I have a VW Golf Plus 1.9tdi. The battery is about 1 year old.
We don't use the car that much, mainly short trips and not every day.
At the moment, the battery just doesn't last. If we don't use the car for a few days it won't start at all. All the electrics come on, but there is not enough juice to turn over the starter. I had the battery tested a little while ago and it was good, about 75% life, just with a quite low charge. The alternator was putting out 24 volts.
Is this normal? How long should the battery last?
Batteries are normally guaranteed for 3 years from most branded suppliers and will easily last twice that if looked after. 24 volts is way to high and will kill it; should be 14 ish.
24 volts isn't normal. Should be around 14 volts. 75% life is very poor after 1 year. My 06 car with it's original battery was tested about 90% after the cold snap last year. IIRC most batteries have a decent warrantee with them these days. If you've got the reciept, take it back where it came from and get them to test it, and change it if you can.
Lots of infrequent short trips won't do it any good though, it's probably not charging up between the high starting load. Give it a decent run every week, at least 30 mins should help.
edit - too much detail slows a response!
24 volts is loads. 14 volts is a normal charging voltage. I'll assume you've mistyped.
Batteries should last 3 years or so, if used reasonably gently. You're currently using the battery about as hard as you can. There will be some current drain when the car is stood (alarm, immobiliser, radio, probably a body ECU etc.), diesels take a lot of grunt to start, and you need to put in some journeys of decent length to get some charge into the battery.
Have you got a garage where you can hook it up to a charger?
Might be worth checking the terminal conectors are clean and tight after the battery was first tested.
Every start of a Car will need approx 20 minutes of running to put the charge you've just used starting it back in (thats assuming the battery is 95-100% charged) the lower the charge the more it'll need untilk it gets to the point where the car won't charge it (use a battery charger 80% charged)
14 Volts is the norm, anything over and you'll end up cooking the battery, sounds like the Alternator could be on itrs way out.
Sorry, yes, 14 volts. Ok, so actually need to use more diesel just to get the battery to last. Unfortunately no garage to put it on a charger.
I'd return the battery and ask for a replacement.
I had the same problem with a petrol Passat, battery tested fine.
Making sure the radio and climate control were turned off before stopping the engine has seemed to fix it... even though their on/off state shouldn't matter when the ignition is off because the ignition controls their power supply. 😕
I bet its something in the car drawing power...got anything hardwired in like phone kits, or an aftermarket CD player?
With a one year old battery the car should be able to stand for weeks before you have any trouble starting it. Your journeys would have to be extremely short for it to fail to recharge sufficiently, and then it wouldn't start after a series of short trips, you wouldn't need to leave it for a few days.
Get a multimeter, and go through the fusebox, (there is often a second one under the bonnet) pulling one fuse at a time and measuring the current across the terminals. If you find any with current passing whilst the ignition is off you may be able to narrow it down further.
Another option would be to get one of those dash solar panels that recharges the battery via the cigar lighter, but they only work if the socket stays live when the ignition is off.
By the way, a battery at 50% charge is pretty much dead, especially if you want it to last any length of time, so 75% isn't great.
Take it for a good drive on a nice sunny afternoon, then try it again the next day. Will it start?
Check to make sure any interior or boot lights are on or anything else that could obviously be draining power from it.
To give you an idea, i have a V6 Mitsubishi SORN at the moment, I leave it parked with the battery disconnected for a month at a time, connect it back up and it starts first time EVERY time (even in winter). Somethings is drawing power from it.
The more the battery is discharged, the less time it will need to recharge a set amount. A very flat battery will charge very quickly due to the voltage difference between it and the alternator, as the battery nears full charge and 13v its charge rate will drop off significantly, to get the last 10% of charge you would need to use a smart multistage charger. An alternator will take many hours of continuous driving to top the battery right up.
So its likely that you are not fully charging the battery each trip, but very unlikely that you are failing to get enough charge into the battery to restart the car.
I still think the most likely culprit is something drawing power.
On motorbikes, aftermarket alarms are usually the culprit - any aftermarket electricals fitted?
Get a multimeter, and go through the fuse box, (there is often a second one under the bonnet) pulling one fuse at a time and measuring the current across the terminals. If you find any with current passing whilst the ignition is off you may be able to narrow it down further.
Some good advice from Spooky,If you have no access to a Fluke/volt meter its possible to "see a slight draw" in dark conditions,the fuse will spark slightly if it is removed and then re-fitted.
boot/glovebox interior light switches are common causes of current draw
(with Ignition off-key remooved) hth
There is an aftermarket reverse sensor fitted (was in the car when I bought it). Will borrow a multimeter and check the fuses. Will this affect the radio where if it loses power it needs a code?
its a good idea to make sure you have code for radio before disconnecting the battery or removing radio fuse
The radio should only need a negligible amount to retain its keycode and station presets. You can disregard that fuse unless the current is significant.