My 91 740 Wagon, 140K, parasitic drain, dead battery

cgreygoose · Post by **cgreygoose** » 22 Apr 2012, 08:41

Hello to the forum and thanks for all of your knowledge in helping people like myself. THis car sat for awhile and after replacing the injectors the car came to life. The engine runs very smooth and I'm needing to drive this as my daily driver but if I don't disconnect the battery at night, by the morning the battery is dead. The new battery was replaced yesterday with another brand new battery, so it's not the battery. I've cleaned off the posts, made sure all connections are clean and tight etc., checked the ground wires. the car will run well sitting in my driveway with the headlights on and other accessories fine for an hour or more and it still keeps the battery charged. I've made sure that all dome lights and other interior lights are off, radio etc. but now I need help in starting with the most likely problem and going down the list.

Where should I start next? I should also borrow or buy a meter to perform this task. Is there a known issue that I need to start with? Its Sunday morning and I really need to drive this to work this week and I don't want to have to pop the hood and disconnect the battery etc. so any direction you can give me would be appreciated.

lummert · Post by **lummert** » 22 Apr 2012, 10:45

Does this car have an aftermarket radio installed?

Post by **billofdurham** » 22 Apr 2012, 11:42

To test for a parasitic draw you do need an ammeter or, better still, a multimeter which can be used for checking wiring, fuses etc later.

I could write a long screed on how to check for a parasitic draw but I think that this shows how easy it is.

Bill.

cgreygoose · Post by **cgreygoose** » 22 Apr 2012, 21:35

its got the Volvo radio installed but the code was lost. it's been turned off. I put the recharged battery in today again to see how long it would last with the car idling and it was dead in under 30mins. I've got to get a meter, I know. Will post back once i get the meter and get a few results to report.

Post by **MoVolvos** » 22 Apr 2012, 22:03

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HA, HA, SOOOO! My son is not the only one to have forgotten to turn off that light switch in the 2000 Odyssey we were borrowing for awhile!

. I think Eric skip the part about the Alarm blaring

when you install a new battery after a parasitic drain kills the battery.

BTW: Eric actually replied in length and corresponded via email for a problem I had. It did take a week but it was nice of him as I am sure he gets a ton of emails. Thanks Bill for the Video as this is by far the easiest and most systematic way as there are others to check the Parasitic Drain.

Blessings,
BKM
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cgreygoose · Post by **cgreygoose** » 30 Apr 2012, 11:29

i borrowed my friends multi meter and followed the excellent directions from the video. I couldn't find the draw so I"m thinking that i might have had it on the wrong settings, will try again tonight after work. I do have a question though, my battery & alternator were both very slowly losing voltages while the engine was idling. Does this mean that my alternator is not good? It seems like a simple question but I don't know the answer. I drove it up to the local parts store where they came out to check the alternator and they told me it was bad. I don't know if it's good or bad, or related to my parasitic draw, if in fact I even have a draw.

Post by **mikealder** » 30 Apr 2012, 11:34

Set the meter to read DC Volts then check the battery voltage with the engine off, it should read around 12,5V if charged, start the car and re-check the battery voltage with the meter and it should 13,8V with the engine running switch on all the lights and heated rear window then re-check the battery voltage again I would expect around 13,8V if the alternator is working correctly.
If with the engine running there is no increase in battery voltage from the initial reading you took with the engine off the alternator is shot - Mike

cgreygoose · Post by **cgreygoose** » 30 Apr 2012, 11:46

ok. so I"m reading up in some of the other posts and I think that my alternator is not working properly. I have the Japanese alternator in my 740 so I assume that it's a different story in terms of fixing it. Dunno, perhaps it can be saved or perhaps not. To recap, if i leave the battery in my car overnight it will be dead in the morning. it's a brand new battery. with my meter connected to my alternator I'm getting a slow drain on the voltage reading. something within the alternator is not doing its job so I need to see if I can fix the alternator by replacing parts, if applicable or replace alternator altogether. so if i can get a confirmation on the next step for me that would be really great.

Post by **billofdurham** » 30 Apr 2012, 13:10

You can buy a "parts kit" for the Nippon Denso alternator but it is basic. Unless you know what needs replacing it would be better to buy a reconditioned unit.

Bill.

cgreygoose · Post by **cgreygoose** » 06 May 2012, 22:17

good news the new alternator did the trick. fixed other issues as well, such as erratic dash functions. after driving it back and forth to work I was able to list it as an excellent running volvo for sale and it sold within a couple of days. On to my next one.