Engine 850: B5254S/2.4/20v: - Battery draining, and intermimttent red warning light! - Page 2

iamrolling · Oct 21st, 2006, 16:59

As promised, here are those voltage readings, taken by removing each of the fuses, then taking a reading, with the engine turned off:

Circuit 6 (Central Locking), 8v, fuse 25
Circuit 7 (Radio amp), Grew slowly to 10v, fuse 15
Circuit 8 (Immob), 9v, fuse 10
Circuit 13 (Hazard/headlamp flashers), 10v, fuse 15
Circuit 15 (Courtesy lights, diagnostics, door warning lamps (remote keyless entry, glove compartment lamp) 2.5v, fuse 10
Circuit 16 (Power antenna, power to caravan, accesories), 8v, fuse 30
All other circuits did not show a voltage to my knowledge.

Alternator readings to follow!

The secondary thatcham immobiliser is fitted on circuit 16 I am pretty sure, because it 'blipped' when I removed the fuse. This secondary device is connected to the central locking system, and is how the previous owner locked/unlocked his car.

Please help me interpret these readings! The radio is unmodified Volvo own.

Conehead · Oct 21st, 2006, 23:31

red warning light on the dash indicates a charging problem.
just because you have the correct voltage it does not mean you have the correct ampage from the battery.
The fact that the battery is 6 months old and so is the alternator could mean a fresh battery could have disguised the fact that a sub-standard amp rated alternator has been fitted.
The first thing I would try is to disconnect the alternator main feed to see if you have an internal short in the reg pack.
Do a volt drop on the alt circuit - connect multimeter to earth on battery and to body of alternator on Volts, with the engine running and lights on. should read 0v but less than 0.5v is ok
do the same on the positive side - same readings.
any varition move the leads along the circuit until you have the right figures and you have foung the faulty wire.
the next thing if that is ok and the battery still drains is to connect an ammeter to the battery,with the ignition off have an assistant open doors and glove box, boot etc and see if the meter reading changes, about 0.8 A for an internal light.
If this still does not find the drain then disconnect fuses one at a time.
as a general rule it will take about 2-3 days for an internal light to drain a good battery to stop a car starting, and a lot quicker for a significant drain.
also you might want to check that dash warning lights are not appearing on the dash when the car is locked and left for a while.

Conehead · Oct 21st, 2006, 23:34

sorry forget to say you want to be checking the ampage not the voltage of these circuits. Disconnect battery neg and place ammeter in line between battery and earth lead.
Dont forget to change the leads back if you then check volts
How many fuses have I blown doing that!

Jod T5 · Oct 23rd, 2006, 07:24

Quote:

Originally Posted by iamrolling

As promised, here are those voltage readings, taken by removing each of the fuses, then taking a reading, with the engine turned off:

Circuit 6 (Central Locking), 8v, fuse 25
Circuit 7 (Radio amp), Grew slowly to 10v, fuse 15
Circuit 8 (Immob), 9v, fuse 10
Circuit 13 (Hazard/headlamp flashers), 10v, fuse 15
Circuit 15 (Courtesy lights, diagnostics, door warning lamps (remote keyless entry, glove compartment lamp) 2.5v, fuse 10
Circuit 16 (Power antenna, power to caravan, accesories), 8v, fuse 30
All other circuits did not show a voltage to my knowledge.

Alternator readings to follow!

The secondary thatcham immobiliser is fitted on circuit 16 I am pretty sure, because it 'blipped' when I removed the fuse. This secondary device is connected to the central locking system, and is how the previous owner locked/unlocked his car.

Please help me interpret these readings! The radio is unmodified Volvo own.

i will check mine late although my initial reaction is that your voltages are very low..(obviously cos the battery is draining)...
i would definately expect your readings to be closer to 12v...http://www.uuhome.de/william.darden/carfaq10.htm
cheers
jod

Jod T5 · Oct 23rd, 2006, 16:38

i have checked mine and all the readings are the same, except my voltage is 12.5 showing the battery is at full power....
you are sure the battery is good, whats the amp/hour...
whats your alternator charging with the engine running...
i think you may need to invest in a heavy duty battery....
cheers
jod

iamrolling · Oct 29th, 2006, 08:14

Battery specs from label: 58 ah, and 570 cold crank amps.

With the engine running (headlights off) the voltage between battery and alternator casing is constant voltage, roughly 12-14V. Apologies for the vagueness, as my crumby analogue multimeter is difficult to read.

Does this shed any light?

Conehead · Oct 29th, 2006, 23:08

Realistically you need to load the alternator, lights on and rev to 1500 rpm
but most give the same reading at idle.
Put lots of load on the car and simulate normal conditions for your average drive. You should get 13.5v - 14.5v.
Be warned though if the battery is gone you will get lower.
If it makes this figure with excess load at idle the alternator is fine.
I went out to a tvr once that kept getting flat batteries and no-one could work out why, it was because he had an 800w stereo that he played v. loud whilst sitting in traffic, and the alternator didn't charge until 2000 rpm.
Do you have an install or sat nav, i-pod attached etc, if so put all these on when you check the charge, turn on all the lights wipers, heted seats etc - not hazards as they are on/off . if you get 13.5v charging at the battery terminals then the alt is ok. If you don't use the pos on the alternator and the earth on the battery and see if it's better.
12v is not good enough, especially in winter.

NugentS · Oct 31st, 2006, 18:09

Also if you have flattened the battery several times then its probably knackered - or at least getting there.

The sort of battery that starts cars does not respond well at all to being flattened - it ruins them.

Sean

Jod T5 · Nov 1st, 2006, 07:22

Quote:

Originally Posted by jod t5

i think you may need to invest in a heavy duty battery....

i agree with ^^^^^
cheers
jod

Conehead · Nov 1st, 2006, 16:13

as far as battery specs go 12.2v is 50 % charged 12.8 is maximum charge
Doesn't matter what the cold crank is see if the battery will turn the engine over with the coils disabled (pref fuel as well) and see if it drops below 9.5 v quickly. this gives a good indication to the condition of the battery.
warning this puts load on the battery so dont do it if its been gassing and stand clear just in case!
570A battery should be heavy duty enough for this car

Oct 21st, 2006, 16:59	#11
iamrolling New Member Last Online: Apr 8th, 2008 07:13 Join Date: Oct 2006 Location: Southampton	Votage readings As promised, here are those voltage readings, taken by removing each of the fuses, then taking a reading, with the engine turned off: Circuit 6 (Central Locking), 8v, fuse 25 Circuit 7 (Radio amp), Grew slowly to 10v, fuse 15 Circuit 8 (Immob), 9v, fuse 10 Circuit 13 (Hazard/headlamp flashers), 10v, fuse 15 Circuit 15 (Courtesy lights, diagnostics, door warning lamps (remote keyless entry, glove compartment lamp) 2.5v, fuse 10 Circuit 16 (Power antenna, power to caravan, accesories), 8v, fuse 30 All other circuits did not show a voltage to my knowledge. Alternator readings to follow! The secondary thatcham immobiliser is fitted on circuit 16 I am pretty sure, because it 'blipped' when I removed the fuse. This secondary device is connected to the central locking system, and is how the previous owner locked/unlocked his car. Please help me interpret these readings! The radio is unmodified Volvo own.

Oct 23rd, 2006, 16:38	#15
Jod T5 Phoenix from the ashes Last Online: Apr 24th, 2024 01:05 Join Date: Jan 2006 Location: Finchingfield	i have checked mine and all the readings are the same, except my voltage is 12.5 showing the battery is at full power.... you are sure the battery is good, whats the amp/hour... whats your alternator charging with the engine running... i think you may need to invest in a heavy duty battery.... cheers jod __________________ Dum Spiro Spero VOC 20419

Oct 29th, 2006, 08:14	#16
iamrolling New Member Last Online: Apr 8th, 2008 07:13 Join Date: Oct 2006 Location: Southampton	Battery specs, and alternator output Battery specs from label: 58 ah, and 570 cold crank amps. With the engine running (headlights off) the voltage between battery and alternator casing is constant voltage, roughly 12-14V. Apologies for the vagueness, as my crumby analogue multimeter is difficult to read. Does this shed any light?

Oct 21st, 2006, 23:31	#12
Conehead Senior Member Last Online: Feb 18th, 2011 10:28 Join Date: Jan 2006 Location: dartford	red warning light on the dash indicates a charging problem. just because you have the correct voltage it does not mean you have the correct ampage from the battery. The fact that the battery is 6 months old and so is the alternator could mean a fresh battery could have disguised the fact that a sub-standard amp rated alternator has been fitted. The first thing I would try is to disconnect the alternator main feed to see if you have an internal short in the reg pack. Do a volt drop on the alt circuit - connect multimeter to earth on battery and to body of alternator on Volts, with the engine running and lights on. should read 0v but less than 0.5v is ok do the same on the positive side - same readings. any varition move the leads along the circuit until you have the right figures and you have foung the faulty wire. the next thing if that is ok and the battery still drains is to connect an ammeter to the battery,with the ignition off have an assistant open doors and glove box, boot etc and see if the meter reading changes, about 0.8 A for an internal light. If this still does not find the drain then disconnect fuses one at a time. as a general rule it will take about 2-3 days for an internal light to drain a good battery to stop a car starting, and a lot quicker for a significant drain. also you might want to check that dash warning lights are not appearing on the dash when the car is locked and left for a while.

Oct 21st, 2006, 23:34	#13
Conehead Senior Member Last Online: Feb 18th, 2011 10:28 Join Date: Jan 2006 Location: dartford	sorry forget to say you want to be checking the ampage not the voltage of these circuits. Disconnect battery neg and place ammeter in line between battery and earth lead. Dont forget to change the leads back if you then check volts How many fuses have I blown doing that!

Oct 29th, 2006, 23:08	#17
Conehead Senior Member Last Online: Feb 18th, 2011 10:28 Join Date: Jan 2006 Location: dartford	Realistically you need to load the alternator, lights on and rev to 1500 rpm but most give the same reading at idle. Put lots of load on the car and simulate normal conditions for your average drive. You should get 13.5v - 14.5v. Be warned though if the battery is gone you will get lower. If it makes this figure with excess load at idle the alternator is fine. I went out to a tvr once that kept getting flat batteries and no-one could work out why, it was because he had an 800w stereo that he played v. loud whilst sitting in traffic, and the alternator didn't charge until 2000 rpm. Do you have an install or sat nav, i-pod attached etc, if so put all these on when you check the charge, turn on all the lights wipers, heted seats etc - not hazards as they are on/off . if you get 13.5v charging at the battery terminals then the alt is ok. If you don't use the pos on the alternator and the earth on the battery and see if it's better. 12v is not good enough, especially in winter.

Oct 31st, 2006, 18:09	#18
NugentS Me Last Online: Oct 29th, 2020 11:41 Join Date: Dec 2002 Location: Somewhere in the UK	Also if you have flattened the battery several times then its probably knackered - or at least getting there. The sort of battery that starts cars does not respond well at all to being flattened - it ruins them. Sean

Nov 1st, 2006, 16:13	#20
Conehead Senior Member Last Online: Feb 18th, 2011 10:28 Join Date: Jan 2006 Location: dartford	as far as battery specs go 12.2v is 50 % charged 12.8 is maximum charge Doesn't matter what the cold crank is see if the battery will turn the engine over with the coils disabled (pref fuel as well) and see if it drops below 9.5 v quickly. this gives a good indication to the condition of the battery. warning this puts load on the battery so dont do it if its been gassing and stand clear just in case! 570A battery should be heavy duty enough for this car

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