6 replies to this topic

[Zacherius (again!)]

Hey all,

I have a problem where the car after a few days ends up with a dead battery.

The battery is new and has been checked. Nothing is left on at night except the standard Rover Alarm.

When stood still and running, the alternator is giving out 13.8 (approx) and the battery is showing (12.8 approx). As soon as I start driving the voltage clock in the car goes from around 14 to about 12.5. If I turn on the lights etc it drops even more.

The alternator appears to be a 45 amp rover alternator, yet looking on some sites to buy a new one they all show the cooper (1996 to 2001) to be a 65amp. Is this right and would this be the problem or could something else be shorting it out and draining the battery.

The only other elctrical thing going wrong is the clock is running about a third of the correct speed ( or I enter a time warp when in the car ).

Please advise, and if its a new alternator I need, where is the best place to get one asap.

Thanks

Matt

[Zacherius (again!)]

Or could it be the battery halfords have supplied ???

[mini-luke]

If a significant amount of voltage is going ''missing'' between the alternator and battery, that suggests a short in the battery cable.

[Zacherius (again!)]

OK. Will check that. My earlier note is wrong, the alternator on the car is a 65amp one.

Does the Voltage clock in the car show the alternator output, or the batteries voltage ??? As it will be almost 14 on idle, then without turning anything on, just driving normal it will drop to 12.5 ?? Or is that normal ?

[Stevie W]

The volt gauge shows the "system" voltage across the battery terminals.
I had a problem like yours many years ago where excessive engine speed caused the alternator voltage cut out regulator to break down and this discharged the battery as the engine was running but all was ok on tickover.
It could therefore be the voltage regulator diode pack on your alternator!
Cheers,
Steve.

[Zacherius (again!)]

Thanks Steve,

All in all from here and other friends, sounds like I should check the lead from the alternator to Battery first and if fine replace the alternator.
Wheres the best and quickest place to get an alternator ?

Cheers. Matt

[Zacherius (again!)]

I've got a price of £110 for a next day delivery of a new Alternator, or £55 to fix mine. With it on its way out i'm just wondering whether its better to buy a new one, as they may repair the current problem and then something else will go wrong ?!?