CTEK battery Charger says fine but no go

I don't understand this: Car is kept in garage (parked for a long time between use) connected to a CTEK charger. The charger does its thing and all the lights are good with the green healthy light on When I go to take the car out the battery is flat and won't turn the engine over Jump start the car go for a drive and the car starts fine after a run Volt meter in the dash reads around 12 or 13 when being driven I know the answer is to use the car more often but at present I can't ! So I am thinking perhaps the CTEK is not working despite indicating it is or there is a big drain on the battery when the car is parked which the CTEK can't keep up with ? Any ideas or is it a case of taking it to a garage for proper testing ? Thanks in advance for any help or ideas it's appreciated :thumbs:

I suspect you need a new battery. I also use a CTEK battery charger, and one morning I started the car - absolutely no problem - but at the end of the day it wouldn't start. The RAC came out and diagnosed a knackered battery. I think what happens is as the battery degraded over time, the CTEK kept the remaining capacity 'charged" at the correct voltage (hence green lights) when the actual power stored in the battery is very low. I had a new Bosch battery fitted, no problems since then. Also 12-13 volts when driving is low. It should be 14 volts. If you fit a new battery and the voltage you see doesn't increase your alternator might be on the way out...(you guessed it, mine failed 6 months after my battery)

So an update: Just been down to my local battery centre expecting to have to buy a new one. Took a note of the volt meter on the way in and it was sat at a constant 14 Had the battery tested under load and the battery turned out to be fine and "in very good condition" So I still don't get how after being parked up it fails to turn over with all the dash lights out or very dim i.e a flat battery, then starts with jump leads and starts on the key afterwards :dont know: Could this be a faulty earth strap or starter motor :?: It seems I will have to take it to the garage or an auto electrician unless we can think of anything else to check .... Thanks for your help so far :thumb:

I had a very similar problem that turned out to be the starter motor, and found this three batteries later (I have a 1000 amp one in the car as a result of this mis diagnosis). The connection on the starter was loose and the starter was faulty (worn out) as well. lots of carbon scoring but the moment you put a starter pack on it it fired up perfectly and drove well. Very big pain to diagnose initially but obvious in the end. Also, it would sometimes start cold, and never restart when hot...

Diagnosis is not rocket science, but a methodical approach by any competent mechanic should track down the fault. An auto electrician might be a good call as you can rest assured they will trace and locate the fault. It's amazing how many mechanics really don't have the right approach when it comes to electrikary or they get out the diagnostic computer and start replacing parts rather than getting out the multimeter and diagnosing

If you have a battery drain that is larger than what the cetek can charge the battery then it will go flat . you need a discharge check with an amp meter to rule this out . Amp meter connected then leave for 1 hour and read off .. 30 milliamps is the norm. These cars do a lamda burn off for the first 30 mins of a shutdown hence the need to wait for an hour or you will see about 0.8 of an amp .