Random car charging problems

[xdarkxfirex]

Started happening in the evening today. I went to the mall, came back and battery died. Boosted, and went to another mall, and it died again. Spent an hour trying to figure out whether it was the battery or not.

Battery reads 12.2-12.5v off, and 12.8-13.5v on. I cleaned the terminals a little with sand paper.


Should I go ahead and replace the alternator and battery together or try cleaning the terminals on the alternator first? Battery doesnt seem very old.

[Saturn4Ever]

If its the original battery then yeah its probably time to replace it. The only way to know for sure is to have it load tested.

[xdarkxfirex]

Its a motomaster, doesnt look too old. This car was bought last month. I cleaned the posts and it runs fine so far. I need to check the connections on the alternator, and do a voltage check without the cable. I started it up many times tonight and it was fine.

I just used my handy multimeter, but I'll take it to partsource and see if they can test both

[billysvue]

Originally Posted by xdarkxfirex

, and do a voltage check without the cable.

What does that mean?

I hope you don't disconnect the battery with the motor running...

[xdarkxfirex]

No not that. On new cars it can cause problems. I meant get it tested for free

[romanster]

Get the battery tested for free anywhere (walmart, etc), sounds like it's likely time to swap it.

When I bought my '08 XR3 in 2012 with 51,000 km, the original AC Delco battery died the NEXT day after I picked it up from the dealer. I couldn't even jump start it, I had to call CAA with their portable boost pack to jump it. The battery still had 3 months of dealer warranty, so they swapped with a new AC Delco one, and it's been trouble free since.

[xdarkxfirex]

The other car we have, i think it still has the original panasonic battery going 8+years on it. It starts fine. The astra, I got tested at partsource, and they told me the cold cranking amps were 850 and I got less than 600. Not really a problem but you will see it more in the winter time.

Anyways, I heard that costco has good deals on batteries, and they are quality built. Might give them a try

[emg77]

Most car parts places will test your battery and charging system for free (Autozone, etc.). It might be the battery, it might be the alternator, it might be corrosion.

[AstraFasta]

Originally Posted by xdarkxfirex

The other car we have, i think it still has the original panasonic battery going 8+years on it. It starts fine. The astra, I got tested at partsource, and they told me the cold cranking amps were 850 and I got less than 600. Not really a problem but you will see it more in the winter time.

Anyways, I heard that costco has good deals on batteries, and they are quality built. Might give them a try

You will see an uptick in recent posts on Astra batteries dying here. You can't complain about 8 years for a battery.

Also, you don't see many Astra issues with starters or related grounding, so the battery is where I would expect the problem comes from.

That said, getting the system checked is easy and worth the effort.

[xdarkxfirex]

I was saying the battery on the toyota I have is probably around 8 years and runs fine. The one on the astra looks fairly new but when it was tested, it got less cold cranking amps

[fdryer]

Originally Posted by xdarkxfirex

Started happening in the evening today. I went to the mall, came back and battery died. Boosted, and went to another mall, and it died again. Battery reads 12.2-12.5v off, and 12.8-13.5v on.......

The battery died (based on your last post) because of a sequence of events. Car batteries are basically used for starting purposes then the alternator takes over supplying all the electrical needs of a vehicle while slow charging the battery for the next start. Since your voltage measurements with engine on shows no more than 13.5v, either the serpentine belt is slipping or the alternator is failing. Most alternators output between 13.3v-14.7v, averaging around 14v+. Right after engine startup, the battery is drained so alternator output is highest to make up for a temporary drop in battery voltage. The higher the alternator output the higher the current so the battery and electrical system sees no more than 15 volts (to protect against electrical damage if voltages go higher) right after engine startup. Soon after, the output begins to drop down to a level always under voltage regulation built into the alternator. So 14.5v allows recharging a battery while supplying all the electrical needs of a car. Your alternator not outputting enough to recharge the battery so it drains each time the engine's started until its nearly drained and the car needs a boost. The battery test results showing a lower CCA simply means the battery is older and aging, having less capacity than when new but still a goof battery. As you mentioned, cold winter temps reveals a battery's strength to hold a charge. A full overnight charge with any wall charger can restore this battery back to a useful life but the alternator and/or belt needs to be examined otherwise the battery will be destroyed from constantly being drained below 80% of its fully charged state. Regular car batteries, the non deep discharge type, are designed to be discharged to no less than 80% of their full capacity and never designed for deep discharge as they lose their capacity if allowed to be used as deep discharge batteries. Used for starting, batteries never discharge deeply and recover with the alternator slow charging it while driving.

Originally Posted by xdarkxfirex

The other car we have, i think it still has the original panasonic battery going 8+years on it. It starts fine. The astra, I got tested at partsource, and they told me the cold cranking amps were 850 and I got less than 600. Not really a problem but you will see it more in the winter time......

While anyone can have a car battery lasting well past their warranty, this is the exception to the rules as most car batteries last right up to their warranty and promptly die. Reasons for longevity? A great electrical system combined with a temperate climate free of extreme temps, neither high desert heat (>100F) nor freezing cold (<32F) where a battery can last longer than most. In NYC, I've never seen a regular battery last beyond its warranty with the longest being an original stock battery lasting 6yrs before croaking. I expected it to die in winter cold but it decided to die on me in summer weather as I tried to leave from work.

Your battery, even with less cca may still give good service but it will require looking into the belt drive system and alternator output as soon as possible to prolong battery life. Cycling a car battery until its drained and recharging it kills it against a battery drained and recharged every time the engine runs (with good battery cables and alternator).

[xdarkxfirex]

Right now it stands at around 12.3-12.4v off, and 13.3-13.4v with alternator on. Battery test failed. Serpentine belt was replaced recently by previous owner because it looks fairly new.


Interestingly enough, my other car after 8 years likely still has the original battery, a panasonic, it stays at 12.5v or higher off, and 14.2v or more on. I'd love to know where you can get these batteries. I've even heard of lithium batteries being sold in cars now

[fdryer]

Not sure if you're fixated on batteries when there's a real possibility that your alternator is failing to provide power for the car and recharge the battery. It would be in your best interests to have the alternator checked. Most autos stores testing car batteries can test alternators, on or off the car.

[xdarkxfirex]

You are right too, I should have that checked. But the part store that checks the alternator would have to have it off the car, and it wouldnt be easy where its located. Might be better to check with a multimeter.

[fdryer]

Originally Posted by xdarkxfirex

Right now it stands at around 12.3-12.4v off, and 13.3-13.4v with alternator on. Battery test failed........

You already measured battery voltage (engine off/12.4v) and alternator output (engine on/13.4V). By having the engine off, you measured battery voltage. With engine running, the alternator is outputting voltage above battery voltage - 13.4v. This isn't enough to recharge the battery and supply all the electrical needs of your car.

Alternator output at 13.4v minus battery voltage of 12.4v = 1 volt difference. Without going into deep electrical theory that I can't explain, all you need to know is the higher the alternator output (measured at the battery terminals) the higher the current output. Maximum alternator output should never go higher than 15 volts. A car I had trouble with cooked a day old new battery with a runaway voltage regulator - the alternator output 17 volts and was hot to touch. The new battery bulged with this over voltage/over current condition.

Here's a brief description of alternator operation;

Regulator

The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second. At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation.

You might be able to find another auto store that can test the alternator on the car. I recall PepBoys tested one of my cars when the alternator and separate voltage regulator were creating problems. Whether you find a store that can test your alternator in the car or removing it for testing, in the end you'll have to decide what to do. Either pay a repair shop to diagnose this electrical issue and make repairs or do it yourself (removing the alternator for store testing. Your choices are limited at this point as your battery is not likely getting a full charge from this alternator. All alternators average around 14.3v, and the difference between yours and normal alternators is the difference between every other car working and yours not.

[xdarkxfirex]

Replaced the alternator today after trying last week spending hours and giving up. I finally got it out, and Its a really tight fit. After replacing it, I took a voltage reading and I get around 13.5v, and 13.3 with the ac on. I think this might be the normal reading with this car. Cables looked fine. With my other one, it would sometimes drop under 13v. I just would be considered if something like that were to happen during winter where you need more juice to start.

[fdryer]

Next time try measuring without a/c. All voltages are measured without loads and simply alters perceptions of what a battery or alternator is outputting. Do you measure battery voltage with lights, radio, heater blower, ignition ON? If you don't then don't load the electrical system by turning on electrical loads. All these electrical loads simply drops voltage readings when you're attempting to measure baseline numbers.

If you were to assume battery voltages should be measured with loads, try measuring voltage when the starter is used. If you see voltage around 10 volts, you'll understand why battery voltage measurements are done with engine off - no loads (baseline). The same for alternator measurement but the engine must be running so the only electrical loads are the EFI system and fuel pump (baseline). All other electrical loads are off; headlights, radio, a/c, blower motor, brake lights, rear window defroster, etc.. When baseline voltages are measured, understanding why voltages vary when electrical accessories are turned on provides a perspective on how alternators work.

[xdarkxfirex]

I did a test again as my battery was starting to go bad. Replaced it. I get around low 13v-14.1v with the engine running and 12.1-12.5v with it off. Normal with this car or should I be concerned? The alternator was also replaced almost 3 months ago by me.

[fdryer]

With a new battery and alternator, as long as wiring is fine the output voltage should be fine. Did you try measuring voltage right after starting up? This is when the battery drains the most in the brief time a starter uses the greatest amount of current from a battery, resulting in a temporary drop in battery capacity/voltage. The alternator outputs the highest voltage with a cold engine startup. If you can monitor for the highest voltage right after starting up and see higher than14.5v (high idle), you're probably fine and set for winter. Measure voltages without using radio, headlights, a/c, etc. Every electrical load throws off voltage measurements so it not wise turn on anything.

[xdarkxfirex]

I measured it on startup and it ranges from lows 13v, and highest ive ever seen it is 14.2v. Usually around 13.2-13.4 mark. I checked the connections again today and pulled apart the alternator to make sure the connection on it was clean(Which it was), sanded it a little and put electric grease on it. Still same/similar result. I checked the voltage via obd2 port, and it has two options, one from control module, other from adapter, which is the same as multimeter. Control module shows 14.1v-14.5v constantly, while the other is lower 1v. I dont know if this is normal or not

As far as the headlights being on or off, I cycled through all of them, and it doesnt make a difference. Radio is never on as well.