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Temperature does affect the flow of electrons. Hence, this is why cars tend to sound slow during startup at sub-32 degree temperatures.

So, at temperatures at or below 32 degrees Fahrenheit, you will see a drop in the battery's output during its starting phase. This is also why manufacturers' list the CCA in addition to the CA for each battery type.

To check if the battery's bad, simply get a multimeter and check the voltage at the battery during specific phases of operation.

I DO NOT RECOMMEND PULLING OF NEGATIVE CABLES DURING OPERATION.

These are the areas I would check below:

1. Check the voltage drop at intial startup. If the battery's voltage drops below 10 volts, chances are you had a bad cell in the battery. Connect the multimeter, and watch it while a friend starts the car. Notice and record the voltage drop during cranking phase.

2. Check the voltage during charging phase. The battery's voltage should be between 13.8 and 14.2 volts during idle. If you voltage is appearing to be at extremely high settings (14.8 and higher), then your regulator internally is malfunctioning. If its lower than that, check your accessory belt for proper tension. If the belt tension is good, then notice and record the output while at idle. You can rev the engine to ~2k RPMS to see if the charging rate increases. If it doesn't increase, then you have a bad connection or the alternator is toast. You can also turn accessories (Headlights, A/C, Heater) on to see how much the voltage drops.

3. Check to see if all the connections are securely attached. Power wires should have clean connections to limit the resistance during operation.

For extended periods longer than ~1 week, I do recommend connecting a battery maintainer. I have to do this with my red top Optima if I leave my car sit longer than a week. Plus, it keeps the battery charged so when you go out to start your car, you know the battery is good. This is must for pleasure cars that don't see daily driving.


These should help all of you on diagosing voltage issues.

DP
 

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Suprafield,You miss one thing out off that excellent write up.A lot of people as the preception that just starting the car and let it run for a period of time,the battery will charge,which is not so.Most alternator doesn't start charging the battery until about 2000-2500 RMP.
 

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ive been having the same problem. so bad at one point that it if i let the car sit for a few days, it would be shot. so since its winter, i pulled the 2 alarm fuses and for the one week i drove it when it was nice, no problems at all. so im starting to think i have a draw somewhere b/c of poor wiring. also, when i got my charging system tested at autozone, it showed that both were shot so i put in a brand new battery. i had no problems at first but then they started again. in my hours of research on this problem, a few people said that a bad alternator would drain the battery. i ended up buying a new alternator which is still sitting in my room. so check to see if you got a draw then check your alternator. that should provide you some answers but also remember, some people who dont have any problems with their battery or alternator still have this issue. i guess its one of the few weaknesses of the supra. worst case scenario, get a battery tender. you will be fine

ryan
 

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The last time i check saw the weather certain part of Ca had snow/heavy rains and 40 to 50degs and that was last week.So i guess Ca does not get cold
That’s not considered cold. No matter how you feel...40-50 degrees Fahrenheit will have ZERO effect on your battery. You do realize places are are below zero and cars still work there
 
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