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michael.anda
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Initially Posted - 12/23/2016 : 16:46:48

I have a boat guy coming down to assist me in getting me up and running next week and I need to have parts handy for his one day visit. Need to pick up some batteries and cabling. 1983 Catalina 25 fin keel. Just the basics, no cruising, live aboard, type stuff just yet. What do I need for cables to reach cabin batteries? Any battery suggestions? I'm a newbie now, but hope to do some overnight coastal cruising before too long.

Mercury outboard

https://www.mercurymarine.com/en/us/engines/outboard/fourstroke/8-99-hp/#specifications

michael.anda
1st Mate

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Response Posted - 12/23/2016 : 16:48:41

ProKicker model
Electric start with tilt

dmpilc
Master Marine Consultant

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Response Posted - 12/23/2016 : 18:40:04

You will want fairly heavy gauge wire to run from the outboard alternator to the battery box, like 8 gauge wire. Run it from the stern, under the quarter berth, forward to the battery box, or "1-2-both" battery switch, with O-ring connectors heat-shrink sealed on each end. Make sure the wire is marine grade. Use 1/4" stainless nut/bolt connectors for the engine cable to wire connectors and heat shrink wrap or black tape wrap.
If you have the "1-2-both" switch, you could use a starting battery and a deep discharge battery. If no switch, go with 2 dual purpose batteries. Make sure you do not use new and old batteries together. The old one might draw down the new one to the "lowest common denominator".

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

Edited by - dmpilc on 12/23/2016 18:44:48

Stinkpotter
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Djibouti
9080 Posts

Response Posted - 12/23/2016 : 21:13:08

I don't believe you need a "starting" battery for a little sailboat outboard. There are several advantages to having two of the same type, brand, and age. I recommend either one or two "dual purpose" batteries (close to being "deep cycle' types)--two if you expect to have some significant amp-users like a TV or anything running off an inverter. For light-duty overnighting (using some lights after dusk and leaving an anchor light on), one Group 24 or Group 27 dual-purpose should be adequate. If you go with one, you don't need a 1-All-2-Off switch--just a similar On-Off rotary that can cut the battery connection to both the outboard and the panel.

If you want to be able to remove the outboard reasonably easily, buy some terminal studs (with wing-nuts and lock washers) you can mount someplace where you can connect the O-terminals on the outboard cables, and then crimp and solder some O-terminals on both ends of the cable from there to the battery switch.

Hopefully your helper knows about wiring... Have him give you a parts list that probably includes heat-shrink terminals, studs, cable, etc. If he doesn't, I'd say you need to get somebody else involved--even the 12 volt system can start a fire, and it can happen "out there" like it did to me once when sailing with someone else on their C-25. Believe me, you don't want that. Don Casey's Sailboat Electrics Simplified is an excellent resource. So is a person who knows what they're doing.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 12/23/2016 21:15:24

Steve Milby
Past Commodore

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Response Posted - 12/24/2016 : 06:30:00

I recommend a group 27 deep cycle battery. Group 27 provides more storage capacity for (depending on where you buy it) about the same price as a group 24. A deep cycle battery will obviously tolerate deep cycling waaaay better than a starting battery. Before you exhaust the battery by cranking it, you'll probably burn up the starter motor. Thus, as a practical matter, a deep cycle battery will provide more starting power than you're ever likely to need for a small outboard engine. I have never used up the cold cranking capacity of my group 27 deep cycle battery in trying to start the diesel engine on my C&C, but have used up it's storage capacity by running the lights and refrigeration too long. That's where the tolerance for deep cycling will be beneficial.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Voyager
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Response Posted - 12/24/2016 : 08:04:57

Fuses, on every wire coming from the positive battery terminal. Fuses, not electro-mechanical circuit breakers. The latter can fail.

For the engine's electric starter, 50-60A fuses, depending on current draw.

For the house lighting and accessories switch panel, 25-30A should do.

If you have any separate high current circuits: stereo, spotlights, inverter (100W or more), each of these circuits should be separately fused.

Fuses should be within a few inches or worst case less than 1 ft from the + terminal of the battery.

Wire gauge and type: Marine wire is stranded and tinned. #6 AWG stranded wire to the engine if it comes with a starter. #10 wire minimum to the house panel, especially if you have cigarette lighter plug receptacles on that circuit. Most switch panels have separate 10-15A fuses for each circuit. Also very nice to have.

A short circuited wire without a fuse is very likely to burn the boat to waterline. Just read about one last night in Greenwich CT. Total loss.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

islander
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Response Posted - 12/24/2016 : 08:06:12

I agree with Steve on using deep cycle battery's. They
take more abuse(discharges) and more charge cycles than starting or duel purpose battery's and are not harmed by using them to start a small motor. I also think that using #8 gauge wire for the charging circuit is overkill. His outboard has a 6 amp charger. WM chart shows 12 or 10 is fine for a 25ft circuit. I'm guessing 12ft each way. I have 12/2 duplex on my Honda charge circuit. Its what the PO had installed and the Honda plug is formed for it. Its been that way since 97 without any problems. After a long 3hr motor back to my dock one day when the wind died I was curious and put my hand on the cable just to check. Ice cold at the engine and at the battery.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 12/24/2016 08:15:37

Voyager
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Response Posted - 12/24/2016 : 10:03:53

Scott. It's not the charging current @6A, it's the starting current @50A. The 2x15' of #12AWG wire measures about 1/2 Ohm, which will dros ~2.5VDC. 2.5Vx50A = 125W dissipated in the cable. It's usually of a short duration so heating would not be a major problem.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

islander
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Response Posted - 12/24/2016 : 10:16:55

Yes Bruce, That's why I said the wire size is just for the charge circuit. I don't have electric start so I didn't recommend a wire size for the starting circuit.How did you come up with the 50amps for the starter motor? I've tried to find that info out without any luck. Is there a label on your starter motor stating the amp draw?

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 12/24/2016 10:32:56

Stinkpotter
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Djibouti
9080 Posts

Response Posted - 12/24/2016 : 12:11:33

Bruce, your Honda 8 has a 20 amp internal fuse protecting the charging and starting circuits. I suspect most other outboards in the 8-10 hp range have similar starting motors, and most have lower amp alternators (like 6 instead of 12), so 20 amps is probably a good bet. 50 would probably be less protection than you'd want.

I have no quarrel with deep cycle batteries as opposed to dual-purpose... But if two batteries are needed and will be on a 1-All-2-Off switch, I prefer making them identical--from my reading and experience, it helps them to last longer since it's less likely one will be drawing down the other due to age or damage. For the usage you describe, Michael, one Group 24 should be plenty, and one Group 27 a little better. We had just one Group 24 for daysailing and occasional overnights with no home entertainment-type systems aboard. (We had a battery-powered boom-box, but generally preferred the sounds of the harbor at night.)

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 12/24/2016 12:12:43

michael.anda
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Response Posted - 12/24/2016 : 19:04:38

I, of course, ended up buying 4 Group 31 AGM's. Want to get a taste of liveaboard life with stereos and TVs and electrical appliances and AC. Overkill?

islander
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Response Posted - 12/26/2016 : 08:50:30

Overkill? I can't answer. You will have @420 amp hrs to use with the 31's but you will need a large inverter and they suck up lots of power. I might have gone with less battery's and a small generator like a Honda 2000 plugged into the shore power inlet.The gen. Would give you unlimited power for anything that is 110 and would be able to charge your battery bank with an onboard charger if they get low from using 12 volt accessories.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 12/26/2016 12:54:53

Voyager
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Response Posted - 12/26/2016 : 11:49:52

Scott - sorry I assumed you have an electric start. 12-2 has plenty of amp-carrying capacity for your alternator circuit however using solid wire rather than stranded makes it challenging to terminate and subject to vibration.

quote:
Stinkpotter said: "...Bruce, your Honda 8 has a 20 amp internal fuse protecting the charging and starting circuits. I suspect most other outboards in the 8-10 hp range have similar starting motors, and most have lower amp alternators (like 6 instead of 12), so 20 amps is probably a good bet. 50 would probably be less protection than you'd want..."

I looked at the circuit diagram in my Honda Marine SHOP MANUAL and it indeed shows a 20A fuse between the charging circuit and the battery connection point however the starter motor is unfused and there is no fuse on the lead going to the battery positive terminal, so Honda manual is silent on that point.
A quick check of the goog does not yield a quick answer on starting current but I'm sticking with 50A.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

islander
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Response Posted - 12/26/2016 : 12:42:37

Bruce, It's marine grade stranded 12/2 duplex wire. A possible clue to the starting motor amp draw would be to remove the engine cover and see what size wire they have that runs from the starter to the outlet on the engine cowling.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Stinkpotter
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Djibouti
9080 Posts

Response Posted - 12/26/2016 : 14:14:23

quote:
Originally posted by Voyager

I looked at the circuit diagram in my Honda Marine SHOP MANUAL and it indeed shows a 20A fuse between the charging circuit and the battery connection point however the starter motor is unfused and there is no fuse on the lead going to the battery positive terminal, so Honda manual is silent on that point.
A quick check of the goog does not yield a quick answer on starting current but I'm sticking with 50A.

I didn't have the circuit diagram--just went on the Owner's Manual statements (paraphrasing) that the fuse controlled both the charging circuit and the starter, and that if the starter doesn't work, it could be the fuse. From that, I assumed the fuse was between the battery cable and a line that branched to both the charging rectifier and the starter solenoid. But apparently not.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Voyager
Master Marine Consultant

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Response Posted - 12/26/2016 : 16:36:44

Wow 4 Group 31s. Where are you going to keep them? One or maybe two underneath the starboard settee. The others in the fender locker (aka dumpster) or under the Vee-berth?
Scott, glad you're using stranded cable.
Dave, as I recall I tried a 25A fuse for the starter circuit. Once that blew, I tried a 30A fuse. Once that blew, I had to change out the standard fuse-block to a larger size socket. I believe I found a 50A fuse and fuse block and installed it in line near the battery. The cable gauge and component size seemed huge, but better safe than sorry.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

islander
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Response Posted - 12/26/2016 : 17:22:38

Bruce, You are close I think. I found a thread on Iboats for a Johnson 9.9 with the same question. He used a clamp on meter on the pos. battery cable and hit the starter. His read 32 amps.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

michael.anda
1st Mate

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Response Posted - 12/27/2016 : 08:36:47

quote:
Originally posted by Voyager

Wow 4 Group 31s. Where are you going to keep them? One or maybe two underneath the starboard settee. The others in the fender locker (aka dumpster) or under the Vee-berth?
Scott, glad you're using stranded cable.
Dave, as I recall I tried a 25A fuse for the starter circuit. Once that blew, I tried a 30A fuse. Once that blew, I had to change out the standard fuse-block to a larger size socket. I believe I found a 50A fuse and fuse block and installed it in line near the battery. The cable gauge and component size seemed huge, but better safe than sorry.

One might power my dinghy if I opt to go trolling motor style. A 3.5 hp outboard sounds like more fun, though. I bought an Intex Mariner 4 recently.

dmpilc
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Response Posted - 12/27/2016 : 10:13:20

For the dinghy, 2.5 hp might be better, especially when it comes to lifting it on/off the boat.

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

GaryB
Master Marine Consultant

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Response Posted - 12/27/2016 : 12:35:18

quote:
Originally posted by michael.anda

I, of course, ended up buying 4 Group 31 AGM's. Want to get a taste of liveaboard life with stereos and TVs and electrical appliances and AC. Overkill?

Yes.

Also, doesn't sound like the Intex is designed for an outboard -- >> Built-in motor mount fittings and a battery pouch let you add an INTEX� motor bracket and trolling motor (sold separately).

Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX

Edited by - GaryB on 12/27/2016 12:38:42

michael.anda
1st Mate

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Response Posted - 12/27/2016 : 16:38:15

Larry, my expectation this week is to get the basics up and running. My boat guy isn't going to tackle anything more. I'll probably end up with two batteries on the boat. We have kayaks that I'd like to experiment with electric motor wise in addition to the inflatable dinghy. The batteries were on sale at Sam's Club and I figured I could find good use for them. As I mentioned previously, I'd like to get a taste of onboard living for future reference. We're recently retired and looking for interesting ways to stay active.

sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 12/27/2016 : 21:39:44

quote:
Originally posted by OLarryR
If 2 batteries are hooked up thru a selector switch but run all the time thru both, one does not get double the load capacity....more like maybe 1.3 times the capacity of one battery.

This statement should be eliminated or corrected.

Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/

dasreboot
Admiral

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Response Posted - 12/28/2016 : 06:04:17

quote:
Originally posted by sethp001

quote:
Originally posted by OLarryR
If 2 batteries are hooked up thru a selector switch but run all the time thru both, one does not get double the load capacity....more like maybe 1.3 times the capacity of one battery.

This statement should be eliminated or corrected.

i'd like to know which is true.

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

Davy J
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Response Posted - 12/28/2016 : 07:43:20

With the switch on "both", the batteries are essentially connected in parallel. When batteries are connected in parallel you are doubling the "amp hours" of one of the batteries.

One group 31 Duracell battery from Sam's has an amp hour rating of 105.
Two connected in parallel should yield 210 "amp hours".

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

Edited by - Davy J on 12/28/2016 07:47:28

islander
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Response Posted - 12/28/2016 : 08:24:51

Yep, With the switch in the "both or all" position it combines both battery's in parallel. This makes your 2 batteries into 1 larger battery. The amps double but the volts(12v) stay the same.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Stinkpotter
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Djibouti
9080 Posts

Response Posted - 12/28/2016 : 08:46:56

Larry's statement could be true if one of the batteries is significantly weakened, which in the "All" position will tend to draw down the other. If one is really damaged, such as having warped plates that are shorting to each other (not likely with AGMs), in the All position the two could have less than 100% of one battery--all the way down to zero. But in good condition, two in parallel will give you roughly double the usable amp hours of one. This is why it's generally a good idea to replace both when either one appears to need it.

Since starting power is more critical to me (with a 3.5 liter V-6 outboard now), when I'm on the hook, I switch to one battery so that if I draw it down, I still have cranking power in the other. You guys can just pull the cord (except on some Yamahas).

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

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