Every six months or so my '95 Buick 3.8, the battery stops being able to start the car, and it always test good but if I put a new one it, the car will start (well for another 5 months or so) anyone have any ideas, other then faulty batt. and alt. I've had it tested and nothing ever tests wrong. Also anyone have any ideas how a batt. that won't start a car, could test as a good batt. it is obvious that it isn't making the cranking amps.
Test the starter for crank pull ampage
Hello! When you say the battery "test good"; What type of test was performed? Was it a cranking power test...How long do you hold the key in the start position? Does it start immediately or does it take several seconds? Does this amount of time increase as time passes?
If a voltage drop is present on the + battery cable or ground cable that supplies the power to the starter motor...More than normal cranking amps will be required every time you start the vehicle in that your holding the key in start longer because the voltage is below +12...A point is then reached where the battery is not capable of supplying enough current to overcome the voltage dropped on the cable or cables and the vehicle will not start...When the battery is tested for cranking amps the voltage drop is no longer present and the battery could very well "test good"...
Disable the ignition...IE...pull the starter relay...Using a volt meter set on 2 volt scale...Place the positive probe on the +battery post...Place the negative probe on the + battery connection on the starter motor...Crank the engine (15 seconds)...You must read less than .6 volts...Do the same on the - battery post to the starter motor housing...Crank the engine...You must read less then .3 volts...
If readings are above normal you've located the fault...Poor connections from the battery to the starter motor...
Let me know what you find.....Guru..........Saailer
I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867
Hello! Let me clarify...It isn't just loose connections...Resistance builds up due to corrosion at the point where the cable (wires) connect to its terminal...The terminal on the cable itself...Also most owners take care of the battery post connections but forget the other end at the starter motor...The problem your vehicle is having; Battery won't start the car but test OK is rather common...In almost every case the culprit is a voltage drop in the + and/or - battery cables to starter...
If you would prefer to skip the test, you can purchase new cables...However, I hate to see a customer spend when perhaps they don't need to...
Your measuring voltage not amps...A load needs to be present to perform the test...We want the engine to merely crank not start...Pull the starter relay...Crank for no more than 15 seconds...#1 voltmeter set on the lowest scale (We want to measure less than 1 volt)...#2 + probe of meter on + battery post...not the cable connector...Place - probe on the other end, at the starter motor...Crank...Must read less than.06 volts...Do exactly the same , only from the - battery post to the case of the starter...must read less than .03 volts...
Replace starter relay...Switch meter to ohms scale X10... Measure from the - battery post to bare metal of chassis...Then from - battery post to the starter case...Both readings should be a dead short...Zero ohms...Let me know what you read...It's 7pm EDT...I'll be here until 10:30...Saailer
Hello! PS...My wife owns a 2000 Buick LeSabre...She has embarrassed many a driver when the light changes...
Saailer
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Ok, if the cranking amps is like 70AMPs or 100 AMPS as measured by an inductive ammeter on the battery cable when starting, and it does NOT start, then it's a bad starter.
However, if it does start, that's normal.
On a car that old, I would check that the battery cable ends are squeaky clean, wire brushed, or even replaced if cleaning is not possible.
Usually, a battery that is tested good will be good under a load test.
Also, try to use an ammeter to find out if there is a drain on the battery above .2 A while it sits there turned off. This could lead to a solution if you investigate where a short may be.
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so your telling me that a lose batt. cable could make the battery seem bad after it reached a point of normal degraded voltage/amperage? It's either all or nothing it starts fine for 6 months with new battery, this is the first time I ever had problems in the summer months. Also, I don't understand why everyone thinks the starter may be the problem (a loss wire I get) but there is no arching or popping sounds. However there is no problems when new battery is installed, at least of six months. I have had similar problems with my olds. cutlass 83' small block. I really think that we are just being sold inferior products. I know 15 years ago I used the same battery in about 20 different cars well after the battery had expired. I will try your suggestions though. Would the slightly loss connection make the service engine light come on but not throw a code. The light keeps coming on, had it at the shop countless times to scan but it never codes anything. Any ideas would be great, it's an old car now with over 260K on it, but when it runs right it will still blow the doors off BMW's whole 300 series. GO BUICK
so what connections am I supposed to hook my amp meter to, to see if there is draw while ignition is off?
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