So, long story short, I ran out of petrol the other day and had to leave the car with the hazards on while I walked the ¾ of a mile to the petrol station I was ironically on my way to, when I got back to the car and filled her up again I tried to restart her a few times but she wouldn’t start – I had also got a flat battery!!. I don’t use the car a lot and the last time had been a 20 minute drive in the cold and dark therefore had the heater and lights on. Obviously I just drained more of the battery than I had charged it up and then having left the hazards on and tried to restart it a few times had totally drained it. So I jump started it using some leads and another car, it started fine and I drove it up and down the A12 say 15 miles to charge it back up a bit. Last weekend I went to move it on the drive, after not having been used for a week, and it wouldn’t start again! Now this all may be nothing and simply down to not having been charged up enough since previously being drained. In the meantime though I had bought a CTECK 5.0 charger and when the car wouldn’t start on my drive I fitted the charger and left it overnight on the reconditioning setting. In the morning all the relevant lights are on the charger and all seems well with the car, it started fine and I was able to move it ok. Now, my question is, is there any way of knowing if the battery is now ok, or if I just simply need to fit a new battery? Or perhaps even if it a faulty alternator?? Are there are other problems it could be down to?? Is there any way of knowing if all is well and it just needed properly recharging?? Obviously it’s not really something I can trial and error as I may just end up being out again for a drive and get a flat battery again.
You need a cheapo multimeter which will help you diagnose the health of your battery and alternator. All instructions online.
Thanks Nick, I have a multimeter, think I can remember doing something similar in the past with it on an old track car that had a faulty alternator. Any guides you have used in particular?
Not done it for a few years either. If you google "multimeter check battery/alternator" I am sure it's all there in text, pictures, videos, smoke signals, braille, serbo-Croatian, Morse code etc
Thanks Nick. I dug out my trusty multimeter (and instructions!!) last night, as mentioned I remember doing the same a few years ago, I think you test the voltage of the battery with ignition off and then with the engine running to see if it increases when the alternator is hopefully working. Will let you know how I get on.
From memory the battery should show around 14.7 volts when the alternator charging / OK condition. And just over 12.5 volts when not charging. You can't do a load test though (a lot of battery / car places will test tour battery though and do a proper test to check for bad plates / cells etc that may not show up on the multi meter) Sent from my HTC Desire EYE using Tapatalk
Thanks, much appreciated. So if it’s showing 12.5V when not charging then I know the battery is ok and has held charge since being reconditioned with the CTECK. And if it reads 14.7 when the engine is running then I know the alternator is charging ok. On the basis that I haven’t used the car since last being charged/reconditioned last weekend, other than I had it running for a few minutes when moving on my drive, would I expect it to have lost much charge and be less than 12.5V? How would I know if it’s just time to bite the bullet and buy a new battery, or if the CTECK has done its thing ok?
I checked the battery, bearing in mind that the car has been sat since last Saturday when it was fully charged/reconditioned and had also ran for a few minutes, it was 12.52 ignition off and then 14.57 when engine running. I checked again when the ignition was turned back off and it had gone down slightly to 12.37. So all sounds that everything is ok, doesn't it? Is the fact it 'only' read 14.57 rather than 14.7 when charging anything to worry about?
"Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts." Mine was 14.57 when charging therefore within the 13.7 to 14.7 range so hopefully the alternator is ok..... And on the basis that my battery wouldn't have been fully charged at 12.52 it was only just under under the 12.6. I will check again at the weekend to see if it's drained down further for any reason.
You need to run the car for a good few miles during the day, so no lights, heater, rear demist etc to get the battery charged, then the battery voltage will read higher, just because the engine is running doesn't mean it's going to read 14.7 volts but after a good run it will. Another way to see if the battery is on is way out is measure the voltage while starting from cold, connect your meter across the battery and put it where you can see it while you hit the start button, voltage will drop but a good battery it should not drop bellow 11 volts.
Checked the voltage last night after having been left since Wednesday and it was reading 12.36, which I think means that it's holding charge ok as it was last 12.37. I gave it a charge over night and this morning it was 12.59. Took it out for a drive, unfortunately needed the wipers, lights and heater on but after the drive it had only gone down to 12.43, so again I think all is ok. Am I reading the results correctly??
Checked it again today after having been left since last weekend and it had only gone down to 12.37 so thankfully I think all is well.
