battery losing charge a mega mystery

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Mike k

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Hi

Iposted that the solenoid was clicking-then following advice all wires checked and clean, replaced battery with a Exide 655 monster and had stater recon with new solenoid and new shaft and cog thingy. Guess what immediately on fitting started 5 times no clicking. 2 weeks later clicking in solenoid 'for england' .Battery discharged with all isolaters on- only started with power pack. I am totally lost now!! Would welcome any advice.Thanks
 
yes soon as she starts voltmeter goes up to 13+ and have done checks whilst running and she is charging fine.Discgarging in between visist.
 
put a dvm in series with the positive battery terminal and the positive lead with everything switched off to see if there's currrent flow? if there is, home in on where the current draw is by disconnecting components until it stops.. ideally need a cct diagram as you can half split to home in on the cause
 
Mike k said:
yes soon as she starts voltmeter goes up to 13+ and have done checks whilst running and she is charging fine.Discgarging in between visist.
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13+ is not charging, what is the + bit ?

You need to see 14+, near to 14.4 volt to have a resonable recharge level.

If you are getting 13.5 volt you are under charging, getting a surface charge only, hence your batteries are going flat while you are away, and you will kill them.

Brian
 
Mike k said:
yes soon as she starts voltmeter goes up to 13+ and have done checks whilst running and she is charging fine.Discgarging in between visist.
Click to expand...

I'm not up to date on modern technology but lead acid batteries are not 12v, they are made up of 6 cells which at full charge produce 2.2v each cell which means 13.2v output. To charge this you need roughly 13.8v.
To stop the battery discharging you could try disconnecting it between visits though this will not find your fault. If you have a meter test between +ve and -ve cables with the battery disconnected and everything turned off and this should give a reading of infinity ohms if perfect (it won't be). On 12v system I would want at least 5 megohms (though 2 is probably fine). Since you said it was a new battery I would suspect you will find a low reading which will drain your battery, then you just have to do the hard part of finding where the fault is (being on a boat water in cable junctions is a strong possibility and some silicone spray or even wd40 can sort this out without stripping stuff out)
Nick Heath:rolleyes:
 
As others have indicated, you have something discharging the battery. On Rafiki, with the main switch off, only the bilge pumps are live. So I would start by checking the system with the mains off, checking if there is any discharge, and if yes, disconnect each of the bilge pumps in turn until you find the culprit. Actually, on full batt charge, are any of the pumps running? Do you have water seeping into the bilges that is being pumped out in your absence?
 
I'd be inclined to have a careful look at the battery isolator switch too, its not unheard of for them to build up a lot of resistance over time, internal corrosion on the contacts.
 
burgundyben said:
I'd be inclined to have a careful look at the battery isolator switch too, its not unheard of for them to build up a lot of resistance over time, internal corrosion on the contacts.
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agree with this, started my engine last year and then realised I had not switched engine battery on... cleaned out isolator switch and all well, so previously engine battery had been live. I always keep an aerosol of electric contact cleaner spray , its a must on a boat IMO , cleans protects and shifts water..
 
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I have no idea how old your alternator is, but older types were fitted with blocking diodes, and if one is u/s it will allow current to drain back to the alternator and drain the battery.

The simple way to test this is to charge the battery. leave for a few hours to stabilise then measure the voltage. Disconnect completely the alternator and then leave for a couple of day. If the voltage is more or less the same, then it is the blocking diodes. If you remove the alternator and have it tested they will confirm it. A new diode pack is only a few quid
 
at the risk of repeating myself, measure the leakage current and disconnect stuff until it stops, whether that be alternators and their diodes, dodgy earths or whatever... If there's a current running it's gonna drain your battery... simples init :)
 
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