Battery and sediment light after new alternator

[jaycey001]

Hi All

I have been reading the other post below about this (3 times now all the way through) but I think I have a different problem (electrical not a strong point of mine)

Ok, so I had the flashing sediment and charge light a few weeks ago and checked the voltage, which was fluctuating at idle so I changed the Alternator for a new one and all has been working fine for the past 400 miles.

But today they started flashing again - I have twin starting batteries and both hold 13 volt over several days of no use and when the engine is running the batteries are about 14.4 Volts. The voltage from the alternator is also stable at 14.4 volts. So I dont think there is a problem with my charging system but something is happening to cause the lights to come on.

Out of interest, I unplugged the two thin wires from the alternator and no lights came on on the dash. Having read quite allot I think I am now confused as what exactly to try next and as the flashing sediment and charge is very intermittent its difficult to know if anything I try has actually fixed it.

As soon as payday comes around I will be joining fully, as this will be my second technical query since ive had the van (about 4 weeks!!)

I will clean up the earth under the bonnet later as a first measure but if anyone could send through a step by step test I would be grateful.

Many Thanks
James

[g8dhe]

The "Charge" signal comes from the alternator itself so disconnecting the wire will stop the signal, it doesn't use the Battery voltage or charging current at all, these are to variable for the purpose.
Its not been unknown for alternators to fail shortly after replacement either.
You don't have a Split Charge Relay using the "Charge" signal do you ? Older SCR systems used to use the "Charge" signal to operate the relay, this is not a good idea at all as it leaves the "Charge" lamp partially lit and the detection circuit in the alternator is not designed to drive a relay either.

[jaycey001]

Thank you for the reply. I do not have a split charge relay (as far as I am aware) my Bongo is a northern Jap model and is fitted with twin starter batteries and the cold weather switch. Both batteries hold exactly the same charge.

I will look into the earthing option and report back.

Many thanks

[jaycey001]

Hi
Just a quick update.

I removed both earth points and cleaned them up and reinstalled them and cleaned all the contacts. So far it has been working well without any lights showing on the dash. Interestingly before all this the Alternator was kicking out 14.6 Volts and now its kicking out 15.4V -

I will report back if the lights reappear.

[g8dhe]

15.4 Volts is way to high!! Exceed 14.6 volts and you will cause the battery to start gassing and releasing Oxygen and Hydrogen, this is seriously unwise territory to be in, do NOT generate any sparks in the vicinity if you have been running the vehicle for more than a few minutes!!

[jaycey001]

Thanks for your reply, I will double check the voltage!!

[jaycey001]

So, an update! Went to take Bongo for a quick run to warm her up and check voltage and the alternator is not kicking anything out at all now.
So I have ordered a used one and will send back the new one for a replacement. It had a years guarantee so should be covered.

Hopefully that is the end of my sediment & charge light issues for a while now....