Battery failure

[P69]

I've got a battery problem.

During the last 5-day trip, the batteries worked very well, but one was hotter than normal. On day 4 it started blowing steam and stinking up the whole boat. I switched the battery selector to 2 so the alternator would stop charging that battery.  Back at the dock, I disconnected the hot lead going from the battery charger to the failed steaming battery,  but the battery charger (the one that run on AC power) would not start unless I put that lead back in.  I then disconnected the pos and neg cables from the steaming battery (and bolted them together so they are connected), but still the charger won't start charging. 

I put a spare starting battery in that position and now, the charger starts and charges, but, even though the amp meter shows full and the charger drops to float charge, when I turn on any  device (water presure pump, cockpit light, spreader light, blower, etc...) the meter for battery 2 bounced down to zero and sometimes inches up to 4 or 7 volts until I turn off that device.


I have two questions

1.  Why do I need a battery in position 1 for the charger to kick in?
2.  What is causing the remaining battery to show full, but drop to very low when I turn on a device?
3.  If anyone knows why battery  1 got hot and blew steam, I'd like to know that.


Here's what I have

Statpower 40+ battery charger, set for battery type: flooded.  Four wires connected to the battery charger. Three red, going to the pos terminal of the three batteries. One black, going to the neg terminal of the engine start battery. The neg terminals of all three batteries are connected together

Three batteries: one engine start battery, one 4D flooded battery and one 4D sealed battery (AGM or gel??).

The battery selector switch has 2, All, 1
The flooded battery is Battery 2 on the switch and the sealed battery is Battery 1.
The battery that got hot and blew steam is the sealed Battery 1.

The flooded Battery 2 got down to 25 percent before I gave up the charger trouble-shoting and started the engine to charge.  This battery stayed below 50% for about a week.

The engine will charge whichever battery is selected on the battery selector (1, 2 or All).
The starter battery is isolated and dedicated to engine.

From the All terminal on the Battery Selector switch, there are red cables going to an unknown device. Anyone know what this is (see linked images)?

http://bodylens.com/battery/mysterybox1.jpg
http://bodylens.com/battery/mysterybox2.jpg

[Della and Dave]

Hi:  That is a little scary.  I can't answer all  the questions, but I am pretty sure that is a Solenoid switch.  If you google Bobina T 503 you get a replacement part that is a solenoid. 

I can't help diagnose your charging problem over the internet easily, but you might check to see if the power to the solenoid is coming from the battery that you took out.  That would mean the solenoid wouldn't switch, directing the battery charging voltage if that is how it's wired.  Many other possibilities though. 

I wish I had a schematic for our boat, I am having to do some battery work myself and figuring out how it is wired has been a headache. I have 6 wires going to the negative terminal on my Batt 2 and I can only explain 3 of them. 

On our boat we have a similar solenoid that is wired in with heavy cable that is for the windless.  Small wires go to the switches to run it up and down. 

West Marine Advisor has an educational piece on batteries that tells you not to mix types of batteries in a bank because of the possibility of overcharging.  It wasn't clear to me if you have that, but if the battery that boiled is a flooded and you have a second AGM or gel on the same bank, or you had the switch on both, that could have been the problem.  (On both essentially you should have have one bank) You can see the article here:  http://www.westmarine.com/WestAdvisor/Selecting-a-Marine-Storage-Battery

[barrylab]

Della and Dave have a point about Gel and AGM on the same network, as they have different charging profiles, but I don't think that would cause the AGM to gas out. If however, the AGM had developed a shorted cell, it would divide the charge voltage across 5 cells instead of 6 and you would get gassing. Lead-acid batteries do have a failure mechanism where the lead plate breaks down and fills the area between the plates shorting out that cell, but usually the glass mat of an AGM prevents a complete short. This failure mechanism is sometimes the result of over discharge (>50%) with partial charge happening repeatedly. If you have a fast discharge battery meant to start an engine, and are using it as a deep discharge this can happen if you're not careful. Fast Discharge batteries (high cranking amps) have textured or finned plates that allow higher surface area at the expense of metal thickness. They charge and discharge faster, but are damaged more easily by deep discharging.

If that black box is a solenoid switch it may be that your alternator has the voltage regulator built in, and therefore can be controlled by only one of the batteries. When the motor charging circuit is set up this way, you need either an isolator or a solenoid switch to connect the two batteries together for charging. The solenoid will physically connect them together with the equivalent of a knife switch. The isolator uses diodes to allow flow from the alternator to go into the battery but not back out. (Different topology, but same basic use). The isolator is more complicated as you need a separate battery cable from the battery to the bank switching.

You say the second battery shows full until you add a load. This suggests a high internal resistance (or possibly a bad connection). If you have an alternator charging system (usually separate from the AC charging system) the voltage may be controlled for only one battery. If the control wire is connected to the first battery and you remove it, it should float to a voltage that tells the charging circuit it's fully charged, showing the behavior you described.

So ... simple test:
1.  plug battery #1 in without #2 connected. Start the engine (with an external charger if necessary) and see if it starts gassing.
2. Plug all the wires/cables you had on #1 onto #2 and see if it charges/gasses.

This should narrow down the failing system.

[P69]

Thanks for the info on this problem and for identifying the T-530 as the windlass reversing solenoid. That makes sense.  I don't think the solenoid is the problem because I don't use it (windlass is off the boat). Now that I know what the T503 is, I will disconnect those cables to get them out of the way.

Here is the crude wiring diagram. There is a spaghetti-mess of wires that make it difficult to trace the wires.
This diagram is the best I could do when tracing.

http://bodylens.com/battery/batterydiagram.pdf

I found the mfg info on the steaming battery and they confirmed that it is a sealed, wet-cell battery, not an AGM or Gel.  That battery is shot.

This sealed battery is about 3 yrs old and I think it is not the best battery because  it's a 4D that I can easily lift out of the port locker and I'm not the strongest around the dock. I think a 40 lb bag of concrete is F'n heavy!  Also, the PO receipts show a price of about $160 for that battery.


Now, I have to resolve the issue of the remaining wet cell (non-sealed) battery showing full charge, but dropping to < 5 volts when any load (other than led cabin lights) is put on it. This battery is older, but date is unknown. 

Other than these two possibilities, does anyone know why a flooded battery will show full charge, but drop to  near zero when  a load is put on it.  I'm talking spreader lights, pressure water pump, 10w halogen light in cockpit, blower. Any one of those will drop the needle to zero.

1. batter failure (i.e. severe sulfation, bad cell)
2. poor connections (i.e. loose ground?)


One more aspect. I'm kinda ashamed to admit this but I checked the water level in the remaining flooded battery that shows full charge and, although the plates were not exposed, I added a total of almost 1 gallon of water to that battery.  I was surprised how much water that thing took. I was not sure where the fill lines were, so I filled to underside of the cylindrical shape that descends from the cap. 

[Della and Dave]

Ironically, I just checked our bat 1 bank, two 6v flooded batteries in series that wouldn't hold much of a charge, and they were almost dry.  I added a gallon and a quarter of distilled h2o to them and they seem to be working so far.  The previous owner got them cheap from Costco.  I got a deal on a sealed AGM Mastervolt slimline 200 Ah battery on clearance at our local West marine, so when I get to priority B items on the list, that's going to be our new Bat 1.  I need to address the battery box first. 

Our bat 2 IS our start battery, so our boat is not wired like yours.  If it is of any help, the Pearson owners manual has a very basic schematic.  It's of limited use because of all the changes over the life of our boat, but anything that is old might be wired like that.  Our battery bank is sort of wired like the book.  A bunch of other stuff has been added though through the years.  I count 6 negative wires off the negative terminal on our start/bat 2 battery.  I understand 3 of the 6, I think. 

[Dale Tanski]

I must admit this has been a very interesting post to follow.  This reply is in regard to the question about what appears to be  fully charged battery until a load is placed upon it.  I have run into this on three occasions in the past.  Two auto related and one tractor.  In all cases, the vehicle ran as advertised in the brochure. 

In the case of the wife's car, she would stop for gas and when she attempted to restart it, it would be it would act like a stone cold dead battery.  Sometimes the lights would work normally until the key was turned.  I kept suspecting a bad ground but that was never found and not the case.  I would arrive at the scene, apply the jumper cables and instantly the dead battery would be healed.  The jumpers were not on 10 seconds, no spark when connecting and the dead vehicle would start like it was new.  This went on for over 6 months with repeated episodes.  I cleaned battery terminals that didn't need it, chased battery cable grounds that were fine and even inspected the starter and starter solenoid. 

Out of desperation I replaced the 3 year old battery and the problem has never returned.  Dead one minute, good to go the next.

We have a small diesel tractor.  You could shut it off at night and in the morning it would crank or click like a dead battery.  I would hook a small 10 amp charger to it that would show fully charged. If you turned the key it would start as normal.  This too went on for months.  I changed the battery and it has been fine for years. 

We had a company van for work.  Turn the key, nothing but click.  Put the battery charger on and it would show fully charged.  A volt meter would chow 12.5 volts all day long but it would not even light the dome light with out draining the voltage to 1 or 2 volts.  Replaced the battery  and the problem was solved.

I suspect that occasionally one will get a battery where an internal connection will go bad.  Under a no load situation it is fully charged.  Under a load the connection heats and moves from the current draw and the circuit is broken.  Occasionally that connection will hold for days/hours/weeks.

Welcome to the twilight zone.

Dale

[PeteW]

A little knowledge of Ohms law can go a long in understanding what otherwise appears like the supernatural. E=IxR or better yet the version of Ohms laws dealing with power P = ExI. P =E^2/R and P = I^2xR.

When Batteries fail, usually the internal resistance (R) goes up. This explains why the voltage is good until you connect a load. The voltage is dropped across the internal resistance which is now high. E=IxR. Often called an IR loss. This also explains why the battery get hot. P= I^2R says the power from the current supplied by the charger is lost as heat in the battery resistance.

Smart Battery chargers and regulators employ curves that are either constant current when the battery is low and then switch to constant voltage when the battery is charged. If that voltage is too high the smart charger may shut off.

Pete

[P69]

Dale,
Your experience with the batteries and, PeteW, your explanation of the law makes me think that the battery is badly sulfated, has one or more dead cells or an internal short.  I found a local source for US Batteries US2200 XC2 (20 hr rate of 232AH) for $120 with no core ($107 with core).

This weekend I will check the remaining battery to see if the additional water fixed its drop-to-zero-on-load problem. If not, I'll call it dead and replace. If it works, I'll use it for now until I can get my ducks in a row and replace it with four 6v GC batteries (2 in series, both pair in parallel).

Thanks for all  of y'all's help.  I'll let you know how the battery replacement goes.

[Della and Dave]

Pete:  we are about to splash this weekend, knock on wood, and I have a related question.  We think the boat won't leak, but with all the work that was done, it might.

That means that our bilge pump mary be the only thing saving us from sinking at the dock while we are away, but that only works if we have battery power.  We can plug in at the dock, but I don't like the idea of leaving our battery charger on all the time, because it could damage the batteries.  (Old style charger, dumb box). My house bank is hot wired (through a fuse) to the bilge pump.   I plan to re-do the bilge pump setup, but have't had time yet. 

What do most people do, add a small trickle charger?   Or am I worrying about the wrong thing, and I should make sure the boat doesn't leak? 

Dave