starter & battery question

[evil_jesus]

the last fe days i have been getting the"click" only when i have been starting the truck up which i have put down to solenoid or motor brushes.
im now questioning that as i have noticed a reduced cranking speed and lights going a little dim on dash when turning over.
my truck has 2 batts, would one batt that goes t*ts up be the cause of my starting issues or is it batt and starter ??

EDIT :
i assume that batteries that are less than 12v are duff either on load or not
also, what amps should my alternator be kicking out

many thanks

[Apache]

Alternator is 80 or 90A if I recall.

A battery *just* under 12V isn't good but not necessarily dead. if it's well under, it's probably knackered.

Much more likely the batteries than the alternator - get them tested. You'll probably need to change both unless one's far newer than the other.

[NiftyNev]

If battery drops below 10V during cranking it is dead.

Nev

[JD_975]

This is a tricky one to answer, a battery is not necessarily duff at any voltage, and a battery that drops below 10V when cranking is not necessarily duff either. The only true way to know would be to get both battery`s charged up and have them tested individually. A single bad cell in a battery wont always cause the battery to read below 12V but it will reduce the ampage available to crank the vehicle which in turn will make it difficult to start.

Again with the alternator the amp rating is not really a practical guide as although you may have a 130 amp alternator that is only to say what it is capable of delivering, the actual amp rating it charges at varies depending on the state of charge in the batterys and the load placed upon it, i.e. good fresh batterys and a low load like daylight driving without the lights on etc the alternator is barely working and the ampage from it may only be 15-20 amps as that is all that is needed, the opposite if it`s been stood for a while and you have headlights on and heaters etc the ampage will ramp up appropriately.

Get the truck running and try a volt meter between the terminals of one of the batterys, if it`s between 13.5 and 14.5 Volts at high idle then your alternator is most likely fine, if your finding (like me currently ) that once started your truck will run and start all day but get worse over a few days then your most likely looking at a couple of shot batterys.

Hope this helps!

[schrodingers-cat]

if your finding (like me currently ) that once started your truck will run and start all day but get worse over a few days then your most likely looking at a couple of shot batterys.

Hope this helps!

Happened to me, it was down to the drive belts, one of them had snapped leaving one that looked like it was off a sewing machine to do the work, it was charging just not charging enough

[evil_jesus]

can anyone tell me the location of the starter motor relay ?

thanks

EDIT -
Found it.

when i turn ignition on i can feel the relay clicking in my hand, the starter solenoid fires which u can hear quite clearly, but motor does not spin.... the is a intermittent fault. what parts do i need or should i just get new starter motor ?

also does the power for the solenoid and the motor come from the same supply ?

Have just also replaced both batteries

thanks