Car battery.

[zoiks]

I have an old 1990 240sx with 240k miles on it. It runs as smooth as I first got it but it has an overheating problem that I need to fix. I checked and as predicted the battery has no charge. Does this mean that the battery will need to be replaced? Will it hold charge once the car is jumped or likely be kaput?
The battery terminals are still connected.

 

[Zenmervolt]

If a battery stays dead for a long period of time, it is almost always completely shot. In the future, something like a battery tender is a good idea. That sort of float charger can do a great job of keeping a battery alive.

ZV

 

[halik]

Originally posted by: Zenmervolt
If a battery stays dead for a long period of time, it is almost always completely shot. In the future, something like a battery tender is a good idea. That sort of float charger can do a great job of keeping a battery alive.

ZV

If the battery is recent, it's not that big of a deal (if you unplug it). My r6 started after 4-5 months of sitting and the 944 starts up w/o problems every other month.

I would say charge it up and see if it hold the charge.

 

[LTC8K6]

1.5 years? It's almost certainly an ex-battery.

 

[Zenmervolt]

Originally posted by: halik

Originally posted by: Zenmervolt
If a battery stays dead for a long period of time, it is almost always completely shot. In the future, something like a battery tender is a good idea. That sort of float charger can do a great job of keeping a battery alive.

ZV

If the battery is recent, it's not that big of a deal (if you unplug it). My r6 started after 4-5 months of sitting and the 944 starts up w/o problems every other month.

I would say charge it up and see if it hold the charge.

My 951 will go 3+ months in the winter. But the OP said 1.5 years. It's not a battery anymore, it's a really freakin' big paperweight.

ZV

 

[radioouman]

Pop the caps off the battery, dump out the fluid and refill it with fresh water.





just kidding.

 

[Zenmervolt]

Originally posted by: radioouman
Pop the caps off the battery, dump out the fluid and refill it with fresh water.





just kidding.

Darn right you're kidding. You can re-use that fluid as Kool-Aid.*










*Do not actually do this.

ZV

 

[rh71]

I don't use my car for a week (which I've done in the past)... but the battery is dead (I get startup lights and upon cranking it just makes a ticking noise). I jump it, then drive around for half hour and three days later I find it's dead again. I jump it once more, drive around for another half hour (highway this time) and the very next day it's dead again (same symptoms). Is there a reason it can't even hold a charge for 1 day other than the battery being useless? I checked no lights switches are left on. While started & running it continually points above 14V at least while before the jump it was at about 9V. Alternator failure, alt belt loose, etc.?

 

[Zenmervolt]

Originally posted by: rh71
I don't use my car for a week (which I've done in the past)... but the battery is dead (I get startup lights and upon cranking it just makes a ticking noise). I jump it, then drive around for half hour and three days later I find it's dead again. I jump it once more, drive around for another half hour (highway this time) and the very next day it's dead again (same symptoms). Is there a reason it can't even hold a charge for 1 day other than the battery being useless? I checked no lights switches are left on. While started & running it continually points above 14V at least while before the jump it was at about 9V. Alternator failure, alt belt loose, etc.?

9 volts is below the 100% discharged voltage, well below. A battery that is going down to 9 volts is not going to be recharged by driving the car for a half-hour. You may be able to rescue it with a bench charger, but if the battery is over 4 years old, it's probably time to replace it. (Batteries will usually last more than 4 years, but a 4 year old battery that has been down to 9 volts is not "young" enough to handle it well and will likely need replacing.)

ZV

 

[LTC8K6]

Yeah, you might rescue it with a slow charge but probably not. I would try it though if the battery isn't too old.

It's also not good for your alternator to keep trying to recharge a battery that's at 9V.

 

[jhu]

I don't understand why car batteries die. Aren't they essentially just two metal electrodes dipped in acid?

 

[rh71]

just found: http://www.batteryuniversity.com/parttwo-42B.htm

< 8 miles = problems? I drive like 3mi. per day roundtrip.

They also mentioned 52% of breakdowns are battery-related. Does a vehicle actually stop mid-run because of battery issues or do they mean unable to start only?

 

[LTC8K6]

I don't understand why car batteries die. Aren't they essentially just two metal electrodes dipped in acid?

TANSTAAFL

 

[rh71]

oh one more thing... is the battery being "recharged" if you're just idling like you're waiting for someone?

 

[LTC8K6]

At idle, alternator output is low. The battery is being charged if it's low, but slowly.

The charging system really is not designed to recharge a dead battery, although it will do that.

 

[Beanie46]

Originally posted by: jhu
I don't understand why car batteries die. Aren't they essentially just two metal electrodes dipped in acid?

Here's what happens in one cell of a car's lead-acid battery (as an example of how all the cells work):

The cell has one plate made of lead and another plate made of lead dioxide, with a strong sulfuric acid electrolyte in which the plates are immersed.

Lead combines with SO4 (sulfate) to create PbSO4 (lead sulfate), plus one electron.

Lead dioxide, hydrogen ions and SO4 ions, plus electrons from the lead plate, create PbSO4 and water on the lead dioxide plate.

As the battery discharges, both plates build up PbSO4 and water builds up in the acid. The characteristic voltage is about 2 volts per cell, so by combining six cells you get a 12-volt battery.


A lead-acid battery has a nice feature -- the reaction is completely reversible. If you apply current to the battery at the right voltage, lead and lead dioxide form again on the plates so you can reuse the battery over and over.

 

[Bignate603]

Originally posted by: Zenmervolt

Originally posted by: radioouman
Pop the caps off the battery, dump out the fluid and refill it with fresh water.





just kidding.

Darn right you're kidding. You can re-use that fluid as Kool-Aid.*










*Do not actually do this.

ZV

You're mixing it up. Antifreeze can be used as koolaid*.










*If by koolaid you mean long painful death.

 

[big man]

Originally posted by: zoiks
I have an old 1990 240sx with 240k miles on it. It runs as smooth as I first got it but it has an overheating problem that I need to fix. I checked and as predicted the battery has no charge. Does this mean that the battery will need to be replaced? Will it hold charge once the car is jumped or likely be kaput?
The battery terminals are still connected.

I see 16 posts and no meaninful answer..............


Take the battery to Autozone, they'll charge it and test to see if it can hold a charge for free.

 

[LTC8K6]

There are three correct answers immediately following the OP.

 

[zoiks]

I'll find out more this weekend. I'm pretty sure that it's shot though.

 

[Zenmervolt]

Originally posted by: big man

Originally posted by: zoiks
I have an old 1990 240sx with 240k miles on it. It runs as smooth as I first got it but it has an overheating problem that I need to fix. I checked and as predicted the battery has no charge. Does this mean that the battery will need to be replaced? Will it hold charge once the car is jumped or likely be kaput?
The battery terminals are still connected.

I see 16 posts and no meaninful answer..............


Take the battery to Autozone, they'll charge it and test to see if it can hold a charge for free.

And that time and effort in testing the battery will tell you what we already know: That a battery which has been sitting for 1.5 years and supplies only 9 volts is a large paperweight.

There are times when something is worth testing and there are times when it's not.

ZV

 

[Zenmervolt]

Originally posted by: Beanie46
The cell has one plate made of lead and another plate made of lead dioxide, with a strong sulfuric acid electrolyte in which the plates are immersed.

Lead combines with SO4 (sulfate) to create PbSO4 (lead sulfate), plus one electron.

Lead dioxide, hydrogen ions and SO4 ions, plus electrons from the lead plate, create PbSO4 and water on the lead dioxide plate.

As the battery discharges, both plates build up PbSO4 and water builds up in the acid. The characteristic voltage is about 2 volts per cell, so by combining six cells you get a 12-volt battery.

A lead-acid battery has a nice feature -- the reaction is completely reversible. If you apply current to the battery at the right voltage, lead and lead dioxide form again on the plates so you can reuse the battery over and over.

The bolded part is incorrect. The reaction is mostly reversible. If it were completely reversible the battery would never need to be replaced. With each use, a tiny portion of a battery's capacity is lost.

Over time the positive plates (also called grids) shed and their surface area decreases with time, which decreases the battery's capacity. This is called plate corrosion, or grid corrosion and is the most common cause of battery failure. If a battery sits in a discharged condition for extended periods of time, something called sulfation can also occur. Sulfation is caused when the lead sulfate crystallizes. Once the lead sulfate has crystallized, it cannot be converted back into lead and lead oxide easily. It is also non-conductive and can coat the plates (grids), reducing their capacity even more. Some expensive chargers have a "desulfation" setting that can partially restore a sulfated battery, but nothing can fully restore it.

ZV

 

[Bu B3ar]

Originally posted by: rh71
I don't use my car for a week (which I've done in the past)... but the battery is dead (I get startup lights and upon cranking it just makes a ticking noise). I jump it, then drive around for half hour and three days later I find it's dead again. I jump it once more, drive around for another half hour (highway this time) and the very next day it's dead again (same symptoms). Is there a reason it can't even hold a charge for 1 day other than the battery being useless? I checked no lights switches are left on. While started & running it continually points above 14V at least while before the jump it was at about 9V. Alternator failure, alt belt loose, etc.?

i had this same problem with my battery, except it only happened when it was moist/raining recently or had been sitting for a decent period of time. turns out one of the battery terminals was cracked/leaking gasses from the acid that was corroding (sp?) the terminal, reducing the contact and hence the charge sent/recieved. If i unhooked the cables, cleaned the terminal and connector, and reconnected it provided a short term fix...until it got humid or rained again. try cleaning it the next time it does the clicking thing, if it fixes it, you may have the same problem, and your mechanic can fix it for you. he replaced the terminal for me, and i still have the same battery with no problems.