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Electrical Issue - Battery or Alternator?

wildfiremaint

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As Deuce said , the battery terminals are different sizes the negative being smaller. Buy them as a pair.
 

commodorev6

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I've been monitoring the battery/car over the past few days. Today, it was at 9.0 volts. I charged the battery again for about 15 minutes today and it quickly reached 12.2 volts. As soon as I put the key into the ignition and turned the key, the voltage dropped instantly back to 8.7 volts within seconds. I haven't seen that voltage drop so quickly before.
 

losh1971

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I've been monitoring the battery/car over the past few days. Today, it was at 9.0 volts. I charged the battery again for about 15 minutes today and it quickly reached 12.2 volts. As soon as I put the key into the ignition and turned the key, the voltage dropped instantly back to 8.7 volts within seconds. I haven't seen that voltage drop so quickly before.
Yep, like I said the battery is cactus, you need a new one.
 

chrisp

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I've been monitoring the battery/car over the past few days. Today, it was at 9.0 volts. I charged the battery again for about 15 minutes today and it quickly reached 12.2 volts. As soon as I put the key into the ignition and turned the key, the voltage dropped instantly back to 8.7 volts within seconds. I haven't seen that voltage drop so quickly before.

A battery that flat has probably entered in to a ‘negative resistance’ region, put it back on the charger and leave it for a long time, the voltage will quickly go up (but the current will be low). As the battery charges it’ll ‘reform‘ and the voltage will drop and the current will go up. Leave it until the voltage comes up again (and the current tappers off).

Most likely, the battery is probably past it, but no harm in trying to charge it for a day or two and see if it comes back. Long term you’ll need a new battery.
 

gtrboyy

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Battery might have dead cell or low on water...could also be past use by date.
 

commodorev6

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Yes, I agree @losh1971 , @chrisp and @gtrboyy. I wanted to be sure it was the battery not the alternator. Both batteries I tried in the car are over 5 years old. Now time to search for a new battery. The current battery is a 550CCA RACV Sealed type.
 

gtrboyy

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Go bigger cca...don't worry if heavier or tad more expensive.

As long as it has long warranty & put trickle charger on it to keep fully charged it will last years
 

losh1971

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Don't know where you are located but if you're in Adelaide I can tell you the cheapest place to get a Century. If you're in Tas I can tell you the cheapest place to get a Supercharge, which are a really good battery.
 

commodorev6

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Go bigger cca...don't worry if heavier or tad more expensive.

As long as it has long warranty & put trickle charger on it to keep fully charged it will last years
@gtrboyy I noticed there is the Century Ultra Hi Performance Car Battery 67 MF with 640CCA. Can you recommend an affordable trickle charger?
 
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commodorev6

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Don't know where you are located but if you're in Adelaide I can tell you the cheapest place to get a Century. If you're in Tas I can tell you the cheapest place to get a Supercharge, which are a really good battery.

@losh1971 thanks for that. I am located in Victoria. Both battery brands are well known so I will consider either.
 
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