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Registered
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1,612 Posts
Discussion Starter #1
I use one group 24 battery on my Oday 23. A couple of weeks ago, I went to start my engine (8hp Tohatsu 4 stroke, electric start), and got nothing. Nada. A quick check showed that someone had inadvertently flicked a switch to "on" on the breaker panel, probably just before we had left the boat the weekend before. That left some lights on for the week, draining the battery completely.

I took the battery home to try and recharge it, but the message screen on my charger flashed out "Not charging. Service or replace battery" almost immediately. This battery was a good four years old, so I wasn't too upset. It was a "dual mode" battery, combining starting power with deep cycle cells. This was the first time I had bought such a battery; all my previous batteries were standard, deep cycle batteries that I used primarily to start my outboard and run my chart plotter and VHF. I almost never use the nav or cabin lights.

Unfortunately, West Marine didn't have a dual mode battery left (end of the season and all that), so I just bought another deep cycle battery. I installed it, started the engine, ran chart plotter and had a fine sail last weekend.

I went to go sailing yesterday, started the engine with the electric start, no problem. But when I shut off the engine after hoisting the sails, I saw that the chartplotter had shut off. When I tried to turn it back on, I got nothing. I then tried to start the engine with the electric start, and it too was dead.

There was no wind, so I didn't linger long. I started the engine with the pull start and headed back in. The chart plotter started right up (the engine has an alternator), and I had no trouble until I approached the dock and throttled way down to idle. At that point, the chart plotter screen started flickering. I shut it off quickly, docked, and took stock. The electric start on the engine was still not working, and I couldn't get the chart plotter to wake up unless the engine was running. However, the VHF turned on (no low battery light either), and the running lights lit up fine.

I took the battery home and hooked it up to my charger. The needle showed it was almost in the "green" zone, and the voltage measured 14.6. It took no more than a couple of hours to fully charge.

What the heck is going on with this battery? I've used deep cycle batteries for 15 years to start my outboard; granted, it wasn't this outboard (the old engine was a Nissan two stroke, but also an 8 hp), and I've never had this problem before. And I could understand if this battery didn't have the cranking amps to start an engine, but I can't understand how it could have enough juice to run the lights and the vhf, but not the chart plotter.

Thoughts? Comments?

My plan now is to just return this battery to West Marine and get a dual mode battery next spring. Any other ideas?

Thanks
 

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One of None
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8,045 Posts
Something is drawing down the battery, is the chargering alternator actually working on the outboard?
Most problems can be found with a simple multimeter
 

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Registered
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640 Posts
Battery charge showed fine when home, other systems ran fine with it while some didn't work at all. Sounds to me like a bad connection or worn switch related to some of the non working items in question as Registered alluded to.

For large draw items like a starter even a slightly dirty connection at the battery terminal can cause it to work intermittently or not at all.
 

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Registered
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6,671 Posts
You could have a dead cell. Best way to determine this is with a hydrometer. The specific gravity of each cell should be equal and read 1.275. If the cell is shorted, your battery charger would not be able to detect this and indicate that the battery is fully charged, while you may have a shorted cell.

Gary
 

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Aspiring Boat Bum
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292 Posts
I would give it 95% that it was a bad connection. Removing and replacing batteries might have left something loose or maybe one of the connections somewhere is corroded. Check the ground side as well as the positive.

The fact that the battery showed good charge at home is a pretty good indication the battery is OK.
 

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Registered
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21,803 Posts
As I understand it, there is no such animal as Dual Mode. Just marketing BS. Deep cycle is what you want, if it’s running your nav/radios and should be just fine to start a small outboard. I think your past experience was coincidental.

It sounds to me that you’ve either got a short somewhere or corroded connection.
 

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Administrator
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270 Posts
Sorry to hear you're having such trouble.

I'd trace my connections with a multimeter and see if something's wrong in your connections. It's tedious work but you may find that one wiggly connection is causing your problem. Like others have said, if the battery was new and reading fine at home, it shouldn't be the problem.

Good luck and keep us updated - I'd like to hear what the end result is :)
 

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Aspiring Boat Bum
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292 Posts
Sorry to hear you're having such trouble.

I'd trace my connections with a multimeter and see if something's wrong in your connections. It's tedious work but you may find that one wiggly connection is causing your problem. Like others have said, if the battery was new and reading fine at home, it shouldn't be the problem.

Good luck and keep us updated - I'd like to hear what the end result is :)
Checking the circuit with a meter is a good place to start but one warning. A corroded or loose connection may show good voltage with no load on the circuit but as soon as you try to draw power from that circuit the voltage can disappear. If possible watch the voltage when you apply a good load or follow up with a physical inspection of all connections.
 

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Registered
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4,715 Posts
No need to exchange the deep cycle battery for a start/deep cycle battery as long as the current battery is not defective. A deep cycle battery will easily start an outboard. In fact it will easily start an inboard diesel.

It definitely sounds like you have something going on with your wiring. With an outboard and single battery, you have a simple system so it should be easy to track down the issue.
 

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Registered
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1,612 Posts
Discussion Starter #11
Thanks guys (and Denise)! Sounds like a bad connection is my prime suspect. I'm going to try and test this out before they haul my boat sometime this week!
 

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Registered
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926 Posts
Just some reassurance about the deep cycle battery. Our 15 hp Saildrive motor is a modified Johnson outboard. We were out sailing on Saturday. Battery number 1 showed about 12.2 volts and started the motor easily. (This is an 8 year old battery). I have experimented in the past by starting the motor with the gauge showing less than 12 volts. Because we sail and avoid motoring, I have 2 batteries, more for peace of mind than necessity. These are very regular inexpensive batteries.
 

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Registered
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Discussion Starter #13
Just some reassurance about the deep cycle battery. Our 15 hp Saildrive motor is a modified Johnson outboard. We were out sailing on Saturday. Battery number 1 showed about 12.2 volts and started the motor easily. (This is an 8 year old battery). I have experimented in the past by starting the motor with the gauge showing less than 12 volts. Because we sail and avoid motoring, I have 2 batteries, more for peace of mind than necessity. These are very regular inexpensive batteries.
Paul: do you have your batteries wired to a switch, or do you run them in series?
 

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Registered
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926 Posts
I have a basic on/off/both switch. I usually use only one battery for everything, and save the other for an emergency...hasn't happened in over 20 years. I try to alternate between them so that hopefully they will wear out sort of evenly. I purchased them new 8 years ago and the meter indicates that they are aging fairly evenly.
I have a basic multi meter stuck with Velcro to the bulkhead and hard wired into the battery circuit, makes monitoring very easy. I spent an extra few dollars for a meter with auto shut off as I often forget to turn it off...it operates on it's own 9 volt battery.
 

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4,609 Posts
So after cleaning ALL connections, and sitting back with a beer, Put the ohmmeter to the terminals of the either neither. Age and water tend to eventually gum the internals .A poor connection in there will be an annoying VD
 

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Registered
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1,612 Posts
Discussion Starter #16
I have a basic on/off/both switch. I usually use only one battery for everything, and save the other for an emergency...hasn't happened in over 20 years. I try to alternate between them so that hopefully they will wear out sort of evenly. I purchased them new 8 years ago and the meter indicates that they are aging fairly evenly.
I have a basic multi meter stuck with Velcro to the bulkhead and hard wired into the battery circuit, makes monitoring very easy. I spent an extra few dollars for a meter with auto shut off as I often forget to turn it off...it operates on it's own 9 volt battery.
Nice. Something to consider for next season.
 

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Registered
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31 Posts
Deep cycle batteries make poor start batteries unless you have one of those which have a special start battery included or extra plates.

If your home charger will not charge--it is often because there needs to be at least eight volts present in the flat battery or the electronically controlled charger will not function. Once it IS charging though--it is OK--so I use a different battery such as a jump-starter in parallel with the flat one just to get the charger to work, then remove the jump starter. After they they seem to charge OK.
 

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Registered
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Deep cycle batteries make poor start batteries unless you have one of those which have a special start battery included or extra plates.
The OP has an 8hp outboard. Deep cycle will work well.

I’ve never heard of a battery with a special start battery included. As far as plates go, there are many different qualities of FLA batteries and plates can be one identifying difference.
 

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Registered
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Another good sailing day yesterday although the wind was at the upper end of our comfort zone. I experimented again. The voltmeter was showing 12.19 volts. I had my wife attempt to start the motor with no choke or throttle( she drives out of the slip while I control the dock lines). The motor cranked very quickly for about 7 or 8 seconds until my wife engaged the choke. It would have turned over for much longer but I wasn't going to risk damaging the starter just to prove a point. Our Saildrive is a 15 hp outboard power head.
 
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