Battery Basics

[rderenzy]

Hello, someone play dad here and help a new boat owner out

I have a small 20ft open bow boat - it has one battery.
I've always charged the battery after each use, before the next boat trip - and used trickle charger.
However, i'm assuming i'm hurting the battery right? because the batter probably never got below 75%, as the alternator should be working

so the real question - is when i should be charging it?
perhaps i have a fear i'll go to launch the boat and the battery is dead becaue the alternator stopped and i wasnt' made aware
OR, the alternator never charged the battery enough


guess i'm just looking for best practice or common procedure here

 

[JASinIL2006]

If you have a smart charger (not just a plain trickle charger), like a battery maintainer, you shouldn't be hurting your battery by topping it off between uses.

Have you checked your battery to see if it's holding a charge between uses? If you're using it occasionally, you shouldn't need to charge it.

 

[rderenzy]

No i have not checked the battery to see the charge - i guess i do not know how to check, i do have a multimeter, can you help teach me how to test to see if its properly holding? but that is a good piont ,i can just see if its got a good health and then i wont trickle charge it - but good point if it sits for many weeks, then i could trickle charge

 

[mike_i]

I agree with what JASinIL2006 said about using a smart charger. If you're charging it that often and it's a wet cell make sure the cells don't dry out.

 

[roffey]

I charge my battery once a year when I get it out of storage.

Your alternator should be charging the battery. The battery should be between 13.5 to 14.5 when the motor is running. If the motor is not running it should read around 12.5 volts. if you don't get 13.5 when the motor is running I would be looking at the alternator..

 

[roscoe]

switch the meter to volts.
put the meter's probes on the two battery terminals, making sure to make good contact.
the meter will read voltage.

 

[JASinIL2006]

A resting charge (24 hours or more after charging) of 12.7 volts is 100%. I think the resting voltage can be as low as 12.4 or 1.25 and the battery will still function well.

I did some rewiring in my boat and I screwed up one of the wires, causing my battery to be somewhat run down the next time I needed it. I've fixed it since then, but it has led me to be a bit paranoid about the state of the battery when it has been sitting idle for several weeks. In those cases, I'll almost always check it with my multimeter a day or two before, and if the charge is questionable, I'll put it on the smart charger. Used regularly, though, like once every week or so, you shouldn't need to charge it unless you're seriously depleting your battery when you're out in the boat. (Or unless you accidentally leave something turned on like a radio or fishfinder.... been there, done that, too!)

 

[tpenfield]

If you are charging the battery before each use in case the battery is low, then use a charger that is meant to charge quickly.

Do you have a volt meter on the boat? That would be an indicator if the alternator has gone out on you. . . as the voltage would be going down during use. If the voltage is staying in a good range (13 - 14 volts), then all is well.

 

[Sprig]

Why are you charging your battery after each use??? This makes no sense to me. Your alternator on your engine should fully charge your battery during a day of use. Unless you are using your battery for auxiliary purposes while the engine is off, your boat will charge up your battery. If your boat sits for a long time without being started then you may have to charge it. I’ve had my boat sit for months and the battery started it without problem.
If you are concerned Your battery may not be sufficiently charged before you head out, just use a volt meter or multi meter to check the charge status.

 

[Captain Caveman]

I have never charged my starting battery. If I were concerned, I would do as others noted and put a battery tester on it before leaving the garage. If you have a volt meter, read the instructions to figure out how to use it. If you don't have one, don't bother. You seem like a perfect candidate for a simple battery tester. I'm not trying to be condescending. I keep on in my truck. You can find them at auto parts stores. You just touch it to the battery and it will tell you the battery condition when the motor is off or when it is running. Nice a simple.

Your charging paranoia might lead to other problems, such as overcharging a good battery.

Worst case scenario at a boat launch is to jump the dead boat battery with your tow vehicle's battery. You could also install a second, deep cycle, battery for running electronics. That can then be used as a backup battery.

 

[roffey]

a battery tester is a good cheap tool to have in the garage. It will tell you what the current charge is and put a load on the battery. It will telll you when its time to replace. I do agree with most here, I think charging the battery after every use is a bad idea. When my battery is suspect I replace it. Its not like to can walk home when the boat does not start, lol

Owning a boat is expensive... and will cost you money, how much depends on what you can do your self at home.

 

[poconojoe]

For peace of mind, you can do a couple things. The easiest is to carry one of those battery jumper pack units with you whenever you go out on the water. They have really nice compact ones now. They used to be much bigger.

Or, you can add a second battery and a marine battery switch. It seems you may not be that knowledgeable when it comes to electrics, so the first choice may be better for you. You could always have a second battery added by a professional.

I have two batteries, a battery switch and a Blue Sea automatic charging relay (acr) that keeps both batteries topped off by the engine's alternator. Wiring up the acr is a little complicated, so I vote you just get one of those jumper packs.

 

[rderenzy]

Thanks all - this case can be locked

apprieciate everyones knowledge and i love the idea of, dont charge it, just check with MM before. thanks!

 

[Leardriver]

I don't have an issue with charging a trailer boat for a couple of hours before use. Out here, we have the mussel inspectors who make us lower our drive up and down, turn on the bilge pump, and I would rather start with a battery that has 100% than 90%.

 

[dingbat]

The only thing I'd add is that trickle chargers are for maintaining a charge, not replacing one. The only time you should need a trickle charger, if at all, is over the winter.

 

[82rude]

On season number 3 of battery being in boat.Has never left since installed,never charged either.Winters are long and cold ,never hurts it one iota.Last battery lasted 96 months!