battery question

[northstarjim]

I purchased my boat at the beginning of last season - new deep cycle battery (wet cell) connected to an alternator on the Atomic 4. No electronics- just nav lights and a few cabin lights. No problems last year with battery. I stored it in my basement over the winter. I charged it up last month - used an automatic 2A/10A charger. Put it in the boat and it started the boat fine. The next time I went to start the boat - it would operate the blower but would not start the motor. I started the motor with a portable power source, ran the motor for a while hoping the alternator would charge it up, but still no luck. Is this battery toast?

[sailingdog]

NorthstarJim-

I stored it in my basement over the winter.

Wet cells self-discharge, and if not constantly topped off with a maintenance type charger, the plates start to sulphate. That will kill the battery prematurely. A wet cell battery may self-discharge as much as 1% or more a day. If it was topped off completely when you stored it... that means it was at less than 10% charge by winter's end—that's assuming a three-month long winter—winter up in New England is more like five months. If it wasn't topped off when you stored it, it was sitting at zero charge for who knows how many weeks. I generally go re-charge my batteries once a week when the boat is in storage over the winter. I could probably go once every two weeks...but why risk it.

Equalizing it might help it...but I kind of doubt it. Neglect kills far more batteries than anything else.

[hellosailor]

"I stored it in my basement over the winter. I charged it up last month "
There you go, you killed it. As wet cells discharge, insoluble sulphur compounds form and the battery takes permanent damage in just 30 days. Every day beyond that--and the battery is turning into a brick. Sometimes, you can get away with ignoring it for six months and still have enough capacity to get by for another season, but not reliably.

Write if off as a battery lesson, and replace it with an "AGM" deep cycle battery. AGM batteries are built differently, and they can withstand six months of sitting in the corner without any permanent damage. Although, I'd still put a charge on it every month, or every other month, because "can" doesn't mean that's best for them. Since they don't self-discharge much, you won't need to charge them up for very long, either.

The Optima spiral-cell batteries are the big brand name in AGM batteries, but you can save a good 30% off their price by buying a flat-plate AGM battery from any distributor, many companies make them these days.

[lbdavis]

SD and hellosailor are probably right about the battery being dead, but you should also check the output of your alternator. Go buy a digital voltmeter at radioshack - it's an indispensable tool for this stuff.

[northstarjim]

Thanks guys - I figured as much. Next winter -what should I do? I have both a trickle charger and a regular battery charger - should I just use the regular 10A charger every couple of weeks or so? or keep the trickle charger attached for longer periods?
Also - how exactly do I check the alternator output? Attach the positive lead at the positive terminal of the alternator and the negative to the other/ground terminal? I assume it should read aroung 13 volts?

[hellosailor]

Either one would do, I'd suggest the trickle charger since it is "enough". How long a period will depend on the amperage it supplies versus what the batteries need. But also, since AGM batteries can't leak acid, you don't need to hide them, you can put them wherever it is convenient.

To check the alternator output, put the plus and minus probes from the meter on the matching battery terminals (an easy and safe place to access) while the engine is running. At "cruising" rpms, you should see 14.4 volts, sometimes as low as 13.8 volts depending on the system and the battery condition. Off by a point or two doesn't matter, there's some float in the meters and tolerance in the systems.

[sailingdog]

I hope, by trickle charger, you mean an intelligent three-stage charger. A 2/10 amp car battery charger will do a pretty good job of frying a deep cycle battery if you're not careful.

The alternator may read as high as 15 volts... depending on the RPM of the engine, the charge level on the battery and whether it is internally or externally regulated. Anything above 14.7 or so is going to boil off electrolyte in the battery if used for an extended period of time. As HS has said, it should read about 14.4-14.6 Volts at cruising speeds.

Originally Posted by northstarjim

Thanks guys - I figured as much. Next winter -what should I do? I have both a trickle charger and a regular battery charger - should I just use the regular 10A charger every couple of weeks or so? or keep the trickle charger attached for longer periods?
Also - how exactly do I check the alternator output? Attach the positive lead at the positive terminal of the alternator and the negative to the other/ground terminal? I assume it should read aroung 13 volts?

[Martinini]

I have been told by Interstate Batteries to never leave a battery sitting on concrete for any length of time because this will hasten discharge. Set it on a piece of wood or a couple of wooden slats so it's not sitting directly on concrete.

[brak]

I had my deep cycle batteries sit all winter prior to buying the boat (and who knows how long before). I had them charged with a less than satisfactory charger last season (before switching to smart charge) and this winter they were on a single small solar battery (which probably did not make enough difference).

In may I charged them one more time with old charger, and it appeared that they are nearly dead - low voltage, not enough power. Then I did two things:
1) added sulphur removing liquid
2) used smart charger to charge them properly (it took a day from where the old charger thought it was done).

The result - batteries are holding 70-80% charge (relative to what they should) and work great.

The lesson here is - sometimes "dead" battery isn't.

[hellosailor]

Brak-
Which magic elixir was that? I've yet to find someone who used one, and still had good batteries six months later. But I'm willing to look & learn!

Martini-
The concrete story has been repeatedly debunked for modern batteries, I find it hard to believe Interstate themselves would tell you that in the last 40 years. Concrete as a problem with old porous battery cases, but for modern plastic cases? Absolute nonsense. The only problem with concrete is that it usually means a slab floor, which is cold, and cold hastens self-discharge and damage. The concrete itself matters about as much as the color of the paint on the car/boat that the battery is located in.

From Interstate's own web FAQ pages:
Interstate Batteries FAQ :: Does it hurt my car battery if I set it on concrete?

A: No, the type of plastic (polypropylene) used in battery cases today is a great electrical insulator, therefore cement causes no electrical discharge effect to the battery. "


Once upon a time, battery cases were wood covered in asphalt, I believe, and that was replaced by "hard" rubber, but plastic has been the rule for a very long time now.