C70: - Have I done something bad to my car???

babelfish69 · Sep 27th, 2008, 01:51

My apologies for a longish first post, but my pride and joy seems to be possesed.
I returned from holiday earlier this week and went to start the car to find the battery flat, not a problem I thought, jumped it from the wife's S40 no problem. At this point I was'nt too concerned, Ive had the car 2 years with the knowledge it had an old battery that was too small anyway. I then take the car for a run (20 miles), but its dead again next morning. I now put it on a charger for the day, which after 10 hours says fully charged. Again starts no problem, next day flat wont start.
Ok I think Ill write the battery off and get a nice new one. So on go'es the new battery using jump leads so I didnt lose power to radio etc. This time correct amp/hrs and everything, and Im a happy boy again.......wrong. After 20 minutes driving I notice assorted warning lights on the dash board coming up, the cabin fan died, then the radio went. I stop have a look cant see anything out of place, so i limp it to work. I stop the car and try to restart it and its flat, but leave it for a couple of hours and it fired up with no warning lights like nothing had ever happened. Driving home on come various lights (ABS, TCS, Brake Warning, Bulb Warning, SRS) radio goes along with the fan again, but this time the trip computer dies with the speedo needle and the mileometer. to top it all the dash lights gradually get dimmer the car lacks power then the engine cuts out completly at the next set of traffic lights. By now Im having a really bad day and you guessed it it would'nt start.
Having looked at various threads on here, the chritmas tree warning lights sound very similar to ED's post, which you guy's put down to his alternator on his 850. Although the battery light isnt one of the lights that came up. But has anyone any idea what's going on with the other stuff? Have i fried the electrics somehow, any suggestions would be greatly recieved to point me in the right direction, Ill be testing the alternator in the morning and hopefully getting my hands on a OBDII reader as well.
Please help me before I attack it ala Basil Fawlty.

NI_Volvo_Nut · Sep 27th, 2008, 07:05

lol'd @ basil fawlty

Sounds like your alternator, that would be my first point of calll before heading for more expensive / complacated areas.

But tell ya what, i'll take a chance and offer ya bad money for her lol

Jod T5 · Sep 27th, 2008, 08:41

Yes i too LOL at Basil Fawtly....
On the 850, if the car is running and the generator fails you get the Christmas Tree effect of 5 or 6 lamps illuminating, including brakes and coolant. This is "normal"....
At suggested check out the generators strength with the engine running, using a multi-meter. You should get 12.7Vish... Also check the belt....
I expect that as the battery was new, it recovered in a couple of hours when left, then drained again...
Cheers
Jod

BrockyV70Turbo · Sep 27th, 2008, 09:21

Could it not also be a very bad earth ??? maybe , perhaps possibly

S60D5NI · Sep 27th, 2008, 09:53

Quote:

Originally Posted by BrockyV70Turbo

Could it not also be a very bad earth ??? maybe , perhaps possibly

A lot of the warning systems rely on the fault condidtion creating a path to earth and collapsing the voltage in the relevant circuit. If you have a bad earth, you loose the referance point. If you remember your physics, voltage is the potential difference between two points. So if you assume 'good' earth is 0 volts and the battery is + 12 volts, the potential difference is 12 volts. With a 'bad' earth, the earth reference voltage will rise. Say it gets to 8 volts - in this case the potential difference is 4 volts (i.e. difference between your 'earth' at 8 volts and battery at 12 volts is now 4 volts).

The fault monitoring systems (i.e. the electronic brain) will most likely then see a fault condition - as far as it's concerned the circuit voltage has dropped from 12 volts to 4 volts - warning lamp lights. If it's a general earth problem (i.e. connection between battery and car body is poor) you will get the 'christmas tree'.

HOWEVER - the same effect will happen if the battery voltage is collapsing. If the alternator is goosed, as you drive along everything is powered from the battery, battery voltage collapses, all warning circuits volage collapses... you see where I'm going!

Therefore, I agree with other posters - it sounds like a classic case of busted alternator.

Jod T5 · Sep 27th, 2008, 10:22

Just to clairify the 850 explanation from the book....

Cheers
Jod

BrockyV70Turbo · Sep 27th, 2008, 10:41

Quote:

Originally Posted by S60D5NI

A lot of the warning systems rely on the fault condidtion creating a path to earth and collapsing the voltage in the relevant circuit. If you have a bad earth, you loose the referance point. If you remember your physics, voltage is the potential difference between two points. So if you assume 'good' earth is 0 volts and the battery is + 12 volts, the potential difference is 12 volts. With a 'bad' earth, the earth reference voltage will rise. Say it gets to 8 volts - in this case the potential difference is 4 volts (i.e. difference between your 'earth' at 8 volts and battery at 12 volts is now 4 volts).

The fault monitoring systems (i.e. the electronic brain) will most likely then see a fault condition - as far as it's concerned the circuit voltage has dropped from 12 volts to 4 volts - warning lamp lights. If it's a general earth problem (i.e. connection between battery and car body is poor) you will get the 'christmas tree'.

HOWEVER - the same effect will happen if the battery voltage is collapsing. If the alternator is goosed, as you drive along everything is powered from the battery, battery voltage collapses, all warning circuits volage collapses... you see where I'm going!

Therefore, I agree with other posters - it sounds like a classic case of busted alternator.

So thats a no then ? LOL
Thanks

S60D5NI · Sep 27th, 2008, 13:31

Quote:

Originally Posted by BrockyV70Turbo

So thats a no then ? LOL
Thanks

The Irish gift-of-the-gab extends to the written word as well you know! LOL

Not a 'no' - it's a 'probably not' for both (earth fault / have I done something bad to my car).

I'm no expert and have been proved wrong many time before. Therefore, if it is an earth fault, I hereby give permission to Brocky to be first to post 'ya boo sucks'.

Cheers & have a great weekend

babelfish69 · Sep 27th, 2008, 17:16

Yet again the forum knowledge base comes up trumps.
Thanks guys, checked the battery out today, only got 10.8v with no rise with the engine running, so looks like the alternator. All I have to do now is figure out how Im going to get the darn thing off......
Oh and by the way NI volvo nut, she may be sickly at the moment, but I aint parting with her yet........however any scraped knuckles or crushed fingers during her repair may result in a different answer.

Sep 27th, 2008, 01:51	#1
babelfish69 New Member Last Online: Apr 26th, 2013 13:25 Join Date: Jan 2007 Location: london	Have I done something bad to my car??? My apologies for a longish first post, but my pride and joy seems to be possesed. I returned from holiday earlier this week and went to start the car to find the battery flat, not a problem I thought, jumped it from the wife's S40 no problem. At this point I was'nt too concerned, Ive had the car 2 years with the knowledge it had an old battery that was too small anyway. I then take the car for a run (20 miles), but its dead again next morning. I now put it on a charger for the day, which after 10 hours says fully charged. Again starts no problem, next day flat wont start. Ok I think Ill write the battery off and get a nice new one. So on go'es the new battery using jump leads so I didnt lose power to radio etc. This time correct amp/hrs and everything, and Im a happy boy again.......wrong. After 20 minutes driving I notice assorted warning lights on the dash board coming up, the cabin fan died, then the radio went. I stop have a look cant see anything out of place, so i limp it to work. I stop the car and try to restart it and its flat, but leave it for a couple of hours and it fired up with no warning lights like nothing had ever happened. Driving home on come various lights (ABS, TCS, Brake Warning, Bulb Warning, SRS) radio goes along with the fan again, but this time the trip computer dies with the speedo needle and the mileometer. to top it all the dash lights gradually get dimmer the car lacks power then the engine cuts out completly at the next set of traffic lights. By now Im having a really bad day and you guessed it it would'nt start. Having looked at various threads on here, the chritmas tree warning lights sound very similar to ED's post, which you guy's put down to his alternator on his 850. Although the battery light isnt one of the lights that came up. But has anyone any idea what's going on with the other stuff? Have i fried the electrics somehow, any suggestions would be greatly recieved to point me in the right direction, Ill be testing the alternator in the morning and hopefully getting my hands on a OBDII reader as well. Please help me before I attack it ala Basil Fawlty.

Sep 27th, 2008, 07:05	#2
NI_Volvo_Nut Volvologist Last Online: Dec 6th, 2023 11:13 Join Date: Aug 2008 Location: Bangor - Norn Iron View Photos By: NI_Volvo_Nut	lol'd @ basil fawlty Sounds like your alternator, that would be my first point of calll before heading for more expensive / complacated areas. But tell ya what, i'll take a chance and offer ya bad money for her lol __________________ What's the matter with the car I'm driving? Can't you tell that it's out of style? Should I get a set of white wall tires? Are you gonna cruise the miracle mile?

Sep 27th, 2008, 08:41	#3
Jod T5 Phoenix from the ashes Last Online: Apr 24th, 2024 01:05 Join Date: Jan 2006 Location: Finchingfield	Yes i too LOL at Basil Fawtly.... On the 850, if the car is running and the generator fails you get the Christmas Tree effect of 5 or 6 lamps illuminating, including brakes and coolant. This is "normal".... At suggested check out the generators strength with the engine running, using a multi-meter. You should get 12.7Vish... Also check the belt.... I expect that as the battery was new, it recovered in a couple of hours when left, then drained again... Cheers Jod __________________ Dum Spiro Spero VOC 20419

Sep 27th, 2008, 09:21	#4
BrockyV70Turbo brockyv70t Last Online: Aug 16th, 2010 18:56 Join Date: Sep 2008 Location: CONGLETON	Could it not also be a very bad earth ??? maybe , perhaps possibly __________________ 1998 Volvo V70 turbo se

Sep 27th, 2008, 10:22	#6
Jod T5 Phoenix from the ashes Last Online: Apr 24th, 2024 01:05 Join Date: Jan 2006 Location: Finchingfield	Just to clairify the 850 explanation from the book.... Cheers Jod __________________ Dum Spiro Spero VOC 20419

Sep 27th, 2008, 17:16	#9
babelfish69 New Member Last Online: Apr 26th, 2013 13:25 Join Date: Jan 2007 Location: london	Yet again the forum knowledge base comes up trumps. Thanks guys, checked the battery out today, only got 10.8v with no rise with the engine running, so looks like the alternator. All I have to do now is figure out how Im going to get the darn thing off...... Oh and by the way NI volvo nut, she may be sickly at the moment, but I aint parting with her yet........however any scraped knuckles or crushed fingers during her repair may result in a different answer. Last edited by babelfish69; Sep 27th, 2008 at 17:24.

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