Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

I have a Ford Courier van. 12 years old, bought from nearly new and done 46K miles only. I think the current battery is about the 3rd I have had for the van.I use it to take the dog out for the most part and consequently only do about 4K miles per annum. Morning trips to the park and weekend country walks are about all it has.
As the wet weather and the frosty weather have come upon us it has begun to be more difficult to start in the morinig, culminating in a total flat battery this mronig. For many years I ahd no problem wiht the van starting but oevr the last 2 years this has become an issue.
Are my problems down to  a lack of charge for the battery and just need to keep buying a new battery each time? or is there another more underlying problem. I am told that the battery is charging OK and that there does not appear to be any underlying problem wiht the van's electrical system.
beofre spedning more money, I would just like some feedabck as to what others feel is the problem. If it is a new battery then I will just buy one, but would appreciate your feedback first  

i would have the battery fully charged...     bring it up to 12.65 volts measured after a minute with the engine off and the headlights on...

12.65 volts is a 100 percent charge...
12.45 volts is a 50 percent charge..
12.25 volts is a 25 percent charge

with the battery fully charged.. you can have the alternator tested...  

the charging system should keep the battery voltage above 14.3 volts...  this is a test that you can do with your digital volt meter... by measuring directly across the battery with a digital volt meter with the engine idling .

if you do not get this much voltage... check the alternator belt for proper tension...    if the belt tension is tight enough ...  the belt won't squeek/ squeel on a cold start up...


( hand held digital volt meters can be purchased starting at about 5 bucks...   decent ones about 20 bucks...  ones that will do all kinds of automotive measurements for 100 bucks.. but the 5 to 20 buck versions work great... )

what happens when it does not charge up to specs...

the belt could be loose...   it takes between 5 and 10 horsepower to make full charge amps...

the diodes in the alternator have started to go...  there are 6 diodes in the rectifier bridge in  most...  there are 3 sets of windings..      2 diodes on each wire...    one positive diode  one negitive diode...

when the alternating current is divided by the diodes... all voltage above 0 goes out the positive diode to the output terminal on the back..        all voltage below 0  goes through the negative diode and into the alternator case  which is bolted to the engine...

when one or more diodes go bad...  the alternator has less output.. and cannot keep up with all the demands of the car..

when the batterys go bad...   (you can tell as the ends of the cases will swell)  the alternator trys to push power in...  harder and harder ...  the diodes heat up and die...

this is one of the reasons that mechanics like to change the battery if the alternator is replaced..   saves them and you the failure that may result...

if you do not drive the car or van enough to put the current back in the battery after you have started the car.. you will be in the problem you describe...    it takes depending on how hard your van is to start..    10 to 20 minutes of running to bring the battery up....   if it has discharged even deeper... it will take longer..   if the alternator is not putting out enough current... it will never catch up...

you can get small solar chargers that lay on the dashboard to help...   but too small won't put out enough to do more than just stopping the battery from discharging..

and... what ever you ***       DO NOT pull the battery cable off to test the charging system.. this damages the diodes as for the instant you do that.. the output amperage that was being pushed into the battery has no place to go.. so the voltage goes up...  it can go over 100 volts for an instant..  that will take the life out of the diodes and other electrical devices in your car...

like the computer, the fuel pump,  the dash board,  the stereo , and of course the alternator..

hope this helps...  

Try checking the battery first and then the ignition.