Mate has a s2 and its charging at 13.8. Randomly is battery goes dead in the cold and u get a click click when trying to start it.

However once jump started its fine and runs and starts again

I also noiced when i put my earth lead to his battery on the eletrical tester it changes from 13.8 to 14.1, as soon as i take earth cable from my car of his battery it goes back to 13.8

how can we get his car that extra 0.3 charge as everyone has said thats what it should charge at with new halfords battery and new recon alternator aswell.

any ideas?

cheers peeps

 

13.8 volts is perfectly ok and good and will NOT cause the problems you describe.
You need to check for a current drain, failing that it could be leaky diodes in the alternator, or even a duff battery even though new.
I have had this same problem with Halfrauds batteries, all they do is leave them on the shelves and check the voltage every so often, then charge any that are low, not the best way to ensure a long life out of a battery.
Forget about 14.3 being correct it is a load of crap, some cars run lower some run higher it is that simple, a lot of vauxhalls run over 15 volts.
tabetha

 

halfords done a test on it the battery and alternator, came back with the battery is good, not 100% mind u, but good. He said the alternator has got a problem, but it spanking new and it had the same problem with the old alternator aswell.

It randomlly just goes dead.

Maybe its the cells in the battery.

On its own the car is charging at 13.8, its just occasionally the battery goes dead.

Only thing thats left on is cat1 alarm and the chirp sensor if u come near it, but that don't go off unless u go up close to it.

Got a feeling a battery change might be needed again.

What do the alternator diodes do?

cheers

 

When the "battery goes dead" is it just the starter that is laying up, or the entire car electrics? If it's only the starter, then make some new cables from the battery to the starter.
The alternator grounds itself to the engine usually only thorugh the mounting bolts. Charging can be poor if the mount or bolts are rusted or painted.

 

rather than replacing the wires what if i put a jump start cable between battery negative and where the starter motor bolts to see if this improves the earth? if it makes no difference then this will rule this problem out?

 

The diodes in the alternator act as one way electrical valves.
Thus they stop the current flow from battery to alternator when the engine is not running, but thier main job is of RECTIFICATION.
A alternator produces negative and postitive current in equal amounts, it stops the negative bits getting through only allowing the positive to charge the battery, this is called a RECTIFIER, which is usually intergrated on most alternators with the regulator which is the bit that controls the AMOUNT of current/voltage.
If there is floating debris from broken plates in the battery this will cause self discharge, if it happens to bridge two plates of opposing material inside the battery, quiet normal this is, I have even washed batteries out before now, older batteries were particularly bad for this, but much better now.
The only sure fire way to know is to disconnect things, I would start by disconnecting the alternator, by means of the 13mm nut/lead, insulate this lead well though, as it is connected directly to the battery !!
tabetha