Leisure battery charging problem

Airecraft

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Wednesday night, after a 400 mile drive , my leisure battery was down to 11.45V:( A couple of hours on a genny got it up to 12.4V and it seems that it is DIScharging from (to?) the alternator:confused: When I start the engine the voltage drops by ~0.2v. The engine battery is charging fine and the leisure batt. charges OK through the 240v charger.
Any ideas on what causes this before I throw myself on the mercy of an autoelectrician?

TIA

Andy
 
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If it is on a split charge relay it sounds like the relay could be malfunctioning and instead of connecting the alternator to the aux battery, the aux is discharging through a light or something. If you can find the relay, you can try replacing it, or disconnecting it to test, and taking the aux feed direct to the main battery positive to see if that makes a difference.
 
Battey charging

Hi. Look at the earth from/to the leisure battery.You could try a jump lead to a known good earth and see if that helps with the engine running.
Simples:)
 
That happened to us, a few weeks ago, the firm who installed the battery omitted to put an earth wire in - so wasn't charging.
 
If you are compatent then disconnect your aux battery and start the engine, once the red alternator light has gone out and the engine has run for a couple of minutes you should then have power going to the aux battery terminals. If you connect an AVO Meter or a simple 12v light across the now disconnected battery terminals you should have power, thats the wires that were connected to the battery not the terminals on the battery. If you do not have power then your battery is not being charged from the engines alternator and you should look to diagnose the relays and such like. (if you do have power then be careful not to let the terminals touch whilst the engine is running each other as you will get quite a spark)

Personally I would try this first. I recently convinced myself that the battery was not being charged from the alternator when it was and I was just expecting it to recharge too quickly. You need to drive quite some way to recharge a battery by the alternator if its been used heavily the night before whereas some good battery chargers will do the job quite quickly in an hour or so.
 
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Leisure battery not charging

Hi Aire on a shoestring,
Having read your post most carefully it would seem as if your leisure battery is properly connected as it charges when you are plugged in to a mains power source. (Correct me if I am Wrong):eek:
Therefore it would seem that your split charge relay is faulty.:(:( These relays are to be found under the bonnet (sometimes under a cover) very close to the van battery. They always have a fuse in the low tension circuit side of the relay. I suggest you locate the relay (often one of three such relays under the bonnet 1 for split charge 2 for auto step retraction 3 for 12v fridge power) carefully remove all fuses, check they are ok, clean the contacts and and after smearing LIGHTLY with vasaline replace. Do likewise for the relays.
Hope this helps.
Regards,
Wanderer:cool:
 
Check the fuse at in the engine compartment to ensure the leisure battery is getting charged. Earths are not a problem as you are able to charge through generator. If earth was faulty no charge would be achieved.

Not sure what your MH is however I have a Swift Kontiki and the fuses are under a cover in the middle of the engine compartment.

I have only recently discovered, as a result of reading the manual, that once the vehicle battery is charged the alternator goes on to a trickle charge. In my case, as a result of a few days draining the leisure battery and not the vehicle battery, I was not able to get a good charge into the leisure batteries. I have a recollection of a split charge relay???? that can overcome this problem?
 
I suppose some generators/chargers may have their own earth connection to complete the circuit depending on the set up: think of the old battery charger with positive and negative croc clips. In which case it would charge via the generator/charger but not via the alternator.

So the battery earth is still worth checking...

... but what I thought was revealing was you said the aux battery was discharging while running. That's why I thought the split charge relay was a more likely fault.
 
I have possibly made an incorrect assumption that you are using a generator to provide 240 volts and then using the MH charger to charge the battery in which case it would not be an negative lead fault. If you are using a generator with a 12volt output connected directly to the battery then negative lead fault is a possibility.

Appears to be a problem round your split charge relay/fuses.

Keep us posted
 
Thanks for all advice advice to date. I have tested the terminals with the battery removed and I do get a negative voltage across them when the engine starts, confirming battery discharge.
I have found the split charge relay near the engine battery and a blade fuse connected to it by a thick cable showed signs of the plastic case melting, along with part of the fuse holder, though the fuse itself has not blown. I replaced this fuse and ran the engine for ten minutes, only to find that the new fuse case had started to melt, but had not blown:confused:
I think I've gone as far as I can with my limited 12v knowledge so its off to the autoelectric man tomorrow. I'll post the outcome.
Thanks again.

Andy
 
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