[mysterybee]

I'm a new boat owner, and I took the advice of a friend who told me to charge up my batteries and leave them on the boat over the winter and they'd be fine. The part that I missed was to disconnect the batteries so that they stay charged.

The result was predictable. I've got no life in my battery bank. What I don't know is whether any of them are still usable, or if they're all junk. How do I find out? Can someone please offer advice on how to test marine batteries that are discharged and may (or may not) have frozen over the winter?

G

 

[aa3jy]

Type of battery..AGM, Wet Cell,etc.?

 

[mysterybee]

There's a 12v starter battery for the motor, 6 6v house batteries and another 12v for the windlass. All are wet batteries. The three banks are fed by a device to divide the charge evenly. This was all part of the configuration the previous owner had in place. My plan was to reduce the house to a single bank, but since everything appears to be discharged, I need to assess whether any of the batteries can still be used.

Can I just plug the boat in to see if any of the batteries can hold a charge? What's the best way to evaluate the condition of the batteries?

G

 

[aa3jy]

Visually check battery fluid levels,voltage resting state and check specific gravity with hydrometer of each cell, if possible, before attempting any further charging.

 

[mysterybee]

Visually check battery fluid levels,voltage resting state and check specific gravity with hydrometer of each cell, if possible, before attempting any further charging.

I've looked in each battery and can verify there is fluid in them, but I have no way of knowing how full they would be if charged, or how full they should be.

I have no idea whatsoever how to check the voltage resting state or specific gravity of each cell.

 

[aa3jy]

If you see plates not covered in liquid then add distilled water up to the bottom of the fill ring. Take a multimeter set for DC voltage range of 20volts and place each probe in adjoining cells and read the individual voltage. Place a hydrometer in each cell and fill with liquid until the float rises and note the specific gravity reading.

These items can be purchased at your local auto parts or hardware store.

 

[hellosailor]

They're all probably trashed, but you can find plenty of threads on this and other forums about how to test them to see if any are worth keeping.

Or take them to any battery distributor and let him try to charge and load test them if you'd rather not get technical.

 

[boatpoker]

Trying to charge freeze damaged batteries could have disasterous consequences. As you don't know what you are looking at I strongly advise you get a competent mechanic to check the batteries out before you attempt a charge.

 

[hellosailor]

A lot of the new (standard by now) automotive type chargers will simply refuse to even try charging a battery that is below 10.5 volts, to prevent possible explosions. A number of car alternators do that as well now.

FWIW.

 

[PitApe]

Put a charger on them and see what happens. They may be toast, or they may charge right up. My guess is that they've probably had some life taken off of them, but they may not be completely trashed. Quickest way to find out is to try charging them.

 

[boatpoker]

Put a charger on them and see what happens. They may be toast, or they may charge right up. My guess is that they've probably had some life taken off of them, but they may not be completely trashed. Quickest way to find out is to try charging them.

That is irresponsible advice to an obviously inexperienced person. Neither he nor you have any idea of what kind of battery charger he has or if the batteries have been freeze damaged. Given the vintage of his boat it is very likely an old ferro-resonant charger that will just keep pumping out voltage til' something goes up in smoke.

I've done too many fire investigations to take this stuff lightly.

 

[PitApe]

That is irresponsible advice to an obviously inexperienced person. Neither he nor you have any idea of what kind of battery charger he has or if the batteries have been freeze damaged. Given the vintage of his boat it is very likely an old ferro-resonant charger that will just keep pumping out voltage til' something goes up in smoke.

I've done too many fire investigations to take this stuff lightly.

I didn't tell him to plug in a 30A rapid charger and go to lunch for a couple of hours.

Maybe I should have been a little more precise --- put a trickle charger on the system and let it charge for a while WHILE YOU KEEP AN EYE ON IT. See if there is any improvement after a few hours. If they seem to be charging, let it charge overnight. If not, they're probably toast.

Oh, and don't tell Boatpoker what you plan on doing; he'll just have kittens.

OK? Happy?

 

[btrayfors]

You really need to rethink this, and think entire battery & charging systems, not just the batteries themselves.

It is folly IMHO to try to take shortcuts and "save" one or more batteries from this lot. Think all new batteries. Then, you'll know what you've got to start with.

Depending on which charger you have, you'll likely have to think of a new smart charger (like a Sterling or ProMariner Ultra Pro) and a new wiring setup.

I'd run ALL charging sources -- battery charger, engine alternator, solar panels if any, wind generator if fitted, etc. -- directly to the singe house bank. Then, use voltage follower devices like the EchoCharge or DuoCharge to automatically maintain the start battery and the windlass battery.

Yes, this is a lot of work, but it simplifies and renders much more reliable your entire 12VDC system on the new boat. Do it right, and you won't have any problems for the next 5-8 years at least.

Try to do it piecemeal, and you'll be struggling with the system continuously, when you probably have other things on the boat which could use your attention.

Bill

 

[boatpoker]

First photo - the wet spot in front of the dinette is battery acid from charging damaged batteries. My fingers were burned before I realized what it was.

Second photo - this AGM was overcharged to the point it burst. the off gassing caused lung damage to the sleeping boat owner.

 

[ravinracin]

Good advice Bill, but if you don't have the money to redo the whole system, then what? leave it sit until you do. In this case I would and have many time done exactly as PitApe has suggested. If the cells are full, then probably no case cracks. Go ahead and put a trickle charger on them. Fluid full, Posts and wiring clean, no corrosion. Go for it.

 

[boatpoker]

Good advice Bill, but if you don't have the money to redo the whole system, then what? leave it sit until you do. In this case I would and have many time done exactly as PitApe has suggested. If the cells are full, then probably no case cracks. Go ahead and put a trickle charger on them. Fluid full, Posts and wiring clean, no corrosion. Go for it.

The OP already stated he didn't know how much electrolyte should be in there.
You really think it's wise to give a neophyte such advice ?

 

[desert rat]

Take a light and look down inside, can you see liquid on the top of the plates. Look in all the cells. Add only a little water. It would be nice if there was water to the top of the lead plates. Add only a little water, acid bubbling out onto the floor is not good for anything, floor or batteries.

 

[Minnewaska]

This is all we know. Parasitic loads fully drained the batteries and the OP is in Toronto. So they froze solid. I'm already concerned about unidentified case cracks and weakened cases. By definition, the plates had to begin to sulfate too.

I'm not a battery pro, but I would not think a trickle charger would reinvigorate a dead, sulfated battery. It may get to full charge, miraculously, but that doesn't mean it's capacity is back.

I would consider this a lesson learned. Batteries can be left aboard over the winter, but need to be fully charged to avoid freezing. Flooded batt will self discharge, even disconnected, so you must still go aboard periodically and recharge over the winter. AGMs and Gels (which I have) will hold a charge longer, but I still top up 2 to 3 times each winter.

It's new battery time, with wisdom we've all acquired by making similar mistakes. What the heck, you need new sooner or later anyway.

 

[mysterybee]

Essentially, what I now have is conflicting instructions. Aside from this thread, I've consulted with a local chandlery, a repair company that operates out of the marina, and a few boating friends with much more experience. I've heard:

a) try to charge them
b) replace everything
c) pretty much every option in between

I've checked all the batteries physically. I see no signs of bulging, cracking or leaking. I'll take a careful look at the water level and fill enough to cover the plates if necessary. I'm not fond of taking safety risks, but nor am I interested in spending thousands of dollars and rewiring the entire boat on a hunch.

I'm going to check the batteries thoroughly (again) for signs of physical damage, I'm going to ensure they have sufficient water levels, and then I'm going to ask a more experienced friend to supervise while I try to charge them. If they take a charge, I'll test them and see if they're worth keeping. If they don't take a charge, I'll discard them.... but at least I'll know for sure.

Obviously I'm a novice and this is a learning experience for me. Hopefully it won't be too expensive a lesson. In either case, I'd like to thank everyone for your input. You may not all have agreed on the solution but you've provided me with a range of options to work from, and that may be the best place to start.

Thanks everyone!

G

 

[Minnewaska]

Your boat, your call. With the possible exception of causing an explosion that impacts other people or boats. Not that I'm predicting it, but it could happen.

Why would replacing your batteries require rewiring the boat? You change, like you change a flashlight battery. Maybe with a little cleaning.

More importantly, even if they charge up to and hold 13+ volts all day, that tells you little. The question is how many amp hours they will provide and that's guaranteed, yes guaranteed, to have been reduced.

I'm willing to bet, even if you can live with the lower capacity, you'll be replacing them very soon anyway. Good luck.