Battery or alternator issues?

[Chiveroni]

Hi (again)

I guess it's because I'm a newbie and I'm finding the issues but I think I have either a dud battery or a bad alternator? I just hope I haven't bought a dud car...

Unlocked the car this evening, opened the boot and connected the smart charger. Showed only 7v. Couldn't unlock the doors with the fob - dead. Manually unlocked the doors and both the tacho and speedo were kind of vibrating and there were clicks coming from inside the dashboard(?) and the central display was kind of pulsing between black and a slight glow. Tried to start it - literally nothing - just the red P warning light flashing very quickly along with another warning light that isn't in my manual - an orange triangle in a circle. Key was locked in the ignition and my smart charger showed Batt! which means a dead battery.

I extracted the key and removed the negative lead from the battery and left it for a while. Then reconnected the battery and charger. Started at 7v, dropped down to about 5v and is slowly moving up to 12v. Still won't start (although could hear something clicking in the engine bay so def sounding more promising) and I have a few fault lights - which i believe is normal with a low battery. So - it's currently charging and I hope will be OK in a few hours. But looks like it's charging AOK

How can I tell if it's just a bad battery that isn't retaining its charge or a good battery but a faulty alternator not charging it?

I'm confident I have driven enough miles after charging it fully (about 35) so that I haven't drained the battery with short trips.

Thanks!

 

[Scaf]

I wouldn’t mess about - for the sake of £100 or less go get yourself a new battery and eliminate that….. chances are it will fix it.
One thing I have found that these car hate than a flat battery is one which just about starts the car, they tend to leave the dash lit up like a Christmas tree.

 

[Oneball]

If you disconnect a battery it should retain its charge for months. So if it’s disconnected and charged today and flat tomorrow it’s goosed. Remember if you do disconnect it to leave the boot open.

 

[safrane]

It's a new car to you so the supplier should be sending you a new battery by post as a minimum.

 

[philw696]

Put money on it being the battery especially if the car was sat around pre purchase.
Check the voltage going into the battery with a multimeter meter.

 

[mowlas]

Hi (again)

I guess it's because I'm a newbie and I'm finding the issues but I think I have either a dud battery or a bad alternator? I just hope I haven't bought a dud car...

Unlocked the car this evening, opened the boot and connected the smart charger. Showed only 7v. Couldn't unlock the doors with the fob - dead. Manually unlocked the doors and both the tacho and speedo were kind of vibrating and there were clicks coming from inside the dashboard(?) and the central display was kind of pulsing between black and a slight glow. Tried to start it - literally nothing - just the red P warning light flashing very quickly along with another warning light that isn't in my manual - an orange triangle in a circle. Key was locked in the ignition and my smart charger showed Batt! which means a dead battery.

I extracted the key and removed the negative lead from the battery and left it for a while. Then reconnected the battery and charger. Started at 7v, dropped down to about 5v and is slowly moving up to 12v. Still won't start (although could hear something clicking in the engine bay so def sounding more promising) and I have a few fault lights - which i believe is normal with a low battery. So - it's currently charging and I hope will be OK in a few hours. But looks like it's charging AOK

How can I tell if it's just a bad battery that isn't retaining its charge or a good battery but a faulty alternator not charging it?

I'm confident I have driven enough miles after charging it fully (about 35) so that I haven't drained the battery with short trips.

Thanks!

If the alternator had completely failed, I don’t think you would have gone 35 miles. However it may be starting to fail and not sufficiently charging the battery. From the information shared so far, it may just be lack of driving use.

The multimeter as @philw696 has suggested is a good investment. I got a cheap one on Amazon. Had a lot of help from the forum diagnosing battery vs alternator for my QP V recently. Useful info here for diagnosing with the multimeter…

https://www.sportsmaserati.com/index.php?threads/help-qp-v-centre-screen-went-dead-as-i-was-driving-now-car-won’t-start.35638/

 

[Chiveroni]

Put money on it being the battery especially if the car was sat around pre purchase.
Check the voltage going into the battery with a multimeter meter.

Thanks for the tip. At the risk of suffering a communal forum eye rolling (I'm not brilliant with electrics) is it just a case of placing my multimeter across the battery positive and negative when the engine is running and checking for a slightly higher voltage? I read between 13.6 and 14.6 volts? Thanks for your patience

 

[mowlas]

Thanks for the tip. At the risk of suffering a communal forum eye rolling (I'm not brilliant with electrics) is it just a case of placing my multimeter across the battery positive and negative when the engine is running and checking for a slightly higher voltage? I read between 13.6 and 14.6 volts? Thanks for your patience

Eye rolls from me as you managed to completely ignore my post above with a link to thread that should answer your questions!

 

[Chiveroni]

If the alternator had completely failed, I don’t think you would have gone 35 miles. However it may be starting to fail and not sufficiently charging the battery. From the information shared so far, it may just be lack of driving use.

The multimeter as @philw696 has suggested is a good investment. I got a cheap one on Amazon. Had a lot of help from the forum diagnosing battery vs alternator for my QP V recently. Useful info here for diagnosing with the multimeter…

https://www.sportsmaserati.com/index.php?threads/help-qp-v-centre-screen-went-dead-as-i-was-driving-now-car-won’t-start.35638/

Excellent - thanks. So please ignore the question I posted this morning. Posted it before I saw this excellent response.

Car has been charging overnight - charger shows it's nearly full. It did start this morning. Once the battery is full I'll disconnect the charger and get the multimeter in operation!

One of the reasons I got the car is for it to be a hobby. I want to learn these things. But kinda learning a lot more, and sooner, than I had planned

 

[Chiveroni]

Eye rolls from me as you managed to completely ignore my post above with a link to thread that should answer your questions!

Yep - please see my previously posted groveling apology. Hadn't refreshed my browser. Sorry about that - lesson learned.

 

[conaero]

Thanks for the tip. At the risk of suffering a communal forum eye rolling (I'm not brilliant with electrics) is it just a case of placing my multimeter across the battery positive and negative when the engine is running and checking for a slightly higher voltage? I read between 13.6 and 14.6 volts? Thanks for your patience

Yes, do a test with the battery fully charged, engine off. Then cold start then another when the car is warm, this is what you should expect:

Off: 11.8 - 12.5v
Cold start: 13.8v
Warm: 13.5v

Due to the self sensing alternator you will never see 14.4v being delivered

 

[mowlas]

Yep - please see my previously posted groveling apology. Hadn't refreshed my browser. Sorry about that - lesson learned.

No worries and my apologies for my overly quick reply! Good luck with this.

Do report back your findings, I’m sure the forum will help with interpreting your data, findings and questions.

 

[Phil H]

Yep - please see my previously posted groveling apology. Hadn't refreshed my browser. Sorry about that - lesson learned.

I'm sorry but that is not grovelling enough, and you must now paint your calipers yellow as a sign of penance!

 

[Ebenezer]

Are yellow calipers the equivalent of the dunce's hat?
Eb

 

[Chiveroni]

I'm sorry but that is not grovelling enough, and you must now paint your calipers yellow as a sign of penance!

I've stood myself in the corner of the room.....

 

[Phil H]

Are yellow calipers the equivalent of the dunce's hat?
Eb

Good thought Eb, the shade to reflect the degree of offending



In retrospect we'll give Chiveroni a pass as we don't want him painted into the corner, and he does have a very nice beastie.

 

[Chiveroni]

I think I'm going to be making many, many mistakes as I learn about the car. My daughter calls it / her "Villanelle" (she calls our XC90 "Bigfoot") - and I think Villanelle is going to keep me on my toes and land me with plenty of egg on my face until I reach a basic level of knowledge. But that's the fun part, right? Right??

Well - it's still charging so I'm thinking it's sounding more like the battery. I'll run the tests suggested by conaero as soon as the battery is full. I've attached a picture of the battery currently installed: 1) should I swap like for like (with regards Ah) or go for something more powerful and b) have I connected the trickle charge cables to ok places (I'll tidy the wiring once the battery is swapped)?

 

[safrane]

I also have an XC90 T8.

 

[Chiveroni]

It's my second XC90 - bought the first of the "new shape" back in 2015 and swapped it November last year for another new one. They are really fantastic cars cars for the family - throw the family in, add their friends, load the bags and off you go. I used to live in Germany - recently moved back to the UK so we do some outrageous journeys in the XC90s - long distance drives down to Austria, South of France, etc. They are so very comfortable for these long journeys.

 

[Chiveroni]

Yes, do a test with the battery fully charged, engine off. Then cold start then another when the car is warm, this is what you should expect:

Off: 11.8 - 12.5v
Cold start: 13.8v
Warm: 13.5v

Due to the self sensing alternator you will never see 14.4v being delivered

Hi Conaero

I removed the battery from charge when it was almost full (according to the display on the battery charger) - been on charge for 18 hours and still not full. Here are the results (sounds like the Eurovision song contest...)

Off: 12.07
Cold start: 13.86v
Warm: 13.31
Warm (with fans running): 12.26

I then reconnected the battery charger and it shows the battery as half empty. I doubt the battery level meter on the charger is super accurate. But it does look like the battery is cream crackered and that the electrical generation system in the car is running as it should be?

Would love to hear your thoughts.