Batteries not charging

[Bawdrons]

Firstly, boat electrics are not my thing - but I am eager to learn!

Came to the boat after a week away and been working on the boat since early this morning, had radio on all day, ran bilge pump water pump, etc. Went to start the engine around tea time only to discover that there was not sufficient power to turn engine, both batteries are at about 9 volts (I usually just turn both batteries on when I'm plugged into the mains so both domestic and engine are drained). I have been monitoring the capacity using a voltmeter and with just led cabin lights on the batteries are slowly depleting, despite being plugged into mains (which is working as I have a heater on and using a laptop). I can only assume that its the charger has failed. Trouble is I don't know where to start or what I am looking for. Help will be greatly appreciated.

Thanks

 

[superheat6k]

My domestic pair have just collapsed and only 3.5 years old.

Get a voltmeter and find some places to measure the system voltage - Battery terminals is obvious but also at say a 12v cigerette lighter socket or instrument feed.

Turn everything off allow the batteries to stabilise then measure and note what the voltage is.
Turn on the charger and see if it increases - yes charger good, batteries bad. No vice versa, but if batteries are left discharged for any period they may not recover.

Progressively turn on some loads around the boat and keep checking the voltage. Look for significant differences between the batteries and at the remoter connections - rule out a bad connection e.g. isolator switch, or cable connection loose / dirty.

If the Battery voltage recovers quickly after the load has gone, and then increases when the charger is turned on, then I would suspect the batteries. Mine were fading right away below 10 volts from 13v after just 20 minutes of moderate load - cabin lights, and testing of the heads electric pump and thats a 250AH pair.

I checked mine this morning with a hydrometer and found that although they have been on continuous trickle charge the SG was very low. The batteries could have stratified due to lack of motion and use, but knackered they are.

New ones ordered today from Alpha Batteries.

 

[annageek]

When you say:

I usually just turn both batteries on when I'm plugged into the mains so both domestic and engine are drained

Do you mean charged instead of drained? Or do you mean when you're NOT plugged into mains?

It does sound very much like the charger is not giving an output, as if the batteries were just knackered, the battery voltage would not deplete with your LED cabin lights. Is it possible to disconnect and see what voltage you have on the charger output? Do you know what charger it is? Any details would help.

Just a thought, but do you have an inverter and transfer switch setup? It's just if the transfer switch isn't working, you may be running your mains appliances from the inverter inadvertantly (and therefore batteries), and the reason the batteries are dropping is due to the load being much greater than the charger can provide. It's unlikely to be this if you've got your heater running... unless you have a huge inverter.

 

[lpdsn]

Get a multi-meter (adequate ones are quite cheap) and start by measuring the output voltage at the battery charger. Be very, very careful not to short out anything with the probes. Either the charger is giving a decent output voltage or it isn't, and you'll diagnose the problem much quicker when you know that.

And as soon as possible, get some temporary means of charging the batteries - say, borrow an emergency pack to start the engines. Sitting at 9V is not doing them any good at all and the longer you leave it the worse the damage will be.

 

[Spyro]

Do you definitely have a charger that is connected and running from the mains?

 

[annageek]

Get a multi-meter (adequate ones are quite cheap) and start by measuring the output voltage at the battery charger. Be very, very careful not to short out anything with the probes. Either the charger is giving a decent output voltage or it isn't, and you'll diagnose the problem much quicker when you know that.

And as soon as possible, get some temporary means of charging the batteries - say, borrow an emergency pack to start the engines. Sitting at 9V is not doing them any good at all and the longer you leave it the worse the damage will be.

+1

 

[VicS]

Firstly, boat electrics are not my thing - but I am eager to learn!

Came to the boat after a week away and been working on the boat since early this morning, had radio on all day, ran bilge pump water pump, etc. Went to start the engine around tea time only to discover that there was not sufficient power to turn engine, both batteries are at about 9 volts (I usually just turn both batteries on when I'm plugged into the mains so both domestic and engine are drained). I have been monitoring the capacity using a voltmeter and with just led cabin lights on the batteries are slowly depleting, despite being plugged into mains (which is working as I have a heater on and using a laptop). I can only assume that its the charger has failed. Trouble is I don't know where to start or what I am looking for. Help will be greatly appreciated.

Thanks

A good place to start leaning the basics is the Boat Electrical Notes on Tony Brookes' TB training website http://www.tb-training.co.uk/

then perhaps with a book of your choice such as Electrics Afloat, by Arthur Garrod. http://www.amazon.co.uk/Practical-Boat-Owners-Electrics-Afloat/dp/0713661496

or the 12 volt Bible for Boats. http://www.amazon.co.uk/The-12-Volt-Bible-Boats/dp/0713667036/ref=pd_bxgy_b_img_y

or Essential Boat Electrics, by Pat Manley. http://www.amazon.co.uk/Essential-Boat-Electrics-Pat-Manley/dp/1909911100/ref=pd_bxgy_b_img_y

The ultimate book, but perhaps not for the beginner, is of course the Boat Owners Mechanical and Electrical Handbook, by Nigel Calder. http://www.amazon.co.uk/Boatowners-...d_sim_b_3?ie=UTF8&refRID=03QHRKGAK1ZT0KSHMRPC


As far as your present problems are concerned Id agree with the idea of getting an inexpensive multimeter. I use Maplin's cheapest for most stuff, no great loss then if I wreck it or drop it in the drink! However until you learn a bit it would be as well perhaps to get the help of someone knowledgeable who can assist you to test and troubleshoot your system.

Without detailed information and/or a wiring diagram its difficult to help via an internet forum.

 

[William_H]

I can sympathise with the OP in that he is completely bewildered by what is presumably a new boat to him. A friend has just bought a 30fter nice but when I looked at the electrics it was bewildering to me. I reckon I know the basics and a bit about common practices but it is still going to take a while to figure just what is going on. It has 2 1,2,both switches although one seems only to work as an on off for the domestic pair. Another seems to choose either or both of the domestic pair. Meanwhile there is a small engine start battery that has no switching. Very confusing. All this despite having a wiring diagram provided which is clearly wrong (outdated).
So to the OP I can only suggest you get someonme to look at the system. Perhaps some one else in the yard who may be able to make sense of what you have. He or you can look for a charger. Are there lights or indications that it has power? Is there an amp meter/ What does it indicate? Meanwhile as said get another charger and put something into those dead batteries. In fairness they may have died of old age and abuse anyway if they don't provide power for very long. good luck olewill

 

[Bawdrons]

Thanks for all the replies and advice Yes, my boat is indeed new to me.

I will be able to do a bit more investigating now that it is light (albeit raining)