Ongoing Flat battery issue

[timh30]

Hi,

For the last 3 years or so I've had an ongoing issue with my car battery going flat. I use the car maybe once or twice a week (as mainly work from home), but the battery usually goes flat within about 5 days of standing. As such I try to put it on charge if I know I wont be using it for a few days, but obviously I sometimes don't know this in advance.

I've now had 2 new volvo batteries (60Ah), I replaced the siren module (as I've read this can be a culprit), and have performed the following checks:

1. Battery draw is 70-80ma after about 15mins when car is locked. I know they say 50ma is max ideal drain, but I have an lpg system installed and integrated mp3 player connected to the head unit - so I assume the extra 20-30ma draw relates to these. However with a 60Ah battery I would still expect the battery to last longer than 5 days? By my calculation assuming the full 60Ah was drawn, it should last approx 31 days (at 80mA rate).

2. With the engine running, I've measured the voltage at battery and it is about 14.2 volts, even when I've put all electical circuits on - i.e. main beam, rear heater element, fans on full, fog lights etc. So this suggests the alternator is ok ? Certainly when the battery is flat and the car jump started, the alternator will then run the car and appears to charge the battery up again, although I have noticed that if I charge the battery up from external charger, it tends to last slightly longer - does this suggest an alternator issue even if alternator voltage appears ok ?

I've just purchased a DC clamp meter from ebay, so hopefully that will help in the troubleshooting, as I can then read the charging current.

The alternator is the original one, and I have read there were some issues with the voltage regulator/diode pack on the early ones - but the 'normal' checks don't intially suggest there is an issue. Just read it may be that when the regulator gets hot, the output voltage can drop and hence charging current - might need to investigate this further (although car has never cut out once running).

Having now purchased my 3rd battery in almost as many years (this time a 77Ah Bosch Silver Battery), I'd like to get this resolved once and for all. So am I expecting too much of the battery with an 80ma draw, or is my alternator not fully charging the battery for some reason and I need a new one, could I have had 2 duff batteries from Volvo (although the original one lasted 7 years) ?

Any help/advice gratefully received.

Tim.

[Jim314]

How and where are you measuring the 80 mA current draw? Did you have the mp3 player and LPG system installed with the original battery? When in relation to the start of this discharge problem were these installed?

Addn in editing

Couldn't you pull the fuses in turn for each of the suspect systems (mp3 player, LPG electrics, alarm) and see the effect on current drain, and on battery flattening?

[Rick Barton]

Stop buying batteries for goodness sake. Get the one's you've got checked before replacing them

[Bernard333]

The Bosch alternator on your car has the diodes connected to the stator coil ends and the regulator/brush pack is separate . Regulators are on ebay for £15 to £30 but I dont know if they are genuine Bosch or cheap copies , you can get a used alternator for around the same price . Its a pity its not your wifes D5 that has the problem as you can get the regulator off without even loosening the alternator but on the petrol version the inlet manifold and other stuff is in the way so its awkward . At 140k miles the brush on mine was substantially substantially worn down . I dont know what mileage you have on yours but I would be removing the regulator on any car with a mileage of 140k or more and checking the state of it . At the same time with the regulator off you can check the diodes but these are not common failures on this alternator unless you have a 1000 watt woofer going all the time . There is a capacitor built into the regulator cover which comes off and is separate from the regulator , you can check this for leakage but they rarely fail . I dont think you could have three faulty batteries in three years its has to be something in the charging system or a light coming on and staying on , I agree 80mA should not flatten a battery in 5 days .

[david philips]

http://www.youtube.com/watch?v=B__DqK90IIc

3 main things i have found are faulty diode in alternator , door lock solenoid,and alarm fault,good luck.

[Jim314]

In reference to Scotty Kilmer's procedure, one has to be careful in disconnecting and reconnecting the battery on these Volvos. There is a procedure for this and failure to follow has a probability of causing inconvenience or damage. Is there an established procedure for measuring the current draw in these Volvos?

Also rather than measuring the voltage across a 1 ohm (10 W) resistor why couldn't one just put the multimeter in current mode and connect it between the battery and the car wiring? I suppose a serious current draw might blow the meter or are these meters protected in the current mode?

Scotty's delivery and his pealing off on a motorcycle without a helmet don't lend credibility to his presentation. Also he referred to the current draw in 'millivolts' when it should be milliamps.

I find this guy's presentation and technique to inspire confidence http://www.youtube.com/watch?v=FybqN...feature=fvwrel. According to him a draw of 0.2 A is not unexpected so 80 mA is nothing. This supports the suggestion of others above that the problem might be that the battery is not being recharged properly. That ought to be easy to test. Just charge the battery with an external charger and see how long the battery lasts with the car sitting.

[KJR]

Mine did that a few years ago and I went around the houses to find a solution. The car was used a few times a week and after 3-4 days standing would be flat. My siren needed replaced(and still does!). I removed the fuse for the siren to prevent the car 'looking' for it and also now slam the bonnet closed. I think the culprit was the contact on the bonnet as I have had no further problems since I have been doing this. I hope this helps.

[timh30]

Originally Posted by Jim314

How and where are you measuring the 80 mA current draw? Did you have the mp3 player and LPG system installed with the original battery? When in relation to the start of this discharge problem were these installed?

Addn in editing

Couldn't you pull the fuses in turn for each of the suspect systems (mp3 player, LPG electrics, alarm) and see the effect on current drain, and on battery flattening?

The 80ma is being measured with the ammeter in series with the battery negative lead. The mp3 player is fairly recent, the LPG predates this issue - although at that time the car was being used pretty much daily - hence the problem may have been present then, but I never noticed it.

[timh30]

Originally Posted by Rick Barton

Stop buying batteries for goodness sake. Get the one's you've got checked before replacing them

lol - thankfully the batteries aren't mega expensive, even volvo's own ones were only about £60. The bosch one I've just bought was £70, but is higher capacity and the new Silver-Calcium technology.

I can confirm the batteries are pretty much knackered - eventually only holding about 12.3 volts after the year or so use (I guess due to sulphation after deep discharging numerous times).

[timh30]

Originally Posted by Bernard333

The Bosch alternator on your car has the diodes connected to the stator coil ends and the regulator/brush pack is separate . Regulators are on ebay for £15 to £30 but I dont know if they are genuine Bosch or cheap copies , you can get a used alternator for around the same price . Its a pity its not your wifes D5 that has the problem as you can get the regulator off without even loosening the alternator but on the petrol version the inlet manifold and other stuff is in the way so its awkward . At 140k miles the brush on mine was substantially substantially worn down . I dont know what mileage you have on yours but I would be removing the regulator on any car with a mileage of 140k or more and checking the state of it . At the same time with the regulator off you can check the diodes but these are not common failures on this alternator unless you have a 1000 watt woofer going all the time . There is a capacitor built into the regulator cover which comes off and is separate from the regulator , you can check this for leakage but they rarely fail . I dont think you could have three faulty batteries in three years its has to be something in the charging system or a light coming on and staying on , I agree 80mA should not flatten a battery in 5 days .

Thanks Bernard, I have my suspicions that the alternator is actually at fault, but the 'normal' tests seem ok. As per the original post, I did just read, that sometimes the regulator on these early alternators can fail when it gets hot, and then recover again.

I might take the plunge and just go for a reconditioned alternator - about £98 delievered here http://www.ebay.co.uk/itm/VOLVO-V70-...ht_3677wt_1135

p.s. my mileage is around 120,000.