Battery help!

[rodgerg]

Two weeks ago I replaced both batteries on my 32. Engine turned over like a dream. Last week I was putting sails etc back on and ran engine for a while, again all great. I should mentioned I have a new wind gen as well which keeps the batteries topped up.
I went down tonight and initially did not get ignition lights. Checked the battery meter and the reading was about four volts. I checked connections and got ignition lights engine would not turn over. Put on battery charger meter immediately showed over 12 volts. Waited a while tried turning over no luck but while trying meter showed way down to four volts again. Both batteries are brand new and show the green internal charged light.
What should I be looking for here? I put vaseline on all connections and they seem tight enough.
as I say help, I am not too clever with electrics!

Rodger

[rene460]

Hi Rodger,

Dropping quickly to four volts indicates something fundamental. Was the new wind generator installed and working well before the batteries were installed? Or was it installed at the same time or since?

Is it possible that the wind generator is connected with the wrong polarity? Either when initially installed, or when the new batteries were installed.

In the mean time I suggest disconnecting the batteries and re- connecting just to the mains charger or even to a separate portable charger. This should allow you to recharge the batteries without delay, as leaving them flat is not recommended.

Rene460

[rodgerg]

The wind generator was installed prior to the battery change, it was working just fine. All I did was disconnect and reconnect the batteries. I even took a photo before I started to ensure I put everything back correctly.

[rene460]

Hi Rodger,

Surely next suspect must be a short circuit somewhere. I assume nothing in the battery box lid with new batteries possibly higher than the older ones.

Again first step is still to disconnect the batteries and get them charged with either on-board charger or a portable charger.

Then to track down the problem before reconnecting the batteries.

A digital multimeter is your best friend there. With a circuit diagram very high on the essential list. First see if battery voltage is affected at all if connected with all circuits switched off. If voltage dips at all with all systems switched off, that is your first clue and narrows search area. Disconnect immediately and start looking. A severe short will possibly show signs of excess heat somewhere.

With luck it is not changed with all systems switched off, then one at a time try switching on various circuits which should identify the rough location of the problem for you to look closer.

Perhaps other forum members have tricks which will help speed up the process.

I hope that helps get you on the way. Alternatively an electrician may be required.

But first disconnect those batteries and make sure you can recharge them!

Rene 460

[sailbleu]

Have you tried switching the mains (plus and minus) off and on again. Sometimes that helps.
I suppose you have main battery circuit breakers no ?

Regards

[rodgerg]

I had a friend switch on the battery charger this morning and will go down tonight. Just wonder if the batteries might have been old stock and needed a boost. I just thought the wind jenny would have taken care of it, however we have not had high winds recently and I know if you can see the blades it's not charging.

[Amun Ra]

Might it be possible for there to be a dead cell in one battery?

If they are connected together a failure in one will drag down the other, which would explain why you have had two 12v batteries discharge almost completely over 2 weeks. Taking them off and recharging them will not necessarily reveal the problem. You will need to check each cell for its Specific Gravity. (I think that's what its called - using a hydrometer)

A dead cell in a 'new' battery sounds to me like the likeliest way to have introduced these symptoms into a previously perfect system. The alternative is to find what is drawing all that current down in a relatively short time.

Good Luck and please let us know what you find!

Best wishes

Julian