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Santiano 07-11-2019 20:52

Troubleshooting Drained batteries and Dead Charger.
Hey all,

I'm just beginning to learn about electrical systems, and would appreciate any pointers yous can give.

I'm connected to shore power at a marina, have a ProSport 6 amp battery charger, and a 12-volt house bank. I have not gotten around to installing a separate starter battery, which I am now regretting. That's a project that will have to happen soon.

I arrived at the boat this evening to find that lights were dim and the fresh water pump was barely turning over. I went to the batteries to check for loose connections and found a negative terminal sparking where the charger was connected. Without turning the charger off, I rearranged and tightened the connection to the negative terminal. The terminal sparked as I did so, and the charger light went from "batteries full" to dead. No lights.

Where on Earth do I start the diagnostic? I cannot find any trip or reset on the charger. It plugs into an AC outlet and runs off the shore power. My outlets connect directly to the AC shore power, and still work fine, but all the built-in DC electronics are nearly dead.

I heartily appreciate any direction you can give me.



rbk 07-11-2019 21:00

Re: Troubleshooting Drained batteries and Dead Charger.
Put a multimeter on the battery at the posts and see if thereís a difference. Follow the cable/wire and check for corrosion and breaks on both red and black lines.

billknny 07-11-2019 21:11

Re: Troubleshooting Drained batteries and Dead Charger.
If you have flooded batteries, sparking at the terminals can lead to ignition of the hydrogen offgass. That can be a VERY nasty result. I know of several boats that has happened to. Sparks around FLA batteries are potentially very dangerous.

Santiano 07-11-2019 21:24

Re: Troubleshooting Drained batteries and Dead Charger.

Originally Posted by billknny (Post 3011505)
If you have flooded batteries, sparking at the terminals can lead to ignition of the hydrogen offgass. That can be a VERY nasty result. I know of several boats that has happened to. Sparks around FLA batteries are potentially very dangerous.

I've looked for some indication of whether they're Flooded AGM or Gel, or what. All it says is "Marine Deepcycle." How do I determine the type?

smac999 07-11-2019 21:50

Re: Troubleshooting Drained batteries and Dead Charger.
A 6 a charger is way to small to keep a battery charged while on the boat.

NYSail 07-11-2019 23:01

Re: Troubleshooting Drained batteries and Dead Charger.
If your battery has caps that can be opened they are flooded. Check water level...... should be about 1/4 inch above plates inside battery. Only use distilled water. If no caps on battery they are agm (sealed) and don’t need servicing.

Good luck!

GordMay 08-11-2019 05:03

Re: Troubleshooting Drained batteries and Dead Charger.
Greetings and welcome aboard the CF, Santiano.

Sailmonkey 08-11-2019 05:27

Re: Troubleshooting Drained batteries and Dead Charger.

Originally Posted by smac999 (Post 3011518)
A 6 a charger is way to small to keep a battery charged while on the boat.

We used one for years with a 440Ah bank.

True, its too small to maintain the batteries when theyíre in use, but for a week at the dock, itíll do the trick.

That said, we found that if the charger was left on while the refrigerator was running the battery voltage would climb to extremely high levels and stay there. These little chargers are only intended to charge a battery that is not in use.

noelex 77 08-11-2019 06:03

Re: Troubleshooting Drained batteries and Dead Charger.
Welcome to the forum Santiano.

From your description I suspect the negative terminal of the battery charger had a poor connection and so the batteries drained to a very low state of charge.

Many smart chargers will not start charging a battery that has very low voltage. They do not recognise a battery is connected if the voltage is below a certain level.

If you can borrow another charger, preferably one of the old dumb chargers this will sart to charge even a very low battery. After a short time the voltage is likely to have risen to level where your smart charger will start working again.

A 6 amp charger is small but providing your electrical needs are modest it should manage fine. 6amps over 24 hours is 144 Ahrs. Many battery chargers will not supply their rated capacity continuously and there are some conversion inefficiencies, so you might have a little less than this, but providing you are not using more than around 120AHrs a day the battery should slowly charge.

Having drained the battery bank this low the batteries may have a permanent and significant loss of capacity, so make sure you fit that starter battery.

sailing_gal 08-11-2019 10:23

Re: Troubleshooting Drained batteries and Dead Charger.
After having drained your batteries so low, you may need to equalize them to get back the capacity. Check with your battery manufacturer to see at what voltage and for how long to charge them.

TrentePieds 08-11-2019 10:41

Re: Troubleshooting Drained batteries and Dead Charger.
Hello Santiano and welcome :-)

You have some valuable replies up above, but since you profess to being a newbie with no particular knowledge of electrics, let me go right back to basics and tell you how I would approach your problem:

1) You haven't said what kind of boat you have, how big it is and whether you sail for short periods ( a few days, a week or two) out of a marina, or whether you need to be independent of the shore for long periods. Those things affect the complexity your electrical installation, but fortunately you can start very simple and "build up" as your experience and your need for independence grows.

So for a boat up to sort-of-36-foot-ish sailed by a newbie, batteries of the kind you have will be sufficient. Two 27-series "Marine Deep Discharge" batteries are not ideal but they are GOOD ENUFF, provided you treat them with respect. And that's IMO what counts. That's what I use in a 30 footer, and I consider them disposable, so they get changed [not charged but changed :-)] every 4 years. My 20 HP Beta (Kubota) takes so little juice to start that there is no need for a separate starter battery at all.

Good battery management starts with ensuring that ALL your electrical connections throughout the boat are clean and tight. If your boat is new to you, then trace all through its wiring and verify the integrity of all the connections and terminals. If you do that conscientiously you won't have to look at them again as long as you own the boat, and you will have a very clear picture, either in your mind, or as I prefer, on paper.

Now we can look at your battery setup. The reason that the wires twixt your main switch (presumably a "1 - 2-both - off" switch) and the batteries, and between the switch and the engine, are fat is that they have to carry a LOT of juice. And because they carry a LOT of juice, loose terminals will corrode and build up resistance to the flow of current VERY fast. So clean these terminals inside and out, making sure that when you assemble them again they are as sailors say, "***** and briney" :-)

You spoke of sparks on the negative terminal. That bespeaks current flowing, i.e. SOME device in the boat was "on" when you disconnected the terminal, or there is a short circuit somewhere in the system. Ensure that 1-2-B-0 switch is off, but leave your "housekeeping" main switch "on", if you have one. Then disconnect the N-terminal again. If it sparks again, you have a short in the system. That's a crude initial way of doing diagnostics. In a future post we can deal with more sophisticated ways of doing these things if necessary.

Batteries are, as you already know, analogous to a savings account at the bank. If you put in as much juice as you take out in any given period of time, you are in clover. If you take out more than you put in you are headed for perdition. Therefore ALWAYS arrange matters so that you CAN put in more than you have to.

This brings us to the matter of an Energy Budget. Such a budget will tell you how much juice you will be taking OUT of the batteries in the normal course of your being aboard, and therefore it tells you also the reciprocal: The MINIMUM you should be able to put back into the batts. Come back to us if you need help with that :-)

And that brings us to the charger that takes its current from the plug-in point on the dock at your marina. Intuitively I think what you have is barely sufficient, but there again, do think about all the things that are in this thread, then we can come back to taking about a suitable charger for your batteries and your circumstances,

All the best


OS2Dude 08-11-2019 11:26

Re: Troubleshooting Drained batteries and Dead Charger.
We had a ProMarine ProSport 20 charger. I came to the boat one day to find the batteries DEAD. All lights but power where out on the charger. Replaced the batteries. (2 98ah AGMs, about $700 to replace) Called PorMarine, they sent me a new plug that tells it what type of battery it is attached to. Came up another time to find the batteries almost dead, but was able to get the engine started and charged the batteries that way. Again, all lights were out except power. Called ProMarine a second time, they told me there was a flaw in the design that allowed the LED that 'reads' the plug to move, and if the unit can't tell what the plug says, it stops charging all together. No alarm light, no buzzer, just NOTHING. They offered to replace the entire charger, but could not guarantee the new unit would not have the same issue. Said there was no way to tell when the 'fix' was implemented... Huh? Since I bought it from West Marine with an extended warranty, I just returned it. Bought two 100V solar panels and controller and have had no issues since.

hamburking 08-11-2019 11:29

Re: Troubleshooting Drained batteries and Dead Charger.
2 Attachment(s)

Originally Posted by smac999 (Post 3011518)
A 6 a charger is way to small to keep a battery charged while on the boat.

I disagree. It would be too small if there is refrigeration. But with LED lights, and not leaving the dock, it should be fine.

But is it a smart charger?

I would start by unplugging (or switching off) shore power (to power off the charger). Then check the water level in the batteries. My experience is that people who don't know anything about batteries tend to have them empty (or very low). Fill as needed with distilled water. Then plug in again and see what the charger does.

Time to get a digital voltmeter!

FWIW, I use a simple/cheap device (bought on ebay for like $3). Its a digital voltmeter that plugs into a 12 volt (cigar type) outlet and constantly shows voltage. It is a wonderful tool that allows you to constantly monitor your batteries. Knowing your batteries (and system) is half the battle.

Many chargers have a current indicator. Thats important info too.

And finally, be sure its a MARINE charger. One feature of a MARINE charger is that it does not put a load on the batteries when not in use. (some/most) AUTOmotive chargers will put a load on the batteries when not in use, and drain them pretty efficiently.

a64pilot 08-11-2019 11:39

Troubleshooting Drained batteries and Dead Charger.
Iím going to bet that the batteries are dead, and he was essentially running off of the charger, then fried the charger, and is now on dead batteries.

In my opinion even a 20 amp charger is too small, and Iíd even go so far as to say that since batteries set the rate at which they will accept a charge, you canít have too big a charger, and that often charging at the highest rate that a battery will accept is good for the bank, it shortens the time a battery has to sulphate and on flooded batteries has a tendency to stir the electrolyte keeping it well mixed up, because stratification is an issue for flooded batteries, more so on big tall batteries of course but itís there even on golf cart batteries.

However as I suspect you will be buying a battery charger, be sure to buy one that you can set the absorption and float voltages yourself to the .1V, donít buy one that has settings for Gel, AGM and flooded, because they may or may not be close to correct as many different batteries of the same type have different voltages, so one setting canít work for all of them.

Santiano 11-11-2019 15:20

Re: Troubleshooting Drained batteries and Dead Charger.
Thanks to everyone who replied!
I bought a cheap automotive 2-amp trickle charger as an emergency device to stop my house bank from losing its ability to hold a charge. I disconnected the two older batteries, and have charged them up to hopefully use as an emergency bank. The two new batteries are charged and running nicely, although I'm careful to use very little power because of the tiny charger.

I'll be ordering about 200watts worth of solar panels, along with a charge controller, by next weekend. The current plan is to rely on solar for the foreseeable future. I'm in a slip for the most part right now, but will be leaving to begin cruising within a year.
I learned a good number of details from yous all, and a few contradictory bits that I'll have to work out for myself!
Cheers, and thanks again!

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