CP27 Battery Recommendation

[relamb]

My 1988 CP27 has two group 24 deep cycle batteries under the bottom companionway step.  I'm taking them out to use elsewhere.
There's several inches of clearance in the compartment lengthwise and some in width, with those batteries.
What's the maximum capacity batteries I can fit in there, and what type is recommended?
I'm considering using that as the house bank and adding a 3rd battery elsewhere for cranking.
Does anyone else have additional battery capacity, if so what, and where are the batteries located?
Rick

[deisher6]

Hey Rick:
I have two batteries, I thought that they were group 24.  They are in the bottom parts of battery boxes and fit snugly.  They are less than a year old.  I use one for everything so far.  I have a charger that keeps both of them topped off when on shore power.  I think of the second battery as a reserve starting battery.

I have used this set up for one year on our present C-27 and 4 years on a previous C-27.
Have not heard of anyone using three batteries.

Not much help I am afraid.

regards charlie

[relamb]

The reason for more batteries is for more running time on the modern conveniences.
The two batteries I have now are pretty old and don't seem to have a lot of capacity, one came with the boat and another I had in the garage since  I have a 1500 watt power inverter and  with those two, I can run the microwave for a couple of minutes (long enough to boil water), or the drip coffee maker just long enough to make one pot of coffee.  Then they're both dead, and of course I can't start the engine.  With the engine running and the 50 amp alternator cranking out full bore (that's maybe 600 watts) I can get some more time.    I just want to pack as much power as I can into the available 2-battery space, and then perhaps have an extra cranking battery elsewhere that's not used for house power.
By the way, one of those portable car jump-starters currently serves as my emergency reserve, and it starts the engine just fine.
Before my self-induced drainage from the microwave, I could never figure out why my batteries would still not stay charged enough to crank the engine, despite the charger breaker being on, and shore power connected.  ...well, come to find out the breaker labeled "charger" has nothing wired to it.  The boat never had a battery charger.

[Allure2sail]

Hi:
I have a third battery setup but not what your looking for. My third battery (a group 27) runs my Maxwell windless and is mounted in a battery box under the vberth on the starboard side. It is kept charged by way of a solar panel with a regulator mounted on the cabin roof next to the grab rail. Works fine, been using this setup for four years. I also have a solar panel on my other two batteries with a three way switch (battery one, two or off) that is mounted on the cabin roof port side next to the companionway hatch. The two panels are the flexable style you can walk on and each one has its own regulator. I know that this doesn't really answer your question so it is more of a FYI.
Bruce
S/V Allure

[relamb]

I'm a fan of reading accident reports so that I have a heads-up on what kind of trouble I'm probably going to get into next.  It seems to be a very common occurance that a boat taking on water gets it's batteries submerged, loses power to it's bilge pump, but the worse thing is they also lose radio power and can't call for help.  I've read of this in three or four situations.  I'm thinking of putting the 3rd battery someplace away from the bilges and higher up, with the ability to at least switch the radio to that battery, just in case.  Alternately, there's a cigarette lighter plug on my portable jumpstarter, I may rig the radio so I can unplug it from boat power and plug it into that.  Already have a cable made so I can charge the jumpstarter back up from the boat 12v system, so that if I use it I can recharge it for the next time without needing to plug it into 110v.

[NateD]

Sounds like you might be able to fit group 27 batteries in there (2.5 inches longer, slightly wider, http://www.batterystuff.com/kb/tools/bci-battery-group-sizes.html). However, microwaving and drip coffee makers are going to be pretty darn rough on a battery bank that small (it would be rough on even 3 or 4 group 27). Your better off finding non-electric ways of heating food/water than building up a battery bank/charging system capable of powering a microwave on a 27 foot boat.

Some type of battery backup placed higher in the boat for the emergency electronics isn't a bad idea, other than you want to keep as much weight down low as possible to help with the righting moment of the boat. If you've got a large electric bilge pump hooked up to an operating float switch and the water is still coming in faster than the pump can keep up, then another battery mounted up high probably isn't going to do you much good once the main bank is submerged and starts to fail. That's manual bilge pump/bucket/engine driven bilge pump/sit on deck and watch the boat sink time. Instead of mounting a house battery up high somewhere, you could keep a handheld VHF and GPS on hand for emergencies (probably should for non-emergency situations anyways). Assuming your ship's radio has a mast-head antenna, that would give you significantly better range than the hand-held, so I do kind of like your idea of wiring in a 12v accessory plug that you could plug into a jump pack for emergencies. But I'm guessing if the water is up past the house battery bank you're going to have so many other things going on that finding and plugging in the jump pack is going to be an inefficient use of your time.

[Allure2sail]

Microwave usage....
I had a small microwave on the boat for one week. Ended up bringing it home and now use it in the garage. It used way to much electricity and killed the batteries twice. Luckily I have two solar panels on board that rescued me. I currently use a one burner butane stove for cooking (coffee, grilling, popcorn and most other stuff). I hardly ever take the time to setup my propane rail grill anymore. I think coffee makers and microwaves use to much electricity on a smaller boat like ours. Bigger boats have gensets for that kind of "stuff".

[relamb]

I lived on the boat for 7 months this winter, and used the microwave and drip coffeemaker daily - but on shore power.  I think my ultimate solution is to get a second 100+ amp alternator, wire it completely independent of the first, and just have it power the inverter.  I can run the engine for 5-10 minutes when I want to cook, and if for some reason the original alternator were to fail or belt to break, I have redundancy.  I'll have to get twin pulleys or a stronger uni-belt setup.
The biggest issue I had living on the boat for that long was refrigeration.  Ice every 2-3 days was a royal pain.  So besides the microwave and coffeepot, I have to power a refrigerator too!  Three batteries and two alternators ought to have me covered.  Along with a bigger diesel tank, and .....  (this reminds me of a yacht I saw that had a stern cockpit extension, about 10 feet added onto the back, so there would be room for the new hot tub)

[wes]

Alternators consume significant horsepower - around 2 hp each, depending on load. That's a big percentage of the output of our small engines, especially if you have the Universal M-12 like mine, which most owners feel is already underpowered for the CP 27.

Wes

[relamb]

Wes, alternators only require horsepower to drive when they are loaded - sending out current.  Many street driven race cars have a field cutout on the alternator so they can be shut off.  They require no power when they're not charging something.  In that case, they only use whatever energy it takes to spin them around unloaded (like by hand) and drive the belt around the pulleys.  One issue with charging your batteries via alternator is that, as you say, they only draw a couple horsepower.  So you end up running the engine for a long time at practically no load, which is inefficient and not that good for the engine.  So I want to load up the engine as much as I can if I'm just running it to make electricity.  But you're right, if I need the engine power to move the boat, I need to cut out the alternator to get back that extra few horsepower.

[Shawn]

Bruce,

"It is kept charged by way of a solar panel with a regulator mounted on the cabin roof next to the grab rail. Works fine, been using this setup for four years. I also have a solar panel on my other two batteries with a three way switch (battery one, two or off) that is mounted on the cabin roof port side next to the companionway hatch. The two panels are the flexable style you can walk on and each one has its own regulator."

What kind of panels are you using? Did you consider feeding both panels to the same regulator (for highest charging ability for any battery) and then use either something like a Blue Seas ACR to automatically combine batteries while charging voltage is present, or a Xantrex Echo Charge. The Xantrex is a voltage follower and will feed up to 15amps into another battery when the main battery has charging voltage present. I have two batteries on the new boat and am adding the Echo Charge next week in preparation to add solar. I am going to connect all charging sources to battery 1 (house) and the Echo Charge will be connected between battery 1 and 2.  If voltage in bank 1 gets to low to start the engine I will use battery 2 for starting. Alternator would be recharging bank 1 and the Echo Charger would be pulling up to 15amp from that charge to replace the wattage used in battery 2 for starting the engine.

Shawn

[moonlight]

Without a doubt this is a job for AGM batteries, two or three, group 27 or group 31 (or two of those and one group 24 for starting).  To get the best life out of them, you may wind up changing your charger, and depending upon how much you motor, you may need a more sophisticated charge regulator controlling the alternator.  But they're the best $/ah out there at this time.  LiFePO4 is getting close, and actually cheaper by the lifecycle cost, but 3x the upfront cost (but last twice as long, 3000+ cycles).

You really need a matched battery set, so one "old battery out of the garage" doesn't suck down a newer battery; unless they're ALWAYS isolated as separate banks.  And before that, you could stand a really good electrical analysis of ins and outs.  I can help you online, but travel cost probably precludes an onsite inspection.

[relamb]

For reference, two group 27 batteries will not fit in the battery compartment under the companionway step on my 1988 CP27
One group 24 and one group 27 fit just fine.

[Allure2sail]

Hi:
You can fit two 27's in that space but you have to eliminate the battery boxes. The group 27 that I have up front under the vburt is in a battery box but like I said before it is totally independent of the rest of the DC electrical system. Next year I'll be moving that 27 from under the vburt to replace one of the other batteries that is getting tired. I'll be replacing that one (for the Maxwell windless) with a group 31 because the battery box will take the slightly bigger and more powerful group 31 battery, and it is not that much more money. I've never had the windless run out of "juice" but I'm just being cautious. The Maxwell windless handles the 125 feet of chain and the 22 pound delta quickset just fine, may even put a 33 pound up there next season !!! I plan on doing not only more cruising but further distances next summer.
Bruce
S/V Allure

[relamb]

Well, in my '88 I can only fit two group 27's by taking the step halfway apart, and setting one of the batteries up on a piece of plywood.  The ears that hold the carrying straps stick out the ends of the battery too far (a quarter inch) and hit each other, the space just isn't wide enough.  I have to overlap the ears one above the other, and also offset them fore/aft because of the brace in the corner of the compartment.  With a crowbar practically I did get them in, but would have a heck of a time getting them back out.  So it's a group 27 deep cycle, and a group 24 starting battery going under the step, and the second group 27 is going someplace else.  By the way, when I was changing them, I added a 200 amp ANL fuse and holder right at each battery.