Dead Batteries After 8 Months? Surely Not!

[stevensuf]

So, my super dooper - piece of excrement batteries died after only 8 months of use, never taken below 50% charge bar the last week or so, and only because the whole 500amp hours were only lasting 2-3 hours and i did not have enough fuel to waste running the engine all night on an Atlantic crossing.

My question is, the shore power charger is 3 stage and fine, the solar charger 3 stage and fine, the alternator is a dumb regulator sits at 14.2v and gives the batteries whatever they will absorb at this voltage and holds them there, now i knew this could have been a long term problem on long motoring journeys, but when the batteries were charged it showed only 10-15 amps at 14.2v surely this should not have fried (ie degassed the batteries so quickly) ???

(bear in mind the boat was probably consuming 10 of those amps, ie the alternator was only pumping 5 amps into 500 amp hours of batteries for longer periods once they were charged)

I am thinking the batteries have been below par since the day i got them.

Answers on a postcard please..

[sailorchic34]

Sounds like you have a bad cell in one of the batteries that pulls the others down. How many batteries do you have and are they wet, gel or agm. If your lucky, you might be able to bypass the bad battery and work on the others...

[noelex 77]

Ouch.
8 months is a terrible life. You need to find the cause. Even poor quality batteries should last much longer under the conditions you have described.

You don't mention the make, or even type of battery. Generally at 2% ie 10A going ino the battery within 0.2v of the absorption voltage the charging should be dropped to float voltage.
Accepting only at 5A @ 14.2v for 500AHrs indicates some overcharging for wet lead acid, but other than using more water it sould not have caused any great problems. For long periods it could be damaging for sealed batteries especially some types of gel batteries.


Check the charging voltages of the battery charger and the solar regulator as well.

Before you give up on them check all the connections do an equalise cycle ( if this is allowed by your battery type) and do a load test.

[Sailorman Ed]

On a related note, my gel cells are still connected to the solar panels and now on the hard. Should I leave it as is and accept charge all winter or bring them home and charge once a month? I currently have the fridge (set on low) as the only load on them and they showed fully charged on the Link monitor the last visit. In North Carolina.

[zeehag]

i think sailorchic has a point--could be a sulfating problem. good luck with this project.

at least batteries that die within the first year of warrantee are covered with full replacement, by most places--i found costco was goo d for this problem, even in mexico..

[stevensuf]

They are sealed agms, 250ah each, in retrospect im sure they were not right from the start, they hardly powered the boat for 15 hrs under way, i have low power everything , leds, keel cooler etc,i never measured accurately, but the gauges indicate less than 10a draw while in motion, so at 15 hours that would be 150ah from the start.

i think noelex may be right, ie they were overcharged by the alternator on the longer motoring runs, but surely the odd bit of abuse should not kill them in such short a time period?

The old batteries were lifeline 440ah in total agms, 5 years old and were giving me 6-8 hours under way without the led nav lights etc probably down to 25% capacity after 5 years, yet the new ones down to 10% capacity after 8 months?

[sailorboy1]

You didn't even seem to really get what I would have expected out of yuor last set of batteries.

I think you have some other hidden issue going on!

[Artif]

First thing to check is your battery monitoring equipment, it may be giving you false readings, i.e your depth of discharge.
2 sets of batteries cooked in relatively short duration suggests problems elsewhere.

[cwyckham]

It sounds like you don't have a Link type battery monitor, so I think we need to know the answers to a number of questions:

How do you know your batteries are dead? How do you know they're only lasting XX number of hours before they need charging or that they are at 50% charge?

How do you know what your drain is at any given time? Do you have an ammeter hooked up? Is it measuring everything going out? Are you sure?

[djmarchand]

AGMs are generally ok as house, deep cycle batteries. But I purchased some generic Group 27 deep cycle batteries from Sam's Club that were not. They were replaced twice under warranty after 4 months each time and finally Sam's agreed to replace them with golf cart batteries. No problems since.

Golf cart batteries are always deep cycle. Other than name batteries like Trojan, Lifeline, etc I wouldn't trust any generic battery to stand up to deep cycle, house service.

David

[newlazydays]

I might be old fashioned but:-

1. I don't like sealed batteries.

2. I am not that keen on gel cells. (Charge them at more than 14.4 volts and they turn to dust.)

I have 6 8ds on my 51 foot sail boat. Conventional heavy duty truck type lead acid batteries. Each has a de-sulphater on it. I seem to get about 5 years on this rig, sometimes more.

I have five solar panels. One wind generator and an 8Kw generator. I also have an 80amp alternator on the main engine. This is a standard non marine alternator.....much cheaper and seem to last just as long.

[Paul L]

What brand AGMs are they? If you search around a bit you will find anumber of stories of AGM failures in under 18 months.

[Vasco]

Originally Posted by djmarchand

AGMs are generally ok as house, deep cycle batteries.

Can't agree with this. AGMs are the worst batteries a cruiser can select. Mine lasted one season! If you're not tied to the dock don't get AGM's. They have to be fully charged regularly. If, like many cruisers, you end up charging them to 85% (the last 15% is too difficult to top up) they will not last. Lots of info on this. Just do a search. I learned the hard way.

[Kettlewell]

AGMs require periodic recharging back up to 100%, which is beyond the capacity of many onboard charging set ups. Read more about them here. Personally, I would go with standard wet-cell 6-volt golf cart batteries. They are better at taking the typical abuse found onboard most cruising sailboats, and even when something does go wrong they are not so expensive to replace.

[mbianka]

Originally Posted by Sailorman Ed

On a related note, my gel cells are still connected to the solar panels and now on the hard. Should I leave it as is and accept charge all winter or bring them home and charge once a month? I currently have the fridge (set on low) as the only load on them and they showed fully charged on the Link monitor the last visit. In North Carolina.

Ed:
I have kept my 12 volt house Gel Cells on board and using solar charging during winter storage for five years now. You should make sure you have a solar charge controller with a setting for charging gel cells though to avoid any overcharging issues. Also if you do not need the refrigerator I would take the load off the batteries during storage. Just let the solar panels keep them topped up until you splash the boat again. When you go to visit it also does not hurt to use the AC battery charger while you are on board too.