Battery? I should know this

I hate just throwing parts at a problem, so I'd like your help with this before I start spending money.

About a week ago I had a couple of hesitant starts. Sort of a slow crank, but only for a revolution or two and then it fired right up. I didn't happen every time. Out of 10 or 12 starts it happened twice. I put a volt meter on the battery - 12.2. I left it on and started the truck. The voltage went down to about 10.2. According to the Chris Fix video I watched this battery should be ok. I found a loose positive connection and tightened it up. When idling the voltage is in the low 14s. All seemed well.

This morning when I turned the key all I got was rapid clicks. I didn't think about it at the time, but my recollection is that the clicking came from behind the dash. Voltage was about 12.1. I had to roll start the truck to get to work.

The battery is a Toyota 84 month battery. It's got about 54 months on it.

 

If you're having dead battery symptoms but have a battery at 12v you most likely have a bad engine to chassis ground.

Look up how to do the "Big 3 Upgrade" 1st gens were known for having kind of wimpy grounds.

 

I'll look for the grounds when I get home. I can trace the one off the battery. Where is the other?

Also, would the battery load tester at the car parts place be impacted by a bad ground? I'm thinking of using that as another diagnostic point, but a reading of "bad" there could still be because of a bad ground it wouldn't add any data to the equation.

 

Nah the auto box store reader wouldn't be effected by a bad ground, all they do is perform a very basic amp capacity check to compare current battery CCA to listed CCA. This can even be done without the battery in the vehicle.

The big three are alternator positive to battery positive, battery negative to chassis and engine block to chassis.

Here's a write up that should work for you:

 

The voltages are important and the one that is concerning is 12.2 V. While cranking the battery voltage will be low and 10.2 V isn't that unusual. While idling you should see about 14 V on the battery (I see about 14.2 V on my truck, alternator and voltage sense are stock but upgraded wiring).

But a battery that is supposed to be fully charged should be more like 12.6 or 12.7 V just sitting there in the morning.

My recommendation would be to buy or borrow a high quality charger and run it overnight or over a weekend, preferably at least 24 hours doing a full 3-step profile (bulk, absorption, float). It would best if you can take the battery out of the truck to remove all the loads from it but if you can't it's not the worst thing.

The important part is that the charge does at least 2 things, a high current bulk initially (20 amps or more if you can) and then floats the battery at 13.6 V for at least 8 hours. Then take it off the charger and let it sit for a couple of hours (this is called a rest). Measure the voltage and see what it settles out to be.

 

I'll do that too. It just occurred to me that my son's 4Runner is sitting in the driveway with a battery that's been on a charger for long time (The Boy is off at school and left his truck at home). I can swap batteries and see how his battery works in my truck, and I can use that time to charge mine.

And run wires.

 

12.1 is a dead battery. A fully charged lead acid, multi-cell battery should read 12.7 volts. Here is an interesting chart on this page, at 12.08 volts you are 35% of battery charge.

https://www.emarineinc.com/Batteries-Maintenance-101

If 12.2 is your resting voltage, your battery is not holding a good charge.

 

battery is dead at that voltage, get toyota to replace if under warranty.

If they don't believe you then tell them to run a load test to see what the CCA is

 

Some 84 month batteries last almost 100 months, some don't even last 60 months. At least in my experience...

When a battery dies, it dies after one or, if I was lucky, after two odd starts like the one you described. If you do any off-road traveling, you might consider replacing your battery before you find yourself umpteen miles from nowhere with a dead battery.

 

You're obviously getting a charge from the alternator since you're at 14+ v when running. 12.2 is pretty low for a battery sitting. As others said, you should be seeing at least 12.7v for a fully charged battery.

If you are driving for a lot of very short trips, and constantly starting it, or running accessories without the engine running, or if you have a parasitic draw (like a stereo or amp or something that's not shutting off, 12.2 might be less unusual. But it's also likely you just have a bad battery. If it's under warranty, get them to replace it.

Drive it around for a while, then bring it home, shut it off and wait a few minutes (usually take a few minutes for the voltage to "settle"), then check voltage. Let it sit overnight and check the voltage again. It should be essentially the same, if it's not, your battery can't hold a charge.

 

In case it wasn't clear from his post, greater than 14 V while the engine is running means your charging system is likely working but doesn't mean the battery is actually accepting a charge.

 

This.

I mean sure, it wouldn't hurt to beef up your ground wiring, but it's not likely the problem, especially since OP wasn't having problems until recently.

The only real reason you'd have issues with the ground or the wire sizing etc... if if you are running a bunch of aftermarket accessories that suck a lot of juice. If you're mostly stock, I wouldn't spend a bunch of time chasing a "wimpy" ground.

 

I went out for lunch and it wouldn't even click. My in-cab voltmeter was reading 9.7. I roll started it, drove it to costco, and put a new interstate battery in it. The initial voltage on that was low, which I attribute to it having sat on a shelf in costco for who knows how long. I'll watch it for a few days.

Thanks for the help.

 

What was the initial voltage of the new battery? If a new batt is charged and then sits, and reduces voltage, it will reduce the life of the battery. That's why most people use battery maintainers. It's not always a small draw that will kill a battery, in some cases it's sitting at a low voltage for a long period of time. I had this issue with my motorcycle, when I found out my battery tender plus! was only charging my AGM batt to 12.6 volts. AGM batteries require a resting voltage of 12.8 volts. Bike sat on the trickle charger all winter, then in the spring, got weak starts and the battery would no longer stay charged. Learned my lesson the hard way. A 0.2 difference in voltage makes a 50% difference in "charge".

https://deepcyclebatterystore.com/how-to-maintain-batteries/

http://www.barryclarkmarine.co.nz/files/BCBG_AGM_12v_v1.pdf

This graph shows approximate battery voltages representing percentage charge for a 12 volt AGM battery. Batteries should not be discharged below half charge or 12.3 volts. Doing so will significantly reduce battery service life. Discharged batteries should be returned to a fully charged state as soon as possible to maximise battery life. Battery life is reduced by deep or prolonged discharge cycles.

 

Wonderful. It was at 11.8. I'm not sure the in-cab voltmeter is all that accurate. But it's not off by .5.

 

I would tell them to give you a new one, personally. Who knows how long it sat at 11.8

 

Much like a man with two watches is never sure what time it is, I never know true voltage.

At home, I tested the battery with two different voltmeters while comparing them to the in-cab reading. In-cab was 12.0. One voltmeter was 12.39, the other 12.52. The in-cab only works with the key in the "on" position, which I think drops the voltage a little bit. So, there's a fair shot that it was above 12.3 real volts when I picked it up. I've got a charger on it now. I'll see what it looks like in the morning.

 

in cab reading will reduce the voltage quickly, yes, since other electronics will be sucking down the power. As far as your voltmeter readings, which one do you trust more? 12.52 resting voltage isn't bad.. 12.39 on the other hand.. not ideal but still okay. Glad you have it on a charger. May be best to have the CCA read, as that may give you a better idea of the battery's condition

 

If it started in the morning when you left for work, and then by lunch time wouldn't start due to being under 10v, your battery is not holding a charge. Even if you left the stereo playing during that time, the battery shouldn't be that dead.

Get a new one under the warranty. If they don't give you a new one, go get a Everready or something.