11.9V is too low for a fully charged battery - should be 12.6V.A quick update after leaving the car for 3 days:
Ignition pos 1: 11.9v
Ignition pos 2: 11.3v
Cranking: 9.5v (engine took a 4 or 5 secs to start, cranking sped was slowly dropping until it fired up)
Once engine running: 14.0v
Good points.11.9V is too low for a fully charged battery - should be 12.6V.
I know the difference is only 0.7V, but this is significant.
I repeat my earlier advice - try connecting a battery charger to see if you can get the battery up to 12.6V.
During lockdown I have been putting a 6A charger on every couple of weeks for about 6 hrs or so. The initial voltage is close to your 11.9V but reaches 12.6V by the time the charger is disconnected. If I start the engine afterwards, the voltage rises rapidly to 14.5V.
It does appear that your battery is not being fully charged between start ups; either you are not driving enough or the alternator is below par.
True if the battery is totally exhausted prior to charging - I never let mine get that low;A battery the size of ours with a 5 amp charger can take DAYS to charge.
True if the battery is totally exhausted prior to charging - I never let mine get that low;
Extract from Service Manual: Open circuit voltage vs % capacity
Note: Open circuit refers to no load on battery, ie battery disconnected.
It is interesting to note that a 0.8V change can result in a 75% change in capacity.
Although much of this topic has been focussed on the starter motor vs alternator, it sometimes happens that problems can occur in more than one component simultaneously, so this shouldn't be discounted.
Just to add my 2p worth...
My car is a 2007 CRD. I know that my battery is on its way out, because the dealership noted this on my last service in March of last year.
I had not driven the car since last Thurday. This morning the EVIC showed the following:
Engine off - key in position 1: 10.6V
(Just about managed to start the engine - the voltage dropped to 9.6)
Engine started: voltage climbed to 14.5V
Driving with dipped headlights and rear demister on: 14.4V - 14.6V
Driving with dipped headlights on: 14.8V - 15V
(Very foggy today!)
I drove to the supermarket (around 11 miles) at speeds between 40 and 70mph. Got back in the car after around 30minutes.
Engine off - key in position 1: 12.5V
(Car started straight away)
Car is booked in for a service and MOT at the end of the months. Told garage to get a new battery ready.
A couple of observations I would make:
- Diesel engines are much more difficult to start in colder weather and take a lot of amps from the battery. To replace the used amps I think it is VERY important not to use the car for very short journeys as the constant charging and discharging will ruin the battery. Also, the alternator (as previously stated) will not have sufficient time to replace the spent charge, therefore the battery will become depleted. Repeatedly starting the car is a very bad idea.
- The voltage of a battery is only half the story: You may well have a battery that shows a voltage of 12.5V, but, may not have enough amps to cranck the car. A standard multimeter (or the EVIC) will not tell you the whole story. You really need a battery tester. The chrysler service manual suggest a 'Midtronics Battery Tester'.
Hope these obervations help.
Yeah, I have 2, a normal one and a tiny one for bike batteries.I remember the days before sealed batteries became the norm, when you could test for specific gravity and accurately determine the charge state and condition of each cell. I still have the hydrometer - gathering dust in the garage.
Exactly mate;Interesting read about batteries -especially the exploding type. I think it must have been in the 80's when a friend of mine experienced such an explosion in his new BMW when driving at high speed down a motorway. Maybe one of those "gel" types?
I also go for the largest battery that will fit into the cradle. My current battery is a Bosch Silver with a 5 yr warranty. Fitted 8 yrs ago, so wondering how much longer it will last. It replaced the original Daimler Chrysler which was only 6 yrs old at the time. I subsequently discovered that the battery was OK, but the alternator was the culprit and only 30k miles on the clock. Fortunately, I didn't dispose of the original battery and kept it for a bench supply in the garage. I put the charger on it infrequently and the voltage never drops below 12.6V.
This happened to me last year. Not the CRD, but my 25 yr old Audi A4 1.9TDi. Nothing to do with battery failure, but a broken ignition switch prevented me stopping the engine. Couldn't use the applying brakes/putting in gear trick to stall engine as that doesn't work with an automatic transmission. Tried disconnecting battery, but engine kept running. I later realised that wasn't a good idea, but didn't seem to have any after effects. I drove the car to my local garage and left it there, key stuck in ignition and engine running. I found out that ignition switch failures in VAG vehicles are not uncommon and particularly in Porsches. Still, can't really complain after 25 yrs. Unfortunately, as I drove to the garage, the starter motor tried to engage a few times and eventually packed up, so that had to be replaced as well as the switch. Thankfully, the resulting bill turned out to be much less than I had feared.Was running purely on alternator.
Fortunately, I've never heard of this problem with a 300C, but quoting Murphy's Law: "If anything can fail, it will".So if my Chrysler decides to"not switch off"; I would have to find the fuel pump fuse I guess.