Battery Problems

ianc1200

ianc1200

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Anybody care to give me an idea what may of been happening here?

My cruiser has a starter and two 135 amp-hour leisure batteries on it's main engine. Both were new April 2006, are kept in the house over winter off the floor and periodically charged up. All the signs were that everything was fully charged before I went out, I then didn't run the engines apart from a short 20 minutes on Saturday morning, until the probem below sufaced. It has two alternators (the leisure charging one 90amp) and two 30W solar panels.
I went out on Friday evening, and had the 12V fridge on, lights etc. Running the inverter Saturday evening the low voltage alarm began to beep. Later the fridge also cut out. During Saturday/Sunday night/morning in the early hours I was awakened by the water pressure pump trying to run but failing.
When I awoke on Sunday morning I put my multi meter across the terminals of the two leisure batteries, both 0.00V. The digital voltmeter on the panel wasn't even showing anything, and the regulator for the solar panels also had it's ting light out. The starter battery was 12.7V.
I was a bit concerned whether it was even safe to start the engine (what would happen if the 90amp alternator tried charging two completely dead batteries?)
However, all was OK, (my clamp on ammeter only showed 25 Amps going in however), ran for 2.5 hours, then a friend brought his load tester down & the result was one was in near perfect condition, the other just off this.

I later put my multi meter in line and found with everything turned off there is still a draw of about 0.3amps.

I feel despite the load test being OK, and there were no further problems yesterday, I ought to buy new batteries anyway, as batteries shouldn't whatever be able to be 100% discharged without there being a serious problem.

Sorry for a long post!

IanC
 
All the signs were that everything was fully charged before I went out, I then didn't run the engines apart from a short 20 minutes on Saturday ...................

All what signs? Sounds like they were just not properly charged in the first place and the fridge flattened them.
 
"Running the inverter Saturday evening the low voltage alarm began to beep. Later the fridge also cut out."

What were you running with the inverter - they use a lot of amps and can easily flatten batteries if not careful.
 
If i am reading this correctly. As far as you were aware everything was OK last Saturday but by Friday, 6days later, things perhaps were not and by Saturday night/Sunday morning you had two flat 135 Ah domestic batteries.
The starter battery was OK though.

You have found a drain of 0.3 amps with everything turned off.

It won't account for 270 Ah going missing in a week, far far from it but the first thing you have to do is trace where this 0.3 amp is going. You will probably have to physically disconnect circuits until you find the cause.

OR has this been going on for longer than a week. When were the batteries installed was it just a week ago or was it several weeks ago.

As boatmike asks can you be absolutely sure the batteries were fully charged in the first place. Did you check either with hydrometer or that they were at 12.7 volts after a 12 hour rest.

Your water pump had not been left on and was running intermittently due to faulty control or pump valves ?

What did you mean to say about the light on the solar panel regulator?

I would not rush out and buy new batteries at this stage. You have to determine the cause of the trouble. Throwing away the cost of two new batteries wont help. They should recover substantially, if not fully, from one complete discharge but you should recharge them without unnecessary delay.

Do you not have a system whereby you can completely isolate the battery bank except for the connection to the solar charger?
 
If you are charging at 25 amp, that's a bit low, I would take of the batteries and have them bench charged, then checked for state. The battery testers now are far better than the old load test type, and you have removed one unkown.

If batteries are ok, then it's a matter of checking with your clamp meter for a large unknown current. Set up boat as it was overnight, and monitor battery current voltage fall with time during the day. To loose say 50% of the battery you must be drawing 10amp, so any fault should be obvious.

The big problem with charging is that they have been run down to 0 volt, so you may get surface charging.

All the best

Brian
 
Thanks for the advice

Re the signs; I believe fully charged because the solar panel regulator has coloured lights which state chharge level, & whether regulator working - ie stopping further charging, also the voltmeter on running the engingine quickly up to 14V level.

The invertor (1.5KW) only running the CD player then a laptop to watch a film.

This occurred over Friday night through to Sunday morning, perhaps 36 hours or so.

I am a bit worried the clamp ammeter is showing only 25 amps, when the 90 amp alternator was charging very flat batteries.

Should have also mentioned I have concerns the fridge thermostat is out, so at lowest setting the fridge is still too cold, perhaps running far more thsn usual so draining the batteries more.

Surely no batteries should be discharged to 0.00Volts and still be usable?

thanks again for the thoughts, much appreciated!

IanC
 
People like LSUK should be able to bench charge and tell you the battery state. I suspect that the 25 amp is surface charge into a flat battery, again bench charge should tell you.

Check your clamp meter, then go round measuring loads, and try and do a rough calc to check your usage over the weekend. Will tell you if flat batteries were resonable.

But it will be cheaper to get them checked out properly, than just buying new, or just poking around and hoping.

Brian
 
Much depends on the age of the batteries. 5 years is perhaps a good life to expect so if they are 3 years old then it might be worth thinking about buying new ones.

You need an installed amp meter so you know what you are draining. A battery management system would be even better to totalise your current drain.

However you need to track down your .3 amp continuous discharge. That is IMHO bad news. Look at FM radio memory, bilge pump or perhaps a burular alarm. All else should be disconnected when you leave the boat. You might like to check that the solar panel controller is not soaking up power when dark.

If you are concerned about batteries. It is a good idea to be able to isolate one service battery from the other after charging then compare apparent service time from each. It will become obvious if one or both are dud.

Lastly yes you can not always be sure batteries were fully charged when you started. Certainly not by little lights.

good luck olewill.
 
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