Car Battery Charge Level Issue

[russ_watters]

TL;DR Summary

My car's battery is not fully charging and/or is discharging significantly while parked. I'm trying to diagnose it.

I drive a 2019 Kia Stinger (purchased in June, 2019) with 22,000 miles on it. It's been having weak battery issues for a while, and I've ignored it but I really shouldn't, so now I'm trying to diagnose it to see if I need a new battery, new alternator or if there is a deeper electrical system issue -- or if I just need to adjust my care.

It has a "silver based battery", which google tells me a calcium-silver lead acid battery. Just a slight twist on a normal lead acid. Nameplate says it is 80 A-hr. I usually drive around 18,000 miles per year, but during COVID it has been down to maybe 6,000 this past year, including stretches where I only drive it a couple of times a week, short distance/time. The car has an auto-stop feature on the engine (the engine stops when the car is stopped), which has activated only rarely in the past year, I would think due to the weak battery. I have occasionally but rarely gotten a battery discharge warning when starting, indicating something is draining the battery while it is off. The only things plugged in all the time that didn't come from the factory are a bluetooth OBD adapter and remote start system.

My theory is that the battery discharges when the car is not in use and then doesn't get charged fully when in use. This weekend though, I drove it 4+ hours/160+ miles in 3 days and the auto-stop feature never engaged. I'd think that should be plenty for a full charge. So when I got home I measured the voltage with a volt-meter, at 12.32V. I then charged it with a quality multi-stage charger at a rate of 20A. Today after taking it off the charger it is at 12.96V. I'll watch it a few days to see how fast it drops.

Not achieving a full charge after several hours of driving implies a potential issue with the alternator, or perhaps the battery isn't accepting a full charge for some reason. But I'm not sure how that could happen.

I'd like to try and measure the discharge rate. I'm thinking of jumpering-in a 1 Ohm resistor and disconnecting the battery so I can measure the draw through the resistor - does that sound reasonable/risky?

Other thoughts on what could be going on here? Thanks.

 

[Lnewqban]

How old is the battery?

 

[hutchphd]

Summary:: My car's battery is not fully charging and/or is discharging significantly while parked. I'm trying to diagnose it.

I'd like to try and measure the discharge rate. I'm thinking of jumpering-in a 1 Ohm resistor and disconnecting the battery so I can measure the draw through the resistor - does that sound reasonable/risky?

You know that the starter motor maybe draws ~100amps will this resistor see that current?
It strikes me that the "auto turn off" is looking at the battery while it is being charged by the engine and failing to see sufficient voltage..If this occurs with a freshly charged battery it seems to indicate a charging system problem. But the system may be smarter than that...don't know.

 

[russ_watters]

You know that the starter motor maybe draws ~100amps will this resistor see that current?

No, I would only be using it to measure the power draw when the ignition is off. At most, I'll measure with the accessories on, but probably not even that. I would hope that while off it draws less than an amp.

It strikes me that the "auto turn off" is looking at the battery while it is being charged by the engine and failing to see sufficient voltage..If this occurs with a freshly charged battery it seems to indicate a charging system problem. But the system may be smarter than that...don't know.

It looks at other things as well, like the HVAC system state and I think engine temp. But I would think mainly it's about the battery voltage.

 

[Borek]

Chances are I am missing something obvious, but I am not sure I get the '1Ω resistor' idea. If you want to just check the current when the ignitions is off, why not to measure the current directly? Meters I have work OK for either 2A current (fused) or 20A (current, no fuse, so can be dangerous for the meter) - and the currents I would expect are in the hundreds mA range.

 

[russ_watters]

Chances are I am missing something obvious, but I am not sure I get the '1Ω resistor' idea. If you want to just check the current when the ignitions is off, why not to measure the current directly? Meters I have work OK for either 2A current (fused) or 20A (current, no fuse, so can be dangerous for the meter) - and the currents I would expect are in the hundreds mA range.

Well, mostly its because the meter I have doesn't do DC Amperage. But also I was thinking I may want to leave it in place for a few days and read the current and voltage periodically, and this way I wouldn't have to repeatedly disconnect and reconnect the battery every time I change what I'm measuring. I suppose this could provide a good excuse to buy a new meter.

 

[Averagesupernova]

Start with a test light in series. If it lights, that's the first clue. If not, a simple dvm set to current will give you what you need to know.

 

[jrmichler]

Auto start/stop and short trips are battery killers. These batteries need to be topped up every week or two with a battery charger. A good computerized battery charger will charge the battery to about 14.8 volts, hold at that voltage for two hours or so, then drop to about a 13.2 volt maintenance charge.

This is a lesson that I learned the hard way after I added manual start/stop to my truck.

 

[russ_watters]

Auto start/stop and short trips are battery killers. These batteries need to be topped up every week or two with a battery charger. A good computerized battery charger will charge the battery to about 14.8 volts, hold at that voltage for two hours or so, then drop to about a 13.2 volt maintenance charge.

This is a lesson that I learned the hard way after I added manual start/stop to my truck.

This is a potential answer I'd considered and am prepared to accept. My battery is a pain to access though so if it comes to that I'll see if I can do a maintenance charge via the cigarette lighter.

 

[Vanadium 50]

I measured the voltage with a volt-meter, at 12.32V.

Too low.

Today after taking it off the charger it is at 12.96V.

A little too low. At best, marginal.

Your battery is almost 3 years old. That's on the early side of needing replacement, but in the last year it's had a hard life. You can probably stretch it out by using a battery tender, but it sounds like it's going sooner rather than later.

You might think about replacing it before it dies.
At midnight.
In the worst part of town.

 

[russ_watters]

A little too low. At best, marginal.

12.76 V now after being off the charger for 4 hours.

Your battery is almost 3 years old. That's on the early side of needing replacement, but in the last year it's had a hard life. You can probably stretch it out by using a battery tender, but it sounds like it's going sooner rather than later.

Almost 2 years, but yes I get that needing replacement may be a possibility. My last car was also a Kia and the OEM battery needed replacement after what I thought was an unreasonably short time as well.

You might think about replacing it before it dies.
At midnight.
In the worst part of town.

I'm not too worried about that since I keep a jumper battery in the trunk, but yeah if I don't figure this out and arrive at a better solution I'll probably get it replaced come winter.

 

[Mark44]

Your battery is almost 3 years old. That's on the early side of needing replacement, but in the last year it's had a hard life.

I get about double that, plus, with my car batteries, but I live in a temperate climate where the temps don't get too extreme either way. I'm told that car batteries in colder climates tend to not last as long. I agree with the auto stop/start being a heavy drain on the battery, especially since you're driving the car only 500 mi/mo.

12.76 V now after being off the charger for 4 hours.

I have a chart on my garage wall. It says that 12.8V for a 12V battery is 75% charged. It's true that trickle chargers take a long time (12 hr or more) to bring a discharged battery up to 100%.

 

[Tom.G]

Here is a DC Clamp-on Ammeter at a decent price:
https://www.amazon.com/dp/B075Z1GH5L/?tag=pfamazon01-20

Not saying it is the 'best' choice, just the first one that met the requirements on Amazon.

There is some info at Battery University:
https://batteryuniversity.com/search/search&keywords=calcium/

Battery University states that:

Calcium, an additive that makes the battery maintenance-free, raises the voltage by 5–8 percent. In addition, heat raises the voltage while cold causes a decrease. Surface charge further fools SoC estimations by showing an elevated voltage immediately after charge; a brief discharge before measurement counteracts the error.

That puts full-charge voltage at 15.3V or greater, note that this is temperature dependent.

You might measure the battery voltage, and current, at fast idle after driving enough to fully charge.

Also measure the charging current immediately after starting, it should be in the 10's of amps.

Another test is leave the engine off and turn on the high-beam headlights. After 10 minutes, measure the Alternator charging current after starting. The current reading for that combination should be close to the Alternator rated current.

Also, many battery shops can do a 'Load Test' of the battery. This consists of a heavy current draw while monitoring the voltage. If there is a 'deep' or 'rapid' drop, the battery is dying/dead, or maybe partially discharged. Of course this depends a lot on the interpretation of the mechanic.

Let us know what you find.

Cheers,
Tom

 

[anorlunda]

A good computerized battery charger will charge the battery to about 14.8 volts, hold at that voltage for two hours or so, then drop to about a 13.2 volt maintenance charge.

That's correct. You're describing the so-called equalizing or de-sulphating cycle.

But it may also be useful to point out that the symptoms of a sulphated lead acid battery is that it appears to charge quickly to full voltage, but it is not really charged. Discharge happens too rapidly too. That sounds like what Russ is seeing.

Sulphation comes by storing the battery at partial charge. That too can result from short trips, followed by parking the car for a long time.

@russ_watters , if you don't have access to a charger with an equalize cycle, a repair shop can usually do it using their charger.

 

[256bits]

I'm not too worried about that since I keep a jumper battery in the trunk, but yeah if I don't figure this out and arrive at a better solution I'll probably get it replaced come winter.

As long as that is charged up every two weeks, at least.
Lead acid batteries loose charge just by sitting around.

Yeah, I had this problem years and years ago when I thought something was draining the battery overnight, as the starting the next morning was non too robust.
After spending needless time checking circuits, end result was a new battery and the problem went away.

FWIW, short trips and many starts put a strain on the charging circuit and battery charge.
Winter, and/or summer, with a lot accessories running - heater, lights, radio, ... and you need say half an hour of good running to get the battery up to full state again. In winter, sometimes I will just sit and rev the engine for 15 minutes after several short trips for battery charging, so it can turn over the engine on a cold morning next.

That again depends upon the charging circuit, and not sure what your car has there - is it an over sized alternator and battery from other cars that do not have the auto stop feature.

 

[Rive]

So when I got home I measured the voltage with a volt-meter, at 12.32V. I then charged it with a quality multi-stage charger at a rate of 20A. Today after taking it off the charger it is at 12.96V.

The voltages looks OK

I would check the charging voltage and also the voltage drop during startup. Seems possible that the car can't charge it full (maybe it's not the right type for this car?). Or something just went wrong.

 

[tech99]

One of the continuous drains on a car battery is the security system, which is a complete nuisance and which cannot be turned off.

 

[anorlunda]

One of the continuous drains on a car battery is the security system, which is a complete nuisance and which cannot be turned off.

No kidding. We had an accident and totaled our Toyota Camry last year (don't worry, no injuries.) I went to the salvage yard to get some personal objects. That dang security system was still active inside that crumpled vehicle. It was like a Terminator that couldn't be killed.

 

[dlgoff]

Summary:: My car's battery is not fully charging and/or is discharging significantly while parked. I'm trying to diagnose it.

I drive a 2019 Kia Stinger (purchased in June, 2019) with 22,000 miles on it. It's been having weak battery issues for a while, and I've ignored it but I really shouldn't, so now I'm trying to diagnose it to see if I need a new battery, new alternator or if there is a deeper electrical system issue -- or if I just need to adjust my care.

It has a "silver based battery", which google tells me a calcium-silver lead acid battery. Just a slight twist on a normal lead acid. Nameplate says it is 80 A-hr. I usually drive around 18,000 miles per year, but during COVID it has been down to maybe 6,000 this past year, including stretches where I only drive it a couple of times a week, short distance/time. The car has an auto-stop feature on the engine (the engine stops when the car is stopped), which has activated only rarely in the past year, I would think due to the weak battery. I have occasionally but rarely gotten a battery discharge warning when starting, indicating something is draining the battery while it is off. The only things plugged in all the time that didn't come from the factory are a bluetooth OBD adapter and remote start system.

My theory is that the battery discharges when the car is not in use and then doesn't get charged fully when in use. This weekend though, I drove it 4+ hours/160+ miles in 3 days and the auto-stop feature never engaged. I'd think that should be plenty for a full charge. So when I got home I measured the voltage with a volt-meter, at 12.32V. I then charged it with a quality multi-stage charger at a rate of 20A. Today after taking it off the charger it is at 12.96V. I'll watch it a few days to see how fast it drops.

Not achieving a full charge after several hours of driving implies a potential issue with the alternator, or perhaps the battery isn't accepting a full charge for some reason. But I'm not sure how that could happen.

I'd like to try and measure the discharge rate. I'm thinking of jumpering-in a 1 Ohm resistor and disconnecting the battery so I can measure the draw through the resistor - does that sound reasonable/risky?

Other thoughts on what could be going on here? Thanks.

Take a peek at my go to place for batteries:
https://batteryuniversity.com/

 

[DaveE]

Maybe not in the DIY spirit, but I would fully charge it, remove it and take it to a shop with a battery tester (a real one, not a guy with a DVM). Most all battery problems show up on a load tester. They'll probably do it for free if they think they can sell you a replacement (go when they're not too busy). You'll either solve your problem or simplify your troubleshooting.

 

[Tom.G]

Some emperical data:

Battery less than 6 months old
5 Hrs after driving: 13.5V
26 Hrs after driving, Temp 63F: 12.2V
after Starting: 11.?V
20 seconds later 14.8V

Conclusion: Yours has one foot in the grave, don't get stuck out in the country at night.

 

[cmb]

Manufacturers have been using poor battery changing algorithms for some time now in a misguided attempt to increase mileage. What happens is modern systems are allowing lead acid batteries to sulfate from 'under-voltage' charging.

Get yourself a good charger that can desulfate and fix the problem yourself. The dealer won't have a clue. Designed by young engineers thinking the technology from the Victorian age will submit to the instructions from the technology of the digital age. A lead acid battery is more akin to a cooking recipe than a logic component, and needs to be treated sympathetically to get the best outcome.

 

[Quester]

The voltages given in this thread are all over the place. It appears some are with the engine running and some are not. There is plenty of information on the internet about charging 12V automobile batteries. Your best bet is to get something very similar to this:

https://www.amazon.com/dp/B01M0ARG3X/?tag=pfamazon01-20

And (carefully following the instructions) use it to monitor your battery. You can test your battery prior to your normal daily driving, then again afterward to determine if your driving is resulting in a lower or higher resultant charge. If you drive less than 1/2 hour at a time on average you are probably slowly killing your battery. Let the meter tell you.

No lead acid automobile battery can produce more than 12.7V open circuit voltage with no load applied. 12.6V is about right for full charge. Measuring the voltage across the battery terminals with the engine running tells you nothing about the state of the battery, only what the charging circuit is delivering under the circumstances. Calcium silver lead acid batteries require a higher charging voltage to charge properly (~14.7V), but, again, let the tester tell you what is going on.

 

[russ_watters]

Little update:

I did get a new multimeter that reads amperage and I found that the draw is about 90 mA. That sounds like a small number, but it multiplies-out to about 20% per week. And at the start of the pandemic I went six weeks on a tank of gas, probably doing about 2 trips a week, never more than a half our on a leg. So it was a rough spring and summer last year for it.

I've done a few charge cycles with a charger that does desulfation:
https://www.amazon.com/dp/B00LHVVFXM/?tag=pfamazon01-20

The cycle is quick though so I'm not sure how much it really does. The initial voltage after charge is still about 13V. I'll probably do some periodic re-charges throughout the summer and see how it goes, but as I said I'll likely replace it before winter.

 

[Averagesupernova]

90 mA isn't insignificant for something that isn't started and run every day. Wonder what's drawing that? I'd pull fuses and see where it's going.

 

[DaveE]

90 mA isn't insignificant for something that isn't started and run every day. Wonder what's drawing that? I'd pull fuses and see where it's going.

My 30 year old pick up truck will often sit neglected for a few months. After I'd killed 2 or 3 batteries, I installed a trickle charger under the hood and leave it plugged it.

Still, unplugged, it will drain the battery in just a week or two, so this quiescent current is something I've been meaning to look into for a few years now. Maybe I'll do it right now...

Does anyone have any idea what is a reasonable value for a 1990 Toyota pickup? Likely suspects (beside the clock with an always on EL display)?

edit: It just occurred to me the trickle charger itself may be a problem.

edit: Charger = 760uA, Truck = 120mA. This would discharge 100AHr in about 35 days. Is this normal for an old truck?

 

[russ_watters]

90 mA isn't insignificant for something that isn't started and run every day. Wonder what's drawing that? I'd pull fuses and see where it's going.

It's a lot for a giant paperweight, but it isn't much for several computers. It wasn't a number that shocked me.

 

[russ_watters]

Probably irrelevant to a 30 year old pickup, but the internet told me if the key fob is too close it might be able to have a continuous conversation with the car. The internet also sells Faraday pouches to eliminate this issue.

 

[DaveE]

Probably irrelevant to a 30 year old pickup, but the internet told me if the key fob is too close it might be able to have a continuous conversation with the car. The internet also sells Faraday pouches to eliminate this issue.

Key fob? LOL.