 volt battery charger

4. A small charger/inverter on the house bank will be a nice convenience on board. Even on small boats, it's nice to be able to (a) charge computers, ipads, phones, etc.; (b) watch a DVD; (c) use a kettle; (d) use power tools; (e) etc etc etc. Will require a bit of rewiring on your AC side, however. As Chris mentioned, if you have better power infrastructure on board, it might inspire you to start anchoring out more.

5. Avoid the "A-B-Both" switches, which inevitably lead to a mistake and dead batts, sooner or later. Keep jumper cables for any emergency start from the house bank (which you will never need to do if you are not taking any power from your start batt for any other purposes).

6. A couple of six volt golf cart batts from Costco, wired in series, will be the ideal house bank for you, but as Chris said, possibly overkill. So if they don't fit in your battery boxes or are otherwise inconvenient to install, don't worry about it. A couple of 12 volt deepish cycle batts would be ok too, even one 12 volt battery, considering your very light usage. But if you can swing it, a couple of golf cart batts will give you room to grow in case you start to spend more time on the hook, for example, or acquire more electrical gear.

7. A regular starting battery is best for the start battery. Contrary to what some people have posted here, deep cycle batteries are not as good for starting a diesel engine. They have thicker plates and can't produce as much peak current, especially at cold temperatures.

8. Make sure your batts are installed in sturdy boxes which are firmly bolted down. This is important. Flying batteries are one of the most dangerous things to happen in case of a roll.

9. Separate shore power battery chargers we already talked about -- now alternators. The ideal way to deal with that is separate alternators for start and house -- that's the way my boat is set up. It is unlikely that that will be practical on your boat for reasonable money. So you will need a split charger. Buy a good one, and if your alternator is not externally regulated, you will need to add that, too (something like Adverc or Balmar). This is essential when using a split charger because there is a slight voltage drop, and only an external regulator is capable of dealing with that (there's a sense wire which goes onto the house bank after the split charger.

10. A somewhat more elegant but more expensive solution to split charging from the alternator is a batter-to-battery charger like the one Sterling makes. Have a look and think about that. You will still want to have the external regular on your alternator, however.

Good luck, and let us know how you get on.

[stargazer ltd]

Well... success.

I installed the two 6v golf cart batteries (Costco) along with my new Sterling charger. I was having difficulty deciding on the size, and I ended up going with 10amp for three reasons (the way I currently use my boat; I don't have refrigeration or heavy loads; and finally, Mark at Sterling suggested the 10 as they have fewer returns).

Installation went flawlessly. Once set, I got a nice 15 hours of charging before taking the boat. Very good!

I still have not hooked up my auxiliary battery yet....

Options: 1 - use the 2nd bank from the Sterling charger?; 2 - buy a dedicated smaller ac charger? 3 - buy an echo charger?

... Line

[Zil]

By auxiliary you mean starter? Just let the engine alternator charge that.