my boat battery

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2021 at 1:08pm
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Totally disconnect battery then check in 2 days as to what the discharge rate is,if nil,then isolator will be faulty,may need a clean as salt crystals making contact..
If battery is discharging when disconnect find receipt and take back.

Yep..
Dont rely on isolating switch.. mine 'broke ' a few months back.. so dismantled it while new on was coming..
They are sealed, but still get a vertigrease (think its called) build up inside ...
Combine that with something in the boat conducting and you have discharge.
Can use ammeter to find out where etc...
But end of the day, disconnect both terminals at the battery, way to go for 100% sure.

PS once the isolation switch was cleaned , seals plus silicone, back working  so have the new spare anyway.
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Post Options Post Options   Likes (1) Likes(1)   Quote Pcj Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2021 at 3:08pm
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ended up with the above from jaycar,cheap but works.
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Do not think batteries are made in NZ anymore,so they are imported and sit on a ship in a container for 3+months.Go to store etc and retailer certainly doesnt test charge or trickle them. So if a batterary can travel/sit on a shelf/container.
Why are we all determanded that we plug them in to a trickle charger??Surely if under 24 months old they should hold charge unless damaged,isolator failure,engine not charging full capacity?
Mine is at least 4yrs and did have a issue with slight discharge hence why I went to above,Can sit for a month put on cheap warehouse charger and its full within 30 minutes.
This is sealed flooded battery.
What type of batteries are people having issues with??flood/gel particular brand??
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Post Options Post Options   Likes (0) Likes(0)   Quote SaltyC Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2021 at 5:23pm
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from Battery Dynamics website:

The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. a lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will loose 80 amps of its 125-amp capacity.
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Post Options Post Options   Likes (0) Likes(0)   Quote Dagwood Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2021 at 8:03am
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Originally posted by letsgetem letsgetem wrote:

Its a 90hp Mercury 4 stroke. The battery is 530cca 52AH.

Not sure if it's related but I've just installed a 100 Merc 4 Stroke. The installer was adamant that the battery needed to be upgraded as they are very sensitive to it. 

The manual (which covers the range from 75 - 115hp) states the min is 1000 Marine cranking amps (MCA), 800 cold cranking amps (CCA) or 65 amp hour (Ah)
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2021 at 8:38am
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Not sure if it's related but I've just installed a 100 Merc 4 Stroke. The installer was adamant that the battery needed to be upgraded as they are very sensitive to it. 

The manual (which covers the range from 75 - 115hp) states the min is 1000 Marine cranking amps (MCA), 800 cold cranking amps (CCA) or 65 amp hour (Ah)

Yes. As described in several previous posts..

The manual spec is for bare engine... that doesnt put out much charge/current at low rpms.
Now throw in a current draw from a winch, or capstan plus gps and few other bits in pieces.. the engine alternator doesnt keep up with the load if battery is min. spec.
So engine running, high draw on say a winch, current/ voltage to things like seal alternator regulator, ignition CD! unit/ coils. They get hot and eventually intermittent loading like this over time they die.

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Post Options Post Options   Likes (0) Likes(0)   Quote letsgetem Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2021 at 9:02am
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OH! For my 90hp mercury 4S, battery needs to be at least 1000 Marine cranking amps (MCA), 800 cold cranking amps (CCA) or 65 amp hour (Ah). 
The new battery I got is only 530cca, not enough. 
Ill get another battery big enough.
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Post Options Post Options   Likes (1) Likes(1)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2021 at 4:54pm
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I replaced my battery few months back for the 2S V6 150 Johnson..
 Factory  Installation and Repair Manual for the 150 and 175 hp
 12V  500cca (620 MCA) with 90 mins reserve capacity or 50 AHr
I replaced with a 720 (or 780 cant rem) CCA.
Alternator rated at 35 amp fully regulated
 Out Put
[email protected] 1000 rpms
33A @ 2000 rpms
38A @4000 rpms


Same Manual for the
 V4 90 and 115 hp
12V  360 CCA (465 MCA) with 90 min reserve capacity  or 50AHr
Alternator is  rated 20 amp fully regulated.
Out Put :
10A @ 1000 rpms
18A @ 2000 rpms
20A @ 4000 rpms
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Post Options Post Options   Likes (0) Likes(0)   Quote Bounty Hunter Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2021 at 7:54pm
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dont place too much weight on the published alternator output - it does give an indication but i wouldnt base calcs on these values.

usually the published output is the 'marketing dept' figures.

you should be looking for the 'hot rated' output values - which are usually 15-20% or so lower 
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As stated, Those are not the 'marketing' BS numbers.. they are from the page in the BRP Installation and Repair Manual...for technicians.
Battery spec from the specs pages and the alternator specs from the testing /specs pages
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Steps. You may know the answer .I have no idea But why do we have so much trouble with marine batteries.suppose to have plates closer together to impacts etc.yet 4x4 vehicles.cars etc travel on roads with pits holes etc equilvent to driving at sea but not so many issues. Is the marine battery a con?? Older car sitting for 2 months battery 3yrs old and started no issues
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Post Options Post Options   Likes (1) Likes(1)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2021 at 8:25am
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Steps. You may know the answer
 maybe... when I get stuff I read manuals, even get the techicans manuals, find out how what.. its just what I have always done.. always interested me since a young kid.

This is what I understand.. as I had the same basic question in my had as you..

Marine batteries must be strapped down.. putting aside other safety issues for now.
they do not like being dropped , sudden shock.. which sound wrong as you state above.
If not well strapped down.. including inside the battery box the closeness of the plates can cause issue, being too close or even touch in extreme conditions.
When the boat comes down hard, most of the energy of the drop is absorbed (apparently) by the boat. If not strapped down the battery gets left in the air, and when hits the deck, its pretty much the shock of its own weight that causes the problem.
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Post Options Post Options   Likes (1) Likes(1)   Quote Kandrew Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2021 at 8:17pm
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The new glass matt batteries are a lot more robust than the older lead acid which haven’t been made for some time. Batteries should always be locked down be it in a car or boat.

The biggest killer of the new glass matt battery is not keeping them charged up, unlike cars, boats sit around and the battery loses charge, amg batteries need a good charger to look after them.

It’s important to have the correct battery for the boat and the electrics on board. Depending on the age of the boat and the type of ignition system some motors require larger batteries so it pays to check the manufacturers recommendation. 2S Hybrid motors like optis and etecs need bigger batteries even for the smaller 90hp motors to keep the battery voltage levels up. If the voltage drops to low the computer will shut down, the motor will sound like it’s winding over ok but it won’t start. Later model 4S use a dynamic voltage ignition system which sense the voltage differently. Too larger battery can be a negative as well. You should always check your battery terminals for tightness and corrosion and I only use Vaseline to coat the battery terminals, spray on oils are conducive and if they are sprayed over the top of the battery can cause the battery to discharge.

Voltmeters are really the only way nowadays to check the change level of the battery, we used to use hydrometers on the old lead acid unsealed batteries which is the best way to check batteries, many times I could pick up a dead cell because the specific gravity would be lower in that cell to the others. Remember digital voltmeters are very sensitive, when you put a sudden load across the battery like lifting the engine or using a capstan, the voltage will drop, normally this doesn’t mean the battery has gone flat it will recover. It’s the continuous loads like fish finders, vhs and stereos that will flatten the battery during the day. This is where keeping an eye on the voltmeter during the day is a good idea, that’s why I like the Ctek comfort light system, easy to keep an eye on and when the yellow light comes on start turning things off. But each to his own.
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Originally posted by Steps Steps wrote:

As stated, Those are not the 'marketing' BS numbers.. they are from the page in the BRP Installation and Repair Manual...for technicians.
Battery spec from the specs pages and the alternator specs from the testing /specs pages

does the product manual declare whether the values are 'hot rated' - if it doesnt stipulate, they probably arent - usually the corrected for load output curves are only available directly from the alternator manufacturers
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 2021 at 9:47am
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Hot rated.. in the actual testing section noting changes as battery charge increases.
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Post Options Post Options   Likes (1) Likes(1)   Quote letsgetem Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2021 at 4:49pm
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Ok, Im probably stupid. There Ive confessed.

I thought my boat battery was losing charge between trips with the motor charging.

But - I was reading battery voltage on my sonar screen. I have now taken battery voltage with a multi-meter directly on the battery (terminals). It shows-
Battery voltage, With everything incl sonar off 12.82v
With sonar on 12.61v
With sonar on, voltage into sonar 12.5-12.6v

And, the battery voltage is NOT going down - over 5 days it stayed at 12.82v. This is the voltage after a trip charging the motor.

I dont know why the voltage on the sonar screen varies (when battery voltage is constant), but it doesnt matter.

It was an interesting discussion, and thank you for your input. 

 
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Post Options Post Options   Likes (0) Likes(0)   Quote Kandrew Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2021 at 5:16pm
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Originally posted by letsgetem letsgetem wrote:

Ok, Im probably stupid. There Ive confessed.

I thought my boat battery was losing charge between trips with the motor charging.

But - I was reading battery voltage on my sonar screen. I have now taken battery voltage with a multi-meter directly on the battery (terminals). It shows-
Battery voltage, With everything incl sonar off 12.82v
With sonar on 12.61v
With sonar on, voltage into sonar 12.5-12.6v

And, the battery voltage is NOT going down - over 5 days it stayed at 12.82v. This is the voltage after a trip charging the motor.

I dont know why the voltage on the sonar screen varies (when battery voltage is constant), but it doesnt matter.

It was an interesting discussion, and thank you for your input. 

 
Interesting but as you say you could chase around looking for the answer, you might be better installing one of these

https://www.burnsco.co.nz/usb-socket-voltmeter-flush-mount
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2021 at 6:18pm
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I am not surprised by those readings. Wherever you have current flow, connections, switches etc, you will get voltage drop.
you can't fix an idiot with duct tape, but it does muffle them for a while...
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I am not surprised by those readings. Wherever you have current flow, connections, switches etc, you will get voltage drop.

Yep , want correct voltages, direct off the battery..The type dash gauge KA mentions are far better than the reading off the gps.. Do not just connect to nearest ground or live wire...ideally run direct to battery, or at least the main buzz bars, clean and check all connections on and between battery ands bars regularly..

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