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Author Topic:   Dual batteries on Montauk 170?
ghefty posted 11-26-2002 08:15 AM ET (US)   Profile for ghefty   Send Email to ghefty  
Would any owners care to share their experiences or opinions on adding a second battery to a 17' boat. My new boat has the 90-4s. I'm adding a stereo, vhf and a gps/sounder unit. On larger boats I've always installed a second battery. I'm just trying to consider the trade offs, loss of space in the storage area, the extra weight, etc. Your comments and guidance is appreciated.

Bigshot posted 11-26-2002 09:01 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I would'nt. Instead get that thingy that connects to the battery that will shut down everything to preserve enough to start the engine and then some. I have 2 batteries on 2 of my boats and all I do is replace twice as many bats.
jimh posted 11-26-2002 11:12 AM ET (US)     Profile for jimh  Send Email to jimh     
Can you pull start a 90-HP 4-stroke?

Will it run if connected to a dead battery?

andygere posted 11-26-2002 11:45 AM ET (US)     Profile for andygere  Send Email to andygere     
It depends on how you use the boat. If you go offshore, even a just a few miles, I think dual batteries are a good idea. If you drift fish with your GPS/fish finder, vhf and stereo on, and you bilge pump is working, it's easy to draw down a battery and get stranded. I have them in my Montauk, with all house loads on #1, and #2 tied only to the starter. When the engine isn't running, I put the battery switch on #1 so #2 is always in reserve for starting. Also, if the boat sits idle for long periods between use, it will always start in the "both" position, which eliminates the need to charge the batteries up with a trickle charger before using the boat.
Bigshot posted 11-26-2002 02:03 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
the problem kids is that if you have 1 good and 1 so-so battery the so-so will constantly drain the good battery and cause more issues than with just one. You would have to be out for a LONG time with a good battery to drain it with electronics. Especially to drain it low enough to not be able to start a 90hp. Also on 2 strokes the compression ratio is like 7:1 if not lower so they do not need a lot of juice to turn over. The 4 strokes, although higher in compression, are still low compared to a motorcyle, etc and look how small those batteries are.
Bigshot posted 11-26-2002 02:05 PM ET (US)     Profile for Bigshot  Send Email to Bigshot one of those $50 jumpstarter gadgets that you only need to bring out on certain occasions. Easier than maintaing 2 bats and you can use it on other battery operated vehicles.
RioRaft posted 11-26-2002 03:07 PM ET (US)     Profile for RioRaft    
I agree with Bigshot, go for the $50 Jumpstart. Easy to handle, easy to care for and a whole bunch of uses. Althouhg you will end up making a lot of new friends as soon as you dock neighbors realize you own one. I have dual batteries in 24 footer (sorry not a Whaler) and find myself dazed and confused as to which position the switch should be set at what time. One bad battery will definitely draw the good one down. On the Montauk just toss it in the console. On a final note I will caution you (I have never had a problem) but during a jump start under a small console I would be sure it is aired out pretty well first (no Hydrogen gas present)as you will have to connect both cable clamps to the battery, it's not like a car where you can always find a secure piece of metal to attach the negative clamp some distance from the battery. Sparks are never a good idea around batteries. I use a roadmaster jumpstart, around 12/14 lbs. and cranks a V8 forever.
Jimm posted 11-26-2002 04:42 PM ET (US)     Profile for Jimm    
Can anyone tell me how long those $50. jump starts last?..Jim
ghefty posted 11-26-2002 06:15 PM ET (US)     Profile for ghefty  Send Email to ghefty     
Thanks for all of your input. I will likely opt for the jump start option, for its versatility. This past summer, I was fishing offshore in a friends boat with dual batteries, we started with the switch in the BOTH position, and at some time during our day fishing one of the batteries developed a short and drained the other battery. Once we identified the offending battery and isolated the good one we were able to radio for help. A passing boater offered his jump start and we were on our way. Thanks again for your help.
James posted 11-26-2002 10:59 PM ET (US)     Profile for James  Send Email to James     
I have twin bastteries with a Guest switch all mounted inside the console of my 170 Montauk. You do not leave too much space for regular life preservers inside the console with the twins so I purchased some Mustang inflatables. Same difference, and you have the additional insurance of the extra battery, which I believe is advisable.

The 170 Montauk is not self-bailing so it is not a good idea to take the transom drain plug off whenever the boat is on the water or even on a rack (ready to drop into the water). This means that the bilge pump is probably going to be operating anytime that it rains. The extra battery allows me to have the confidence that one battery will be charged well enough to start the engine without incident, while the other battery may be somewhat drained by the bilge pump.


Victor posted 11-26-2002 11:24 PM ET (US)     Profile for Victor  Send Email to Victor     
The jump starter is one way I have gone. But be careful to secure it. These things are quite fragile. I smashed one up pretty badly, but I was lucky it still worked.
BMR posted 11-27-2002 08:59 AM ET (US)     Profile for BMR    
The bilge pump on the 170 Montauk is wired through a switch that can be placed in the off position. The intent is to allow the user to leave the boat in the water or stored with the plug out and not have the pump cycle on and off.

Well, off to use the Montauk, have a nice day.

andygere posted 11-27-2002 01:15 PM ET (US)     Profile for andygere  Send Email to andygere     
Did you ever try to jumpstart a boat in a rolling sea or fast moving current while your boat moves ever closer to rocks, pilings, bridges, large vessels etc.? Better yet, ever try to rope start a 90 hp motor in those conditions? For my money, flipping a switch and turning the key is a lot easier and safer. Stuff never seems to go wrong in good weather and calm seas with plenty of help around. The other thing is that you have to remember to charge the jumpstart packs. My boat batteries charge every time I run the boat. Also, a second battery offers more protection from bad connections, worn/broken cables and possibly swamping. The issue of one battery draining the other is only a problem if you have dissimlar batteries or one bad one and one good one. Replace them in pairs and maintain them properly and this won't be an issue. If #1 goes dead, don't try to start the boat in the "both" position, go to #2 only, and charge #1 with an AC charger when you get home. JimH explains this in his excellent reference article. The extra weight is not a problem, and the only downside I see is the cost of the battery, cables and switch.
James posted 11-27-2002 04:53 PM ET (US)     Profile for James  Send Email to James     

I know about turning the bilge pump switch to the "OFF" position.

In the OFF condition, if the boat is in the water or in a rack and the plug is in, you get to walk in the accumulated rainwater while you get to turn the pump on.

If the plug is out of the bilge and the boat is in the water (or is dropped into the water)you get to find out for the rest of us how much water gets into and stays inside the 170.

Either way, you get your feet wet in order to do the pump out. Possibly not a problem in Florida, but usually an uncomfortable experience in New Jersey.

There are usually ways around anything, and some may be effective. For the relatively low cost, I chose the convenience and safety of the twin batteries.


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