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Ok, First post here on ETCG!! Looking for some insight. I am the original owner to a 2008 Toyota Tacoma Prerunner 4.0L V6. It has 115k miles and Automatic Transmission. I work from home and sometimes do not driver my truck for 2-3 days or so. In the past few months I’ve had an issue with the battery being drained to the point that the truck will not start. A simple jump for my girlfriends car and I good to go. Overtime I tell myself its an isolated issue and won’t happen again. Well I’m done lying to myself. This passed Sunday, Easter, we drove 5 miles to church. The truck started fine at my house. 1.5 hours later after church the truck battery was done. Not enough power to start the truck and of course it was flooding! Nothing was left on either. This is what I figure. The truck has 115k miles on it and I assumed the alternator would be done by now. I was waiting for it to go because I decided to replace the belt when I replace the alternator. However after testing using an ETCG video I think its the battery. Yesterday I disconnected both terminals from the battery and charged it for several hours. The voltage then was 12.74. I let it sit disconnected until this morning (~18 hrs) where it had dropped to 12.51 volts. Is that a normal amount of discharge for the battery to have by just sitting there? Seems high to me. Well moving on, I cleaned the battery terminals and attached the cables securely. I checked the alternator cables and they too were secure. Once again i tested the battery voltage and got 12.44 volts. Thats makes 12.44 as my battery charge baseline. I then started the truck and tested alternator voltage and got 14.18. I checked the belt tension and it was tight, no slack. I then loaded the alternator by turning on everything i could inside the truck; high beams, fog lights, stereo system with 500 watt amp, AC max, dome lights, blinker, wipers. I tested the alternator under load and got 13.87 volt which is more than .5 volts over my battery charge (12.44) level and according to the ETCG video I was good there. My battery is only 2.5 years old from Advanced Auto. Batteries used to last 4-6 years but now I’m told they’re crap and 3 years tops lifetime. So I’m looking for information. All signs in my mind point to possible battery failure. I would have bet on alternator but apparently not. I’m looking at going with an Interstate battery if I have to replace battery. Always wanted an Optima Yellow Top[ but I read they are crap now since moving to Mexico. Side note: I had advance test my truck yesterday morning and they said to charge battery (which I did yesterday afternoon) and that the alternator show a small dip in power for just a moment. Signs its starting to wear out he said and my starter was fine. I then went to AutoZone and had them test it and battery was bad they said. They couldn’t test alternator at all. Lastly I drove to O’Reillys and they tested it too. They claim the voltage regulator, which is internal in my truck, could be bad. Looking for answers. Any information is helpful and appreciated. Thanks for looking.
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If you had your battery load tested and it fails.
You pretty much answered your question.
You state under full load your seeing 13.87 volt output from the alternator.
A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery. When a battery is near fully charged the alternator will cease to put out sufficient voltage to charge the battery and the reading you will get from the battery probing method will simply be the voltage coming from the battery itself.If you’ve run your car for a long time and while the car is running the voltage reading is in the 13-14 volt range, but then you shut the car off and the battery voltage instantly drops to well below 12 volts (10 volts or under; 9 volts or under in freezing weather conditions), it is likely that your battery needs maintenance or replaced.
Your likely to lose some voltage due to the surface charge bleeding off after charging. Your alternator voltage seems OK. The voltage is one thing and should stay fairly Constant while the engine is running.
The more accessories you have running the more current (amperage) your alternator must generate to charge the battery. In essence, your alternator maybe putting out the correct voltage but may not be generating enough amperage to charge the battery.
If the battery failed the load test then replace the battery.
After charging the battery last night and starting this topic post this morning and went back to advanced at lunch today. They tested it again and said that my CCA were down and that I should charge the battery. The CCA were down to 515 on a battery rating of 585. The tech/salesman claimed that one crank can drain the battery that much and i should drive 30 miles too charge it up. I then explained that I don’t drive it everyday and that after 2-3 days it won’t start. He then recommended that I crank it at least once a day. Umm, not everyone drives daily and this type of maintenance shouldn’t be required for any car. Seems like he wasn’t getting the issue or just didn’t care. I guess a new interstate battery is in my future.
Make sure you have nothing draining the battery as it sits. It should be able to sit for along time and still start. Heck my one truck sat all winter without being started and it fired up fine after approx 4 months of sitting. Although we didn’t really have winter this year lol
I agree but mine can’t sit three or four days. I had it sit overnight last night not even connected to the truck and it drops almost .25 volts. Is that normal discharge for resting?
It will bleed off the surface charge pretty quick. Make sure the battery is clean. A slight amount of gunk can actually conduct and drain your battery. But after the surface charge drains off your battery should not keep draining just sitting.
I think you have a parasitic voltage draw. Check this video out: https://youtu.be/KF1gijj03_0
[quote=”brandonlamb25″ post=162697]I saw that video and tested clean.[/quote]
If there are no dips then replace the battery. If it is fairly new and still under warranty go to the place of purchase and have them exchange it. It should be free in that caseIt was an advance auto parts battery with a two year warranty that ended 6 months ago. I’m going Interstate with my next battery. Are remanufactured batteries any good? Apparently my local interstate division offers new and remanufactured. Thoughts?
You get good and bad in either remans or new. As long as a warranty is provided you should be safe. I’ve had good luck with interstates myself
[quote=”shaun” post=162701]You get good and bad in either remans or new. As long as a warranty is provided you should be safe. I’ve had good luck with interstates myself[/quote]
Yes the warranty itself is what matters. usually batteries will start failing right after the warranty ends. That is how it has always happened to me anyways.My luck as well. The new carries a 2.5 year replacement warranty and 5 year prorated coverage. The remanufactured one has a 30 day warranty which has me concerned.
[quote=”brandonlamb25″ post=162703]My luck as well. The new carries a 2.5 year replacement warranty and 5 year prorated coverage. The remanufactured one has a 30 day warranty which has me concerned.[/quote]
That’s pretty bad for a reman. You get 30 day warranty from the wreckers here. I would go with new if I were you.
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