Dying battery
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Beginning Member
Joined: Nov 2022
Posts: 19
Dying battery
Was wondering if I have a dying battery. Now that it's cold I go out to start the Blazer and turn the key pump runs slow no crank from starter. If I cycle the key about 50 times try to get it to start it will finally roll over and start/ run fine restart fine. Is my battery just not good enough anymore getting to cold at night. It would do that last winter when we had a wind chill of -40. Any helps appreciated
BF Veteran
Joined: Jan 2007
Posts: 4,632
From: Florida
A dying battery can have intermittent behavior during its death cycle (low water, sulfated lead plates and/or shorted cells) and cold always reduces a batteries capacity. The battery doesn't care about wind chill, only absolute temperature. Your skin cares because of evaporative cooling.
The definitive test for a battery is a load test where a big resistor like a carbon pile or wire wound coil loads the battery at around 100 amps and you see how much the voltage drops. Most auto parts stores can do this for you. You can do a reasonable version of this by measuring your battery voltage at the battery posts to make sure you are near 12.6v and then measuring same as you try to start the truck and seeing how much it drops. The classic minimum is 9.5v but unless its really cold that should be 10.5-11.0v on our small blocks. To make sure that a battery is taking and holding a proper charge go for a long run or put the battery on a charger. Then knock the surface charge off the battery plates (if a charger was used) by turning the headlights on for 30 seconds. Then everything off and test the voltage at the battery terminals again. Should be at least 12.5v, lower if really cold. You can also see how much it drops during the night which can be a separate problem.
The very first thing though is you have to make sure that all of your electrical connections are clean and tight, especially the battery cable attachment points, and the big cable to the starter, although they all matter.
George
The definitive test for a battery is a load test where a big resistor like a carbon pile or wire wound coil loads the battery at around 100 amps and you see how much the voltage drops. Most auto parts stores can do this for you. You can do a reasonable version of this by measuring your battery voltage at the battery posts to make sure you are near 12.6v and then measuring same as you try to start the truck and seeing how much it drops. The classic minimum is 9.5v but unless its really cold that should be 10.5-11.0v on our small blocks. To make sure that a battery is taking and holding a proper charge go for a long run or put the battery on a charger. Then knock the surface charge off the battery plates (if a charger was used) by turning the headlights on for 30 seconds. Then everything off and test the voltage at the battery terminals again. Should be at least 12.5v, lower if really cold. You can also see how much it drops during the night which can be a separate problem.
The very first thing though is you have to make sure that all of your electrical connections are clean and tight, especially the battery cable attachment points, and the big cable to the starter, although they all matter.
George
BF Guru
Joined: Dec 2016
Posts: 5,610
From: Moscow, ID
About the only things to add to what George wrote is to see if you can find the date on the battery. If it is five years or older, it is reasonable that it is on its last legs.
The other is that for super cold environments you can install a battery warmer blanket. This would help even new batteries. If you need that though, you likely would need a block heater too.
The other is that for super cold environments you can install a battery warmer blanket. This would help even new batteries. If you need that though, you likely would need a block heater too.
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