Battery being drained

[Beadybc]

Hello I'm having issues with my modified 940's battery being drained after a few outings.

It's a new battery.

Unplugging the battery in between usages doesn't fix the issue.

This is to be expected since I have added a few new things to the car:
- New aftermarket Bluetooth radio
- Electronic boost gauge
- Electronic AFR gauge

What would I have to refresh/upgrade to handle the new stress?

Car is a late 1997 945 B230FK with a 19T at 1.3 Bar.

[Forrest]

I should not have thought that those accessories of themselves would be the cause of draining a new battery. It seems more likely that it is not charging properly. What voltage output are you getting from the alternator? Is it within an acceptable range for your battery to charge? Note that if the battery is a modern silver/calcium one and the alternator is unmodified original then the answer is probably no. Does the charge light come on the dash when the ignition is turned to position ii and go out when the car starts running? This “exciter” circuit is crucial to the proper operation of the alternator. Check the thin wire that connects to a terminal probably marked D+ on the back of the alternator.

[360beast]

You've given the answer away yourself by saying unplugging the battery between usage it still drains, it's a duff battery.

Edit: now I read it again are you saying it drains when unplugged or drains after plugging it back in?

[Beadybc]

Originally Posted by Forrest

I should not have thought that those accessories of themselves would be the cause of draining a new battery. It seems more likely that it is not charging properly. What voltage output are you getting from the alternator? Is it within an acceptable range for your battery to charge? Note that if the battery is a modern silver/calcium one and the alternator is unmodified original then the answer is probably no. Does the charge light come on the dash when the ignition is turned to position ii and go out when the car starts running? This “exciter” circuit is crucial to the proper operation of the alternator. Check the thin wire that connects to a terminal probably marked D+ on the back of the alternator.

We did the check last week on the alternator and the voltage was lower than the 13.5V that is required (I can't remember exact figures).

The alternator is the original.

I just wanted to get an idea from others as to what other problems could be assisting with this issue before straight away going and asking what good replacements would be. I will check that wire.

Could you guide me towards a good replacement for the original alternator?

[Clan]

Originally Posted by Beadybc

We did the check last week on the alternator and the voltage was lower than the 13.5V that is required (I can't remember exact figures).

The alternator is the original.

I just wanted to get an idea from others as to what other problems could be assisting with this issue before straight away going and asking what good replacements would be. I will check that wire.

Could you guide me towards a good replacement for the original alternator?

It is not necessarily the alternator check carefully the earth wire ( blue?) and the red power wire and it's terminal which goes up from the Alternator . Also the main blue earth wire from engine to chassis.

check the voltage on the alternator terminal itself and see if it differs to the measurement on the battery + with the engine running,

A final test with the engine running put the voltmeter between Battery + and Alternator + that will measure Volt drop in all the joints and cable Idealy it should be near 0

do the same with the Earth, voltmeter between engine block and battery -negative.

[940volvoman]

I had this problem which I put up with for a long time,Volvo 940 1998.

In the end, following the advice of the helpful people on this forum, I added an extra battery positive and negative,together with an additional blue earth wire
at the alternator. I also replaced the diode pack within the alternator.

Together this helped a lot, but ultimately Mr Laird Scooby suggested that I upgrade the battery to the larger lead acid one fitted to the diesel models not the calcium types. The alternator cant handle it.

With an occasional top up from a battery maintainer things seem to have improved massively, although the discharge still occurs.The speakers in the boot emit a very quirt shhhhhhh sound when the car is switched off, but I have no idea what it is or why.Its now manageable,though

Hope this helps

Shaun

[Clan]

Originally Posted by 940volvoman

I had this problem which I put up with for a long time,Volvo 940 1998.

In the end, following the advice of the helpful people on this forum, I added an extra battery positive and negative,together with an additional blue earth wire
at the alternator. I also replaced the diode pack within the alternator.

Together this helped a lot, but ultimately Mr Laird Scooby suggested that I upgrade the battery to the larger lead acid one fitted to the diesel models not the calcium types. The alternator cant handle it.

With an occasional top up from a battery maintainer things seem to have improved massively, although the discharge still occurs.The speakers in the boot emit a very quirt shhhhhhh sound when the car is switched off, but I have no idea what it is or why.Its now manageable,though

Hope this helps

Shaun

It sounds as if the external amplifier may be faulty or its triggering wire is live when it shouldn't be??

[Rversteeg]

Together this helped a lot, but ultimately Mr Laird Scooby suggested that I upgrade the battery to the larger lead acid one fitted to the diesel models not the calcium types. The alternator cant handle it.

The alternator charging voltage can be increased by changing the regulator for the one in the attachment. I bought it some time ago, but have not installed it yet.

In my case an additional wire directly between alternator and battery (original wire runs via the starter motor and the mutual point at the start motor connector deteriorates over time) already improved the charging voltage on the battery itself. Choose a thick enough wire, as in worst case, if the cable via the starter motor breaks, it should be able to take the full 100A charging current!

[940volvoman]

"It sounds as if the external amplifier may be faulty or its triggering wire is live when it shouldn't be??"

I didnt realise the later models still had the external amp fitted.

Where would I look,what does it look like?And its triggering wire??

[baggy798]

What's the parasitic drain? Mine was around 50mA so I guess that's the normal range. If it's significantly higher, pull each fuse in turn and see if there's a difference.

Voltage at my alternator is 14.2v and 14v at the battery terminals, between the alternator body and the battery negative terminal it should be well under 0.2V.



Voltage between the alternator power terminal and the battery positive terminal should also be under 0.2V.



I forgot what my reading was, but voltage between the battery negative terminal and the engine block should be under 0.2V too.

If the alternator is not putting out at least 14v it's usually the regulator.