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Author Topic:   Dual Batteries/170 Montauk
Goosedog posted 09-15-2003 10:36 AM ET (US)   Profile for Goosedog  
Is anyone running dual batteries on their 170? I've got the 90hp 4-stroke and plan to install stereo, vhf, & gps/sounder. Is it overkill? Thanks.
BarryGreen posted 09-15-2003 11:41 AM ET (US)     Profile for BarryGreen  Send Email to BarryGreen     
IMHO, it's not related to boat size. If you can't start your engine by pulling on a rope, you need high quality dual batteries.


gimcrack225 posted 09-15-2003 12:06 PM ET (US)     Profile for gimcrack225    
If you have a place to put them I would consider it. I learned after years of sailboat cruising that you have a "starting battery" and a "house battery" As you add more electrical accessories the chance of having a weak battery at the wrong time increase. Depends also on where you might be when your battery is just too discharged to turn the motor the time that the motor just doesn't want to start until the 6th try because the stereo has been blasting away and there is vapor lock or water in the gas line.
I just got a 21'WA Whaler that has one battery, I am adding a second. Avoid pre-key turn apprehension.
JohnJ80 posted 09-15-2003 12:37 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
I totally concur with the thoughts on a house battery and a cranking battery.

Newer engines with all the electronics need a high quality battery to start.

On my Dauntless 15 with a 2003 Evinrude FICHT 75Hp on it, I have all the accessories on the second battery and only the starter on the first battery (cranking). The Cranking battery is a marine starting battery and the second battery is a marine deep discharge. I also use the deep discharge for my trolling battery. In a pinch, I could swap batteries and start the engine with the house battery.

Traditionally this has meant that you need to have one of those 1-2-Both-Off rotary switches that you find on all the sailboats (I, too, am an offshore sailor). However that is not practical for a small outboard powered boat.

What I did was to connect my batteries via this device:

What this thing does is to first charge your cranking battery. Once this is fully charged, it then charges the house battery. This thing has worked flawlessly all year for me and I never have to lug batteries out of the boat. Best of all it keeps both batteries topped off (best for the batteries) and I have never had to lug my trolling battery up to the house for charging (no power at the dock and it is up a 50' bluff - not fun with a 58lb battery).

I think this sort of setup is perfect for the higher electrical demands of the newer motors. It has worked perfectly for me.


poker13 posted 09-15-2003 03:10 PM ET (US)     Profile for poker13    
The instructions have this warning:

Do not install the Stealth I on the bottom of your battery compartment or other area where there is a chance of flooding or submersion!

Danger of Electrocution!" if the boat gets swamped while the engine is running and charging the batteries, then what? Am I dead meat?

Barney posted 09-15-2003 07:44 PM ET (US)     Profile for Barney  Send Email to Barney     
Goose, Just as an option, I bought one of those carry on jump starters for around $45 delivered to the door. I only carry it when going off shore and can use it at home when a car battery dies. Just a thought. Jim
Barney posted 09-15-2003 07:44 PM ET (US)     Profile for Barney  Send Email to Barney     
Oh, I give credit to Big Shot on that idea. Jim
ghefty posted 09-16-2003 08:11 AM ET (US)     Profile for ghefty  Send Email to ghefty     
I'll second Jim's idea. I carry a jumper pack. Mine is placed in a battery box (to protect against flooding) with some foam in the bottom (to cushion the ride).

I had a situation on a friend's boat when one of their two batteries developed a short, the battery switch at the time was set to "Both", this allowed the bad battery to drain the remaining good one, by the time we realized it we had only enough juice for the VHF to call for help. A nearby boater came to our rescue with their jumper pack, and we were on our way. Lesson: If you have dual batteries, never leave the switch set to "Both".

The jumper pack also allows me to return the favor when it's my turn to do so.


Goosedog posted 09-16-2003 09:16 AM ET (US)     Profile for Goosedog    
Thanks to all for the suggestions.
James posted 09-16-2003 11:06 PM ET (US)     Profile for James  Send Email to James     
I ordered the 170 with dual batteries and a Guest selector switch, all mounted inside the 170 console, and I am very happy to have done so. It provides a lot of peace of mind. Not too much floor space is left over but the floor area is workable and you always have a fresh battery to depend on for starting the engine.


JohnJ80 posted 09-17-2003 11:56 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
I mounted my stealth charger on a piece of that plastic marine board stuff, high up on the forward inside face of the console. It is not in a position to get swamped - by then the batteries are already under about a foot of water anyhow.

The danger of electrocution is if you have the AC version attached AND plugged in AND swamped. I don't think you are going to have this as a problem in most operating conditions unless you have a very, very long AC power cord. You are not going to get elecrocuted by 12 or 24V.

bobeson posted 09-19-2003 12:02 AM ET (US)     Profile for bobeson  Send Email to bobeson     

I had the dealer put dual batteries into my 170 prior to delivery. They put in a Perko switch to select either or both. The dealer claims the Perko has a big advantage over other brands because it is make-before-break when switching batteries, so you can switch over with the motor running. I suspect at least some other switches also have this feature, but I haven't researched it myself.

As to the adviseability of using two batteries, I can't comment other than to say it seems like a good idea, as running down a battery enough to prevent restarting my motor would really suck. However, the two batteries do occupy a significant fraction of what precious little storage space I have in the console, so that chafes a bit. Also, I need to remember to switch from one battery to the other periodically, to keep them both evenly charged, which I sometimes forget to do. This runs the risk of premature battery failure, and I often wish I had some automated charging solution that didn't require active intervention. However, it's not a big enough issue that I've felt compelled to address it, so I wouldn't sweat it too much. I use the boat often enough that forgetting to switch once or twice doesn't kill the unused battery.

I should also add that in one year and perhaps 35 days of use, I've never come close to running down the battery enough to prevent restarting the motor. However, I haven't been using any electrical loads other than VHF, FF and GPS, so drain has been minimal. When I get around to installing downriggers, and my new kicker is mounted (this weekend!) then I suspect the dual-battery feature may be called into more active use, since I won't be charging while trolling.

Holy Cow posted 09-19-2003 12:28 AM ET (US)     Profile for Holy Cow  Send Email to Holy Cow     
All sounds Good! But what if you have recieved more RAIN than ever and the Bilge Pump has to continuiously work over a month? Of course that means I have not taken out the PLUG. Does the 2003 170 'Tauk have all the juice needed to start up the 90 Four Merc? Just a thought! How much Juice does that RULE need to expell all those rain storms? Just wondering before i take her to Martha's Vineyard on the 4th from Dartmouth, Mass. Guess I better see if the 90 Merc turns over before I trailer her 345 mile to the ramp! I do like the convienent carry all Jump Start/Booster for that quick start me up!

But never the less... How many COLD CRANKING AMPS does the 170 battery have? and how many bilges will she make before a JUMP would even be needed???

Oh Just got the new Fender lamps and B.W. also through in a new water proof set of tail lights too, since it took over 2 month to have them sent to me! I used a Polyurethane Caulk Sealant to secure the fender lights in the Rubber Gromet. Will also be using it for the actual mounting to the Poly trailer fender as well! Took one long haul to Montauk, L.I. and all four fender lamps bounced off and when I got home the taillights didn't work! No wonder B.W. has gone to a different TRAILER! H.C.

jimh posted 09-19-2003 05:18 AM ET (US)     Profile for jimh  Send Email to jimh     
Please start a new thread to discuss problems with trailer lights, etc.



Ferdinando posted 09-22-2003 09:27 PM ET (US)     Profile for Ferdinando  Send Email to Ferdinando     
I installed a gizmo called Priority Start in my Montauk, it's supposed to shut off all power to keep enough juice to crank the engine, so if I have my radio on all day & my depth finder it will shut them down at a pre-determined
voltage level which is supposed to get me on my way.

I've had it for about 2 yrs and so far so good............


chaimemet posted 09-22-2003 10:48 PM ET (US)     Profile for chaimemet  Send Email to chaimemet     
2 no maintenance batteries in boxes perko switch and hour meter installed at delivery run a rule transom pump for live well
AQUANUT posted 09-25-2003 10:45 PM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
I have a 2044 170-MONTAUK powered by a 2004 [Mercury] 115-HP 4-stroke EFI. I am getting ready to install a custom T-Top which will accommodate:

--a set of two speaker boxes for a hailer speaker and an extension speaker for the OCEANUS-brand VHF transceiver
--four high wattage miniature floodlights

There is also a stereo (which is a thumper), a Magellan Marine GPS and a cell-phone via dc ports (minimal current draw), and, oh yes, a LOWRANCE X-91 Sonar

This is why I have two batteries in my console. Unfortunately, the charging system on the 4 stroke is considerably less than that of the new Mercury Optimax 115-HP.

I just rigged and tested one this week--Man o man, Whatta 2-stroke!

Maybe next time when I upgrade to the Outrage. Hmm...twins would be nice...(LOL).

Battery-1 gets me out there; battery-2 is (just in case) to get me home!

Barney posted 10-03-2003 08:34 PM ET (US)     Profile for Barney  Send Email to Barney     
Goosedog, Did you make a choice? I've used the jump pack already to get one on the kid's cars started. On a barrier island trip recently I overheard one boat call another for his jump pack. He needed a boost. I think a lot of people use them. Jim
jimh posted 10-04-2003 06:23 PM ET (US)     Profile for jimh  Send Email to jimh     
[Repaired broken hyperlink--jimh.]
Goosedog posted 10-06-2003 09:27 AM ET (US)     Profile for Goosedog    
Barney, still waiting. I haven't bought the additional electronics yet. Thanks.

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