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| JWL Member Since: 26 Oct 2011 Location: Hereford Posts: 3443   
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I have a 2002 Td5 110 with a strange problem. Tonight coming back from a club meeting I went through some puddles that were a bit deeper than anticipated which were deep enough to throw water up and over the roof. I had all my lights on(full beam plus 4x100w spots) fan on full speed demisting the windscreen so a fair load on the electrics and when through the puddle I got fan belt squeal then all the lights brightened back again, can't say as I had noticed they had dimmed due to the amount of water being splashed skywards. I have a battery monitor on and it was reading 12.4v, i.e not charging and never charged for the rest of the trip home which was about a mile. It didn't make any difference whether I turned everything off or on, the state of the battery stayed the same. I stopped and started a couple of times and still no change but if I added my second battery into the circuit by means of a manually switched relay the voltage went up to 14.4v and you could hear a change in engine note signifying load on the alternator. Disconnect the 2nd battery and the alternator stopped charging. The second battery is not connected to any voltage sensitive fancy switching, it is just a simple relay that when switched joins the +ive terminals together and the live feed is from the 2nd battery, through a toggle switch then relay to energise the switch then a battery -ive so has no connection to the vehicle electrics.
Long and short of it is I'm confused as to why connecting a fully charged battery fires up the alternator whereas putting a load on the vehicle such as lights or fan won't. I'll have to look in the morning in daylight and when things have dried out, it may be that by putting the second battery in the loop gives a better earth but I'm sure that the second battery is earthed through the main battery set up. |
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11th Jan 2013 12:04am |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610  
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Maybe I'm reading it wrong but as each battery cell normally equates to 2 volts or just over when fully charged is it possible you have a cell that's 'thrown it's hand in' (shorted out) on one of your batteries perhaps? Swap the two over and see if the fault transfers to the second battery position.
 If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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11th Jan 2013 9:57am |
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| JWL Member Since: 26 Oct 2011 Location: Hereford Posts: 3443
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I'm confident that both batteries are OK, just changed secondary battery. The problem is that the alternator does not appear to kick into charging mode untill I join the second battery into the system/circuit which in the cold light of day tells me that there is an earthing problem that isn't sorted untill the second battery is connected and allows the charging circuit to find an earth.
After I've had a coffee and a sit down I'm off to investigate, been off on the school run and sorting the pony out this morning(It may be that my meter is picking up a reading from the same battery on both settings due to my workmanship  ) |
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11th Jan 2013 11:06am |
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| JWL Member Since: 26 Oct 2011 Location: Hereford Posts: 3443
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Doh feel a bit of a prat now but a simple job to rectify
 Yesterday I had a look at why my front A bar spots weren't working, I have wired in a relay just behind the front nearside headlight taking the trigger via an inline fuse from the full beam wire at the headlamp. The main feed is from my remote solonoids for the front winch which are in the same location in a waterproof box. When I had put my new battery to replace my last second leisure battery I had inadvertently swopped over the feed to the winch which meant the feed wire for the spots was now connected to a negative terminal, swopped round at the battery and all fine. Whilst trying to tidy up the spaghetti under the seatbox I had connected a few smaller wires for different auxillary feeds to the second battery and in doing so I had put both monitor wires to the same battery
Another simple fix I then spent an hour putting a programmable timer I got from fleabay into the circuit for the Eberspacher, that is now relegated to a hidden shelf in the garage as I couldn't get the damn thing to work  Seemed to work when I tested it in the house but couldn't get the damned thing to work in the motor so to keep my health  and temper on an even keel I gave up |
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11th Jan 2013 3:30pm |
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