Batteries Went Dead Overnight - Beginner

[MarkSF]

Originally Posted by deblen

You "saw that all cells.. needed water" and the batteries were "bought in Jun '15"
Suggests to me that they have been overcharged ("boiled") either by your alt. or shore power charger.
No way should they need water in 6 mos.
Boiling them will substantially reduce their capacity.
Top them up with distilled water & re-charge them with a good 3 stage charger.Verify that they are being charged at 14.4V or so using a digital volt meter. This should revive them.
Welcome to boating!

Cheers/ Len

Second this. You got through that electrolyte rather fast. What kind of charger do you have?

My batteries used to need topping off regularly until I bought the temperature sensor for the Xantrex. Electrolyte usage has dropped right off. I suspect that the "normal" temperature mode was overcharging the batteries in hot weather.

The original post is missing some vital information. What is the Ah rating of the batteries, and how much did you use before they went flat? This is something you should be aware of, and keeping track of.

Finally, why do you have two batteries, and only one bank? One battery should be kept in reserve for starting. At this point, I'm sure you can appreciate why.

[Cheechako]

About all you can do is refill them and see if they are ok. Probably are being that new. I have a jump pack. I looked at a lot of reviews and bought one with a good reputation. However, I discovered they wont start a big engine if the batteries are truly flat. Not sure how well they will work with a diesel as I used it with a V8 marine application. The other thing is, you need to charge them up often, they don't do well just sitting forever then trying to use them. Good to have in a pinch though, they are pretty cheap now days. I think I paid $80 for a better one.


I also agree you must be overcharging or something... your batteries shouldnt go that dry that fast.

[ramblinrod]

Originally Posted by theodyssey

hi all.

am sure this question has been answered before, but am anchored up in Swansboro and trying to find answers quickly.

long story short - came back to the boat last night to find that my batteries had both died.

the facts:

- they're AC Delco Marine
- bought in June '15
- used for the first time Sept '16
- being new, didn't know about keeping them 'wet' - so to speak - and saw that all cells desperately needed water
- they had been working fine since then [boatyard + shore power], and for the past 3 days
- 2 days ago, I had been both charging my iPhone + Macbook [computer] all day.
- anchored in Swansboro 2 nights ago, used a few LED lights, kept my 12v cooler on
- and then sometime between yesterday morning and last night, they died

so I'm about to call Boat US for a jump start, but am wondering which of the above do you think contributed to this? [meaning - what lesson do I learn from this?]

many thanks!

ps - speaking of which, does anyone have a good emergency jump pack they use? am seeing some tiny ones on Amazon that can charge either a phone or give your diesel a jump

Ugghh. If you want your batteries to live, stop murdering them.

1. Never discharge your batteries below 50% SOC (state of charge), as measured at rest (no charge or load applied within 12 hours), at 12.2 Vdc.

2. Never let your batteries run dry.

3. Never let your batteries sit in a discharged state for any length of time.

Without knowing your battery capacity, let's guess that you have 2 x 80 Ah (Amp-hours) of capacity.

Since you never want to discharge below 50%, you have 80 Ah of capacity.

Lets assume your electronic cooler draws 4 A when operating, and has a 50% duty cycle (1/2 the time, it is not running, because the temperature setpoints are satisfied), resulting in a 2 Ah average draw.

All these assumptions should be verified.

But based on assumptions, without any other load, your cooler will take your batteries down to 50% SOC (from 100%) in 80 Ah usable capacity / 2 Ah draw = 40 hours.

That your new batteries boiled dry that quickly makes me suspicious that are using a ferro-resonant charger. If so, do not leave this on the batteries all the time. (If it is an automotive type with clamps, get it off the boat.) For permanent connection and your battery capacity, an inexpensive 10A marine 3 stage charger will recharge your batteries from 50% depleted overnight, and will keep a float on them to ensure they are topped off but not boiled off.

If you plan to be away from shore power for more than say 24 hours, (starting out with 100% SOC) I would recommend about 200 W of solar panel and a PWM controller.

For a booster pack, you would need one that can deliver at least 1000 A (to start a diesel) and it would have to fully charged with batteries in good condition, with an engine that requires few cranks to start. I recommend 2000A. (A gas engine that starts well needs a little less oomph.)

Ramblin Rod
Marine Service Provider
About Sheen Marine

[MarkSF]

My boat used to have a ferro-resonant charger, and batteries lasted a year or two. It was replaced with a Xantrex 3-stage, and they are going strong after 5 years (they did start to go downhill after that).

[Stu Jackson]

Originally Posted by deblen

Google "Maine Sail" for bat. & switch wiring ideas.
Perhaps someone could post Maine's wiring link here-I can't access mine at the moment.

Here ya go:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings | SailboatOwners.com Forums


These come from here, which supplies a lot of the material folks are suggesting you need to learn:

Electrical Systems 101 Electrical Systems 101

[Capt_Flrp]

Newer starting batteries don't "normally" recover after being completely discharged. Good luck.

[reed1v]

Originally Posted by Capt_Flrp

Newer starting batteries don't "normally" recover after being completely discharged. Good luck.

Which is why i suggested he get new batteries. The old one's not only will not fully charge, but will drain quicker now the plates are probably compromised. So much can go wrong with a boat. Hopefully he did not over tighten his standing rigging. Now that can really go wrong.

[Derek010]

I purchased one of those tiny ebay jump starters about 3 months ago and glad I did. Don't go for the cheapest, look at the numbers. I paid under $40 for mine and its rated 400a. It has 2 usb ports to charge phones and tablets and a cord to charge laptops. I jumped a Cadillac escalade and that has me sold on them. I still have my big red dinosaur jump box but probably gonna be recycled soon.

[Terra Nova]

Originally Posted by darylat8750

...you will have a much more pleasant boating experience if you make the effort to get a firm grasp of basic 12 volt batteries and systems...

This.

And pickup a volt/ohm meter.

[reed1v]

The portable jump starters are basically a small car battery. They tend to lose at least one percent( 1% )of their voltage charge per month. So by five months, the voltage level is usually below what is needed to "jump" a regular battery. We use them all the time up here since we often must start up the auxillary generators when the regular power goes out(typical island living off Maine's coast). So keep them plugged in or plug them in when you think your going to need them.
Also we found even the most expensive ones(big red box) we got at an auto supply place only lasted three years before it would not hold a full charge. Otoh, a big box store bought one(small gray thing) still is going strong after three years. Price does not seem proportionate to quality.

[Captain Dharma]

Originally Posted by a64pilot

Coming from others comments, if they are 12V batts and Delco, they aren't deep cycle even if the label says they are.


Sent from my iPhone using Cruisers Sailing Forum

Hi - Not to hijack this thread, but I'm nearing the end (haha) of refitting my 1984 Present 38 trunk deck trawler. I'm at the stage where I need to build a house bank. Since I figure that my worst day usage would be about 350 ah (average daily 175-250), the goal is 750 amp hours. My mechanic and I are wondering what batteries to buy? I have a 22"L x 12"W x 10"H box under the floor boards between the engines but anything taller than 8" means I will need to reroute some hoses. I currently have 390ah in dual purpose AGMs in my starting bank, but I don't want to tap into that reserve until it comes time to recharge or start the engines. I see the Rolls , Trojans, Surrettes and all the other AGMs available. What is the cheapest option available to me to get a bank that size that a non-techie like me can live with? I'm looking at AGM 4Ds, but I'm open to suggestion. A local distributer has AC Delco 4Ds at a decent price. Should I run away? Thanks.

[mowerandy]

Quick comment re jump-start packs; Here in Oz the market is full of cheap Chinese made jump packs of various rated capacities.
I have owned a couple, and currently a 1900Amp rated pack. The thing is that the rating is probably measured at the terminals of the battery inside the pack rather than at the lead clamps, because my 1900 cannot crank my car or boat effectively if I disconnect their house batteries (both rated only 570amps).
Might be labelled 1900amps but cannot even deliver 400 I would estimate!
This means that if you need to jump your house battery with the pack then the only way is to leave it attached to the house battery for long enough for it to boost-charge up to cranking amps. a few minutes generally and then start while it is still attached.
Now if you fail a cell of your house battery, or make it sick enough not to take charge effectively, then you are going to need more than one of these cheap start packs to get going again. I found this out by surprise in the garage - which was a lot better than at sea, or in the outback!

[Ian Johnstone]

Mate,

Do yourself a favor and learn about batteries and boats if you wish to use them. There is a plentiful supply of info on the web or you could even read a book like the 12V Doctor.

[jwcolby54]

Originally Posted by a64pilot

Some of those peltier coolers I believe suck a few amps, yet do little actual cooling.

Uhhh what?

Mine from Walmart sucks 6 amps but will consistently cool the inside of my cooler 30 degrees below ambient.

Hardly "little actual cooling".

[jwcolby54]

Originally Posted by Capt_Flrp

Newer starting batteries don't "normally" recover after being completely discharged. Good luck.

I don't think that is true, although what you mean by "recover" is relevant here. What is true is that:

1) Most batteries will take ten or so complete discharges.
2) Each complete discharge DOES damage the battery, resulting in the battery able to hold less current the next time (will not "fully charge", will hold less and less charge each time.)
3) The length of time it remains fully discharged matters a lot. Fully discharging a battery just one time, but leaving it that way for a year will likely kill it. Leaving it that way for a couple of days will most definitely not. It WILL definitely damage it to some extent.