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Need Some Advice on Charging System Saab 9000

Every day last week after work, ( last week was a cold week) I barely had enough battery reserve to spin over the engine. Luckily after a few short groans it always started. Each time, before cranking, the in dash digital voltmeter was in the 11.5 to 12.0 range ( not pretty). Each night I put it on a charger and in the morning, I had power to spare. On Wed it was in the shop and I was told that there was nothing wrong with the charging system or the battery. All connections have been cleaned and tightened. The battery is 12 months old and is an 850 CCA . I tried to get a replacement as the batterty has a 6 yr warranty with a no cost replacement for 24 months. The garage refued, saying that the battery load tested fine and that the problem had to be with the car......however....no problem could be found with the car ( catch 22) . The drain on the battery with the car parked,( alarm not set) was 50 milliamps. That certainly is not the problem. I insisted that this problem was directly related to the cold, not the car. The output of the alternator is a steady 14.2 - 14.3 with lights ,heater and sound system etc all on. Right now I have the battery cable lifted and an ammeter hooked up in series. I am only seeing the same 50 milliamp draw. I turned various accessories on and off to see if anything was staying energized but the load always returned to 50 milliamps. I have been monitoring for about 3 hours and all is still well. I just opened my garage door so the temp will fall to -16. I will monitor the drain throughout the night and see if the drain changes. I am not sure what to do next except maybe I should go to a different garage where I will probably have to buy a new battery and forget my warranty. One thing that I did notice that was my fuel pump really sucks down my battery. If the car has been parked for a few hours, the fuel pump will cut in as soon as the key is in the on position. I noticed that it pulls the battery voltage down by .5 volts. That pump must pull some serious current. I dare not try to measure it as my meter is only rated for 10 amps. The pump is fused at 20. Any ideas of what I can do myself before going off to another garage??

Reply to
Radar166
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If that's before cranking, then something is a bit wrong, although 12 volts is the nominal voltage, it's really happier at a bit more than that.

Bet this was in a nice warm shop, wasn't it?

So no alternator problems, although I think the voltage is a bit high, but not by much. 14.2 volts is about 2.36 volts/cell, and that's just fine for charging, but it's trying to charge. (normal rest voltage is about 2.2 volts/cell for floating, iirc). That's where the 13.8 volts for mobile radio equipment comes in.

I suspect that you might be having a temperature problem with the battery. I'd take an analog voltmeter (unless yours can measure and hold a minimum) and then measure the voltage:

1) open circuit without the key in the ignition. 2) key in, off position 3) key in, run position 4) key in, start position

Voltage on the average battery under those circumstances can be as little as about 8 to 9 volts while cranking.

If the battery goes down by 0.5 volts on a 15 to 20 amp load, that's perhaps a bit much, although it might be average. That says that the internal resistance is about .0333 ohms, which will drop 5 volts (assuming nothing else drops anything) at 150 amps. However much the starter is rated at, will give you an idea. That would get you from

12 down to 7, or the nominal 13.8 down to 8.8.

I'm thinking that the battery has a cold problem.

If you can, measure the specific gravity in the morning, which will also tell you if you are getting a full charge. Get something with a gauge on it, not the silly little balls.

If all else fails, you can get a battery tester at Harbor Freight (only if on sale)... or go to an autozone or battery store which often has a battery checker. Of course, you don't want to be driving the car there...

In removing the battery, always remove the - lead first, that way, the only thing you have to worry about is touching the - terminal with the wrench. If you try to remove the + lead first, touching the engine with the wrench will short out the battery.

Hope that this helps.

Harvey.

Reply to
Harvey White

Well I made it through the night without detecting any appreciable drain from the battery ( stayed steady at 50 milliamps as expected). The temp hit a crispy low of -16. This morning when I turned the key, the in-dash volt momentary flashed at 12.3 and instantly dropped to 11.8. When I cranked the engine it dropped to 9.5 and did not sound too happy about it. All these slow grinding starts cant be good for my starter, unless it is part of the problem. Tomorrow I will return to my garage and grovel for a new replacement battery. Wish me luck.

Reply to
Radar166

9.5 volts is pretty close to the appropriate voltage. You might want to check what the nominal voltage when starting should be. I'm not sure, otherwise, I'd mention it.

Does it crank faster with a booster battery?

Could you be using a viscous oil (such as 10W-40 rather than 5W-40), lower than is recommended for your car at -16? These could have an affect as well.

Harvey

Reply to
Harvey White

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